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Nagel AS, Vetrova OS, Rudenko NV, Karatovskaya AP, Zamyatina AV, Andreeva-Kovalevskaya ZI, Salyamov VI, Egorova NA, Siunov AV, Ivanova TD, Boziev KM, Brovko FA, Solonin AS. A High-Homology Region Provides the Possibility of Detecting β-Barrel Pore-Forming Toxins from Various Bacterial Species. Int J Mol Sci 2024; 25:5327. [PMID: 38791367 PMCID: PMC11120785 DOI: 10.3390/ijms25105327] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2024] [Revised: 04/12/2024] [Accepted: 04/16/2024] [Indexed: 05/26/2024] Open
Abstract
The pathogenicity of many bacteria, including Bacillus cereus and Staphylococcus aureus, depends on pore-forming toxins (PFTs), which cause the lysis of host cells by forming pores in the membranes of eukaryotic cells. Bioinformatic analysis revealed a region homologous to the Lys171-Gly250 sequence in hemolysin II (HlyII) from B. cereus in over 600 PFTs, which we designated as a "homologous peptide". Three β-barrel PFTs were used for a detailed comparative analysis. Two of them-HlyII and cytotoxin K2 (CytK2)-are synthesized in Bacillus cereus sensu lato; the third, S. aureus α-toxin (Hla), is the most investigated representative of the family. Protein modeling showed certain amino acids of the homologous peptide to be located on the surface of the monomeric forms of these β-barrel PFTs. We obtained monoclonal antibodies against both a cloned homologous peptide and a 14-membered synthetic peptide, DSFNTFYGNQLFMK, as part of the homologous peptide. The HlyII, CytK2, and Hla regions recognized by the obtained antibodies, as well as an antibody capable of suppressing the hemolytic activity of CytK2, were identified in the course of this work. Antibodies capable of recognizing PFTs of various origins can be useful tools for both identification and suppression of the cytolytic activity of PFTs.
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Affiliation(s)
- Alexey S. Nagel
- FSBIS FRC Pushchino Scientific Centre of Biological Research, G.K. Skryabin Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, 5 Prospekt Nauki, 142290 Pushchino, Moscow Region, Russia; (A.S.N.); (Z.I.A.-K.); (V.I.S.); (A.V.S.); (T.D.I.); (A.S.S.)
| | - Olesya S. Vetrova
- Pushchino Branch, Shemyakin–Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 6 Prospekt Nauki, 142290 Pushchino, Moscow Region, Russia; (O.S.V.); (A.P.K.); (A.V.Z.); (K.M.B.); (F.A.B.)
| | - Natalia V. Rudenko
- Pushchino Branch, Shemyakin–Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 6 Prospekt Nauki, 142290 Pushchino, Moscow Region, Russia; (O.S.V.); (A.P.K.); (A.V.Z.); (K.M.B.); (F.A.B.)
| | - Anna P. Karatovskaya
- Pushchino Branch, Shemyakin–Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 6 Prospekt Nauki, 142290 Pushchino, Moscow Region, Russia; (O.S.V.); (A.P.K.); (A.V.Z.); (K.M.B.); (F.A.B.)
| | - Anna V. Zamyatina
- Pushchino Branch, Shemyakin–Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 6 Prospekt Nauki, 142290 Pushchino, Moscow Region, Russia; (O.S.V.); (A.P.K.); (A.V.Z.); (K.M.B.); (F.A.B.)
| | - Zhanna I. Andreeva-Kovalevskaya
- FSBIS FRC Pushchino Scientific Centre of Biological Research, G.K. Skryabin Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, 5 Prospekt Nauki, 142290 Pushchino, Moscow Region, Russia; (A.S.N.); (Z.I.A.-K.); (V.I.S.); (A.V.S.); (T.D.I.); (A.S.S.)
| | - Vadim I. Salyamov
- FSBIS FRC Pushchino Scientific Centre of Biological Research, G.K. Skryabin Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, 5 Prospekt Nauki, 142290 Pushchino, Moscow Region, Russia; (A.S.N.); (Z.I.A.-K.); (V.I.S.); (A.V.S.); (T.D.I.); (A.S.S.)
| | - Nadezhda A. Egorova
- Federal State Budgetary Educational Institution of Higher Education “Ryazan State University Named for S.A. Yesenin”, 46 st. Svobody, 390000 Ryazan, Ryazan Region, Russia;
| | - Alexander V. Siunov
- FSBIS FRC Pushchino Scientific Centre of Biological Research, G.K. Skryabin Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, 5 Prospekt Nauki, 142290 Pushchino, Moscow Region, Russia; (A.S.N.); (Z.I.A.-K.); (V.I.S.); (A.V.S.); (T.D.I.); (A.S.S.)
| | - Tatiana D. Ivanova
- FSBIS FRC Pushchino Scientific Centre of Biological Research, G.K. Skryabin Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, 5 Prospekt Nauki, 142290 Pushchino, Moscow Region, Russia; (A.S.N.); (Z.I.A.-K.); (V.I.S.); (A.V.S.); (T.D.I.); (A.S.S.)
| | - Khanafi M. Boziev
- Pushchino Branch, Shemyakin–Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 6 Prospekt Nauki, 142290 Pushchino, Moscow Region, Russia; (O.S.V.); (A.P.K.); (A.V.Z.); (K.M.B.); (F.A.B.)
| | - Fedor A. Brovko
- Pushchino Branch, Shemyakin–Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 6 Prospekt Nauki, 142290 Pushchino, Moscow Region, Russia; (O.S.V.); (A.P.K.); (A.V.Z.); (K.M.B.); (F.A.B.)
| | - Alexander S. Solonin
- FSBIS FRC Pushchino Scientific Centre of Biological Research, G.K. Skryabin Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, 5 Prospekt Nauki, 142290 Pushchino, Moscow Region, Russia; (A.S.N.); (Z.I.A.-K.); (V.I.S.); (A.V.S.); (T.D.I.); (A.S.S.)
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Fichant A, Lanceleur R, Hachfi S, Brun-Barale A, Blier AL, Firmesse O, Gallet A, Fessard V, Bonis M. New Approach Methods to Assess the Enteropathogenic Potential of Strains of the Bacillus cereus Group, including Bacillus thuringiensis. Foods 2024; 13:1140. [PMID: 38672813 PMCID: PMC11048917 DOI: 10.3390/foods13081140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2024] [Revised: 04/03/2024] [Accepted: 04/04/2024] [Indexed: 04/28/2024] Open
Abstract
Bacillus cereus (Bc) is a wide group of Gram-positive and spore-forming bacteria, known to be the etiological agents of various human infections, primarily food poisoning. The Bc group includes enteropathogenic strains able to germinate in the digestive tract and to produce enterotoxins such as Nhe, Hbl, and CytK. One species of the group, Bacillus thuringiensis (Bt), has the unique feature of producing insecticidal crystals during sporulation, making it an important alternative to chemical pesticides to protect crops from insect pest larvae. Nevertheless, several studies have suggested a link between the ingestion of pesticide strains and human cases of food poisoning, calling their safety into question. Consequently, reliable tools for virulence assessment are worth developing to aid decision making in pesticide regulation. Here, we propose complementary approaches based on two biological models, the human intestinal Caco-2 cell line and the insect Drosophila melanogaster, to assess and rank the enteric virulence potency of Bt strains in comparison with other Bc group members. Using a dataset of 48 Bacillus spp. strains, we showed that some Bc group strains, including Bt, were able to induce cytotoxicity in Caco-2 cells with concomitant release of IL-8 cytokine, a landmark of pro-inflammatory response. In the D. melanogaster model, we were able to sort a panel of 39 strains into four different classes of virulence, ranging from no virulence to strong virulence. Importantly, for the most virulent strains, mortality was associated with a loss of intestinal barrier integrity. Interestingly, although strains can share a common toxinotype, they display different degrees of virulence, suggesting the existence of specific mechanisms of virulence expression in vivo in the intestine.
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Affiliation(s)
- Arnaud Fichant
- Laboratory for Food Safety, University Paris-Est, French Agency for Food, Environmental and Occupational Health & Safety (ANSES), 94700 Maisons-Alfort, France; (A.F.); (O.F.)
