1
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Kranzler M, Walser V, Stark TD, Ehling-Schulz M. A poisonous cocktail: interplay of cereulide toxin and its structural isomers in emetic Bacillus cereus. Front Cell Infect Microbiol 2024; 14:1337952. [PMID: 38596651 PMCID: PMC11002159 DOI: 10.3389/fcimb.2024.1337952] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Accepted: 03/11/2024] [Indexed: 04/11/2024] Open
Abstract
Food intoxications evoked by emetic Bacillus cereus strains constitute a serious threat to public health, leading to emesis and severe organ failure. The emetic peptide toxin cereulide, assembled by the non-ribosomal peptide synthetase CesNRPS, cannot be eradicated from contaminated food by usual hygienic measures due to its molecular size and structural stability. Next to cereulide, diverse chemical variants have been described recently that are produced concurrently with cereulide by CesNRPS. However, the contribution of these isocereulides to the actual toxicity of emetic B. cereus, which produces a cocktail of these toxins in a certain ratio, is still elusive. Since cereulide isoforms have already been detected in food remnants from foodborne outbreaks, we aimed to gain insights into the composition of isocereulides and their impact on the overall toxicity of emetic B. cereus. The amounts and ratios of cereulide and isocereulides were determined in B. cereus grown under standard laboratory conditions and in a contaminated sample of fried rice balls responsible for one of the most severe food outbreaks caused by emetic B. cereus in recent years. The ratios of variants were determined as robust, produced either under laboratory or natural, food-poisoning conditions. Examination of their actual toxicity in human epithelial HEp2-cells revealed that isocereulides A-N, although accounting for only 10% of the total cereulide toxins, were responsible for about 40% of the total cytotoxicity. An this despite the fact that some of the isocereulides were less cytotoxic than cereulide when tested individually for cytotoxicity. To estimate the additive, synergistic or antagonistic effects of the single variants, each cereulide variant was mixed with cereulide in a 1:9 and 1:1 binary blend, respectively, and tested on human cells. The results showed additive and synergistic impacts of single variants, highlighting the importance of including not only cereulide but also the isocereulides in routine food and clinical diagnostics to achieve a realistic toxicity evaluation of emetic B. cereus in contaminated food as well as in patient samples linked to foodborne outbreaks. Since the individual isoforms confer different cell toxicity both alone and in association with cereulide, further investigations are needed to fully understand their cocktail effect.
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Affiliation(s)
- Markus Kranzler
- Institute of Microbiology, Department of Pathobiology, University of Veterinary Medicine, Vienna, Austria
| | - Veronika Walser
- Food Chemistry and Molecular and Sensory Science, Technical University of Munich, Freising, Germany
| | - Timo D. Stark
- Food Chemistry and Molecular and Sensory Science, Technical University of Munich, Freising, Germany
| | - Monika Ehling-Schulz
- Institute of Microbiology, Department of Pathobiology, University of Veterinary Medicine, Vienna, Austria
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2
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Bacillus cereus Toxin Repertoire: Diversity of (Iso)cereulide(s). MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27030872. [PMID: 35164132 PMCID: PMC8840689 DOI: 10.3390/molecules27030872] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 01/14/2022] [Accepted: 01/19/2022] [Indexed: 11/17/2022]
Abstract
The emetic Bacillus cereus toxin cereulide (1) poses a significant safety risk in the food industry, causing emesis and nausea after consumption of contaminated foods. Analogously to cereulide, the structures of various isocereulides, namely, isocereulides A–G, have been recently reported and could also be identified in B. cereus-contaminated food samples. The HPLC fractionation of B. cereus extracts allows us to isolate additional isocereulides. By applying MSn sequencing, post-hydrolytic dipeptide, amino acid and α-hydroxy acid analyses using UPLC-ESI-TOF-MS to purify the analytes, seven new isocereulides H–N (2–8) could be elucidated in their chemical structures. The structure elucidation was supported by one-dimensional and two-dimensional NMR spectra of the isocereulides H (2), K (5), L and N (6 + 8) and M (7). The toxicity of 2–8 was investigated in a HEp-2 cell assay to determine their respective 50% effective concentration (EC50). Thus, 2–8 exhibited EC50 values ranging from a 0.4- to 1.4-fold value compared to cereulide (1). Missing structure-activity correlations indicate the necessity to determine the toxic potential of all naturally present isocereulides as single compounds to be able to perform a thorough toxicity evaluation of B. cereus-contaminated foods in the future.
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3
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Fayad N, Koné KM, Gillis A, Mahillon J. Bacillus cytotoxicus Genomics: Chromosomal Diversity and Plasmidome Versatility. Front Microbiol 2021; 12:789929. [PMID: 34992589 PMCID: PMC8725734 DOI: 10.3389/fmicb.2021.789929] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Accepted: 11/17/2021] [Indexed: 11/16/2022] Open
Abstract
Bacillus cytotoxicus is the thermotolerant representative of the Bacillus cereus group. This group, also known as B. cereus sensu lato, comprises both beneficial and pathogenic members and includes psychrotolerant and thermotolerant species. Bacillus cytotoxicus was originally recovered from a fatal outbreak in France in 1998. This species forms a remote cluster from the B. cereus group members and reliably contains the cytk-1 gene, coding for a cytotoxic variant of cytotoxin K. Although this species was originally thought to be homogenous, intra-species diversity has been recently described with four clades, six random amplified polymorphic DNA (RAPD) patterns, and 11 plasmids profiles. This study aimed to get new insights into the genomic diversity of B. cytotoxicus and to decipher the underlying chromosomal and plasmidial variations among six representative isolates through whole genome sequencing (WGS). Among the six sequenced strains, four fitted the previously described genomic clades A and D, while the remaining two constituted new distinct branches. As for the plasmid content of these strains, three large plasmids were putatively conjugative and three small ones potentially mobilizable, harboring coding genes for putative leaderless bacteriocins. Mobile genetic elements, such as prophages, Insertion Sequences (IS), and Bacillus cereus repeats (bcr) greatly contributed to the B. cytotoxicus diversity. As for IS elements and bcr, IS3 and bcr1 were the most abundant elements and, along with the group II intron B.c.I8, were found in all analyzed B. cytotoxicus strains. When compared to other B. cytotoxicus strains, the type-strain NVH 391-98 displayed a relatively low number of IS. Our results shed new light on the contribution of mobile genetic elements to the genome plasticity of B. cytotoxicus and their potential role in horizontal gene transfer.
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Affiliation(s)
- Nancy Fayad
- Laboratory of Food and Environmental Microbiology, Earth and Life Institute, Louvain-la-Neuve, Belgium
- School of Pharmacy, Lebanese American University, Byblos, Lebanon
| | - Klèma Marcel Koné
- Laboratory of Food and Environmental Microbiology, Earth and Life Institute, Louvain-la-Neuve, Belgium
| | - Annika Gillis
- Laboratory of Food and Environmental Microbiology, Earth and Life Institute, Louvain-la-Neuve, Belgium
| | - Jacques Mahillon
- Laboratory of Food and Environmental Microbiology, Earth and Life Institute, Louvain-la-Neuve, Belgium
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4
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Antequera‐Gómez ML, Díaz‐Martínez L, Guadix JA, Sánchez‐Tévar AM, Sopeña‐Torres S, Hierrezuelo J, Doan HK, Leveau JH, de Vicente A, Romero D. Sporulation is dispensable for the vegetable-associated life cycle of the human pathogen Bacillus cereus. Microb Biotechnol 2021; 14:1550-1565. [PMID: 33955675 PMCID: PMC8313275 DOI: 10.1111/1751-7915.13816] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 03/18/2021] [Accepted: 04/03/2021] [Indexed: 11/28/2022] Open
Abstract
Bacillus cereus is a common food-borne pathogen that is responsible for important outbreaks of food poisoning in humans. Diseases caused by B. cereus usually exhibit two major symptoms, emetic or diarrheic, depending on the toxins produced. It is assumed that after the ingestion of contaminated vegetables or processed food, spores of enterotoxigenic B. cereus reach the intestine, where they germinate and produce the enterotoxins that are responsible for food poisoning. In our study, we observed that sporulation is required for the survival of B. cereus in leaves but is dispensable in ready-to-eat vegetables, such as endives. We demonstrate that vegetative cells of B. cereus that are originally impaired in sporulation but not biofilm formation are able to reach the intestine and cause severe disorders in a murine model. Furthermore, our findings emphasise that the number of food poisoning cases associated with B. cereus is underestimated and suggest the need to revise the detection protocols, which are based primarily on spores and toxins.
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Affiliation(s)
- María Luisa Antequera‐Gómez
- Departamento de MicrobiologíaInstituto de Hortofruticultura Subtropical y Mediterránea "La Mayora"Universidad de Málaga‐Consejo Superior de Investigaciones Científicas (IHSM‐UMA‐CSIC)Universidad de MálagaBulevar Louis Pasteur 31 (Campus Universitario de teatinos)Málaga29071Spain
| | - Luis Díaz‐Martínez
- Departamento de MicrobiologíaInstituto de Hortofruticultura Subtropical y Mediterránea "La Mayora"Universidad de Málaga‐Consejo Superior de Investigaciones Científicas (IHSM‐UMA‐CSIC)Universidad de MálagaBulevar Louis Pasteur 31 (Campus Universitario de teatinos)Málaga29071Spain
| | - Juan Antonio Guadix
- Departamento de Biología AnimalFacultad de CienciasUniversidad de Málaga ‐ IBIMACampus de Teatinos s/nMálaga29071Spain
- Centro Andaluz de Nanomedicina y Biotecnología (BIONAND)Junta de AndalucíaUniversidad de MálagaC/ Severo Ochoa 35Campanillas (Málaga)29590Spain
| | - Ana María Sánchez‐Tévar
- Departamento de Biología AnimalFacultad de CienciasUniversidad de Málaga ‐ IBIMACampus de Teatinos s/nMálaga29071Spain
- Centro Andaluz de Nanomedicina y Biotecnología (BIONAND)Junta de AndalucíaUniversidad de MálagaC/ Severo Ochoa 35Campanillas (Málaga)29590Spain
| | - Sara Sopeña‐Torres
- Departamento de MicrobiologíaInstituto de Hortofruticultura Subtropical y Mediterránea "La Mayora"Universidad de Málaga‐Consejo Superior de Investigaciones Científicas (IHSM‐UMA‐CSIC)Universidad de MálagaBulevar Louis Pasteur 31 (Campus Universitario de teatinos)Málaga29071Spain
| | - Jesús Hierrezuelo
- Departamento de MicrobiologíaInstituto de Hortofruticultura Subtropical y Mediterránea "La Mayora"Universidad de Málaga‐Consejo Superior de Investigaciones Científicas (IHSM‐UMA‐CSIC)Universidad de MálagaBulevar Louis Pasteur 31 (Campus Universitario de teatinos)Málaga29071Spain
| | - Hung K. Doan
- Department of Plant PathologyUniversity of CaliforniaDavisCAUSA
| | | | - Antonio de Vicente
- Departamento de MicrobiologíaInstituto de Hortofruticultura Subtropical y Mediterránea "La Mayora"Universidad de Málaga‐Consejo Superior de Investigaciones Científicas (IHSM‐UMA‐CSIC)Universidad de MálagaBulevar Louis Pasteur 31 (Campus Universitario de teatinos)Málaga29071Spain
| | - Diego Romero
- Departamento de MicrobiologíaInstituto de Hortofruticultura Subtropical y Mediterránea "La Mayora"Universidad de Málaga‐Consejo Superior de Investigaciones Científicas (IHSM‐UMA‐CSIC)Universidad de MálagaBulevar Louis Pasteur 31 (Campus Universitario de teatinos)Málaga29071Spain
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5
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Zhong W, Shahbaz O, Teskey G, Beever A, Kachour N, Venketaraman V, Darmani NA. Mechanisms of Nausea and Vomiting: Current Knowledge and Recent Advances in Intracellular Emetic Signaling Systems. Int J Mol Sci 2021; 22:5797. [PMID: 34071460 PMCID: PMC8198651 DOI: 10.3390/ijms22115797] [Citation(s) in RCA: 57] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 05/20/2021] [Accepted: 05/21/2021] [Indexed: 02/07/2023] Open
Abstract
Nausea and vomiting are common gastrointestinal complaints that can be triggered by diverse emetic stimuli through central and/or peripheral nervous systems. Both nausea and vomiting are considered as defense mechanisms when threatening toxins/drugs/bacteria/viruses/fungi enter the body either via the enteral (e.g., the gastrointestinal tract) or parenteral routes, including the blood, skin, and respiratory systems. While vomiting is the act of forceful removal of gastrointestinal contents, nausea is believed to be a subjective sensation that is more difficult to study in nonhuman species. In this review, the authors discuss the anatomical structures, neurotransmitters/mediators, and corresponding receptors, as well as intracellular emetic signaling pathways involved in the processes of nausea and vomiting in diverse animal models as well as humans. While blockade of emetic receptors in the prevention of vomiting is fairly well understood, the potential of new classes of antiemetics altering postreceptor signal transduction mechanisms is currently evolving, which is also reviewed. Finally, future directions within the field will be discussed in terms of important questions that remain to be resolved and advances in technology that may help provide potential answers.
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Affiliation(s)
- Weixia Zhong
- Department of Basic Medical Sciences, College of Osteopathic Medicine of the Pacific, Western University of Health Sciences, 309 East Second Street, Pomona, CA 91766, USA; (W.Z.); (G.T.); (V.V.)
| | - Omar Shahbaz
- School of Medicine, Universidad Iberoamericana, Av. Francia 129, Santo Domingo 10203, Dominican Republic;
| | - Garrett Teskey
- Department of Basic Medical Sciences, College of Osteopathic Medicine of the Pacific, Western University of Health Sciences, 309 East Second Street, Pomona, CA 91766, USA; (W.Z.); (G.T.); (V.V.)
| | - Abrianna Beever
- Graduate College of Biomedical Sciences, Western University of Health Sciences, Pomona, CA 91766, USA; (A.B.); (N.K.)
| | - Nala Kachour
- Graduate College of Biomedical Sciences, Western University of Health Sciences, Pomona, CA 91766, USA; (A.B.); (N.K.)
| | - Vishwanath Venketaraman
- Department of Basic Medical Sciences, College of Osteopathic Medicine of the Pacific, Western University of Health Sciences, 309 East Second Street, Pomona, CA 91766, USA; (W.Z.); (G.T.); (V.V.)
- Graduate College of Biomedical Sciences, Western University of Health Sciences, Pomona, CA 91766, USA; (A.B.); (N.K.)
| | - Nissar A. Darmani
- Department of Basic Medical Sciences, College of Osteopathic Medicine of the Pacific, Western University of Health Sciences, 309 East Second Street, Pomona, CA 91766, USA; (W.Z.); (G.T.); (V.V.)
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6
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Adrover-Castellano ML, Schmidt JJ, Sherman DH. Biosynthetic Cyclization Catalysts for the Assembly of Peptide and Polyketide Natural Products. ChemCatChem 2021; 13:2095-2116. [PMID: 34335987 PMCID: PMC8320681 DOI: 10.1002/cctc.202001886] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Indexed: 12/13/2022]
Abstract
Many biologically active natural products are synthesized by nonribosomal peptide synthetases (NRPSs), polyketide synthases (PKSs) and their hybrids. These megasynthetases contain modules possessing distinct catalytic domains that allow for substrate initiation, chain extension, processing and termination. At the end of a module, a terminal domain, usually a thioesterase (TE), is responsible for catalyzing the release of the NRPS or PKS as a linear or cyclized product. In this review, we address the general cyclization mechanism of the TE domain, including oligomerization and the fungal C-C bond forming Claisen-like cyclases (CLCs). Additionally, we include examples of cyclization catalysts acting within or at the end of a module. Furthermore, condensation-like (CT) domains, terminal reductase (R) domains, reductase-like domains that catalyze Dieckmann condensation (RD), thioesterase-like Dieckmann cyclases, trans-acting TEs from the penicillin binding protein (PBP) enzyme family, product template (PT) domains and others will also be reviewed. The studies summarized here highlight the remarkable diversity of NRPS and PKS cyclization catalysts for the production of biologically relevant, complex cyclic natural products and related compounds.