- Université Côte d’Azur, CNRS, INRAE, ISA, 06903 Sophia-Antipolis, France; (S.H.); (A.B.-B.); (A.G.)
| | - Rachelle Lanceleur
- Fougères Laboratory, French Agency for Food, Environmental and Occupational Health & Safety (ANSES), 35306 Fougères, France; (R.L.); (A.-L.B.); (V.F.)
| | - Salma Hachfi
- Université Côte d’Azur, CNRS, INRAE, ISA, 06903 Sophia-Antipolis, France; (S.H.); (A.B.-B.); (A.G.)
| | - Alexandra Brun-Barale
- Université Côte d’Azur, CNRS, INRAE, ISA, 06903 Sophia-Antipolis, France; (S.H.); (A.B.-B.); (A.G.)
| | - Anne-Louise Blier
- Fougères Laboratory, French Agency for Food, Environmental and Occupational Health & Safety (ANSES), 35306 Fougères, France; (R.L.); (A.-L.B.); (V.F.)
| | - Olivier Firmesse
- Laboratory for Food Safety, University Paris-Est, French Agency for Food, Environmental and Occupational Health & Safety (ANSES), 94700 Maisons-Alfort, France; (A.F.); (O.F.)
| | - Armel Gallet
- Université Côte d’Azur, CNRS, INRAE, ISA, 06903 Sophia-Antipolis, France; (S.H.); (A.B.-B.); (A.G.)
| | - Valérie Fessard
- Fougères Laboratory, French Agency for Food, Environmental and Occupational Health & Safety (ANSES), 35306 Fougères, France; (R.L.); (A.-L.B.); (V.F.)
| | - Mathilde Bonis
- Laboratory for Food Safety, University Paris-Est, French Agency for Food, Environmental and Occupational Health & Safety (ANSES), 94700 Maisons-Alfort, France; (A.F.); (O.F.)
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Gummelt C, Dupke S, Howaldt S, Zimmermann F, Scholz HC, Laue M, Klee SR. Analysis of Sporulation in Bacillus cereus Biovar anthracis Which Contains an Insertion in the Gene for the Sporulation Factor σ K. Pathogens 2023; 12:1442. [PMID: 38133325 PMCID: PMC10745906 DOI: 10.3390/pathogens12121442] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Revised: 12/08/2023] [Accepted: 12/11/2023] [Indexed: 12/23/2023] Open
Abstract
Bacillus cereus biovar anthracis (Bcbva) is an untypical pathogen causing a fatal anthrax-like disease in a variety of wildlife species in African rainforest areas. In contrast to Bacillus anthracis and most species of the B. cereus group, all strains of the Bcbva cluster contain a 22 kb insertion in the sigK gene which encodes the essential late sporulation sigma factor σK. This insertion is excised during sporulation in a site-specific recombination process resulting in an intact sigK gene and a circular molecule. The sporulation kinetics of two strains each of Bcbva and B. anthracis were compared by the expression analysis of eight sporulation-associated genes, including sigK, using reverse transcriptase quantitative real-time PCR. In addition, morphological sporulation stages were analyzed and quantified by electron microscopy. Our results indicated that the necessary excision of the insertion in Bcbva neither delayed nor inhibited its sporulation. In two spontaneous mutants of Bcbva, the excision of the sigK insertion and sporulation were impeded due to mutations in the spo0A and spoVG regulator genes, respectively. The spo0A frameshift mutation was overcome by intragenic suppression in a revertant which was able to sporulate normally, despite an M171S amino acid exchange in the global regulator Spo0A. A screening of the NCBI database identified further strains of the B. cereus group which possess unrelated insertions in the sigK gene, and two strains containing almost identical insertions at the same gene position. Some of the sigK insertions encode putative prophages, whereas the Bcbva insertion encoded a type I restriction-modification system. The function of these insertions and if they are possibly essential for sporulation remains to be assessed.
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Affiliation(s)
- Constanze Gummelt
- Highly Pathogenic Microorganisms (ZBS 2), Centre for Biological Threats and Special Pathogens, Robert Koch Institute, 13353 Berlin, Germany; (C.G.); (S.D.); (S.H.); (H.C.S.)
| | - Susann Dupke
- Highly Pathogenic Microorganisms (ZBS 2), Centre for Biological Threats and Special Pathogens, Robert Koch Institute, 13353 Berlin, Germany; (C.G.); (S.D.); (S.H.); (H.C.S.)
| | - Sabine Howaldt
- Highly Pathogenic Microorganisms (ZBS 2), Centre for Biological Threats and Special Pathogens, Robert Koch Institute, 13353 Berlin, Germany; (C.G.); (S.D.); (S.H.); (H.C.S.)
| | - Fee Zimmermann
- Epidemiology of Highly Pathogenic Microorganisms (P3), Robert Koch Institute, 13353 Berlin, Germany;
| | - Holger C. Scholz
- Highly Pathogenic Microorganisms (ZBS 2), Centre for Biological Threats and Special Pathogens, Robert Koch Institute, 13353 Berlin, Germany; (C.G.); (S.D.); (S.H.); (H.C.S.)
| | - Michael Laue
- Advanced Light and Electron Microscopy (ZBS 4), Centre for Biological Threats and Special Pathogens, Robert Koch Institute, 13353 Berlin, Germany;
| | - Silke R. Klee
- Highly Pathogenic Microorganisms (ZBS 2), Centre for Biological Threats and Special Pathogens, Robert Koch Institute, 13353 Berlin, Germany; (C.G.); (S.D.); (S.H.); (H.C.S.)
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Sokolov S, Brovko F, Solonin A, Nikanova D, Fursova K, Artyemieva O, Kolodina E, Sorokin A, Shchannikova M, Dzhelyadin T, Ermakov A, Boziev K, Zinovieva N. Genomic analysis and assessment of pathogenic (toxicogenic) potential of Staphylococcus haemolyticus and Bacillus paranthracis consortia isolated from bovine mastitis in Russia. Sci Rep 2023; 13:18646. [PMID: 37903798 PMCID: PMC10616132 DOI: 10.1038/s41598-023-45643-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Accepted: 10/22/2023] [Indexed: 11/01/2023] Open
Abstract
Three stable microbial consortia, each composed of Bacillus paranthracis and Staphylococcus haemolyticus strains, were isolated from milk of cows diagnosed with mastitis in three geographically remote regions of Russia. The composition of these consortia remained stable following multiple passages on culture media. Apparently, this stability is due to the structure of the microbial biofilms formed by the communities. The virulence of the consortia depended on the B. paranthracis strains. It seems plausible that the ability of the consortia to cause mastitis in cattle was affected by mutations of the cytK gene of B. paranthracis.
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Affiliation(s)
- Sergei Sokolov
- Laboratory of Microbiology, L.K. Ernst Federal Science Center for Animal Husbandry, Dubrovitsy, 142132, Russia.
- Laboratory of Plasmid Biology, Federal Research Center "Pushchino Scientific Center for Biological Researches", G.K. Skryabin Institute of Biochemistry & Physiology of Microorganisms of the Russian Academy of Sciences, Pushchino, 142290, Russia.
| | - Fedor Brovko
- Laboratory of Microbiology, L.K. Ernst Federal Science Center for Animal Husbandry, Dubrovitsy, 142132, Russia
- Laboratory of Immunochemistry, Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, Pushchino, 142290, Russia
| | - Alexander Solonin
- Laboratory of Plasmid Biology, Federal Research Center "Pushchino Scientific Center for Biological Researches", G.K. Skryabin Institute of Biochemistry & Physiology of Microorganisms of the Russian Academy of Sciences, Pushchino, 142290, Russia
| | - Daria Nikanova
- Laboratory of Microbiology, L.K. Ernst Federal Science Center for Animal Husbandry, Dubrovitsy, 142132, Russia
| | - Ksenia Fursova
- Laboratory of Immunochemistry, Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, Pushchino, 142290, Russia
| | - Olga Artyemieva
- Laboratory of Microbiology, L.K. Ernst Federal Science Center for Animal Husbandry, Dubrovitsy, 142132, Russia
| | - Evgenia Kolodina
- Laboratory of Microbiology, L.K. Ernst Federal Science Center for Animal Husbandry, Dubrovitsy, 142132, Russia
| | - Anatoly Sorokin
- Laboratory of Cell Genome Functioning Mechanisms, Federal Research Center "Pushchino Scientific Center for Biological Researches", Institute of Cell Biophysics of the Russian Academy of Sciences, Pushchino, 142290, Russia
| | - Margarita Shchannikova
- Laboratory of Immunochemistry, Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, Pushchino, 142290, Russia
| | - Timur Dzhelyadin
- Laboratory of Cell Genome Functioning Mechanisms, Federal Research Center "Pushchino Scientific Center for Biological Researches", Institute of Cell Biophysics of the Russian Academy of Sciences, Pushchino, 142290, Russia
| | - Artem Ermakov
- Laboratory of Cell Genome Functioning Mechanisms, Federal Research Center "Pushchino Scientific Center for Biological Researches", Institute of Cell Biophysics of the Russian Academy of Sciences, Pushchino, 142290, Russia
| | - Khanafy Boziev
- Laboratory of Immunochemistry, Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, Pushchino, 142290, Russia
| | - Natalia Zinovieva
- Laboratory of Microbiology, L.K. Ernst Federal Science Center for Animal Husbandry, Dubrovitsy, 142132, Russia
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Nagel AS, Rudenko NV, Luchkina PN, Karatovskaya AP, Zamyatina AV, Andreeva-Kovalevskaya ZI, Siunov AV, Brovko FA, Solonin AS. Region Met225 to Ile412 of Bacillus cereus Hemolysin II Is Capable to Agglutinate Red Blood Cells. Molecules 2023; 28:molecules28083581. [PMID: 37110815 PMCID: PMC10140989 DOI: 10.3390/molecules28083581] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2023] [Revised: 03/28/2023] [Accepted: 04/18/2023] [Indexed: 04/29/2023] Open
Abstract
Hemolysin II (HlyII) is one of the virulence factors of the opportunistic bacterium Bacillus cereus belonging to the group of β-pore-forming toxins. This work created a genetic construct encoding a large C-terminal fragment of the toxin (HlyIILCTD, M225-I412 according to the numbering of amino acid residues in HlyII). A soluble form of HlyIILCTD was obtained using the SlyD chaperone protein. HlyIILCTD was first shown to be capable of agglutinating rabbit erythrocytes. Monoclonal antibodies against HlyIILCTD were obtained by hybridoma technology. We also proposed a mode of rabbit erythrocyte agglutination by HlyIILCTD and selected three anti-HlyIILCTD monoclonal antibodies that inhibited the agglutination.