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Affiliation(s)
| | - Jennifer J Schmidt
- Life Sciences Institute, University of Michigan, 210 Washtenaw Avenue, Ann Arbor, MI 48109-2216 (USA)
| | - David H Sherman
- Life Sciences Institute, University of Michigan, 210 Washtenaw Avenue, Ann Arbor, MI 48109-2216 (USA)
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7
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Bacillus cereus Toxins. Toxins (Basel) 2021; 13:toxins13050295. [PMID: 33919248 PMCID: PMC8143130 DOI: 10.3390/toxins13050295] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Accepted: 04/18/2021] [Indexed: 11/20/2022] Open
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8
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Spears JL, Kramer R, Nikiforov AI, Rihner MO, Lambert EA. Safety Assessment of Bacillus subtilis MB40 for Use in Foods and Dietary Supplements. Nutrients 2021; 13:nu13030733. [PMID: 33668992 PMCID: PMC7996492 DOI: 10.3390/nu13030733] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 02/16/2021] [Accepted: 02/18/2021] [Indexed: 12/31/2022] Open
Abstract
With the growing popularity of probiotics in dietary supplements, foods, and beverages, it is important to substantiate not only the health benefits and efficacy of unique strains but also safety. In the interest of consumer safety and product transparency, strain identification should include whole-genome sequencing and safety assessment should include genotypic and phenotypic studies. Bacillus subtilis MB40, a unique strain marketed for use in dietary supplements, and food and beverage, was assessed for safety and tolerability across in silico, in vitro, and in vivo studies. MB40 was assessed for the absence of undesirable genetic elements encoding toxins and mobile antibiotic resistance. Tolerability was assessed in both rats and healthy human volunteers. In silico and in vitro testing confirmed the absence of enterotoxin and mobile antibiotic resistance genes of safety concern to humans. In rats, the no-observed-adverse-effect level (NOAEL) for MB40 after repeated oral administration for 14 days was determined to be 2000 mg/kg bw/day (equivalent to 3.7 × 1011 CFU/kg bw/day). In a 28 day human tolerability trial, 10 × 109 CFU/day of MB40 was well tolerated. Based on genome sequencing, strain characterization, screening for undesirable attributes and evidence of safety by appropriately designed safety evaluation studies in rats and humans, Bacillus subtilis MB40 does not pose any human health concerns under the conditions tested.
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Affiliation(s)
| | | | - Andrey I. Nikiforov
- Toxicology Regulatory Services, Charlottesville, VA 22911, USA; (A.I.N.); (M.O.R.)
| | - Marisa O. Rihner
- Toxicology Regulatory Services, Charlottesville, VA 22911, USA; (A.I.N.); (M.O.R.)
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9
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Bonis M, Felten A, Pairaud S, Dijoux A, Maladen V, Mallet L, Radomski N, Duboisset A, Arar C, Sarda X, Vial G, Mistou MY, Firmesse O, Hennekinne JA, Herbin S. Comparative phenotypic, genotypic and genomic analyses of Bacillus thuringiensis associated with foodborne outbreaks in France. PLoS One 2021; 16:e0246885. [PMID: 33607651 PMCID: PMC7895547 DOI: 10.1371/journal.pone.0246885] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Accepted: 01/28/2021] [Indexed: 11/18/2022] Open
Abstract
Bacillus thuringiensis (Bt) belongs to the Bacillus cereus (Bc) group, well known as an etiological agent of foodborne outbreaks (FBOs). Bt distinguishes itself from other Bc by its ability to synthesize insecticidal crystals. However, the search for these crystals is not routinely performed in food safety or clinical investigation, and the actual involvement of Bt in the occurrence of FBOs is not known. In the present study, we reveal that Bt was detected in the context of 49 FBOs declared in France between 2007 and 2017. In 19 of these FBOs, Bt was the only microorganism detected, making it the most likely causal agent. Searching for its putative origin of contamination, we noticed that more than 50% of Bt isolates were collected from dishes containing raw vegetables, in particular tomatoes (48%). Moreover, the genomic characterization of isolates showed that most FBO-associated Bt isolates exhibited a quantified genomic proximity to Bt strains, used as biopesticides, especially those from subspecies aizawai and kurstaki. Taken together, these results strengthen the hypothesis of an agricultural origin for the Bt contamination and call for further investigations on Bt pesticides.
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Affiliation(s)
- Mathilde Bonis
- Laboratory for Food Safety, French Agency for Food, Environmental and Occupational Health & Safety (ANSES), Université Paris-Est, Maisons-Alfort, France
| | - Arnaud Felten
- Laboratory for Food Safety, French Agency for Food, Environmental and Occupational Health & Safety (ANSES), Université Paris-Est, Maisons-Alfort, France
| | - Sylvie Pairaud
- Laboratory for Food Safety, French Agency for Food, Environmental and Occupational Health & Safety (ANSES), Université Paris-Est, Maisons-Alfort, France
| | - Angélie Dijoux
- Laboratory for Food Safety, French Agency for Food, Environmental and Occupational Health & Safety (ANSES), Université Paris-Est, Maisons-Alfort, France
| | - Véronique Maladen
- Laboratory for Food Safety, French Agency for Food, Environmental and Occupational Health & Safety (ANSES), Université Paris-Est, Maisons-Alfort, France
| | - Ludovic Mallet
- Laboratory for Food Safety, French Agency for Food, Environmental and Occupational Health & Safety (ANSES), Université Paris-Est, Maisons-Alfort, France
| | - Nicolas Radomski
- Laboratory for Food Safety, French Agency for Food, Environmental and Occupational Health & Safety (ANSES), Université Paris-Est, Maisons-Alfort, France
| | - Arnaud Duboisset
- Regulated Products Assessment Department, French Agency for Food, Environmental and Occupational Health & Safety (ANSES), Université Paris-Est, Maisons-Alfort, France
| | - Chantal Arar
- Regulated Products Assessment Department, French Agency for Food, Environmental and Occupational Health & Safety (ANSES), Université Paris-Est, Maisons-Alfort, France
| | - Xavier Sarda
- Regulated Products Assessment Department, French Agency for Food, Environmental and Occupational Health & Safety (ANSES), Université Paris-Est, Maisons-Alfort, France
| | - Gaelle Vial
- Regulated Products Assessment Department, French Agency for Food, Environmental and Occupational Health & Safety (ANSES), Université Paris-Est, Maisons-Alfort, France
| | - Michel-Yves Mistou
- Laboratory for Food Safety, French Agency for Food, Environmental and Occupational Health & Safety (ANSES), Université Paris-Est, Maisons-Alfort, France
| | - Olivier Firmesse
- Laboratory for Food Safety, French Agency for Food, Environmental and Occupational Health & Safety (ANSES), Université Paris-Est, Maisons-Alfort, France
- * E-mail:
| | - Jacques-Antoine Hennekinne
- Laboratory for Food Safety, French Agency for Food, Environmental and Occupational Health & Safety (ANSES), Université Paris-Est, Maisons-Alfort, France
| | - Sabine Herbin
- Laboratory for Food Safety, French Agency for Food, Environmental and Occupational Health & Safety (ANSES), Université Paris-Est, Maisons-Alfort, France
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10
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Barbieri G, Ferrari C, Mamberti S, Gabrieli P, Castelli M, Sassera D, Ursino E, Scoffone VC, Radaelli G, Clementi E, Sacchi L, Ferrari E, Gasperi G, Albertini AM. Identification of a Novel Brevibacillus laterosporus Strain With Insecticidal Activity Against Aedes albopictus Larvae. Front Microbiol 2021; 12:624014. [PMID: 33679643 PMCID: PMC7925996 DOI: 10.3389/fmicb.2021.624014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 01/19/2021] [Indexed: 11/13/2022] Open
Abstract
Bacterial species able to produce proteins that are toxic against insects have been discovered at the beginning of the last century. However, up to date only two of them have been used as pesticides in mosquito control strategies targeting larval breeding sites: Bacillus thuringensis var. israelensis and Lysinibacillus sphaericus. Aiming to expand the arsenal of biopesticides, bacterial cultures from 44 soil samples were assayed for their ability to kill larvae of Aedes albopictus. A method to select, grow and test the larvicidal capability of spore-forming bacteria from each soil sample was developed. This allowed identifying 13 soil samples containing strains capable of killing Ae. albopictus larvae. Among the active isolates, one strain with high toxicity was identified as Brevibacillus laterosporus by 16S rRNA gene sequencing and by morphological characterization using transmission electron microscopy. The new isolate showed a larvicidal activity significantly higher than the B. laterosporus LMG 15441 reference strain. Its genome was phylogenomically characterized and compared to the available Brevibacillus genomes. Thus, the new isolate can be considered as a candidate adjuvant to biopesticides formulations that would help preventing the insurgence of resistance.
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Affiliation(s)
- Giulia Barbieri
- Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, Pavia, Italy
| | - Carolina Ferrari
- Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, Pavia, Italy
| | - Stefania Mamberti
- Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, Pavia, Italy
| | - Paolo Gabrieli
- Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, Pavia, Italy.,Department of Biosciences, University of Milan, Milan, Italy
| | - Michele Castelli
- Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, Pavia, Italy
| | - Davide Sassera
- Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, Pavia, Italy
| | - Emanuela Ursino
- Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, Pavia, Italy
| | - Viola Camilla Scoffone
- Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, Pavia, Italy
| | - Giacomo Radaelli
- Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, Pavia, Italy
| | - Emanuela Clementi
- Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, Pavia, Italy
| | - Luciano Sacchi
- Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, Pavia, Italy
| | - Eugenio Ferrari
- Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, Pavia, Italy
| | - Giuliano Gasperi
- Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, Pavia, Italy
| | - Alessandra M Albertini
- Department of Biology and Biotechnology "Lazzaro Spallanzani", University of Pavia, Pavia, Italy
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11
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Ellouze M, Buss Da Silva N, Rouzeau-Szynalski K, Coisne L, Cantergiani F, Baranyi J. Modeling Bacillus cereus Growth and Cereulide Formation in Cereal-, Dairy-, Meat-, Vegetable-Based Food and Culture Medium. Front Microbiol 2021; 12:639546. [PMID: 33679675 PMCID: PMC7925994 DOI: 10.3389/fmicb.2021.639546] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Accepted: 01/18/2021] [Indexed: 11/24/2022] Open
Abstract
This study describes the simultaneous Bacillus cereus growth and cereulide formation, in culture medium and cereal-, dairy-, meat-, and vegetable-based food matrices. First, bacterial growth experiments were carried out under a wide range of temperatures (from 9 to 45°C), using the emetic reference strain F4810/72, in the above-mentioned matrices. Then, the generated data were put in a modeling framework where the response variable was a vector of two components: the concentration of B. cereus and that of its toxin, cereulide. Both were considered time-, temperature- and matrix-dependent. The modeling was carried out in a series of steps: the parameters fitted in one step became the response variable of the following step. Using the square root link function, the maximum specific growth rate of the organism and the time to the appearance of quantifiable cereulide were modeled against temperature by cardinal parameters models (CPM), for each matrix. Finally, a validation study was carried out on an independent data set obtained in the same matrices and using various Bacillus cereus strains. Results showed that both growth and toxin-formation depended on the food matrix and on the environment but not in the same way. Thus, the matrix (culture medium), where the highest growth rate of B. cereus was observed, was not the medium where the shortest time to quantifiable cereulide occurred. While the cereal-based matrix generated the smallest growth rates (0.41-times smaller than culture medium did), quantifiable cereulide appeared in it at earlier times compared to the other tested matrices. In fact, three groups of matrices could be distinguished based on their ability to support cereulide formation (1) the cereal-based matrix (highest), (2) the culture medium and the dairy-based matrix (intermediate), and (3) the meat- and vegetable-based matrices (lowest). This ranking between the matrices is quite different from that based on their suitability to the growth of the organism. Our models can be used in HACCP studies, to improve shelf-life predictions and, generally, microbiological food safety assessments of products for which B. cereus is the main concern.
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Affiliation(s)
- Mariem Ellouze
- Food Safety Microbiology, Food Safety Research Department, Institute of Food Safety and Analytical Sciences, Nestlé Research, Lausanne, Switzerland
| | - Nathália Buss Da Silva
- Laboratory of Food Microbiology, Wageningen University & Research, Wageningen, Netherlands
| | - Katia Rouzeau-Szynalski
- Food Safety Microbiology, Food Safety Research Department, Institute of Food Safety and Analytical Sciences, Nestlé Research, Lausanne, Switzerland
| | - Laura Coisne
- Food Safety Microbiology, Food Safety Research Department, Institute of Food Safety and Analytical Sciences, Nestlé Research, Lausanne, Switzerland
| | - Frédérique Cantergiani
- Food Safety Microbiology, Food Safety Research Department, Institute of Food Safety and Analytical Sciences, Nestlé Research, Lausanne, Switzerland
| | - József Baranyi
- Institute of Nutrition, University of Debrecen, Debrecen, Hungary
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12
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Kalbhenn EM, Bauer T, Stark TD, Knüpfer M, Grass G, Ehling-Schulz M. Detection and Isolation of Emetic Bacillus cereus Toxin Cereulide by Reversed Phase Chromatography. Toxins (Basel) 2021; 13:toxins13020115. [PMID: 33557428 PMCID: PMC7915282 DOI: 10.3390/toxins13020115] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 01/30/2021] [Accepted: 02/01/2021] [Indexed: 12/17/2022] Open
Abstract
The emetic toxin cereulide is a 1.2 kDa dodecadepsipeptide produced by the food pathogen Bacillus cereus. As cereulide poses a serious health risk to humans, sensitive and specific detection, as well as toxin purification and quantification, methods are of utmost importance. Recently, a stable isotope dilution assay tandem mass spectrometry (SIDA–MS/MS)-based method has been described, and an method for the quantitation of cereulide in foods was established by the International Organization for Standardization (ISO). However, although this SIDA–MS/MS method is highly accurate, the sophisticated high-end MS equipment required for such measurements limits the method’s suitability for microbiological and molecular research. Thus, we aimed to develop a method for cereulide toxin detection and isolation using equipment commonly available in microbiological and biochemical research laboratories. Reproducible detection and relative quantification of cereulide was achieved, employing reversed phase chromatography (RPC). Chromatographic signals were cross validated by ultraperformance liquid chromatography–mass spectrometry (UPLC–MS/MS). The specificity of the RPC method was tested using a test panel of strains that included non-emetic representatives of the B. cereus group, emetic B. cereus strains, and cereulide-deficient isogenic mutants. In summary, the new method represents a robust, economical, and easily accessible research tool that complements existing diagnostics for the detection and quantification of cereulide.
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Affiliation(s)
- Eva Maria Kalbhenn
- Functional Microbiology, Institute of Microbiology, Department of Pathobiology, University of Veterinary Medicine Vienna, 1210 Vienna, Austria; (E.M.K.); (T.B.)
| | - Tobias Bauer
- Functional Microbiology, Institute of Microbiology, Department of Pathobiology, University of Veterinary Medicine Vienna, 1210 Vienna, Austria; (E.M.K.); (T.B.)
| | - Timo D. Stark
- Chair of Food Chemistry and Molecular Sensory Science, Technical University of Munich, Lise-Meitner-Straße 34, 85354 Freising, Germany;
| | - Mandy Knüpfer
- Bundeswehr Institute of Microbiology, Neuherbergstraße 11, 80937 Munich, Germany; (M.K.); (G.G.)
| | - Gregor Grass
- Bundeswehr Institute of Microbiology, Neuherbergstraße 11, 80937 Munich, Germany; (M.K.); (G.G.)
| | - Monika Ehling-Schulz
- Functional Microbiology, Institute of Microbiology, Department of Pathobiology, University of Veterinary Medicine Vienna, 1210 Vienna, Austria; (E.M.K.); (T.B.)