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Affiliation(s)
- Alexey S Nagel
- G.K. Skryabin Institute of Biochemistry and Physiology of Microorganisms, FRC Pushchino Scientific Centre of Biological Research, Russian Academy of Sciences, 5 Prospekt Nauki, 142290 Pushchino, Moscow Region, Russia
| | - Natalia V Rudenko
- Pushchino Branch, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 6 Prospekt Nauki, 142290 Pushchino, Moscow Region, Russia
| | - Polina N Luchkina
- G.K. Skryabin Institute of Biochemistry and Physiology of Microorganisms, FRC Pushchino Scientific Centre of Biological Research, Russian Academy of Sciences, 5 Prospekt Nauki, 142290 Pushchino, Moscow Region, Russia
| | - Anna P Karatovskaya
- Pushchino Branch, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 6 Prospekt Nauki, 142290 Pushchino, Moscow Region, Russia
| | - Anna V Zamyatina
- Pushchino Branch, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 6 Prospekt Nauki, 142290 Pushchino, Moscow Region, Russia
| | - Zhanna I Andreeva-Kovalevskaya
- G.K. Skryabin Institute of Biochemistry and Physiology of Microorganisms, FRC Pushchino Scientific Centre of Biological Research, Russian Academy of Sciences, 5 Prospekt Nauki, 142290 Pushchino, Moscow Region, Russia
| | - Alexander V Siunov
- G.K. Skryabin Institute of Biochemistry and Physiology of Microorganisms, FRC Pushchino Scientific Centre of Biological Research, Russian Academy of Sciences, 5 Prospekt Nauki, 142290 Pushchino, Moscow Region, Russia
| | - Fedor A Brovko
- Pushchino Branch, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 6 Prospekt Nauki, 142290 Pushchino, Moscow Region, Russia
| | - Alexander S Solonin
- G.K. Skryabin Institute of Biochemistry and Physiology of Microorganisms, FRC Pushchino Scientific Centre of Biological Research, Russian Academy of Sciences, 5 Prospekt Nauki, 142290 Pushchino, Moscow Region, Russia
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Birt HWG, Pattison AB, Skarshewski A, Daniells J, Raghavendra A, Dennis PG. The core bacterial microbiome of banana (Musa spp.). ENVIRONMENTAL MICROBIOME 2022; 17:46. [PMID: 36076285 PMCID: PMC9461194 DOI: 10.1186/s40793-022-00442-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Accepted: 08/15/2022] [Indexed: 06/15/2023]
Abstract
BACKGROUND Bananas (Musa spp.) are a globally significant crop and are severely afflicted by diseases for which there are no effective chemical controls. Banana microbiomes may provide novel solutions to these constraints but are difficult to manage due to their high diversity and variability between locations. Hence 'common core' taxa, which are a subset of the microbiome that frequent all, or most, individuals of a host species, represent logical targets for the development of microbiome management approaches. Here, we first performed a pot experiment to characterise the effects of two factors that are likely to differ between farms (viz. edaphic conditions and host genotype) on bacterial diversity in bulk soil and seven plant compartments. From this experiment, we created shortlisted core 'candidates' that were then refined using a survey of 52 field-grown Musa spp. We confirmed the importance of the core through network analysis and by comparing the sequences of our core taxa with those reported in 22 previous studies. RESULTS Diversity was found to differ between plant compartments and soils, but not genotypes. Therefore, we identified populations that were frequent across most plants irrespective of the soil in which they were grown. This led to the selection of 36 'common core' bacteria, that represented 65-95% of the dominant taxa in field-grown plants and were identified as highly interconnected 'hubs' using network analysis - a characteristic shown to be indicative of microbes that influence host fitness in studies of other plants. Lastly, we demonstrated that the core taxa are closely related to banana-associated bacteria observed on five other continents. CONCLUSIONS Our study provides a robust list of common core bacterial taxa for Musa spp. Further research may now focus on how changes in the frequencies and activities of these most persistent taxa influence host fitness. Notably, for several of our core taxa, highly similar populations have already been isolated in previous studies and may be amenable to such experimentation. This contribution should help to accelerate the development of effective Musa spp. microbiome management practices.
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Affiliation(s)
- Henry W. G. Birt
- School of Earth and Environmental Sciences, The University of Queensland, Brisbane, QLD 4072 Australia
| | - Anthony B. Pattison
- School of Earth and Environmental Sciences, The University of Queensland, Brisbane, QLD 4072 Australia
- Department of Agriculture and Fisheries, Centre for Wet Tropics Agriculture, 24 Experimental Station Road, South Johnstone, QLD 4859 Australia
| | - Adam Skarshewski
- School of Earth and Environmental Sciences, The University of Queensland, Brisbane, QLD 4072 Australia
| | - Jeff Daniells
- Department of Agriculture and Fisheries, Centre for Wet Tropics Agriculture, 24 Experimental Station Road, South Johnstone, QLD 4859 Australia
| | - Anil Raghavendra
- School of Earth and Environmental Sciences, The University of Queensland, Brisbane, QLD 4072 Australia
| | - Paul G. Dennis
- School of Earth and Environmental Sciences, The University of Queensland, Brisbane, QLD 4072 Australia
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Dervyn R, Kavanaugh DW, Cormontagne D, Glasset B, Ramarao N. Identification of a New Pathogenicity Island Within the Large pAH187_270 Plasmid Involved in Bacillus cereus Virulence. Front Cell Infect Microbiol 2022; 11:788757. [PMID: 35127556 PMCID: PMC8811155 DOI: 10.3389/fcimb.2021.788757] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2021] [Accepted: 10/21/2021] [Indexed: 11/25/2022] Open
Abstract
Objectives Bacillus cereus is responsible for food poisoning and rare but severe clinical infections. The pathogenicity of B. cereus strains varies from harmless to lethal strains. The objective of this study was to characterize three B. cereus isolates isolated from the same patient and identify their virulence potentials. Methods Three isolates of B. cereus were isolated from various blood samples from a patient who developed sepsis following a central venous catheter infection. The three isolates were compared by WGS, genotyping and SNP analysis. Furthermore, the isolates were compared by phenotypical analysis including bacterial growth, morphology, germination efficacy, toxin production, antibiotic susceptibility and virulence in an insect model of infection. Results According to WGS and genotyping, the 3 isolates were shown to be identical strains. However, the last recovered strain had lost the mega pAH187_270 plasmid. This last strain showed different phenotypes compared to the first isolated strain, such as germination delay, different antibiotic susceptibility and a decreased virulence capacity towards insects. A 50- kbp region of pAH187_270 plasmid was involved in the virulence potential and could thus be defined as a new pathogenicity island of B. cereus. Conclusions These new findings help in the understanding of B. cereus pathogenic potential and complexity and provide further hints into the role of large plasmids in the virulence of B. cereus strains. This may provide tools for a better assessment of the risks associated with B. cereus hospital contamination to improve hygiene procedure and patient health.
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Kavanaugh DW, Porrini C, Dervyn R, Ramarao N. The pathogenic biomarker alcohol dehydrogenase protein is involved in Bacillus cereus virulence and survival against host innate defence. PLoS One 2022; 17:e0259386. [PMID: 34982789 PMCID: PMC8726459 DOI: 10.1371/journal.pone.0259386] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Accepted: 10/18/2021] [Indexed: 11/19/2022] Open
Abstract
Bacillus cereus is a spore forming bacteria recognized among the leading agents responsible for foodborne outbreaks in Europe. B. cereus is also gaining notoriety as an opportunistic human pathogen inducing local and systemic infections. The real incidence of such infection is likely underestimated and information on genetic and phenotypic characteristics of the incriminated strains is generally scarce. We have recently analyzed a large strain collection of varying pathogenic potential. Screening for biomarkers to differentiate among clinical and non-clinical strains, a gene encoding an alcohol dehydrogenase-like protein was identified among the leading candidates. This family of proteins has been demonstrated to be involved in the virulence of several bacterial species. The relevant gene was knocked out to elucidate its function with regards to resistance to host innate immune response, both in vitro and in vivo. Our results demonstrate that the adhB gene plays a significant role in resistance to nitric oxide and oxidative stress in vitro, as well as its pathogenic ability with regards to in vivo toxicity. These properties may explain the pathogenic potential of strains carrying this newly identified virulence factor.
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Affiliation(s)
- Devon W. Kavanaugh
- Micalis Institute, INRAE, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| | - Constance Porrini
- Micalis Institute, INRAE, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| | - Rozenn Dervyn
- Micalis Institute, INRAE, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| | - Nalini Ramarao
- Micalis Institute, INRAE, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
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9
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Consentino L, Rejasse A, Crapart N, Bevilacqua C, Nielsen-LeRoux C. Laser capture microdissection to study Bacillus cereus iron homeostasis gene expression during Galleria mellonella in vivo gut colonization. Virulence 2021; 12:2104-2121. [PMID: 34374318 PMCID: PMC8366545 DOI: 10.1080/21505594.2021.1959790] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Bacillus cereus is a Gram-positive opportunistic pathogen closely related to the entomopathogen, Bacillus thuringiensis, both of which are involved in intestinal infections. Iron is an essential micronutrient for full growth and virulence of pathogens during infection. However, little is known about iron homeostasis during gut infection. Therefore, we aimed to assess the expression of B. cereus genes related to bacterial iron homeostasis, virulence and oxidative stress. The hypothesis is that the expression of such genes would vary between early and later stage colonization in correlation to gut cell damage. To perform the study, a germ-free Galleria mellonella model was set up in order to adapt the use of Laser-capture microdissection (LCM), to select precise areas in the gut lumen from frozen whole larval cryo-sections. Analyses were performed from alive larvae and the expression of targeted genes was assessed byspecific pre-amplification of mRNA followed by quantitative PCR. Firstly, the results reinforce the reliability of LCM, despite a low amount of bacterial RNA recovered. Secondly, bacterial genes involved in iron homeostasis are expressed in the lumen at both 3 and 16 hours post force-feeding. Thirdly, iron gene expression is slightly modulated during gut infection, and lastly, the mRNA of G. mellonella encoding for ferritin and transferrin iron storage and transport are recovered too. Therefore, iron homeostasis should play a role in B. cereus gut colonization. Furthermore, we demonstrate for the first time the value of using LCM for specific in situ gene expression analysis of extracellular bacteria in a whole animal.
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Affiliation(s)
- Laurent Consentino
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, Jouy-en-Josas, France
| | - Agnès Rejasse
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, Jouy-en-Josas, France
| | - Nicolas Crapart
- Université Paris Saclay, INRAE, AgroParisTech, UMR GABI, Abridge, Jouy En Josas, France.,Exilone, Elancourt, France
| | - Claudia Bevilacqua
- Université Paris Saclay, INRAE, AgroParisTech, UMR GABI, Abridge, Jouy En Josas, France
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10
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Kavanaugh DW, Glasset B, Dervyn R, Guérin C, Plancade S, Herbin S, Brisabois A, Nicolas P, Ramarao N. New genetic biomarkers to differentiate non-pathogenic from clinically relevant Bacillus cereus strains. Clin Microbiol Infect 2021; 28:137.e1-137.e8. [PMID: 34111580 DOI: 10.1016/j.cmi.2021.05.035] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 05/18/2021] [Accepted: 05/22/2021] [Indexed: 01/14/2023]
Abstract
OBJECTIVES Bacillus cereus is responsible for food poisoning and rare but severe clinical infections. The pathogenicity of strains varies from harmless to lethal strains. However, there are currently no markers, either alone or in combination, to differentiate pathogenic from non-pathogenic strains. The objective of the study was to identify new genetic biomarkers to differentiate non-pathogenic from clinically relevant B. cereus strains. METHODS A first set of 15 B. cereus strains were compared by RNAseq. A logistic regression model with lasso penalty was applied to define combination of genes whose expression was associated with strain pathogenicity. The identified markers were checked for their presence/absence in a collection of 95 B. cereus strains with varying pathogenic potential (food-borne outbreaks, clinical and non-pathogenic). Receiver operating characteristic area under the curve (AUC) analysis was used to determine the combination of biomarkers, which best differentiate between the "disease" versus "non-disease" groups. RESULTS Seven genes were identified during the RNAseq analysis with a prediction to differentiate between pathogenic and non-pathogenic strains. The validation of the presence/absence of these genes in a larger collection of strains coupled with AUC prediction showed that a combination of four biomarkers was sufficient to accurately discern clinical strains from harmless strains, with an AUC of 0.955, sensitivity of 0.9 and specificity of 0.86. CONCLUSIONS These new findings help in the understanding of B. cereus pathogenic potential and complexity and may provide tools for a better assessment of the risks associated with B. cereus contamination to improve patient health and food safety.
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Affiliation(s)
| | | | - Rozenn Dervyn
- INRAE, Micalis, University Paris-Sacly, Jouy-en-Josas, France
| | - Cyprien Guérin
- INRAE, MaIAGE, Université Paris-Saclay, Jouy-en-Josas, France
| | - Sandra Plancade
- INRAE, MaIAGE, Université Paris-Saclay, Jouy-en-Josas, France
| | - Sabine Herbin
- ANSES, Universtité Paris-Est, Laboratory of Food Safety, Maisons-Alfrot, France
| | - Anne Brisabois
- ANSES, Universtité Paris-Est, Laboratory of Food Safety, Maisons-Alfrot, France
| | - Pierre Nicolas
- INRAE, MaIAGE, Université Paris-Saclay, Jouy-en-Josas, France
| | - Nalini Ramarao
- INRAE, Micalis, University Paris-Sacly, Jouy-en-Josas, France.
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11
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Porrini C, Guérin C, Tran SL, Dervyn R, Nicolas P, Ramarao N. Implication of a Key Region of Six Bacillus cereus Genes Involved in Siroheme Synthesis, Nitrite Reductase Production and Iron Cluster Repair in the Bacterial Response to Nitric Oxide Stress. Int J Mol Sci 2021; 22:ijms22105079. [PMID: 34064887 PMCID: PMC8151001 DOI: 10.3390/ijms22105079] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 05/01/2021] [Accepted: 05/04/2021] [Indexed: 12/30/2022] Open
Abstract
Bacterial response to nitric oxide (NO) is of major importance for bacterial survival. NO stress is a main actor of the eukaryotic immune response and several pathogenic bacteria have developed means for detoxification and repair of the damages caused by NO. However, bacterial mechanisms of NO resistance by Gram-positive bacteria are poorly described. In the opportunistic foodborne pathogen Bacillus cereus, genome sequence analyses did not identify homologs to known NO reductases and transcriptional regulators, such as NsrR, which orchestrate the response to NO of other pathogenic or non-pathogenic bacteria. Using a transcriptomic approach, we investigated the adaptation of B. cereus to NO stress. A cluster of 6 genes was identified to be strongly up-regulated in the early phase of the response. This cluster contains an iron-sulfur cluster repair enzyme, a nitrite reductase and three enzymes involved in siroheme biosynthesis. The expression pattern and close genetic localization suggest a functional link between these genes, which may play a pivotal role in the resistance of B. cereus to NO stress during infection.