- Correspondence:
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13
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Risk of Bacillus cereus in Relation to Rice and Derivatives. Foods 2021; 10:foods10020302. [PMID: 33540849 PMCID: PMC7913059 DOI: 10.3390/foods10020302] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 01/19/2021] [Accepted: 01/26/2021] [Indexed: 11/18/2022] Open
Abstract
Rice is a very popular food throughout the world and the basis of the diet of the citizens of many countries. It is used as a raw material for the preparation of many complex dishes in which different ingredients are involved. Rice, as a consequence of their cultivation, harvesting, and handling, is often contaminated with spores of Bacillus cereus, a ubiquitous microorganism found mainly in the soil. B. cereus can multiply under temperature conditions as low as 4 °C in foods that contain rice and have been cooked or subjected to treatments that do not produce commercial sterility. B. cereus produces diarrhoeal or emetic foodborne toxin when the consumer eats food in which a sufficient number of cells have grown. These circumstances mean that every year many outbreaks of intoxication or intestinal problems related to this microorganism are reported. This work is a review from the perspective of risk assessment of the risk posed by B. cereus to the health of consumers and of some control measures that can be used to mitigate such a risk.
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14
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The Food Poisoning Toxins of Bacillus cereus. Toxins (Basel) 2021; 13:toxins13020098. [PMID: 33525722 PMCID: PMC7911051 DOI: 10.3390/toxins13020098] [Citation(s) in RCA: 113] [Impact Index Per Article: 37.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 01/14/2021] [Accepted: 01/25/2021] [Indexed: 12/13/2022] Open
Abstract
Bacillus cereus is a ubiquitous soil bacterium responsible for two types of food-associated gastrointestinal diseases. While the emetic type, a food intoxication, manifests in nausea and vomiting, food infections with enteropathogenic strains cause diarrhea and abdominal pain. Causative toxins are the cyclic dodecadepsipeptide cereulide, and the proteinaceous enterotoxins hemolysin BL (Hbl), nonhemolytic enterotoxin (Nhe) and cytotoxin K (CytK), respectively. This review covers the current knowledge on distribution and genetic organization of the toxin genes, as well as mechanisms of enterotoxin gene regulation and toxin secretion. In this context, the exceptionally high variability of toxin production between single strains is highlighted. In addition, the mode of action of the pore-forming enterotoxins and their effect on target cells is described in detail. The main focus of this review are the two tripartite enterotoxin complexes Hbl and Nhe, but the latest findings on cereulide and CytK are also presented, as well as methods for toxin detection, and the contribution of further putative virulence factors to the diarrheal disease.
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15
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Jessberger N, Dietrich R, Granum PE, Märtlbauer E. The Bacillus cereus Food Infection as Multifactorial Process. Toxins (Basel) 2020; 12:E701. [PMID: 33167492 PMCID: PMC7694497 DOI: 10.3390/toxins12110701] [Citation(s) in RCA: 61] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Revised: 10/30/2020] [Accepted: 11/02/2020] [Indexed: 02/06/2023] Open
Abstract
The ubiquitous soil bacterium Bacillus cereus presents major challenges to food safety. It is responsible for two types of food poisoning, the emetic form due to food intoxication and the diarrheal form emerging from food infections with enteropathogenic strains, also known as toxico-infections, which are the subject of this review. The diarrheal type of food poisoning emerges after production of enterotoxins by viable bacteria in the human intestine. Basically, the manifestation of the disease is, however, the result of a multifactorial process, including B. cereus prevalence and survival in different foods, survival of the stomach passage, spore germination, motility, adhesion, and finally enterotoxin production in the intestine. Moreover, all of these processes are influenced by the consumed foodstuffs as well as the intestinal microbiota which have, therefore, to be considered for a reliable prediction of the hazardous potential of contaminated foods. Current knowledge regarding these single aspects is summarized in this review aiming for risk-oriented diagnostics for enteropathogenic B. cereus.
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Affiliation(s)
- Nadja Jessberger
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität München, Schönleutnerstr. 8, 85764 Oberschleißheim, Germany; (R.D.); (E.M.)
| | - Richard Dietrich
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität München, Schönleutnerstr. 8, 85764 Oberschleißheim, Germany; (R.D.); (E.M.)
| | - Per Einar Granum
- Department of Food Safety and Infection Biology, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, P.O. Box 5003 NMBU, 1432 Ås, Norway;
| | - Erwin Märtlbauer
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität München, Schönleutnerstr. 8, 85764 Oberschleißheim, Germany; (R.D.); (E.M.)
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16
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Alonzo DA, Schmeing TM. Biosynthesis of depsipeptides, or Depsi: The peptides with varied generations. Protein Sci 2020; 29:2316-2347. [PMID: 33073901 DOI: 10.1002/pro.3979] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 10/11/2020] [Accepted: 10/13/2020] [Indexed: 12/11/2022]
Abstract
Depsipeptides are compounds that contain both ester bonds and amide bonds. Important natural product depsipeptides include the piscicide antimycin, the K+ ionophores cereulide and valinomycin, the anticancer agent cryptophycin, and the antimicrobial kutzneride. Furthermore, database searches return hundreds of uncharacterized systems likely to produce novel depsipeptides. These compounds are made by specialized nonribosomal peptide synthetases (NRPSs). NRPSs are biosynthetic megaenzymes that use a module architecture and multi-step catalytic cycle to assemble monomer substrates into peptides, or in the case of specialized depsipeptide synthetases, depsipeptides. Two NRPS domains, the condensation domain and the thioesterase domain, catalyze ester bond formation, and ester bonds are introduced into depsipeptides in several different ways. The two most common occur during cyclization, in a reaction between a hydroxy-containing side chain and the C-terminal amino acid residue in a peptide intermediate, and during incorporation into the growing peptide chain of an α-hydroxy acyl moiety, recruited either by direct selection of an α-hydroxy acid substrate or by selection of an α-keto acid substrate that is reduced in situ. In this article, we discuss how and when these esters are introduced during depsipeptide synthesis, survey notable depsipeptide synthetases, and review insight into bacterial depsipeptide synthetases recently gained from structural studies.
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Affiliation(s)
- Diego A Alonzo
- Department of Biochemistry and Centre de Recherche en Biologie Structurale, McGill University, Montréal, Quebec, Canada
| | - T Martin Schmeing
- Department of Biochemistry and Centre de Recherche en Biologie Structurale, McGill University, Montréal, Quebec, Canada
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17
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Liu C, Yu P, Yu S, Wang J, Guo H, Zhang Y, Zhang J, Liao X, Li C, Wu S, Gu Q, Zeng H, Zhang Y, Wei X, Zhang J, Wu Q, Ding Y. Assessment and molecular characterization of Bacillus cereus isolated from edible fungi in China. BMC Microbiol 2020; 20:310. [PMID: 33054711 PMCID: PMC7557095 DOI: 10.1186/s12866-020-01996-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Accepted: 10/05/2020] [Indexed: 12/17/2022] Open
Abstract
Background Bacillus cereus is a foodborne pathogen commonly found in nature and food and can cause food spoilage and health issues. Although the prevalence of B. cereus in foods has been reported worldwide, the extent of contamination in edible fungi, which has become increasingly popular as traditional or functional food, is largely unknown. Here we investigated the prevalence, toxin genes’ distribution, antibiotic resistance, and genetic diversity of B. cereus isolated from edible fungi in China. Results Six hundred and ninety-nine edible fungi samples were collected across China, with 198 (28.3%) samples found to be contaminated by B. cereus, with an average contamination level of 55.4 most probable number (MPN)/g. Two hundred and forty-seven B. cereus strains were isolated from the contaminated samples. Seven enterotoxin genes and one cereulide synthetase gene were detected. The detection frequencies of all enterotoxin genes were ≥ 80%, whereas the positive rate of the cesB gene in B. cereus was 3%. Most isolates were resistant to penicillins, β-lactam/β-lactamase inhibitor combinations, cephems, and ansamycins, but were susceptible to penems, aminoglycosides, macrolides, ketolide, glycopeptides, quinolones, phenylpropanol, tetracyclines, lincosamides, streptogramins, and nitrofurans. Meanwhile, 99.6% of all isolates displayed multiple antimicrobial resistance to three or more classes of antimicrobials. Using genetic diversity analysis, all isolates were defined in 171 sequence types (STs), of which 83 isolates were assigned to 78 new STs. Conclusions This study provides large-scale insight into the prevalence and potential risk of B. cereus in edible fungi in China. Approximately one-third of the samples were contaminated with B. cereus, and almost all isolates showed multiple antimicrobial resistance. Detection frequencies of all seven enterotoxin genes were equal to or more than 80%. These new findings may indicate a need for proper pre-/post-processing of edible fungi to eliminate B. cereus, thereby preventing the potential risk to public health.
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Affiliation(s)
- Chengcheng Liu
- Guangdong Institute of Microbiology, Guangdong Academy of Science, State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbial Safety and Health, Guangdong Open Laboratory of Applied Microbiology, Xianlie Zhong Road 100#, 58th Building, Guangzhou, 510070, China.,Department of Food Science and Technology, Institute of Food Safety and Nutrition, Jinan University, Huangpu Ave. 601, Guangzhou, 510632, China
| | - Pengfei Yu
- Guangdong Institute of Microbiology, Guangdong Academy of Science, State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbial Safety and Health, Guangdong Open Laboratory of Applied Microbiology, Xianlie Zhong Road 100#, 58th Building, Guangzhou, 510070, China.,Department of Food Science and Technology, Institute of Food Safety and Nutrition, Jinan University, Huangpu Ave. 601, Guangzhou, 510632, China
| | - Shubo Yu
- Guangdong Institute of Microbiology, Guangdong Academy of Science, State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbial Safety and Health, Guangdong Open Laboratory of Applied Microbiology, Xianlie Zhong Road 100#, 58th Building, Guangzhou, 510070, China
| | - Juan Wang
- College of Food Science, South China Agricultural University, Guangzhou, China
| | - Hui Guo
- Guangdong Institute of Microbiology, Guangdong Academy of Science, State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbial Safety and Health, Guangdong Open Laboratory of Applied Microbiology, Xianlie Zhong Road 100#, 58th Building, Guangzhou, 510070, China.,Department of Food Science and Technology, Institute of Food Safety and Nutrition, Jinan University, Huangpu Ave. 601, Guangzhou, 510632, China
| | - Ying Zhang
- Guangdong Institute of Microbiology, Guangdong Academy of Science, State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbial Safety and Health, Guangdong Open Laboratory of Applied Microbiology, Xianlie Zhong Road 100#, 58th Building, Guangzhou, 510070, China.,Department of Food Science and Technology, Institute of Food Safety and Nutrition, Jinan University, Huangpu Ave. 601, Guangzhou, 510632, China
| | - Junhui Zhang
- Guangdong Institute of Microbiology, Guangdong Academy of Science, State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbial Safety and Health, Guangdong Open Laboratory of Applied Microbiology, Xianlie Zhong Road 100#, 58th Building, Guangzhou, 510070, China.,Department of Food Science and Technology, Institute of Food Safety and Nutrition, Jinan University, Huangpu Ave. 601, Guangzhou, 510632, China
| | - Xiyu Liao
- Guangdong Institute of Microbiology, Guangdong Academy of Science, State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbial Safety and Health, Guangdong Open Laboratory of Applied Microbiology, Xianlie Zhong Road 100#, 58th Building, Guangzhou, 510070, China.,Department of Food Science and Technology, Institute of Food Safety and Nutrition, Jinan University, Huangpu Ave. 601, Guangzhou, 510632, China
| | - Chun Li
- Department of Food Science and Technology, Institute of Food Safety and Nutrition, Jinan University, Huangpu Ave. 601, Guangzhou, 510632, China
| | - Shi Wu
- Guangdong Institute of Microbiology, Guangdong Academy of Science, State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbial Safety and Health, Guangdong Open Laboratory of Applied Microbiology, Xianlie Zhong Road 100#, 58th Building, Guangzhou, 510070, China
| | - Qihui Gu
- Guangdong Institute of Microbiology, Guangdong Academy of Science, State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbial Safety and Health, Guangdong Open Laboratory of Applied Microbiology, Xianlie Zhong Road 100#, 58th Building, Guangzhou, 510070, China
| | - Haiyan Zeng
- Guangdong Institute of Microbiology, Guangdong Academy of Science, State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbial Safety and Health, Guangdong Open Laboratory of Applied Microbiology, Xianlie Zhong Road 100#, 58th Building, Guangzhou, 510070, China
| | - Youxiong Zhang
- Guangdong Institute of Microbiology, Guangdong Academy of Science, State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbial Safety and Health, Guangdong Open Laboratory of Applied Microbiology, Xianlie Zhong Road 100#, 58th Building, Guangzhou, 510070, China
| | - Xianhu Wei
- Guangdong Institute of Microbiology, Guangdong Academy of Science, State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbial Safety and Health, Guangdong Open Laboratory of Applied Microbiology, Xianlie Zhong Road 100#, 58th Building, Guangzhou, 510070, China
| | - Jumei Zhang
- Guangdong Institute of Microbiology, Guangdong Academy of Science, State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbial Safety and Health, Guangdong Open Laboratory of Applied Microbiology, Xianlie Zhong Road 100#, 58th Building, Guangzhou, 510070, China
| | - Qingping Wu
- Guangdong Institute of Microbiology, Guangdong Academy of Science, State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbial Safety and Health, Guangdong Open Laboratory of Applied Microbiology, Xianlie Zhong Road 100#, 58th Building, Guangzhou, 510070, China.
| | - Yu Ding
- Guangdong Institute of Microbiology, Guangdong Academy of Science, State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbial Safety and Health, Guangdong Open Laboratory of Applied Microbiology, Xianlie Zhong Road 100#, 58th Building, Guangzhou, 510070, China. .,Department of Food Science and Technology, Institute of Food Safety and Nutrition, Jinan University, Huangpu Ave. 601, Guangzhou, 510632, China.
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18
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Tran SL, Cormontagne D, Vidic J, André-Leroux G, Ramarao N. Structural Modeling of Cell Wall Peptidase CwpFM (EntFM) Reveals Distinct Intrinsically Disordered Extensions Specific to Pathogenic Bacillus cereus Strains. Toxins (Basel) 2020; 12:toxins12090593. [PMID: 32937845 PMCID: PMC7551459 DOI: 10.3390/toxins12090593] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 09/04/2020] [Accepted: 09/09/2020] [Indexed: 12/21/2022] Open
Abstract
The emergence of B. cereus as an opportunistic food-borne pathogen has intensified the need to distinguish strains of public health concern. The heterogeneity of the diseases associated with B. cereus infections emphasizes the versatility of these bacteria strains to colonize their host. Nevertheless, the molecular basis of these differences remains unclear. Several toxins are involved in virulence, particularly in gastrointestinal disorders, but there are currently no biological markers able to differentiate pathogenic from harmless strains. We have previously shown that CwpFM is a cell wall peptidase involved in B. cereus virulence. Here, we report a sequence/structure/function characterization of 39 CwpFM sequences, chosen from a collection of B. cereus with diverse virulence phenotypes, from harmless to highly pathogenic strains. CwpFM is homology-modeled in silico as an exported papain-like endopeptidase, with an N-terminal end composed of three successive bacterial Src Homology 3 domains (SH3b1–3) likely to control protein–protein interactions in signaling pathways, and a C-terminal end that contains a catalytic NLPC_P60 domain primed to form a competent active site. We confirmed in vitro that CwpFM is an endopeptidase with a moderate peptidoglycan hydrolase activity. Remarkably, CwpFMs from pathogenic strains harbor a specific stretch of twenty residues intrinsically disordered, inserted between the SH3b3 and the catalytic NLPC_P60 domain. This strongly suggests this linker as a marker of differentiation between B. cereus strains. We believe that our findings improve our understanding of the pathogenicity of B. cereus while advancing both clinical diagnosis and food safety.