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Affiliation(s)
- Constance Porrini
- Micalis Institute, AgroParisTech, INRAE, Université Paris-Saclay, 78350 Jouy-en-Josas, France; (C.P.); (S.-L.T.); (R.D.)
| | - Cyprien Guérin
- MaIAGE, INRAE, Université Paris-Saclay, 78350 Jouy-en-Josas, France; (C.G.); (P.N.)
| | - Seav-Ly Tran
- Micalis Institute, AgroParisTech, INRAE, Université Paris-Saclay, 78350 Jouy-en-Josas, France; (C.P.); (S.-L.T.); (R.D.)
| | - Rozenn Dervyn
- Micalis Institute, AgroParisTech, INRAE, Université Paris-Saclay, 78350 Jouy-en-Josas, France; (C.P.); (S.-L.T.); (R.D.)
| | - Pierre Nicolas
- MaIAGE, INRAE, Université Paris-Saclay, 78350 Jouy-en-Josas, France; (C.G.); (P.N.)
| | - Nalini Ramarao
- Micalis Institute, AgroParisTech, INRAE, Université Paris-Saclay, 78350 Jouy-en-Josas, France; (C.P.); (S.-L.T.); (R.D.)
- Correspondence:
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12
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Glasset B, Sperry M, Dervyn R, Herbin S, Brisabois A, Ramarao N. The cytotoxic potential of Bacillus cereus strains of various origins. Food Microbiol 2021; 98:103759. [PMID: 33875199 DOI: 10.1016/j.fm.2021.103759] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 01/10/2021] [Accepted: 01/29/2021] [Indexed: 12/21/2022]
Abstract
B. cereus is a human pathogen associated with food poisoning leading to gastrointestinal disorders, as well as local and severe systemic infections. The pathogenic spectrum of B. cereus ranges from strains used as probiotics in humans to lethal highly toxic strains. In this study, we gathered a collection of 100 strains representative of the pathological diversity of B. cereus in humans, and characterized these strains for their cytotoxic potential towards human cells. We analyzed the correlation between cytotoxicity to epithelial and macrophage cells and the combination of 10 genes suspected to play a role during B. cereus virulence. We highlight genetic differences among isolates and studied correlations between genetic signature, cytotoxicity and strain pathological status. We hope that our findings will improve our understanding of the pathogenicity of B. cereus, thereby making it possible to improve both clinical diagnosis and food safety.
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Affiliation(s)
- Benjamin Glasset
- Micalis Institute, INRAE, AgroParisTech, Université Paris-Saclay, 78350, Jouy-en-Josas, France; Université Paris-Est, Anses, Laboratory for Food Safety, 94700, Maisons-Alfort, France
| | - Mylène Sperry
- Micalis Institute, INRAE, AgroParisTech, Université Paris-Saclay, 78350, Jouy-en-Josas, France
| | - Rozenn Dervyn
- Micalis Institute, INRAE, AgroParisTech, Université Paris-Saclay, 78350, Jouy-en-Josas, France
| | - Sabine Herbin
- Université Paris-Est, Anses, Laboratory for Food Safety, 94700, Maisons-Alfort, France
| | - Anne Brisabois
- Université Paris-Est, Anses, Laboratory for Food Safety, 94700, Maisons-Alfort, France
| | - Nalini Ramarao
- Micalis Institute, INRAE, AgroParisTech, Université Paris-Saclay, 78350, Jouy-en-Josas, France.
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13
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Shikov AE, Malovichko YV, Lobov AA, Belousova ME, Nizhnikov AA, Antonets KS. The Distribution of Several Genomic Virulence Determinants Does Not Corroborate the Established Serotyping Classification of Bacillus thuringiensis. Int J Mol Sci 2021; 22:2244. [PMID: 33668147 PMCID: PMC7956386 DOI: 10.3390/ijms22052244] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 02/02/2021] [Accepted: 02/18/2021] [Indexed: 02/06/2023] Open
Abstract
Bacillus thuringiensis, commonly referred to as Bt, is an object of the lasting interest of microbiologists due to its highly effective insecticidal properties, which make Bt a prominent source of biologicals. To categorize the exuberance of Bt strains discovered, serotyping assays are utilized in which flagellin serves as a primary seroreactive molecule. Despite its convenience, this approach is not indicative of Bt strains' phenotypes, neither it reflects actual phylogenetic relationships within the species. In this respect, comparative genomic and proteomic techniques appear more informative, but their use in Bt strain classification remains limited. In the present work, we used a bottom-up proteomic approach based on fluorescent two-dimensional difference gel electrophoresis (2D-DIGE) coupled with liquid chromatography/tandem mass spectrometry(LC-MS/MS) protein identification to assess which stage of Bt culture, vegetative or spore, would be more informative for strain characterization. To this end, the proteomic differences for the israelensis-attributed strains were assessed to compare sporulating cultures of the virulent derivative to the avirulent one as well as to the vegetative stage virulent bacteria. Using the same approach, virulent spores of the israelensis strain were also compared to the spores of strains belonging to two other major Bt serovars, namely darmstadiensis and thuringiensis. The identified proteins were analyzed regarding the presence of the respective genes in the 104 Bt genome assemblies available at open access with serovar attributions specified. Of 21 proteins identified, 15 were found to be encoded in all the present assemblies at 67% identity threshold, including several virulence factors. Notable, individual phylogenies of these core genes conferred neither the serotyping nor the flagellin-based phylogeny but corroborated the reconstruction based on phylogenomics approaches in terms of tree topology similarity. In its turn, the distribution of accessory protein genes was not confined to the existing serovars. The obtained results indicate that neither gene presence nor the core gene sequence may serve as distinctive bases for the serovar attribution, undermining the notion that the serotyping system reflects strains' phenotypic or genetic similarity. We also provide a set of loci, which fit in with the phylogenomics data plausibly and thus may serve for draft phylogeny estimation of the novel strains.
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Affiliation(s)
- Anton E. Shikov
- Laboratory for Proteomics of Supra-Organismal Systems, All-Russia Research Institute for Agricultural Microbiology (ARRIAM), 196608 St. Petersburg, Russia; (A.E.S.); (Y.V.M.); (M.E.B.); (A.A.N.)
- Faculty of Biology, St. Petersburg State University (SPbSU), 199034 St. Petersburg, Russia;
| | - Yury V. Malovichko
- Laboratory for Proteomics of Supra-Organismal Systems, All-Russia Research Institute for Agricultural Microbiology (ARRIAM), 196608 St. Petersburg, Russia; (A.E.S.); (Y.V.M.); (M.E.B.); (A.A.N.)
- Faculty of Biology, St. Petersburg State University (SPbSU), 199034 St. Petersburg, Russia;
| | - Arseniy A. Lobov
- Faculty of Biology, St. Petersburg State University (SPbSU), 199034 St. Petersburg, Russia;
- Laboratory of Regenerative Biomedicine, Institute of Cytology of the Russian Academy of Science, 194064 St. Petersburg, Russia
| | - Maria E. Belousova
- Laboratory for Proteomics of Supra-Organismal Systems, All-Russia Research Institute for Agricultural Microbiology (ARRIAM), 196608 St. Petersburg, Russia; (A.E.S.); (Y.V.M.); (M.E.B.); (A.A.N.)
| | - Anton A. Nizhnikov
- Laboratory for Proteomics of Supra-Organismal Systems, All-Russia Research Institute for Agricultural Microbiology (ARRIAM), 196608 St. Petersburg, Russia; (A.E.S.); (Y.V.M.); (M.E.B.); (A.A.N.)
- Faculty of Biology, St. Petersburg State University (SPbSU), 199034 St. Petersburg, Russia;
| | - Kirill S. Antonets
- Laboratory for Proteomics of Supra-Organismal Systems, All-Russia Research Institute for Agricultural Microbiology (ARRIAM), 196608 St. Petersburg, Russia; (A.E.S.); (Y.V.M.); (M.E.B.); (A.A.N.)
- Faculty of Biology, St. Petersburg State University (SPbSU), 199034 St. Petersburg, Russia;
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14
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Bacillus cereus Induces Severe Infections in Preterm Neonates: Implication at the Hospital and Human Milk Bank Level. Toxins (Basel) 2021; 13:toxins13020123. [PMID: 33562185 PMCID: PMC7915446 DOI: 10.3390/toxins13020123] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 01/18/2021] [Accepted: 02/02/2021] [Indexed: 12/15/2022] Open
Abstract
Human breast milk (HBM) is a source of essential nutrients for infants and is particularly recommended for preterm neonates when their own mother’s milk is not available. It provides protection against infections and decreases necrotizing enterocolitis and cardiovascular diseases. Nevertheless, HBM spoilage can occur due to contamination by pathogens, and the risk of a shortage of HBM is very often present. B. cereus is the most frequent ubiquitous bacteria responsible for HBM being discarded. It can contaminate HBM at all stages, from its collect point to the storage and delivery. B. cereus can induce severe infection in newborns with very low birth weight, with sometimes fatal outcomes. Although the source of contamination is rarely identified, in some cases, HBM was suspected as a potential source. Even if the risk is low, as infection due to B. cereus in preterm infants should not be overlooked, human milk banks follow strict procedures to avoid contamination, to accurately identify remaining bacteria following pasteurization and to discard non-compliant milk samples. In this review, we present a literature overview of B. cereus infections reported in neonates and the suspected sources of contamination. We highlight the procedures followed by the human milk banks from the collection of the milk to its microbiological characterization in Europe. We also present improved detection and decontamination methods that might help to decrease the risk and to preserve the public’s confidence in this vital biological product for infants whose mothers cannot breastfeed.