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Affiliation(s)
- Seav-Ly Tran
- Micalis Institute, INRAE, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France; (S.-L.T.); (D.C.); (J.V.)
| | - Delphine Cormontagne
- Micalis Institute, INRAE, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France; (S.-L.T.); (D.C.); (J.V.)
| | - Jasmina Vidic
- Micalis Institute, INRAE, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France; (S.-L.T.); (D.C.); (J.V.)
| | - Gwenaëlle André-Leroux
- MaIAGE, INRAE, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France
- Correspondence: (G.A.-L.); (N.R.)
| | - Nalini Ramarao
- Micalis Institute, INRAE, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France; (S.-L.T.); (D.C.); (J.V.)
- Correspondence: (G.A.-L.); (N.R.)
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19
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Zhang Y, Chen M, Yu P, Yu S, Wang J, Guo H, Zhang J, Zhou H, Chen M, Zeng H, Wu S, Pang R, Ye Q, Xue L, Zhang S, Li Y, Zhang J, Wu Q, Ding Y. Prevalence, Virulence Feature, Antibiotic Resistance and MLST Typing of Bacillus cereus Isolated From Retail Aquatic Products in China. Front Microbiol 2020; 11:1513. [PMID: 32719669 PMCID: PMC7347965 DOI: 10.3389/fmicb.2020.01513] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Accepted: 06/10/2020] [Indexed: 11/13/2022] Open
Abstract
Bacillus cereus is one of the most important foodborne pathogenic microorganisms, which can lead to gastrointestinal and non-gastrointestinal diseases. However, the potential risk of B. cereus in aquatic products in China has not been comprehensively evaluated yet. In this study, a total of 860 aquatic samples from three types of retail aquatic products were collected from 39 major cities in China from 2011 to 2016. The contamination, distribution of virulence genes, antibiotic resistance and genetic diversity of B. cereus isolates were measured and analyzed. Of all the samples, 219 (25.47%) were positive for B. cereus and 1.83% (4/219) of the samples had contamination levels of more than 1,100 most probable number (MPN)/g. Different isolates had virulence potential, within which 59.6% (164/275) contained all three kinds of enterotoxin genes (nhe, hbl, and cytK-2) and 5.1% (14/275) possessed cereulide encoding gene cesB. The antimicrobial resistance profiles revealed the universal antibiotic resistance to rifampin and most β-lactams, suggesting the necessity to continuously monitor the antibiotic resistance of B. cereus in aquatic products and to control drug use in aquaculture. In sum, our study indicates the potential hazards of B. cereus isolated from aquatic products to customers and may provide a reference for clinical treatment caused by B. cereus.
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Affiliation(s)
- Ying Zhang
- Department of Food Science and Technology, Institute of Food Safety and Nutrition, Jinan University, Guangzhou, China
- State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbial Safety and Health, Guangdong Open Laboratory of Applied Microbiology, Guangdong Institute of Microbiology, Guangzhou, China
| | - Mengfei Chen
- Department of Food Science and Technology, Institute of Food Safety and Nutrition, Jinan University, Guangzhou, China
- State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbial Safety and Health, Guangdong Open Laboratory of Applied Microbiology, Guangdong Institute of Microbiology, Guangzhou, China
| | - Pengfei Yu
- Department of Food Science and Technology, Institute of Food Safety and Nutrition, Jinan University, Guangzhou, China
- State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbial Safety and Health, Guangdong Open Laboratory of Applied Microbiology, Guangdong Institute of Microbiology, Guangzhou, China
| | - Shubo Yu
- State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbial Safety and Health, Guangdong Open Laboratory of Applied Microbiology, Guangdong Institute of Microbiology, Guangzhou, China
| | - Juan Wang
- College of Food Science, South China Agricultural University, Guangzhou, China
| | - Hui Guo
- Department of Food Science and Technology, Institute of Food Safety and Nutrition, Jinan University, Guangzhou, China
- State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbial Safety and Health, Guangdong Open Laboratory of Applied Microbiology, Guangdong Institute of Microbiology, Guangzhou, China
| | - Junhui Zhang
- Department of Food Science and Technology, Institute of Food Safety and Nutrition, Jinan University, Guangzhou, China
- State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbial Safety and Health, Guangdong Open Laboratory of Applied Microbiology, Guangdong Institute of Microbiology, Guangzhou, China
| | - Huan Zhou
- Department of Food Science and Technology, Institute of Food Safety and Nutrition, Jinan University, Guangzhou, China
- State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbial Safety and Health, Guangdong Open Laboratory of Applied Microbiology, Guangdong Institute of Microbiology, Guangzhou, China
| | - Moutong Chen
- State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbial Safety and Health, Guangdong Open Laboratory of Applied Microbiology, Guangdong Institute of Microbiology, Guangzhou, China
| | - Haiyan Zeng
- State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbial Safety and Health, Guangdong Open Laboratory of Applied Microbiology, Guangdong Institute of Microbiology, Guangzhou, China
| | - Shi Wu
- State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbial Safety and Health, Guangdong Open Laboratory of Applied Microbiology, Guangdong Institute of Microbiology, Guangzhou, China
| | - Rui Pang
- State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbial Safety and Health, Guangdong Open Laboratory of Applied Microbiology, Guangdong Institute of Microbiology, Guangzhou, China
| | - Qinghua Ye
- State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbial Safety and Health, Guangdong Open Laboratory of Applied Microbiology, Guangdong Institute of Microbiology, Guangzhou, China
| | - Liang Xue
- State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbial Safety and Health, Guangdong Open Laboratory of Applied Microbiology, Guangdong Institute of Microbiology, Guangzhou, China
| | - Shuhong Zhang
- State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbial Safety and Health, Guangdong Open Laboratory of Applied Microbiology, Guangdong Institute of Microbiology, Guangzhou, China
| | - Ying Li
- State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbial Safety and Health, Guangdong Open Laboratory of Applied Microbiology, Guangdong Institute of Microbiology, Guangzhou, China
| | - Jumei Zhang
- State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbial Safety and Health, Guangdong Open Laboratory of Applied Microbiology, Guangdong Institute of Microbiology, Guangzhou, China
| | - Qingping Wu
- State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbial Safety and Health, Guangdong Open Laboratory of Applied Microbiology, Guangdong Institute of Microbiology, Guangzhou, China
| | - Yu Ding
- Department of Food Science and Technology, Institute of Food Safety and Nutrition, Jinan University, Guangzhou, China
- State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbial Safety and Health, Guangdong Open Laboratory of Applied Microbiology, Guangdong Institute of Microbiology, Guangzhou, China
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20
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Heberlig GW, Boddy CN. Thioesterase from Cereulide Biosynthesis Is Responsible for Oligomerization and Macrocyclization of a Linear Tetradepsipeptide. JOURNAL OF NATURAL PRODUCTS 2020; 83:1990-1997. [PMID: 32519859 DOI: 10.1021/acs.jnatprod.0c00333] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Cereulide is a toxic cyclic depsidodecapeptide produced in Bacillus cereus by two nonribosomal peptide synthetases, CesA and CesB. While highly similar in structure to valinomycin and with a homologous biosynthetic gene cluster, recent work suggests that cereulide is produced via a different mechanism that relies on a noncanonical coupling of two didepsipeptide-peptidyl carrier protein (PCP) bound intermediates. Ultimately this alternative mechanism generates a tetradepsipeptide-PCP bound intermediate that differs from the tetradepsipeptide-PCP intermediate predicted from canonical activity of CesA and CesB. To differentiate between the mechanisms, both tetradepsipeptides were prepared as N-acetyl cysteamine thioesters (SNAC), and the ability of the purified recombinant terminal CesB thioesterase (CesB TE) to oligomerize and macrocyclize each substrate was probed. Only the canonical substrate is converted to cereulide, ruling out the alternative mechanism. It was demonstrated that CesB TE can use related tetradepsipeptide substrates, such as the valinomycin tetradespipetide and a hybrid cereulide-valinomycin tetradepsipetide in conjunction with its native substrate to generate chimeric natural products. This work clarifies the biosynthetic origins of cereulide and provides a powerful biocatalyst to access analogues of these ionophoric natural products.
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Affiliation(s)
- Graham W Heberlig
- Department of Chemistry and Biomolecular Sciences Centre for Chemical and Synthetic Biology, University of Ottawa, Ottawa, ON K1N 6N5, Canada
| | - Christopher N Boddy
- Department of Chemistry and Biomolecular Sciences Centre for Chemical and Synthetic Biology, University of Ottawa, Ottawa, ON K1N 6N5, Canada
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21
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High-Throughput 16S rRNA Gene Sequencing of Butter Microbiota Reveals a Variety of Opportunistic Pathogens. Foods 2020; 9:foods9050608. [PMID: 32397488 PMCID: PMC7278763 DOI: 10.3390/foods9050608] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Revised: 05/03/2020] [Accepted: 05/08/2020] [Indexed: 02/07/2023] Open
Abstract
Microbial contamination of dairy products with a high fat content (e.g., butter) has been studied insufficiently. No studies using modern molecular methods to investigate microbial communities in butter have been conducted so far. In this work, we used high-throughput sequencing and Sanger sequencing of individual bacterial colonies to analyze microbial content of commercially available butter brands. A total of 21 samples of commercially available butter brands were analyzed. We identified a total of 94 amplicon sequence variants corresponding to different microbial taxa. The most abundant lactic acid bacteria in butter were Lactobacillus kefiri, Lactobacillus parakefiri, Lactococcus taiwanensis and Lactococcus raffinolactis. A large amount of Streptococcus spp. bacteria (87.9% of all identified bacteria) was found in one of the butter samples. Opportunistic pathogens such as Bacillus cereus group, Pseudomonas aeruginosa, Cronobacter spp., Escherichia coli, Listeria innocua, Citrobacter spp., Enterococcus spp., Klebsiella pneumonia were detected. The analyzed butter samples were most strongly contaminated with bacteria from the Bacillus cereus group, and to a lesser extent - with Cronobacter spp. and Enterococcus spp. The plating and Sanger sequencing of individual colonies revealed the presence of Enterobacter cloacae and Staphylococcus epidermidis. The Sanger sequencing also showed the presence of Cronobacter sakazakii in butter which can be dangerous for children under the age of 1 year. We demonstrated that butter is a good growth medium for opportunistic pathogenic bacteria. Our data indicate that despite the fact that butter is a dairy product with a long shelf life, it should be subjected to quality control for the presence of opportunistic bacteria.
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22
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Park KM, Kim HJ, Jeong M, Koo M. Enterotoxin Genes, Antibiotic Susceptibility, and Biofilm Formation of Low-Temperature-Tolerant Bacillus cereus Isolated from Green Leaf Lettuce in the Cold Chain. Foods 2020; 9:foods9030249. [PMID: 32106606 PMCID: PMC7142467 DOI: 10.3390/foods9030249] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Revised: 02/20/2020] [Accepted: 02/25/2020] [Indexed: 12/25/2022] Open
Abstract
The prevalence and characteristics of low-temperature-tolerant Bacillus cereus (psychrotolerant B. cereus) in green leaf lettuce collected during cold chain were investigated. Among the 101 isolated B. cereus samples, only 18 were capable of growth at 7 °C, and these isolates shared potential health hazard characteristics with mesophilic isolates. Most psychrotolerant B. cereus isolates contained various combinations of nheA, nheB, nheC, hblA, hblA, hblC, hblD, cytK, and entFM. Most isolates of psychrotolerant B. cereus possessed at least two enterotoxin genes and 28% of isolates harbored tested nine enterotoxin genes. Additionally, the psychrotolerant B. cereus isolates showed resistance to tetracycline and rifampin and intermediate levels of resistance to clindamycin. A total of 23% of isolates among psychrotolerant B. cereus displayed a high level of biofilm formation at 7 °C than at 10 °C or 30 °C. The results of this study indicate that cold distribution and storage for green leaf lettuce may fail to maintain food safety due to the presence of enterotoxigenic, antibiotic-resistant, and strong biofilm forming psychrotolerant B. cereus isolates, which therefore poses a potential health risk to the consumer. Our findings provide the first account of the prevalence and characteristics of psychrotolerant B. cereus isolated from green leaf lettuce during cold storage, suggesting a potential hazard of psychrotolerant B. cereus isolates to public health and the food industry.
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Affiliation(s)
- Kyung Min Park
- Food Biotechnology, Korea University of Science & Technology, Daejeon 34113, Korea; (K.M.P.); (H.J.K.)
- Consumer Safety, Korea Food Research Institute, Wanju-gun 55365, Korea;
| | - Hyun Jung Kim
- Food Biotechnology, Korea University of Science & Technology, Daejeon 34113, Korea; (K.M.P.); (H.J.K.)
- Consumer Safety, Korea Food Research Institute, Wanju-gun 55365, Korea;
| | - Mooncheol Jeong
- Consumer Safety, Korea Food Research Institute, Wanju-gun 55365, Korea;
| | - Minseon Koo
- Food Biotechnology, Korea University of Science & Technology, Daejeon 34113, Korea; (K.M.P.); (H.J.K.)
- Food Analysis Center, Korea Food Research Institute, Wanju-gun 55365, Korea
- Correspondence: ; Tel.: +82-63-219-9161; Fax: +82-63-219-9876
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23
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Abstract
Natural products from microorganisms are important small molecules that play roles in various biological processes like cellular growth, motility, nutrient acquisition, stress response, biofilm formation, and defense. It is hypothesized that pathogens exploit these molecules to regulate virulence and persistence during infections. Here, we present selected examples of signaling natural products from human pathogenic bacteria that use these metabolites to gain a competitive advantage. Targeting these signaling systems provides novel strategies to antimicrobial treatments.
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Affiliation(s)
- Zhijuan Hu
- Department of Chemical and Biomolecular Engineering, University of California Berkeley, 201 Gilman Hall, Berkeley, California 94720, United States
| | - Wenjun Zhang
- Department of Chemical and Biomolecular Engineering, University of California Berkeley, 201 Gilman Hall, Berkeley, California 94720, United States
- Chan Zuckerberg Biohub, San Francisco, California 94158, United States
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24
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Okutani A, Inoue S, Noguchi A, Kaku Y, Morikawa S. Whole-genome sequence-based comparison and profiling of virulence-associated genes of Bacillus cereus group isolates from diverse sources in Japan. BMC Microbiol 2019; 19:296. [PMID: 31842760 PMCID: PMC6915864 DOI: 10.1186/s12866-019-1678-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Accepted: 12/09/2019] [Indexed: 02/07/2023] Open
Abstract
Background The complete genome sequences of 44 Bacillus cereus group isolates collected from diverse sources in Japan were analyzed to determine their genetic backgrounds and diversity levels in Japan. Multilocus sequence typing (MLST) and core-genome single-nucleotide polymorphism (SNP) typing data from whole-genome sequences were analyzed to determine genetic diversity levels. Virulence-associated gene profiles were also used to evaluate the genetic backgrounds and relationships among the isolates. Results The 44 B. cereus group isolates, including soil- and animal-derived isolates and isolates recovered from hospitalized patients and food poisoning cases, were genotyped by MLST and core-genome SNP typing. Genetic variation among the isolates was identified by the MLST and core-genome SNP phylogeny comparison against reference strains from countries outside of Japan. Exploratory principal component analysis and nonmetric multidimensional scaling (NMDS) analyses were used to assess the genetic similarities among the isolates using gene presence and absence information and isolate origins as the metadata. A significant correlation was seen between the principal components and the presence of genes encoding hemolysin BL and emetic genetic determinants in B. cereus, and the capsule proteins in B. anthracis. NMDS showed that the cluster of soil isolates overlapped with the cluster comprising animal-derived and clinical isolates. Conclusions Molecular and epidemiological analyses of B. cereus group isolates in Japan suggest that the soil- and animal-derived bacteria from our study are not a significant risk to human health. However, because several of the clinical isolates share close genetic relationships with the environmental isolates, both molecular and epidemiological surveillance studies could be used effectively to estimate virulence in these important pathogens.