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15
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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: 99] [Impact Index Per Article: 33.0] [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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16
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Rudenko N, Nagel A, Zamyatina A, Karatovskaya A, Salyamov V, Andreeva-Kovalevskaya Z, Siunov A, Kolesnikov A, Shepelyakovskaya A, Boziev K, Melnik B, Brovko F, Solonin A. A Monoclonal Antibody against the C-Terminal Domain of Bacillus cereus Hemolysin II Inhibits HlyII Cytolytic Activity. Toxins (Basel) 2020; 12:E806. [PMID: 33352744 PMCID: PMC7767301 DOI: 10.3390/toxins12120806] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 11/19/2020] [Accepted: 12/16/2020] [Indexed: 01/13/2023] Open
Abstract
Bacillus cereus is the fourth most common cause of foodborne illnesses that produces a variety of pore-forming proteins as the main pathogenic factors. B. cereus hemolysin II (HlyII), belonging to pore-forming β-barrel toxins, has a C-terminal extension of 94 amino acid residues designated as HlyIICTD. An analysis of a panel of monoclonal antibodies to the recombinant HlyIICTD protein revealed the ability of the antibody HlyIIC-20 to inhibit HlyII hemolysis. A conformational epitope recognized by HlyIIC-20 was found. by the method of peptide phage display and found that it is localized in the N-terminal part of HlyIICTD. The HlyIIC-20 interacted with a monomeric form of HlyII, thus suppressing maturation of the HlyII toxin. Protection efficiencies of various B. cereus strains against HlyII were different and depended on the epitope amino acid composition, as well as, insignificantly, on downstream amino acids. Substitution of L324P and P324L in the hemolysins ATCC14579T and B771, respectively, determined the role of leucine localized to the epitope in suppressing the hemolysis by the antibody. Pre-incubation of HlyIIC-20 with HlyII prevented the death of mice up to an equimolar ratio. A strategy of detecting and neutralizing the toxic activity of HlyII could provide a tool for monitoring and reducing B. cereus pathogenicity.
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Affiliation(s)
- Natalia Rudenko
- Pushchino Branch, Shemyakin–Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 6 Prospekt Nauki, 142290 Pushchino, Moscow Region, Russia; (A.Z.); (A.K.); (A.S.); (K.B.); (F.B.)
| | - Alexey Nagel
- FSBIS FRC Pushchino Scientific Centre of Biological Research, G.K. Skryabin Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, 5 Prospekt Nauki, 142290 Pushchino, Moscow Region, Russia; (A.N.); (V.S.); (Z.A.-K.); (A.S.); (A.K.); (A.S.)
| | - Anna Zamyatina
- Pushchino Branch, Shemyakin–Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 6 Prospekt Nauki, 142290 Pushchino, Moscow Region, Russia; (A.Z.); (A.K.); (A.S.); (K.B.); (F.B.)
- Pushchino State Institute of Natural Sciences, 3 Prospekt Nauki, 142290 Pushchino, Moscow Region, Russia
| | - Anna Karatovskaya
- Pushchino Branch, Shemyakin–Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 6 Prospekt Nauki, 142290 Pushchino, Moscow Region, Russia; (A.Z.); (A.K.); (A.S.); (K.B.); (F.B.)
| | - Vadim Salyamov
- FSBIS FRC Pushchino Scientific Centre of Biological Research, G.K. Skryabin Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, 5 Prospekt Nauki, 142290 Pushchino, Moscow Region, Russia; (A.N.); (V.S.); (Z.A.-K.); (A.S.); (A.K.); (A.S.)
| | - Zhanna Andreeva-Kovalevskaya
- FSBIS FRC Pushchino Scientific Centre of Biological Research, G.K. Skryabin Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, 5 Prospekt Nauki, 142290 Pushchino, Moscow Region, Russia; (A.N.); (V.S.); (Z.A.-K.); (A.S.); (A.K.); (A.S.)
| | - Alexander Siunov
- FSBIS FRC Pushchino Scientific Centre of Biological Research, G.K. Skryabin Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, 5 Prospekt Nauki, 142290 Pushchino, Moscow Region, Russia; (A.N.); (V.S.); (Z.A.-K.); (A.S.); (A.K.); (A.S.)
| | - Alexander Kolesnikov
- FSBIS FRC Pushchino Scientific Centre of Biological Research, G.K. Skryabin Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, 5 Prospekt Nauki, 142290 Pushchino, Moscow Region, Russia; (A.N.); (V.S.); (Z.A.-K.); (A.S.); (A.K.); (A.S.)
| | - Anna Shepelyakovskaya
- Pushchino Branch, Shemyakin–Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 6 Prospekt Nauki, 142290 Pushchino, Moscow Region, Russia; (A.Z.); (A.K.); (A.S.); (K.B.); (F.B.)
| | - Khanafiy Boziev
- Pushchino Branch, Shemyakin–Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 6 Prospekt Nauki, 142290 Pushchino, Moscow Region, Russia; (A.Z.); (A.K.); (A.S.); (K.B.); (F.B.)
| | - Bogdan Melnik
- Protein Institute of the Russian Academy of Sciences, 4 Prospekt Nauki, 142290 Pushchino, Moscow Region, Russia;
| | - Fedor Brovko
- Pushchino Branch, Shemyakin–Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 6 Prospekt Nauki, 142290 Pushchino, Moscow Region, Russia; (A.Z.); (A.K.); (A.S.); (K.B.); (F.B.)
| | - Alexander Solonin
- FSBIS FRC Pushchino Scientific Centre of Biological Research, G.K. Skryabin Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, 5 Prospekt Nauki, 142290 Pushchino, Moscow Region, Russia; (A.N.); (V.S.); (Z.A.-K.); (A.S.); (A.K.); (A.S.)
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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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18
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Ramarao N, Tran SL, Marin M, Vidic J. Advanced Methods for Detection of Bacillus cereus and Its Pathogenic Factors. SENSORS (BASEL, SWITZERLAND) 2020; 20:E2667. [PMID: 32392794 PMCID: PMC7273213 DOI: 10.3390/s20092667] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 05/02/2020] [Accepted: 05/05/2020] [Indexed: 12/21/2022]
Abstract
Bacillus cereus is an opportunistic foodborne pathogen causing food intoxication and infectious diseases. Different toxins and pathogenic factors are responsible for diarrheal syndrome, like nonhemolytic enterotoxin Nhe, hemolytic enterotoxin Hbl, enterotoxin FM and cytotoxin K, while emetic syndrome is caused by the depsipeptide cereulide toxin. The traditional method of B. cereus detection is based on the bacterial culturing onto selective agars and cells enumeration. In addition, molecular and chemical methods are proposed for toxin gene profiling, toxin quantification and strain screening for defined virulence factors. Finally, some advanced biosensors such as phage-based, cell-based, immunosensors and DNA biosensors have been elaborated to enable affordable, sensitive, user-friendly and rapid detection of specific B. cereus strains. This review intends to both illustrate the state of the B. cereus diagnostic field and to highlight additional research that is still at the development level.
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Affiliation(s)
- Nalini Ramarao
- INRAE, AgroParisTech, Micalis Institute, Université Paris-Saclay, 78350 Jouy-en-Josas, France; (S.-L.T.); (M.M.)
| | | | | | - Jasmina Vidic
- INRAE, AgroParisTech, Micalis Institute, Université Paris-Saclay, 78350 Jouy-en-Josas, France; (S.-L.T.); (M.M.)