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Affiliation(s)
- Akiko Okutani
- Department of Veterinary Science, National Institute of Infectious Diseases, Tokyo, Japan.
| | - Satoshi Inoue
- Department of Veterinary Science, National Institute of Infectious Diseases, Tokyo, Japan
| | - Akira Noguchi
- Department of Veterinary Science, National Institute of Infectious Diseases, Tokyo, Japan
| | - Yoshihiro Kaku
- Department of Veterinary Science, National Institute of Infectious Diseases, Tokyo, Japan
| | - Shigeru Morikawa
- Department of Veterinary Science, National Institute of Infectious Diseases, Tokyo, Japan.,Faculty of Veterinary Medicine, Okayama University of Science, Imabari, Ehime, Japan
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25
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Yu P, Yu S, Wang J, Guo H, Zhang Y, Liao X, Zhang J, Wu S, Gu Q, Xue L, Zeng H, Pang R, Lei T, Zhang J, Wu Q, Ding Y. Bacillus cereus Isolated From Vegetables in China: Incidence, Genetic Diversity, Virulence Genes, and Antimicrobial Resistance. Front Microbiol 2019; 10:948. [PMID: 31156567 PMCID: PMC6530634 DOI: 10.3389/fmicb.2019.00948] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2019] [Accepted: 04/15/2019] [Indexed: 12/24/2022] Open
Abstract
Bacillus cereus is a food-borne opportunistic pathogen that can induce diarrheal and emetic symptoms. It is widely distributed in different environments and can be found in various foods, including fresh vegetables. As their popularity grows worldwide, the risk of bacterial contamination in fresh vegetables should be fully evaluated, particularly in vegetables that are consumed raw or processed minimally, which are not commonly sterilized by enough heat treatment. Thereby, it is necessary to perform potential risk evaluation of B. cereus in vegetables. In this study, 294 B. cereus strains were isolated from vegetables in different cities in China to analyze incidence, genetic polymorphism, presence of virulence genes, and antimicrobial resistance. B. cereus was detected in 50% of all the samples, and 21/211 (9.95%) of all the samples had contamination levels of more than 1,100 MPN/g. Virulence gene detection revealed that 95 and 82% of the isolates harbored nheABC and hblACD gene clusters, respectively. Additionally, 87% of the isolates harbored cytK gene, and 3% of the isolates possessed cesB. Most strains were resistant to rifampicin and β-lactam antimicrobials but were sensitive to imipenem, gentamicin, ciprofloxacin, kanamycin, telithromycin, ciprofloxacin, and chloramphenicol. In addition, more than 95.6% of the isolates displayed resistance to three kinds of antibiotics. Based on multilocus sequence typing, all strains were classified into 210 different sequence types (STs), of which 145 isolates were assigned to 137 new STs. The most prevalent ST was ST770, but it included only eight isolates. Taken together, our research provides the first reference for the incidence and characteristics of B. cereus in vegetables collected throughout China, indicating a potential hazard of B. cereus when consuming vegetables without proper handling.
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Affiliation(s)
- Pengfei Yu
- Department of Food Science and Technology, Institute of Food Safety and Nutrition, Jinan University, Guangzhou, China.,State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangdong Open Laboratory of Applied Microbiology, Guangdong Institute of Microbiology, Guangzhou, China
| | - Shubo Yu
- State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangdong Open Laboratory of Applied Microbiology, Guangdong Institute of Microbiology, Guangzhou, China
| | - Juan Wang
- College of Food Science, South China Agricultural University, Guangzhou, China
| | - Hui Guo
- Department of Food Science and Technology, Institute of Food Safety and Nutrition, Jinan University, Guangzhou, China.,State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangdong Open Laboratory of Applied Microbiology, Guangdong Institute of Microbiology, Guangzhou, China
| | - Ying Zhang
- Department of Food Science and Technology, Institute of Food Safety and Nutrition, Jinan University, Guangzhou, China.,State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangdong Open Laboratory of Applied Microbiology, Guangdong Institute of Microbiology, Guangzhou, China
| | - Xiyu Liao
- Department of Food Science and Technology, Institute of Food Safety and Nutrition, Jinan University, Guangzhou, China.,State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangdong Open Laboratory of Applied Microbiology, Guangdong Institute of Microbiology, Guangzhou, China
| | - Junhui Zhang
- Department of Food Science and Technology, Institute of Food Safety and Nutrition, Jinan University, Guangzhou, China.,State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangdong Open Laboratory of Applied Microbiology, Guangdong Institute of Microbiology, Guangzhou, China
| | - Shi Wu
- State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangdong Open Laboratory of Applied Microbiology, Guangdong Institute of Microbiology, Guangzhou, China
| | - Qihui Gu
- State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangdong Open Laboratory of Applied Microbiology, Guangdong Institute of Microbiology, Guangzhou, China
| | - Liang Xue
- State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangdong Open Laboratory of Applied Microbiology, Guangdong Institute of Microbiology, Guangzhou, China
| | - Haiyan Zeng
- State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangdong Open Laboratory of Applied Microbiology, Guangdong Institute of Microbiology, Guangzhou, China
| | - Rui Pang
- State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangdong Open Laboratory of Applied Microbiology, Guangdong Institute of Microbiology, Guangzhou, China
| | - Tao Lei
- State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangdong Open Laboratory of Applied Microbiology, Guangdong Institute of Microbiology, Guangzhou, China
| | - Jumei Zhang
- State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangdong Open Laboratory of Applied Microbiology, Guangdong Institute of Microbiology, Guangzhou, China
| | - Qingping Wu
- State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangdong Open Laboratory of Applied Microbiology, Guangdong Institute of Microbiology, Guangzhou, China
| | - Yu Ding
- Department of Food Science and Technology, Institute of Food Safety and Nutrition, Jinan University, Guangzhou, China.,State Key Laboratory of Applied Microbiology Southern China, Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangdong Open Laboratory of Applied Microbiology, Guangdong Institute of Microbiology, Guangzhou, China
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26
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Ehling-Schulz M, Lereclus D, Koehler TM. The Bacillus cereus Group: Bacillus Species with Pathogenic Potential. Microbiol Spectr 2019; 7:10.1128/microbiolspec.gpp3-0032-2018. [PMID: 31111815 PMCID: PMC6530592 DOI: 10.1128/microbiolspec.gpp3-0032-2018] [Citation(s) in RCA: 235] [Impact Index Per Article: 47.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Indexed: 12/17/2022] Open
Abstract
The Bacillus cereus group includes several Bacillus species with closely related phylogeny. The most well-studied members of the group, B. anthracis, B. cereus, and B. thuringiensis, are known for their pathogenic potential. Here, we present the historical rationale for speciation and discuss shared and unique features of these bacteria. Aspects of cell morphology and physiology, and genome sequence similarity and gene synteny support close evolutionary relationships for these three species. For many strains, distinct differences in virulence factor synthesis provide facile means for species assignment. B. anthracis is the causative agent of anthrax. Some B. cereus strains are commonly recognized as food poisoning agents, but strains can also cause localized wound and eye infections as well as systemic disease. Certain B. thuringiensis strains are entomopathogens and have been commercialized for use as biopesticides, while some strains have been reported to cause infection in immunocompromised individuals. In this article we compare and contrast B. anthracis, B. cereus, and B. thuringiensis, including ecology, cell structure and development, virulence attributes, gene regulation and genetic exchange systems, and experimental models of disease.
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Affiliation(s)
- Monika Ehling-Schulz
- Institute of Microbiology, Department of Pathology, University of Veterinary Medicine, 1210 Vienna, Austria
| | - Didier Lereclus
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France
| | - Theresa M Koehler
- Department of Microbiology and Molecular Genetics, McGovern Medical School, University of Texas Health Science Center - Houston, Houston, TX 77030
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27
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Bauer T, Sipos W, Stark TD, Käser T, Knecht C, Brunthaler R, Saalmüller A, Hofmann T, Ehling-Schulz M. First Insights Into Within Host Translocation of the Bacillus cereus Toxin Cereulide Using a Porcine Model. Front Microbiol 2018; 9:2652. [PMID: 30464760 PMCID: PMC6234764 DOI: 10.3389/fmicb.2018.02652] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Accepted: 10/17/2018] [Indexed: 11/13/2022] Open
Abstract
Bacillus cereus is a gram-positive pathogen mainly known to evoke two types of foodborne poisonings. The diarrheal syndrome is caused by enterotoxins produced during growth in the intestine. In contrast, the emetic type is caused by the dodecadepsipeptide cereulide pre-formed in food. Usually, both diseases are self-limiting but occasionally more severe forms, including fatal ones, are reported. Since the mechanisms of cereulide toxin uptake and translocation within the body as well as the mechanism of its toxic action are still unknown, we used a porcine model to investigate the uptake, routes of excretion and distribution of cereulide within the host. Pigs were orally challenged with cereulide using single doses of 10-150 μg cereulide kg-1 body weight to study acute effects or using daily doses of 10 μg cereulide kg-1 body weight administered for 7 days to investigate effects of longtime, chronic exposure. Our study showed that part of cereulide ingested with food is rapidly excreted with feces while part of the cereulide toxin is absorbed, passes through membranes and is distributed within the body. Results from the chronic trial indicate bioaccumulation of cereulide in certain tissues and organs, such as kidney, liver, muscles and fat tissues. Beside its detection in various tissues and organs, our study also demonstrated that cereulide is able to cross the blood-brain-barrier, which may partially explain the cerebral effects reported from human intoxication cases. The neurobehavioral symptoms, such as seizures and lethargy, observed in our porcine model resemble those reported from human food borne intoxications. The rapid onset of these symptoms indicates direct effects of cereulide on the central nervous system (CNS), which warrant further research. The porcine model presented here might be useful to study the specific neurobiological effect in detail. Furthermore, our study revealed that typical diagnostic specimens used in human medicine, such as blood samples and urine, are not suitable for diagnostics of food borne cereulide intoxications. Instead, screening of fecal samples by SIDA-LC-MS may represent a simple and non-invasive method for detection of cereulide intoxications in clinical settings as well as in foodborne outbreak situations.
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Affiliation(s)
- Tobias Bauer
- Department of Pathobiology, Functional Microbiology, Institute of Microbiology, University of Veterinary Medicine Vienna, Vienna, Austria
| | - Wolfgang Sipos
- University Clinic for Swine, Department for Farm Animals and Veterinary Public Health, University of Veterinary Medicine Vienna, Vienna, Austria
| | - Timo D Stark
- Chair of Food Chemistry and Molecular Sensory Science, Technische Universität München, Freising, Germany
| | - Tobias Käser
- Department of Pathobiology, Institute of Immunology, University of Veterinary Medicine Vienna, Vienna, Austria.,Department of Population Health and Pathobiology, College of Veterinary Medicine, North Carolina State University (NCSU), Raleigh, NC, United States
| | - Christian Knecht
- University Clinic for Swine, Department for Farm Animals and Veterinary Public Health, University of Veterinary Medicine Vienna, Vienna, Austria
| | - Rene Brunthaler
- Department of Pathobiology, Institute of Pathology and Forensic Veterinary Medicine, University of Veterinary Medicine Vienna, Vienna, Austria
| | - Armin Saalmüller
- Department of Pathobiology, Institute of Immunology, University of Veterinary Medicine Vienna, Vienna, Austria
| | - Thomas Hofmann
- Chair of Food Chemistry and Molecular Sensory Science, Technische Universität München, Freising, Germany
| | - Monika Ehling-Schulz
- Department of Pathobiology, Functional Microbiology, Institute of Microbiology, University of Veterinary Medicine Vienna, Vienna, Austria
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28
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Harwood CR, Mouillon JM, Pohl S, Arnau J. Secondary metabolite production and the safety of industrially important members of the Bacillus subtilis group. FEMS Microbiol Rev 2018; 42:721-738. [PMID: 30053041 PMCID: PMC6199538 DOI: 10.1093/femsre/fuy028] [Citation(s) in RCA: 113] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Accepted: 07/17/2018] [Indexed: 11/14/2022] Open
Abstract
Members of the 'Bacillus subtilis group' include some of the most commercially important bacteria, used for the production of a wide range of industrial enzymes and fine biochemicals. Increasingly, group members have been developed for use as animal feed enhancers and antifungal biocontrol agents. The group has long been recognised to produce a range of secondary metabolites and, despite their long history of safe usage, this has resulted in an increased focus on their safety. Traditional methods used to detect the production of secondary metabolites and other potentially harmful compounds have relied on phenotypic tests. Such approaches are time consuming and, in some cases, lack specificity. Nowadays, accessibility to genome data and associated bioinformatical tools provides a powerful means for identifying gene clusters associated with the synthesis of secondary metabolites. This review focuses primarily on well-characterised strains of B. subtilis and B. licheniformis and their synthesis of non-ribosomally synthesised peptides and polyketides. Where known, the activities and toxicities of their secondary metabolites are discussed, together with the limitations of assays currently used to assess their toxicity. Finally, the regulatory framework under which such strains are authorised for use in the production of food and feed enzymes is also reviewed.
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Affiliation(s)
- Colin R Harwood
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biology, Newcastle University, Newcastle upon Tyne NE2 4AX, UK
| | - Jean-Marie Mouillon
- Department of Fungal Strain Technology and Strain Approval Support, Novozymes A/S, Krogshoevej 36, DK-2880 Bagsvaerd, Denmark
| | - Susanne Pohl
- Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biology, Newcastle University, Newcastle upon Tyne NE2 4AX, UK
| | - José Arnau
- Department of Fungal Strain Technology and Strain Approval Support, Novozymes A/S, Krogshoevej 36, DK-2880 Bagsvaerd, Denmark
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29
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Riol CD, Dietrich R, Märtlbauer E, Jessberger N. Consumed Foodstuffs Have a Crucial Impact on the Toxic Activity of Enteropathogenic Bacillus cereus. Front Microbiol 2018; 9:1946. [PMID: 30174669 PMCID: PMC6107707 DOI: 10.3389/fmicb.2018.01946] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Accepted: 07/31/2018] [Indexed: 11/13/2022] Open
Abstract
Enteropathogenic Bacillus cereus cause diarrhea due to the production of enterotoxins in the intestine. To start this process, spores have to be ingested together with contaminated food and survive the stomach passage. In this study, the influence of consumed foodstuffs on spore survival as well as on cytotoxicity toward colon epithelial cells was investigated. Spore survival of 20 enteropathogenic and apathogenic B. cereus strains during simulated stomach passage was highly strain-specific and did not correlate with the toxic potential. Survival of three tested strains was strain-specifically altered by milk products. Whereas milk, a follow-on formula and rice pudding had only little influence, spores seemed to be protected by milk products with high fat content such as whipped cream and mascarpone. Furthermore, tested milk products decreased the toxic activity of three B. cereus strains toward CaCo-2 cells. Investigating the individual components, lactoferrin, a skim milk powder and vitamins C, B5 and A showed the most inhibiting effects. On the other hand, biotin, vitamin B3 and another skim milk powder even enhanced cytotoxicity. Further studies suggested that these inhibiting effects result only partially from inhibiting cell binding, but rather from blocking the interaction between the single enterotoxin components.
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Affiliation(s)
- Claudia Da Riol
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Richard Dietrich
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Erwin Märtlbauer
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Nadja Jessberger
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität München, Munich, Germany
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30
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Decleer M, Jovanovic J, Vakula A, Udovicki B, Agoua RSEK, Madder A, De Saeger S, Rajkovic A. Oxygen Consumption Rate Analysis of Mitochondrial Dysfunction Caused by Bacillus cereus Cereulide in Caco-2 and HepG2 Cells. Toxins (Basel) 2018; 10:E266. [PMID: 30004412 PMCID: PMC6070949 DOI: 10.3390/toxins10070266] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Revised: 06/20/2018] [Accepted: 06/22/2018] [Indexed: 12/28/2022] Open
Abstract
The emetic syndrome of Bacillus cereus is a food intoxication caused by cereulide (CER) and manifested by emesis, nausea and in most severe cases with liver failure. While acute effects have been studied in the aftermath of food intoxication, an exposure to low doses of cereulide might cause unnoticed damages to the intestines and liver. The toxicity which relies on the mitochondrial dysfunction was assessed on Caco-2 and HepG2 cells after exposure of one, three and ten days to a range of low doses of cereulide. Oxygen consumption rate analyses were used to study the impact of low doses of CER on the bioenergetics functions of undifferentiated Caco-2 and HepG2 cells using Seahorse XF extracellular flux analyzer. Both Caco-2 and HepG2 cells experienced measurable mitochondrial impairment after prolonged exposure of 10 days to 0.25 nM of cereulide. Observed mitochondrial dysfunction was greatly reflected in reduction of maximal cell respiration. At 0.50 nM CER, mitochondrial respiration was almost completely shut down, especially in HepG2 cells. These results corresponded with a severe reduction in the amount of cells and an altered morphology, observed by microscopic examination of the cells. Accurate and robust quantification of basal respiration, ATP production, proton leak, maximal respiration, spare respiratory capacity, and non-mitochondrial respiration allowed better understanding of the effects of cereulide in underlying respiratory malfunctions in low-dose exposure.
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Affiliation(s)
- Marlies Decleer
- Department of Food Technology, Food Safety and Health, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000 Ghent, Belgium.
- Laboratory of Food Analysis, Department of Bioanalysis, Faculty of Pharmaceutical Sciences, Ghent University, Ottergemsesteenweg 460, 9000 Ghent, Belgium.
| | - Jelena Jovanovic
- Department of Food Technology, Food Safety and Health, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000 Ghent, Belgium.
| | - Anita Vakula
- Department of Food Preservation Engineering, Faculty of Technology, University of Novi Sad, Bulevar Cara Lazara 1, 21000 Novi Sad, Serbia.
| | - Bozidar Udovicki
- Department of Food Safety and Food Quality Management, Faculty of Agriculture, University of Belgrade, Nemanjina 6, 11081 Zemun-Belgrade, Serbia.
| | - Rock-Seth E K Agoua
- Department of Food Technology, Food Safety and Health, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000 Ghent, Belgium.
| | - Annemieke Madder
- Department of Organic and Macromolecular Chemistry, Organic and Biomimetic Chemistry Research Group, Faculty of Sciences, Campus Sterre, Krijgslaan 281, Building S4, 9000 Gent, Belgium.
| | - Sarah De Saeger
- Laboratory of Food Analysis, Department of Bioanalysis, Faculty of Pharmaceutical Sciences, Ghent University, Ottergemsesteenweg 460, 9000 Ghent, Belgium.
| | - Andreja Rajkovic
- Department of Food Technology, Food Safety and Health, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000 Ghent, Belgium.
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Gao T, Ding Y, Wu Q, Wang J, Zhang J, Yu S, Yu P, Liu C, Kong L, Feng Z, Chen M, Wu S, Zeng H, Wu H. Prevalence, Virulence Genes, Antimicrobial Susceptibility, and Genetic Diversity of Bacillus cereus Isolated From Pasteurized Milk in China. Front Microbiol 2018; 9:533. [PMID: 29632521 PMCID: PMC5879084 DOI: 10.3389/fmicb.2018.00533] [Citation(s) in RCA: 88] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Accepted: 03/08/2018] [Indexed: 12/28/2022] Open
Abstract
Bacillus cereus is a common and important food-borne pathogen that can be found in various food products. Due to low-temperature sterilization for a short period of time, pasteurization is not sufficient for complete elimination of B. cereus in milk, thereby cause severe economic loss and food safety problems. It is therefore of paramount importance to perform risk assessment of B. cereus in pasteurized milk. In this study, we isolated B. cereus from pasteurized milk samples in different regions of China, and evaluated the contamination situation, existence of virulence genes, antibiotic resistance profile and genetic polymorphism of B. cereus isolates. Intriguingly, 70 samples (27%) were found to be contaminated by B. cereus and the average contamination level was 111 MPN/g. The distribution of virulence genes was assessed toward 10 enterotoxigenic genes (hblA, hblC, hblD, nheA, nheB, nheC, cytK, entFM, bceT, and hlyII) and one emetic gene (cesB). Forty five percent strains harbored enterotoxigenic genes hblACD and 93% isolates contained nheABC gene cluster. The positive rate of cytK, entFM, bceT, hlyII, and cesB genes were 73, 96, 75, 54, and 5%, respectively. Antibiotic susceptibility assessment showed that most of the isolates were resistant to β-lactam antibiotics and rifampicin, but susceptible to other antibiotics such as ciprofloxacin, gentamicin and chloramphenicol. Total multidrug-resistant population was about 34%. In addition, B. cereus isolates in pasteurized milk showed a high genetic diversity. In conclusion, our findings provide the first reference on the prevalence, contamination level and characteristics of B. cereus isolated from pasteurized milk in China, suggesting a potential high risk of B. cereus to public health and dairy industry.
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Affiliation(s)
- Tiantian Gao
- University of Chinese Academy of Sciences, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China
- State Key Laboratory of Applied Microbiology, Southern China and Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangdong Open Laboratory of Applied Microbiology, Guangdong Institute of Microbiology, Guangzhou, China
| | - Yu Ding
- Department of Food Science and Technology, Jinan University, Guangzhou, China
| | - Qingping Wu
- State Key Laboratory of Applied Microbiology, Southern China and Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangdong Open Laboratory of Applied Microbiology, Guangdong Institute of Microbiology, Guangzhou, China
| | - Juan Wang
- College of Food Science, South China Agricultural University, Guangzhou, China
| | - Jumei Zhang
- State Key Laboratory of Applied Microbiology, Southern China and Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangdong Open Laboratory of Applied Microbiology, Guangdong Institute of Microbiology, Guangzhou, China
| | - Shubo Yu
- State Key Laboratory of Applied Microbiology, Southern China and Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangdong Open Laboratory of Applied Microbiology, Guangdong Institute of Microbiology, Guangzhou, China
| | - Pengfei Yu
- State Key Laboratory of Applied Microbiology, Southern China and Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangdong Open Laboratory of Applied Microbiology, Guangdong Institute of Microbiology, Guangzhou, China
- Department of Food Science and Technology, Jinan University, Guangzhou, China
| | - Chengcheng Liu
- State Key Laboratory of Applied Microbiology, Southern China and Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangdong Open Laboratory of Applied Microbiology, Guangdong Institute of Microbiology, Guangzhou, China
- Department of Food Science and Technology, Jinan University, Guangzhou, China
| | - Li Kong
- State Key Laboratory of Applied Microbiology, Southern China and Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangdong Open Laboratory of Applied Microbiology, Guangdong Institute of Microbiology, Guangzhou, China
- Department of Food Science and Technology, Jinan University, Guangzhou, China
| | - Zhao Feng
- State Key Laboratory of Applied Microbiology, Southern China and Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangdong Open Laboratory of Applied Microbiology, Guangdong Institute of Microbiology, Guangzhou, China
- Department of Food Science and Technology, Jinan University, Guangzhou, China
| | - Moutong Chen
- State Key Laboratory of Applied Microbiology, Southern China and Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangdong Open Laboratory of Applied Microbiology, Guangdong Institute of Microbiology, Guangzhou, China
| | - Shi Wu
- State Key Laboratory of Applied Microbiology, Southern China and Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangdong Open Laboratory of Applied Microbiology, Guangdong Institute of Microbiology, Guangzhou, China
| | - Haiyan Zeng
- State Key Laboratory of Applied Microbiology, Southern China and Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangdong Open Laboratory of Applied Microbiology, Guangdong Institute of Microbiology, Guangzhou, China
| | - Haoming Wu
- State Key Laboratory of Applied Microbiology, Southern China and Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, Guangdong Open Laboratory of Applied Microbiology, Guangdong Institute of Microbiology, Guangzhou, China
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Whole-Genome Characterization of Bacillus cereus Associated with Specific Disease Manifestations. Infect Immun 2018; 86:IAI.00574-17. [PMID: 29158433 DOI: 10.1128/iai.00574-17] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Accepted: 11/13/2017] [Indexed: 12/17/2022] Open
Abstract
Bacillus cereus remains an important cause of infections, particularly in immunocompromised hosts. While typically associated with enteric infections, disease manifestations can be quite diverse and include skin infections, bacteremia, pneumonia, and meningitis. Whether there are any genetic correlates of bacterial strains with particular clinical manifestations remains unknown. To address this gap in understanding, we undertook whole-genome analysis of B. cereus strains isolated from patients with a range of disease manifestations, including noninvasive colonizing disease, superficial skin infections, and invasive bacteremia. Interestingly, strains involved in skin infection tended to form a distinct genetic cluster compared to isolates associated with invasive disease. Other disease manifestations, despite not being exclusively clustered, nonetheless had unique genetic features. The unique features associated with the specific types of infections ranged from traditional virulence determinants to metabolic pathways and gene regulators. These data represent the largest genetic analysis to date of pathogenic B. cereus isolates with associated clinical parameters.
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Evidence for Complex Formation of the Bacillus cereus Haemolysin BL Components in Solution. Toxins (Basel) 2017; 9:toxins9090288. [PMID: 28926954 PMCID: PMC5618221 DOI: 10.3390/toxins9090288] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Revised: 09/11/2017] [Accepted: 09/12/2017] [Indexed: 02/08/2023] Open
Abstract
Haemolysin BL is an important virulence factor regarding the diarrheal type of food poisoning caused by Bacillus cereus. However, the pathogenic importance of this three-component enterotoxin is difficult to access, as nearly all natural B. cereus culture supernatants additionally contain the highly cytotoxic Nhe, the second three-component toxin involved in the aetiology of B. cereus-induced food-borne diseases. To better address the toxic properties of the Hbl complex, a system for overexpression and purification of functional, cytotoxic, recombinant (r)Hbl components L2, L1 and B from E. coli was established and an nheABC deletion mutant was constructed from B. cereus reference strain F837/76. Furthermore, 35 hybridoma cell lines producing monoclonal antibodies (mAbs) against Hbl L2, L1 and B were generated. While mAbs 1H9 and 1D8 neutralized Hbl toxicity and thus, represent important tools for future investigations of the mode-of-action of Hbl on the target cell surface, mAb 1D7, in contrast, even enhanced Hbl toxicity by supporting the binding of Hbl B to the cell surface. By using the specific mAbs in Dot blots, indirect and hybrid sandwich enzyme immuno assays (EIAs), complex formation between Hbl L1 and B, as well as L1 and L2 in solution could be shown for the first time. Surface plasmon resonance experiments with the rHbl components confirmed these results with KD values of 4.7 × 10−7 M and 1.5 × 10−7 M, respectively. These findings together with the newly created tools lay the foundation for the detailed elucidation of the molecular mode-of-action of the highly complex three-component Hbl toxin.
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Geng P, Tian S, Yuan Z, Hu X. Identification and genomic comparison of temperate bacteriophages derived from emetic Bacillus cereus. PLoS One 2017; 12:e0184572. [PMID: 28886124 PMCID: PMC5590980 DOI: 10.1371/journal.pone.0184572] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Accepted: 08/25/2017] [Indexed: 01/21/2023] Open
Abstract
Cereulide-producing Bacillus cereus isolates can cause serious emetic (vomiting) syndrome and even acute lethality. As mobile genetic elements, the exploration of prophages derived from emetic B. cereus isolates will help in our understanding of the genetic diversity and evolution of these pathogens. In this study, five temperate phages derived from cereulide-producing B. cereus strains were induced, with four of them undergoing genomic sequencing. Sequencing revealed that they all belong to the Siphoviridae family, but presented in different forms in their hosts. PfNC7401 and PfIS075 have typical icosahedral heads, probably existing alone as phagemids in the host with self-replicating capability in the lysogenic state. PfEFR-4, PfEFR-5, and PfATCC7953 have elongated heads, with the genomes of the former two identified as linear dsDNA, which could be integrated into the host genome during the lysogenic state. Genomic comparison of the four phages with others also derived from emetic B. cereus isolates showed similar genome structures and core genes, thus displaying host spectrum specificity. In addition, phylogenic analysis based on the complete genome and conserved tail fiber proteins of 36 Bacillus species-derived phages confirmed that the phages derived from emetic B. cereus strains were highly similar. Furthermore, one endolysin LysPfEFR-4 was cloned and showed lytic activity against all tested emetic B. cereus strains and cross-lytic activity against some other pathogenic bacteria, implying a potential to control bacterial contamination in the food supply.
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Affiliation(s)
- Peiling Geng
- Key Laboratory of Special Pathogens and Biosafety, Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
- University of the Chinese Academy of Sciences, Beijing, China
| | - Shen Tian
- Key Laboratory of Special Pathogens and Biosafety, Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
| | - Zhiming Yuan
- Key Laboratory of Special Pathogens and Biosafety, Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
- * E-mail: (XH); (ZY)
| | - Xiaomin Hu
- Key Laboratory of Special Pathogens and Biosafety, Center for Emerging Infectious Diseases, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, China
- * E-mail: (XH); (ZY)
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Nielsen DS, Shepherd NE, Xu W, Lucke AJ, Stoermer MJ, Fairlie DP. Orally Absorbed Cyclic Peptides. Chem Rev 2017; 117:8094-8128. [PMID: 28541045 DOI: 10.1021/acs.chemrev.6b00838] [Citation(s) in RCA: 266] [Impact Index Per Article: 38.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Peptides and proteins are not orally bioavailable in mammals, although a few peptides are intestinally absorbed in small amounts. Polypeptides are generally too large and polar to passively diffuse through lipid membranes, while most known active transport mechanisms facilitate cell uptake of only very small peptides. Systematic evaluations of peptides with molecular weights above 500 Da are needed to identify parameters that influence oral bioavailability. Here we describe 125 cyclic peptides containing four to thirty-seven amino acids that are orally absorbed by mammals. Cyclization minimizes degradation in the gut, blood, and tissues by removing cleavable N- and C-termini and by shielding components from metabolic enzymes. Cyclization also folds peptides into bioactive conformations that determine exposure of polar atoms to solvation by water and lipids and therefore can influence oral bioavailability. Key chemical properties thought to influence oral absorption and bioavailability are analyzed, including molecular weight, octanol-water partitioning, hydrogen bond donors/acceptors, rotatable bonds, and polar surface area. The cyclic peptides violated to different degrees all of the limits traditionally considered to be important for oral bioavailability of drug-like small molecules, although fewer hydrogen bond donors and reduced flexibility generally favored oral absorption.