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19
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Mazzantini D, Fonnesu R, Celandroni F, Calvigioni M, Vecchione A, Mrusek D, Bange G, Ghelardi E. GTP-Dependent FlhF Homodimer Supports Secretion of a Hemolysin in Bacillus cereus. Front Microbiol 2020; 11:879. [PMID: 32435240 PMCID: PMC7218170 DOI: 10.3389/fmicb.2020.00879] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Accepted: 04/15/2020] [Indexed: 01/09/2023] Open
Abstract
The multidomain (B-NG) protein FlhF, a flagellar biogenesis regulator in several bacteria, is the third paralog of the signal recognition particle (SRP)-GTPases Ffh and FtsY, which are known to drive protein-delivery to the plasma membrane. Previously, we showed that FlhF is required for Bacillus cereus pathogenicity in an insect model of infection, being essential for physiological peritrichous flagellation, for motility, and for the secretion of virulence proteins. Among these proteins, we found that the L2 component of hemolysin BL, one of the most powerful toxins B. cereus produces, was drastically reduced by the FlhF depletion. Herein, we demonstrate that B. cereus FlhF forms GTP-dependent homodimers in vivo since the replacement of residues critical for their GTP-dependent homodimerization alters this ability. The protein directly or indirectly controls flagellation by affecting flagellin-gene transcription and its overproduction leads to a hyperflagellated phenotype. On the other hand, FlhF does not affect the expression of the L2-encoding gene (hblC), but physically binds L2 when in its homodimeric form, recruiting the protein to the plasma membrane for secretion. We additionally show that FlhF overproduction increases L2 secretion and that the FlhF/L2 interaction requires the NG domain of FlhF. Our findings demonstrate the peculiar behavior of B. cereus FlhF, which is required for the correct flagellar pattern and acts as SRP-GTPase in the secretion of a bacterial toxin subunit.
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Affiliation(s)
- Diletta Mazzantini
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy
| | - Rossella Fonnesu
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy
| | - Francesco Celandroni
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy
| | - Marco Calvigioni
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy
| | - Alessandra Vecchione
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy
| | - Devid Mrusek
- Center for Synthetic Microbiology (SYNMIKRO) and Department of Chemistry, Philipps University, Marburg, Germany
| | - Gert Bange
- Center for Synthetic Microbiology (SYNMIKRO) and Department of Chemistry, Philipps University, Marburg, Germany
| | - Emilia Ghelardi
- Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy
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20
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Demers-Mathieu V, Mathijssen G, Fels S, Chace DH, Medo E. Impact of vaccination during pregnancy and staphylococci concentration on the presence of Bacillus cereus in raw human milk. J Perinatol 2020; 40:1323-1330. [PMID: 31919400 PMCID: PMC7223849 DOI: 10.1038/s41372-019-0586-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Revised: 12/10/2019] [Accepted: 12/21/2019] [Indexed: 01/03/2023]
Abstract
OBJECTIVE This study aimed to determine whether vaccination during pregnancy, prematurity, and staphylococci concentration influenced the presence of B. cereus or staphylococcal enterotoxins (SEs) in raw human milk from healthy mothers. STUDY DESIGN Human milk samples were collected from 152 healthy women. B. cereus, S. aureus and coagulase-negative staphylococci (CNS) were enumerated using selective agar culture media. The detection of B. cereus spores and SEs were determined using ELISA. RESULTS CNS and B. cereus concentrations in milk from non-vaccinated mothers were higher than that from mothers vaccinated during pregnancy, but S. aureus did not differ. Prematurity did not affect B. cereus or staphylococci in human milk. S. aureus and CNS concentrations in human milk with the presence of B. cereus were higher than that with the absence of B. cereus. Viable B. cereus was present in 9.2% of raw human milk samples whereas SEs were not detected in any samples. CONCLUSIONS Vaccination during pregnancy and low concentration of staphylococci could reduce the risk of B. cereus in raw human milk. The screening of B. cereus in raw human milk must be performed before pasteurization to reduce the risk of B. cereus infection in preterm infants.
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Affiliation(s)
- Veronique Demers-Mathieu
- Department of Neonatal Immunology and Microbiology, Medolac Laboratories A Public Benefit Corporation, Boulder City, NV, USA.
| | - Gabrielle Mathijssen
- Department of Neonatal Immunology and Microbiology, Medolac Laboratories A Public Benefit Corporation, Boulder City, NV USA
| | - Shawn Fels
- Department of Neonatal Immunology and Microbiology, Medolac Laboratories A Public Benefit Corporation, Boulder City, NV USA
| | - Donald H. Chace
- Department of Neonatal Immunology and Microbiology, Medolac Laboratories A Public Benefit Corporation, Boulder City, NV USA
| | - Elena Medo
- Department of Neonatal Immunology and Microbiology, Medolac Laboratories A Public Benefit Corporation, Boulder City, NV USA
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21
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Cui Y, Märtlbauer E, Dietrich R, Luo H, Ding S, Zhu K. Multifaceted toxin profile, an approach toward a better understanding of probiotic Bacillus cereus. Crit Rev Toxicol 2019; 49:342-356. [PMID: 31116061 DOI: 10.1080/10408444.2019.1609410] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Strains of the Bacillus cereus group have been widely used as probiotics for human beings, food animals, plants, and environmental remediation. Paradoxically, B. cereus is responsible for both gastrointestinal and nongastrointestinal syndromes and represents an important opportunistic food-borne pathogen. Toxicity assessment is a fundamental issue to evaluate safety of probiotics. Here, we summarize the state of our current knowledge about the toxins of B. cereus sensu lato to be considered for safety assessment of probiotic candidates. Surfactin-like emetic toxin (cereulide) and various enterotoxins including nonhemolytic enterotoxin, hemolysin BL, and cytotoxin K are responsible for food poisoning outbreaks characterized by emesis and diarrhea. In addition, other factors, such as hemolysin II, Certhrax, immune inhibitor A1, and sphingomyelinase, contribute to toxicity and overall virulence of B. cereus.
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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 , China.,State Key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agricultural University , Beijing , China
| | - Erwin Märtlbauer
- Department of Veterinary Sciences, Ludwig-Maximilians-University Munich , Oberschleißheim , Germany
| | - Richard Dietrich
- Department of Veterinary Sciences, Ludwig-Maximilians-University Munich , Oberschleißheim , Germany
| | - Hailing Luo
- State Key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agricultural University , Beijing , China
| | - Shuangyang Ding
- National Center for Veterinary Drug Safety Evaluation, College of Veterinary Medicine, China Agricultural University , Beijing , China
| | - Kui Zhu
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Veterinary Medicine, China Agricultural University , Beijing , China.,National Center for Veterinary Drug Safety Evaluation, College of Veterinary Medicine, China Agricultural University , Beijing , China
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22
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Dubois T, Lemy C, Perchat S, Lereclus D. The signaling peptide NprX controlling sporulation and necrotrophism is imported into Bacillus thuringiensis by two oligopeptide permease systems. Mol Microbiol 2019; 112:219-232. [PMID: 31017318 DOI: 10.1111/mmi.14264] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/18/2019] [Indexed: 11/30/2022]
Abstract
The infectious cycle of Bacillus thuringiensis in the insect host is regulated by quorum sensors of the RNPP family. The activity of these regulators is modulated by their cognate signaling peptides translocated into the bacterial cells by oligopeptide permeases (Opp systems). In B. thuringiensis, the quorum sensor NprR is a bi-functional regulator that connects sporulation to necrotrophism. The binding of the signaling peptide NprX switches NprR from a dimeric inhibitor of sporulation to a tetrameric transcriptional activator involved in the necrotrophic lifestyle of B. thuringiensis. Here, we report that NprX is imported into the bacterial cells by two different oligopeptide permease systems. The first one is Opp, the system known to be involved in the import of the signaling peptide PapR in B. thuringiensis and Bacillus cereus. The second, designated as Npp (NprX peptide permease), was not previously described. We show that at least two substrate binding proteins (SBPs) are able to translocate NprX through OppBCDF. In contrast, we demonstrate that a unique SBP (NppA) can translocate NprX through NppDFBC. We identified the promoter of the npp operon, and we showed that transcription starts at the onset of stationary phase and is repressed by the nutritional regulator CodY during the exponential growth phase.