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Affiliation(s)
- Daniel S Nielsen
- Division of Chemistry and Structural Biology, and ‡Australian Research Council Centre of Excellence in Advanced Molecular Imaging, Institute for Molecular Bioscience, The University of Queensland , Brisbane, QLD 4072, Australia
| | - Nicholas E Shepherd
- Division of Chemistry and Structural Biology, and ‡Australian Research Council Centre of Excellence in Advanced Molecular Imaging, Institute for Molecular Bioscience, The University of Queensland , Brisbane, QLD 4072, Australia
| | - Weijun Xu
- Division of Chemistry and Structural Biology, and ‡Australian Research Council Centre of Excellence in Advanced Molecular Imaging, Institute for Molecular Bioscience, The University of Queensland , Brisbane, QLD 4072, Australia
| | - Andrew J Lucke
- Division of Chemistry and Structural Biology, and ‡Australian Research Council Centre of Excellence in Advanced Molecular Imaging, Institute for Molecular Bioscience, The University of Queensland , Brisbane, QLD 4072, Australia
| | - Martin J Stoermer
- Division of Chemistry and Structural Biology, and ‡Australian Research Council Centre of Excellence in Advanced Molecular Imaging, Institute for Molecular Bioscience, The University of Queensland , Brisbane, QLD 4072, Australia
| | - David P Fairlie
- Division of Chemistry and Structural Biology, and ‡Australian Research Council Centre of Excellence in Advanced Molecular Imaging, Institute for Molecular Bioscience, The University of Queensland , Brisbane, QLD 4072, Australia
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Jeßberger N, Rademacher C, Krey VM, Dietrich R, Mohr AK, Böhm ME, Scherer S, Ehling-Schulz M, Märtlbauer E. Simulating Intestinal Growth Conditions Enhances Toxin Production of Enteropathogenic Bacillus cereus. Front Microbiol 2017; 8:627. [PMID: 28446903 PMCID: PMC5388749 DOI: 10.3389/fmicb.2017.00627] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Accepted: 03/28/2017] [Indexed: 01/17/2023] Open
Abstract
Bacillus cereus is a ubiquitous bacterial pathogen increasingly reported to be the causative agent of foodborne infections and intoxications. Since the enterotoxins linked to the diarrheal form of food poising are foremost produced in the human intestine, the toxic potential of enteropathogenic B. cereus strains is difficult to predict from studies carried out under routine cultivation procedures. In this study, toxigenic properties of a panel of strains (n = 19) of diverse origin were compared using cell culture medium pre-incubated with CaCo-2 cells to mimic intestinal growth conditions. Shortly after contact of the bacteria with the simulated host environment, enterotoxin gene expression was activated and total protein secretion of all strains was accelerated. Although the signal stimulating enterotoxin production still needs to be elucidated, it could be shown that it originated from the CaCo-2 cells. Overall, our study demonstrates that the currently used methods in B. cereus diagnostics, based on standard culture medium, are not allowing a conclusive prediction of the potential health risk related to a certain strain. Thus, these methods should be complemented by cultivation procedures that are simulating intestinal host conditions.
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Affiliation(s)
- Nadja Jeßberger
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität MünchenOberschleißheim, Germany
| | - Corinna Rademacher
- Functional Microbiology, Department of Pathobiology, Institute of Microbiology, University of Veterinary Medicine ViennaVienna, Austria
| | - Viktoria M Krey
- Lehrstuhl für Mikrobielle Ökologie, Zentralinstitut für Ernährungs- und Lebensmittelforschung, Wissenschaftszentrum Weihenstephan, Technische Universität MünchenFreising, Germany
| | - Richard Dietrich
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität MünchenOberschleißheim, Germany
| | - Ann-Katrin Mohr
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität MünchenOberschleißheim, Germany
| | - Maria-Elisabeth Böhm
- Lehrstuhl für Mikrobielle Ökologie, Zentralinstitut für Ernährungs- und Lebensmittelforschung, Wissenschaftszentrum Weihenstephan, Technische Universität MünchenFreising, Germany
| | - Siegfried Scherer
- Lehrstuhl für Mikrobielle Ökologie, Zentralinstitut für Ernährungs- und Lebensmittelforschung, Wissenschaftszentrum Weihenstephan, Technische Universität MünchenFreising, Germany
| | - Monika Ehling-Schulz
- Functional Microbiology, Department of Pathobiology, Institute of Microbiology, University of Veterinary Medicine ViennaVienna, Austria
| | - Erwin Märtlbauer
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität MünchenOberschleißheim, Germany
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Jung SM, Kim NO, Cha I, Na HY, Chung GT, Kawk HS, Hong S. Surveillance of Bacillus cereus Isolates in Korea from 2012 to 2014. Osong Public Health Res Perspect 2017; 8:71-77. [PMID: 28443227 PMCID: PMC5402853 DOI: 10.24171/j.phrp.2017.8.1.10] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Objectives To investigate the prevalence and toxin production characteristics of non-emetic and emetic Bacillus cereus strains isolated via the laboratory surveillance system in Korea. Methods A total of 667 B. cereus strains were collected by the Korea National Research Institute of Health laboratory surveillance system from 2012 to 2014. The collected strains were analyzed by geographical region, season, patient age, and patient sex. Additionally, the prevalence rates of enterotoxin and emetic toxin genes were evaluated. Results The isolation rate of B. cereus strains increased during the summer, but the isolation rate was evenly distributed among patient age groups. Emetic toxin was produced by 20.2% of the isolated strains. The prevalence rates of five enterotoxin genes (entFM, nheA, cytK2, hblC, and bceT) were 85.0, 78.6, 44.5, 36.6, and 29.7%, respectively, among non-emetic strains and 77.8, 59.3, 17.8, 11.9 and 12.6%, respectively, among emetic strains. Thus, the prevalence rates of all five enterotoxin genes were lower in emetic B. cereus. Conclusion The prevalence of enterotoxin genes differed between non-emetic and emetic B. cereus strains. Among emetic B. cereus strains, the prevalence rates of two enterotoxin genes (cytK2 and hblC) were lower than those among the non-emetic strains. In both the emetic and non-emetic strains isolated in Korea, nheA and entFM were the most prevalent enterotoxin genes.
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Affiliation(s)
- Su-Mi Jung
- Division of Enteric Diseases, Center for Infectious Diseases, National Research Institute of Health, Osong, Korea
| | - Nan-Ok Kim
- Division of Enteric Diseases, Center for Infectious Diseases, National Research Institute of Health, Osong, Korea
| | - Injun Cha
- Division of Enteric Diseases, Center for Infectious Diseases, National Research Institute of Health, Osong, Korea
| | - Hae-Young Na
- Division of Enteric Diseases, Center for Infectious Diseases, National Research Institute of Health, Osong, Korea
| | - Gyung Tae Chung
- Division of Enteric Diseases, Center for Infectious Diseases, National Research Institute of Health, Osong, Korea
| | - Hyo Sun Kawk
- Division of Enteric Diseases, Center for Infectious Diseases, National Research Institute of Health, Osong, Korea
| | - Sahyun Hong
- Division of Enteric Diseases, Center for Infectious Diseases, National Research Institute of Health, Osong, Korea
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McClure RA, Goering AW, Ju KS, Baccile JA, Schroeder FC, Metcalf WW, Thomson RJ, Kelleher NL. Elucidating the Rimosamide-Detoxin Natural Product Families and Their Biosynthesis Using Metabolite/Gene Cluster Correlations. ACS Chem Biol 2016; 11:3452-3460. [PMID: 27809474 DOI: 10.1021/acschembio.6b00779] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
As microbial genome sequencing becomes more widespread, the capacity of microorganisms to produce an immense number of metabolites has come into better view. Utilizing a metabolite/gene cluster correlation platform, the biosynthetic origins of a new family of natural products, the rimosamides, were discovered. The rimosamides were identified in Streptomyces rimosus and associated with their NRPS/PKS-type gene cluster based upon their high frequency of co-occurrence across 179 strains of actinobacteria. This also led to the discovery of the related detoxin gene cluster. The core of each of these families of natural products contains a depsipeptide bond at the point of bifurcation in their unusual branched structures, the origins of which are definitively assigned to nonlinear biosynthetic pathways via heterologous expression in Streptomyces lividans. The rimosamides were found to antagonize the antibiotic activity of blasticidin S against Bacillus cereus.
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Affiliation(s)
- Ryan A. McClure
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Anthony W. Goering
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Kou-San Ju
- Carl R.
Woese Institute for Genomic Biology, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
| | - Joshua A. Baccile
- Boyce Thompson
Institute and Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Frank C. Schroeder
- Boyce Thompson
Institute and Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - William W. Metcalf
- Carl R.
Woese Institute for Genomic Biology, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
- Department of Microbiology, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
| | - Regan J. Thomson
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
| | - Neil. L Kelleher
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
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Screening of Cytotoxic B. cereus on Differentiated Caco-2 Cells and in Co-Culture with Mucus-Secreting (HT29-MTX) Cells. Toxins (Basel) 2016; 8:toxins8110320. [PMID: 27827957 PMCID: PMC5127117 DOI: 10.3390/toxins8110320] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Revised: 10/09/2016] [Accepted: 10/31/2016] [Indexed: 12/18/2022] Open
Abstract
B. cereus is an opportunistic foodborne pathogen able to cause diarrhoea. However, the diarrhoeal potential of a B. cereus strain remains difficult to predict, because no simple correlation has yet been identified between the symptoms and a unique or a specific combination of virulence factors. In this study, 70 B. cereus strains with different origins (food poisonings, foods and environment) have been selected to assess their enterotoxicity. The B. cereus cell-free supernatants have been tested for their toxicity in vitro, on differentiated (21 day-old) Caco-2 cells, using their ATP content, LDH release and NR accumulation. The genetic determinants of the main potential enterotoxins and virulence factors (ces, cytK, entFM, entS, hbl, nhe, nprA, piplC and sph) have also been screened by PCR. This analysis showed that none of these genes was able to fully explain the enterotoxicity of B. cereus strains. Additionally, in order to assess a possible effect of the mucus layer in vitro, a cytotoxicity comparison between a monoculture (Caco-2 cells) and a co-culture (Caco-2 and HT29-MTX mucus-secreting cells) model has been performed with selected B. cereus supernatants. It appeared that, in these conditions, the mucus layer had no notable influence on the cytotoxicity of B. cereus supernatants.
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Kranzler M, Stollewerk K, Rouzeau-Szynalski K, Blayo L, Sulyok M, Ehling-Schulz M. Temperature Exerts Control of Bacillus cereus Emetic Toxin Production on Post-transcriptional Levels. Front Microbiol 2016; 7:1640. [PMID: 27826288 PMCID: PMC5078297 DOI: 10.3389/fmicb.2016.01640] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2016] [Accepted: 10/03/2016] [Indexed: 11/20/2022] Open
Abstract
In recent years, the emetic toxin cereulide, produced by Bacillus cereus, has gained high relevance in food production and food safety. Cereulide is synthesized non-ribosomal by the multi-enzyme complex Ces-NRPS, which is encoded on a megaplasmid that shares its backbone with the Bacillus anthracis pX01 toxin plasmid. Due to its resistance against heat, proteolysis and extreme pH conditions, the formation of this highly potent depsipeptide toxin is of serious concern in food processing procedures including slow cooling procedures and/or storage of intermediate products at ambient temperatures. So far, systematic data on the effect of extrinsic factors on cereulide synthesis has been lacking. Thus, we investigated the influence of temperature, a central extrinsic parameter in food processing, on the regulation of cereulide synthesis on transcriptional, translational and post-translational levels over the growth temperature range of emetic B. cereus. Bacteria were grown in 3°C interval steps from 12 to 46°C and cereulide synthesis was followed from ces gene transcription to cereulide toxin production. This systematic study revealed that temperature is a cardinal parameter, which primarily impacts cereulide synthesis on post-transcriptional levels, thereby altering the composition of cereulide isoforms. Our work also highlights that the risk of cereulide production could not be predicted from growth parameters or sole cell numbers. Furthermore, for the first time we could show that the formation of the recently identified cereulide isoforms is highly temperature dependent, which may have great importance in terms of food safety and predictive microbiology. Notably the production of isocereulide A, which is about 10-fold more cytotoxic than cereulide, was specifically supported at low temperatures.
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Affiliation(s)
- Markus Kranzler
- Functional Microbiology, Institute of Microbiology, Department of Pathobiology, University of Veterinary Medicine Vienna Vienna, Austria
| | - Katharina Stollewerk
- Functional Microbiology, Institute of Microbiology, Department of Pathobiology, University of Veterinary Medicine Vienna Vienna, Austria
| | | | - Laurence Blayo
- Food Safety Microbiology, Nestec Ltd, Nestlé Research Center Lausanne, Switzerland
| | - Michael Sulyok
- Center for Analytical Chemistry, Department of Agrobiotechnology, IFA Tulln, University of Natural Resources and Life Sciences Vienna (BOKU) Vienna, Austria
| | - Monika Ehling-Schulz
- Functional Microbiology, Institute of Microbiology, Department of Pathobiology, University of Veterinary Medicine Vienna Vienna, Austria
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41
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Didier A, Dietrich R, Märtlbauer E. Antibody Binding Studies Reveal Conformational Flexibility of the Bacillus cereus Non-Hemolytic Enterotoxin (Nhe) A-Component. PLoS One 2016; 11:e0165135. [PMID: 27768742 PMCID: PMC5074587 DOI: 10.1371/journal.pone.0165135] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Accepted: 10/06/2016] [Indexed: 11/18/2022] Open
Abstract
The non-hemolytic enterotoxin complex (Nhe) is supposed to be the main virulence factor of B. cereus causing a diarrheal outcome of food poisoning. This tripartite toxin consists of the single components NheA, -B and -C all of them being necessary for maximum toxicity. In the past, research activities aiming to elucidate the mode-of-action of Nhe were mostly focused on the B- and C-component. In this study the generation of novel monoclonal antibodies (mAb) and their thorough characterization enabled the determination of key features for NheA. By the means of immunoaffinity chromatography it could be shown that NheA does not interact with -B and -C in solution. Additionally, the establishment of a highly sensitive sandwich-EIA now enables the detection of NheA in B. cereus supernatants down to 20 pg ml-1.Peptide-based epitope mapping in combination with partially deleted recombinant NheA fragments allowed the allocation of the binding regions for the three mAbs under study. Furthermore, by different EIA set-ups the conformational flexibility of NheA could be shown. For two of the antibodies under study different mechanisms of NheA neutralization were proven. Due to prevention of complete pore formation by one of the antibodies, NheA could be detected in an intermediate stage of the tripartite complex on the cell surface. Taken together, the results obtained in the present study allow a refinement of the mode-of-action for the Nhe toxin-complex.
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Affiliation(s)
- A. Didier
- Department of Veterinary Science, Ludwig-Maximilians Universität München, Oberschleißheim, Germany
- * E-mail:
| | - R. Dietrich
- Department of Veterinary Science, Ludwig-Maximilians Universität München, Oberschleißheim, Germany
| | - E. Märtlbauer
- Department of Veterinary Science, Ludwig-Maximilians Universität München, Oberschleißheim, Germany
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42
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Kato K, Matsumura Y, Yamamoto M, Nagao M, Ito Y, Takakura S, Ichiyama S. Erratum to: Seasonal trend and clinical presentation of Bacillus cereus bloodstream infection: association with summer and indwelling catheter. Eur J Clin Microbiol Infect Dis 2016; 35:875-83. [PMID: 27010814 DOI: 10.1007/s10096-016-2618-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Bacillus cereus, an opportunistic pathogen, can cause fatal infection. However, B. cereus bloodstream infections (BSIs) have not been well characterised. From 2008 to 2013, B. cereus isolates from all of the specimens and patients with B. cereus BSIs were identified. Environmental samples were collected to detect B. cereus contamination. We also characterised the clinical presentation of B. cereus BSI through analyses of risk factors for BSI and mortality. A total of 143 clinical B. cereus isolates was detected. Fifty-one patients with nosocomial infections were diagnosed as B. cereus BSI, and 37 had contaminated blood cultures. The number of B. cereus isolates and BSI patients was significantly greater from June to September than from January to April (3.4 vs. 1.0 per month and 1.4 vs. 0.2, respectively). All BSIs were nosocomial and related to central or peripheral vascular catheter. Urinary catheter [odds ratio (OR) 6.93, 95 % confidence interval (CI) 2.40-20.0] was the independent risk factor associated with BSI patients when compared to patients regarded as contaminated. In-hospital mortality among BSI patients was 20 % and was associated with urinary catheter (OR 12.3, 95 % CI 0.67-225, p=0.045) and higher Charlson index (OR 1.99, 95 % CI 1.26-3.12). The number of B. cereus isolates and BSI increased during summer. Inpatients with indwelling vascular or urinary catheters should be carefully monitored for potential B. cereus BSIs.
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Affiliation(s)
- K Kato
- Department of Clinical Laboratory Medicine, Kyoto University Graduate School of Medicine, 54 Shogoin-Kawaharacho, Sakyo-ku, Kyoto, 606-8507, Japan
| | - Y Matsumura
- Department of Clinical Laboratory Medicine, Kyoto University Graduate School of Medicine, 54 Shogoin-Kawaharacho, Sakyo-ku, Kyoto, 606-8507, Japan.
| | - M Yamamoto
- Department of Clinical Laboratory Medicine, Kyoto University Graduate School of Medicine, 54 Shogoin-Kawaharacho, Sakyo-ku, Kyoto, 606-8507, Japan
| | - M Nagao
- Department of Clinical Laboratory Medicine, Kyoto University Graduate School of Medicine, 54 Shogoin-Kawaharacho, Sakyo-ku, Kyoto, 606-8507, Japan
| | - Y Ito
- Department of Respiratory Medicine, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - S Takakura
- Department of Clinical Laboratory Medicine, Kyoto University Graduate School of Medicine, 54 Shogoin-Kawaharacho, Sakyo-ku, Kyoto, 606-8507, Japan
| | - S Ichiyama
- Department of Clinical Laboratory Medicine, Kyoto University Graduate School of Medicine, 54 Shogoin-Kawaharacho, Sakyo-ku, Kyoto, 606-8507, Japan
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Whole-Genome Sequences of Seven Strains of Bacillus cereus Isolated from Foodstuff or Poisoning Incidents. GENOME ANNOUNCEMENTS 2016; 4:4/3/e00435-16. [PMID: 27284145 PMCID: PMC4901214 DOI: 10.1128/genomea.00435-16] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We present here the whole shotgun genome sequences of seven strains of Bacillus cereus isolated from foodstuff samples or food poisoning incidents.
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Cui Y, Liu Y, Liu X, Xia X, Ding S, Zhu K. Evaluation of the Toxicity and Toxicokinetics of Cereulide from an Emetic Bacillus cereus Strain of Milk Origin. Toxins (Basel) 2016; 8:toxins8060156. [PMID: 27275834 PMCID: PMC4926125 DOI: 10.3390/toxins8060156] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2016] [Revised: 05/06/2016] [Accepted: 05/11/2016] [Indexed: 02/07/2023] Open
Abstract
Bacillus cereus is an opportunistic foodborne agent causing food poisoning and many infectious diseases. The heat-stable emetic toxin cereulide is one of the most prevalent toxins produced by pathogenic B. cereus, resulting in symptoms such as emesis and liver failure. In the present work, the toxicity and toxicokinetics of cereulide from an emetic B. cereus isolate (CAU45) of raw milk were evaluated. The production of cereulide was tested by a cytotoxicity test and enzyme immunoassay, and confirmed by the presence of the ces (cereulide synthetase) gene and the ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method. All results showed that the amount and toxicity of cereulide produced by CAU45 was 7 to 15.3 folds higher than the reference emetic B. cereus DSMZ 4312. Cereulide in plasma was collected at different time points after a single intravenous injection to evaluate its toxicokinetics in rabbits. The maximum concentration of cereulide was achieved in 2.6 ± 3.4 h after administration, with the elimination half-life of 10.8 ± 9.1 h, which expands our understanding of the toxic effects of cereulide. Together, it suggests that urgent sanitary practices are needed to eliminate emetic toxins and emetic B. cereus in raw milk.
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Affiliation(s)
- Yifang Cui
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China.
| | - Yuan Liu
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China.
| | - Xiaoye Liu
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China.
| | - Xi Xia
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China.
| | - Shuangyang Ding
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China.
| | - Kui Zhu
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China.
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA.
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45
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Cassilly CD, Maddox MM, Cherian PT, Bowling JJ, Hamann MT, Lee RE, Reynolds TB. SB-224289 Antagonizes the Antifungal Mechanism of the Marine Depsipeptide Papuamide A. PLoS One 2016; 11:e0154932. [PMID: 27183222 PMCID: PMC4868317 DOI: 10.1371/journal.pone.0154932] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Accepted: 04/21/2016] [Indexed: 12/20/2022] Open
Abstract
In order to expand the repertoire of antifungal compounds a novel, high-throughput phenotypic drug screen targeting fungal phosphatidylserine (PS) synthase (Cho1p) was developed based on antagonism of the toxin papuamide A (Pap-A). Pap-A is a cyclic depsipeptide that binds to PS in the membrane of wild-type Candida albicans, and permeabilizes its plasma membrane, ultimately causing cell death. Organisms with a homozygous deletion of the CHO1 gene (cho1ΔΔ) do not produce PS and are able to survive in the presence of Pap-A. Using this phenotype (i.e. resistance to Pap-A) as an indicator of Cho1p inhibition, we screened over 5,600 small molecules for Pap-A resistance and identified SB-224289 as a positive hit. SB-224289, previously reported as a selective human 5-HT1B receptor antagonist, also confers resistance to the similar toxin theopapuamide (TPap-A), but not to other cytotoxic depsipeptides tested. Structurally similar molecules and truncated variants of SB-224289 do not confer resistance to Pap-A, suggesting that the toxin-blocking ability of SB-224289 is very specific. Further biochemical characterization revealed that SB-224289 does not inhibit Cho1p, indicating that Pap-A resistance is conferred by another undetermined mechanism. Although the mode of resistance is unclear, interaction between SB-224289 and Pap-A or TPap-A suggests this screening assay could be adapted for discovering other compounds which could antagonize the effects of other environmentally- or medically-relevant depsipeptide toxins.
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Affiliation(s)
- Chelsi D. Cassilly
- Department of Microbiology, University of Tennessee, Knoxville, Tennessee, United States of America
| | - Marcus M. Maddox
- Department of Chemical Biology and Therapeutics, St. Jude Children’s Research Hospital, Memphis, Tennessee, 38105, United States of America
| | - Philip T. Cherian
- Department of Chemical Biology and Therapeutics, St. Jude Children’s Research Hospital, Memphis, Tennessee, 38105, United States of America
| | - John J. Bowling
- Department of Chemical Biology and Therapeutics, St. Jude Children’s Research Hospital, Memphis, Tennessee, 38105, United States of America
| | - Mark T. Hamann
- Department of Drug Discovery and Biomedical Sciences, College of Pharmacy, Medical University of South Carolina, Medical University of South Carolina, Charleston, South Carolina, United States of America
| | - Richard E. Lee
- Department of Chemical Biology and Therapeutics, St. Jude Children’s Research Hospital, Memphis, Tennessee, 38105, United States of America
| | - Todd B. Reynolds
- Department of Microbiology, University of Tennessee, Knoxville, Tennessee, United States of America
- * E-mail:
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Gopal N, Hill C, Ross PR, Beresford TP, Fenelon MA, Cotter PD. The Prevalence and Control of Bacillus and Related Spore-Forming Bacteria in the Dairy Industry. Front Microbiol 2015; 6:1418. [PMID: 26733963 PMCID: PMC4685140 DOI: 10.3389/fmicb.2015.01418] [Citation(s) in RCA: 147] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Accepted: 11/30/2015] [Indexed: 01/14/2023] Open
Abstract
Milk produced in udder cells is sterile but due to its high nutrient content, it can be a good growth substrate for contaminating bacteria. The quality of milk is monitored via somatic cell counts and total bacterial counts, with prescribed regulatory limits to ensure quality and safety. Bacterial contaminants can cause disease, or spoilage of milk and its secondary products. Aerobic spore-forming bacteria, such as those from the genera Sporosarcina, Paenisporosarcina, Brevibacillus, Paenibacillus, Geobacillus and Bacillus, are a particular concern in this regard as they are able to survive industrial pasteurization and form biofilms within pipes and stainless steel equipment. These single or multiple-species biofilms become a reservoir of spoilage microorganisms and a cycle of contamination can be initiated. Indeed, previous studies have highlighted that these microorganisms are highly prevalent in dead ends, corners, cracks, crevices, gaskets, valves and the joints of stainless steel equipment used in the dairy manufacturing plants. Hence, adequate monitoring and control measures are essential to prevent spoilage and ensure consumer safety. Common controlling approaches include specific cleaning-in-place processes, chemical and biological biocides and other novel methods. In this review, we highlight the problems caused by these microorganisms, and discuss issues relating to their prevalence, monitoring thereof and control with respect to the dairy industry.
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Affiliation(s)
- Nidhi Gopal
- Teagasc Food Research CentreCork, Ireland
- School of Microbiology, University College CorkCork, Ireland
| | - Colin Hill
- School of Microbiology, University College CorkCork, Ireland
- APC Microbiome InstituteCork, Ireland
| | - Paul R. Ross
- College of Science, Engineering and Food Science, University College CorkCork, Ireland
| | | | | | - Paul D. Cotter
- Teagasc Food Research CentreCork, Ireland
- APC Microbiome InstituteCork, Ireland
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47
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Lücking G, Frenzel E, Rütschle A, Marxen S, Stark TD, Hofmann T, Scherer S, Ehling-Schulz M. Ces locus embedded proteins control the non-ribosomal synthesis of the cereulide toxin in emetic Bacillus cereus on multiple levels. Front Microbiol 2015; 6:1101. [PMID: 26528255 PMCID: PMC4602138 DOI: 10.3389/fmicb.2015.01101] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Accepted: 09/23/2015] [Indexed: 11/13/2022] Open
Abstract
The emetic toxin cereulide produced by Bacillus cereus is synthesized by the modular enzyme complex Ces that is encoded on a pXO1-like megaplasmid. To decipher the role of the genes adjacent to the structural genes cesA/cesB, coding for the non-ribosomal peptide synthetase (NRPS), gene inactivation- and overexpression mutants of the emetic strain F4810/72 were constructed and their impact on cereulide biosynthesis was assessed. The hydrolase CesH turned out to be a part of the complex regulatory network controlling cereulide synthesis on a transcriptional level, while the ABC transporter CesCD was found to be essential for post-translational control of cereulide synthesis. Using a gene inactivation approach, we show that the NRPS activating function of the phosphopantetheinyl transferase (PPtase) embedded in the ces locus was complemented by a chromosomally encoded Sfp-like PPtase, representing an interesting example for the functional interaction between a plasmid encoded NRPS and a chromosomally encoded activation enzyme. In summary, our results highlight the complexity of cereulide biosynthesis and reveal multiple levels of toxin formation control. ces operon internal genes were shown to play a pivotal role by acting at different levels of toxin production, thus complementing the action of the chromosomal key transcriptional regulators AbrB and CodY.
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Affiliation(s)
- Genia Lücking
- Department of Microbiology, Central Institute for Food and Nutrition Research (Zentralinstitut für Ernährungs- und Lebensmittelforschung), Technische Universität München Freising, Germany
| | - Elrike Frenzel
- Functional Microbiology, Institute of Microbiology, Department of Pathobiology, University of Veterinary Medicine Vienna Vienna, Austria
| | - Andrea Rütschle
- Department of Microbiology, Central Institute for Food and Nutrition Research (Zentralinstitut für Ernährungs- und Lebensmittelforschung), Technische Universität München Freising, Germany
| | - Sandra Marxen
- Chair of Food Chemistry and Molecular Sensory Science, Technische Universität München Freising, Germany
| | - Timo D Stark
- Chair of Food Chemistry and Molecular Sensory Science, Technische Universität München Freising, Germany
| | - Thomas Hofmann
- Chair of Food Chemistry and Molecular Sensory Science, Technische Universität München Freising, Germany
| | - Siegfried Scherer
- Department of Microbiology, Central Institute for Food and Nutrition Research (Zentralinstitut für Ernährungs- und Lebensmittelforschung), Technische Universität München Freising, Germany ; Lehrstuhl für Mikrobielle Ökologie, Wissenschaftszentrum Weihenstephan, Technische Universität München Freising, Germany
| | - Monika Ehling-Schulz
- Functional Microbiology, Institute of Microbiology, Department of Pathobiology, University of Veterinary Medicine Vienna Vienna, Austria
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Abstract
Developments in the use of genomics to guide natural product discovery and a recent emphasis on understanding the molecular mechanisms of microbiota-host interactions have converged on the discovery of small molecules from the human microbiome. Here, we review what is known about small molecules produced by the human microbiota. Numerous molecules representing each of the major metabolite classes have been found that have a variety of biological activities, including immune modulation and antibiosis. We discuss technologies that will affect how microbiota-derived molecules are discovered in the future and consider the challenges inherent in finding specific molecules that are critical for driving microbe-host and microbe-microbe interactions and understanding their biological relevance.
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Affiliation(s)
- Mohamed S Donia
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA.
| | - Michael A Fischbach
- Department of Bioengineering and Therapeutic Sciences and the California Institute for Quantitative Biosciences, University of California, San Francisco, San Francisco, CA 94158, USA.
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Alonzo DA, Magarvey NA, Schmeing TM. Characterization of cereulide synthetase, a toxin-producing macromolecular machine. PLoS One 2015; 10:e0128569. [PMID: 26042597 PMCID: PMC4455996 DOI: 10.1371/journal.pone.0128569] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Accepted: 04/28/2015] [Indexed: 01/14/2023] Open
Abstract
Cereulide synthetase is a two-protein nonribosomal peptide synthetase system that produces a potent emetic toxin in virulent strains of Bacillus cereus. The toxin cereulide is a depsipeptide, as it consists of alternating aminoacyl and hydroxyacyl residues. The hydroxyacyl residues are derived from keto acid substrates, which cereulide synthetase selects and stereospecifically reduces with imbedded ketoreductase domains before incorporating them into the growing depsipeptide chain. We present an in vitro biochemical characterization of cereulide synthetase. We investigate the kinetics and side chain specificity of α-keto acid selection, evaluate the requirement of an MbtH-like protein for adenylation domain activity, assay the effectiveness of vinylsulfonamide inhibitors on ester-adding modules, perform NADPH turnover experiments and evaluate in vitro depsipeptide biosynthesis. This work also provides biochemical insight into depsipeptide-synthesizing nonribosomal peptide synthetases responsible for other bioactive molecules such as valinomycin, antimycin and kutzneride.
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Affiliation(s)
- Diego A. Alonzo
- Department of Biochemistry, McGill University, Montréal, QC H3G 0B1, Canada
| | - Nathan A. Magarvey
- Department of Chemistry & Chemical Biology, McMaster University, M.G. DeGroote Institute for Infectious Disease Research, 1200 Main St. W, Hamilton, Ontario L8N 3Z5, Canada
| | - T. Martin Schmeing
- Department of Biochemistry, McGill University, Montréal, QC H3G 0B1, Canada
- Groupe de Recherche Axé sur la Structure des Protéines (GRASP), McGill University, Montréal, QC H3G 0B1, Canada
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50
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Tewari A, Abdullah S. Bacillus cereus food poisoning: international and Indian perspective. JOURNAL OF FOOD SCIENCE AND TECHNOLOGY 2015; 52:2500-11. [PMID: 25892750 PMCID: PMC4397285 DOI: 10.1007/s13197-014-1344-4] [Citation(s) in RCA: 96] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Revised: 03/14/2014] [Accepted: 03/26/2014] [Indexed: 10/25/2022]
Abstract
Food borne illnesses result from eating food or drinking beverages that are contaminated with chemical matter, heavy metals, parasites, fungi, viruses and Bacteria. Bacillus cereus is one of the food-borne disease causing Bacteria. Species of Bacillus and related genera have long been troublesome to food producers on account of their resistant endospores. Their spores may be present on various types of raw and cooked foods, and their ability to survive high cooking temperatures requires that cooked foods be served hot or cooled rapidly to prevent the growth of this bacteria. Bacillus cereus is well known as a cause of food poisoning, and much more is now known about the toxins produced by various strains of this species, so that its significance in such episodes are clearer. However, it is still unclear why such cases are so rarely reported worldwide.
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Affiliation(s)
- Anita Tewari
- />School of Public Health & Zoonoses, Guru Angad Dev Veterinary and Animal Sciences University, Ludhiana, Punjab 141004 India
| | - Swaid Abdullah
- />Veterinary Parasitology & Ecology Group, School of Biological Sciences, University of Bristol, Bristol, UK
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