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Affiliation(s)
- Thomas Dubois
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, 78350, France
| | - Christelle Lemy
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, 78350, France
| | - Stéphane Perchat
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, 78350, France
| | - Didier Lereclus
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, 78350, France
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23
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Porcine Gastric Mucin Triggers Toxin Production of Enteropathogenic Bacillus cereus. Infect Immun 2019; 87:IAI.00765-18. [PMID: 30745328 DOI: 10.1128/iai.00765-18] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Accepted: 01/21/2019] [Indexed: 02/01/2023] Open
Abstract
Enteropathogenic Bacillus cereus causes foodborne infections due to the production of pore-forming enterotoxins in the intestine. Before that, spores have to be ingested, survive the stomach passage, and germinate. Thus, before reaching epithelial cells, B. cereus comes in contact with the intestinal mucus layer. In the present study, different aspects of this interaction were analyzed. Total RNA sequencing revealed major transcriptional changes of B. cereus strain F837/76 upon incubation with porcine gastric mucin (PGM), comprising genes encoding enterotoxins and further putative virulence factors, as well as proteins involved in adhesion to and degradation of mucin. Indeed, PGM was partially degraded by B. cereus via secreted, EDTA-sensitive proteases. The amount of enterotoxins detectable in culture media supplemented with PGM was also clearly increased. Tests of further strains revealed that enhancement of enterotoxin production upon contact with PGM is broadly distributed among B. cereus strains. Interestingly, evidence was found that PGM can also strain-specifically trigger germination of B. cereus spores and that vegetative cells actively move toward mucin. Overall, our data suggest that B. cereus is well adapted to the host environment due to massive transcriptome changes upon contact with PGM, attributing mucin an important and, thus far, neglected role in pathogenesis.
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24
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Haydar A, Tran SL, Guillemet E, Darrigo C, Perchat S, Lereclus D, Coquet L, Jouenne T, Ramarao N. InhA1-Mediated Cleavage of the Metalloprotease NprA Allows Bacillus cereus to Escape From Macrophages. Front Microbiol 2018; 9:1063. [PMID: 29875760 PMCID: PMC5974196 DOI: 10.3389/fmicb.2018.01063] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Accepted: 05/04/2018] [Indexed: 12/20/2022] Open
Abstract
Bacillus cereus is a Gram-positive spore-forming bacterium causing food poisoning and serious opportunistic infections. These infections are characterized by bacterial accumulation in the host despite the induction of inflammation. To circumvent inflammation, bacteria must resist the bactericidal activity of professional phagocytes, which constitute a first line of host defense against pathogens. Interactions between phagocytic cells and B. cereus are still poorly characterized and the mechanism of resistance to the host immune system is not known yet. We have previously shown that the spores are phagocytosed by macrophages but survive and escape from these cells. The metalloprotease InhA1 is a key effector involved in these processes. inhA1-deficient spores are retained intracellularly, in contrast to the wild type strain spores. NprA is also a B. cereus metalloprotease able to cleave tissue components such as fibronectin, laminin, and collagen. Here, we show that NprA, concomitantly secreted with InhA1 in the B. cereus secretome, is essential to promote bacterial escape from macrophages. We show that InhA1 cleaves NprA at specific sites. This cleavage allows liberation of the mature form of the NprA protein in the supernatant of the wild type strain. This mature form of NprA is actually the principal effector allowing bacterial escape from host macrophages.
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Affiliation(s)
- Abbass Haydar
- INRA, Micalis Institute, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| | - Seav-Ly Tran
- INRA, Micalis Institute, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| | - Elisabeth Guillemet
- INRA, Micalis Institute, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| | - Claire Darrigo
- INRA, Micalis Institute, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| | - Stéphane Perchat
- INRA, Micalis Institute, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| | - Didier Lereclus
- INRA, Micalis Institute, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| | - Laurent Coquet
- CNRS, UMR 6270, Normandy University, UNIROUEN, Plate-forme PISSARO, Mont-Saint-Aignan, France
| | - Thierry Jouenne
- CNRS, UMR 6270, Normandy University, UNIROUEN, Plate-forme PISSARO, Mont-Saint-Aignan, France
| | - Nalini Ramarao
- INRA, Micalis Institute, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
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25
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Desriac N, Postollec F, Coroller L, Pavan S, Combrisson J, Hallier-Soulier S, Sohier D. Trustworthy Identification of Resistance Biomarkers of Bacillus weihenstephanensis: Workflow of the Quality Assurance Procedure. FOOD ANAL METHOD 2017. [DOI: 10.1007/s12161-017-1058-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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26
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Felten A, Guillier L, Radomski N, Mistou MY, Lailler R, Cadel-Six S. Genome Target Evaluator (GTEvaluator): A workflow exploiting genome dataset to measure the sensitivity and specificity of genetic markers. PLoS One 2017; 12:e0182082. [PMID: 28750049 PMCID: PMC5531552 DOI: 10.1371/journal.pone.0182082] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Accepted: 07/12/2017] [Indexed: 11/30/2022] Open
Abstract
Most of the bacterial typing methods used to discriminate isolates in medical or food safety microbiology are based on genetic markers used as targets in PCR or hybridization experiments. These DNA typing methods are important tools for studying prevalence and epidemiology, for conducting surveillance, investigations and control of biological hazard sources. In that perspective, it is crucial to insure that the chosen genetic markers have the greatest specificity and sensitivity. The wealth of whole-genome sequences available for many bacterial species offers the opportunity to evaluate the performance of these genetic markers. In the present study, we have developed GTEvaluator, a bioinformatics workflow which ranks genetic markers depending on their sensitivity and specificity towards groups of well-defined genomes. GTEvaluator identifies the most performant genetic markers to target individuals among a population. The individuals (i.e. a group of genomes within a collection) are defined by any kind of particular phenotypic or biological properties inside a related population (i.e. collection of genomes). The performance of the genetic markers is computed by a distance value which takes into account both sensitivity and specificity. In this study we report two examples of GTEvaluator application. In the first example Bacillus phenotypic markers were evaluated for their capacity to distinguish B. cereus from B. thuringiensis. In the second experiment, GTEvaluator measured the performance of genetic markers dedicated to the molecular serotyping of Salmonella enterica. In one in silico experiment it was possible to test 64 markers onto 134 genomes corresponding to 14 different serotypes.
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Affiliation(s)
- Arnaud Felten
- Université PARIS-EST, ANSES, Laboratory for Food Safety, Maisons-Alfort, France
| | - Laurent Guillier
- Université PARIS-EST, ANSES, Laboratory for Food Safety, Maisons-Alfort, France
| | - Nicolas Radomski
- Université PARIS-EST, ANSES, Laboratory for Food Safety, Maisons-Alfort, France
| | - Michel-Yves Mistou
- Université PARIS-EST, ANSES, Laboratory for Food Safety, Maisons-Alfort, France
| | - Renaud Lailler
- Université PARIS-EST, ANSES, Laboratory for Food Safety, Maisons-Alfort, France
| | - Sabrina Cadel-Six
- Université PARIS-EST, ANSES, Laboratory for Food Safety, Maisons-Alfort, France
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27
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Chaves JQ, de Paiva EP, Rabinovitch L, Vivoni AM. Molecular Characterization and Risk Assessment of Bacillus cereus Sensu Lato Isolated from Ultrahigh-Temperature and Pasteurized Milk Marketed in Rio de Janeiro, Brazil. J Food Prot 2017; 80:1060-1065. [PMID: 28556679 DOI: 10.4315/0362-028x.jfp-16-448] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The presence of Bacillus cereus in milk is a major concern in the dairy industry. In this study 27 Bacillus cereus sensu lato isolates from pasteurized and ultrahigh-temperature (UHT) milk (24 whole UHT and 4 pasteurized samples) collected at supermarket chains in Rio de Janeiro, Brazil, were evaluated to assess the potential risk for food poisoning. Toxigenic and virulence profiles were defined by gene-specific PCR. Affiliation to phylogenetic groups was assigned by panC sequencing. Microbiological analysis revealed the presence of B. cereus s.l. in eight (33.3%) brands (six brands of UHT and two brands of pasteurized milk). Twenty-seven isolates were recovered (13 B. cereus and 14 Bacillus thuringiensis ). Predominant toxigenic patterns were type I (contains all toxin genes except ces) and type II (does not contain cytK and ces), with seven (25.9%) isolates each. Predominant virulence patterns were type 2 (does not contain hlyII or shp) and type 3 (contains all virulence genes), with five (18.5%) isolates each. All isolates belonged to phylogenetic groups III and IV. Presence of hbl, piplc, and sph was associated with group IV isolates. Our results suggest that B. thuringiensis and B. cereus sensu stricto should be considered potential foodborne pathogens. Because the majority of the milk isolates studied have the potential to cause food poisoning because of the high prevalence of toxin and virulence genes and the specific phylogenetic group affiliations, these milk products can be potentially hazardous for human consumption.
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Affiliation(s)
- Jeane Q Chaves
- Laboratório de Fisiologia Bacteriana, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
| | - Eislaine P de Paiva
- Laboratório de Fisiologia Bacteriana, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
| | - Leon Rabinovitch
- Laboratório de Fisiologia Bacteriana, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
| | - Adriana M Vivoni
- Laboratório de Fisiologia Bacteriana, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
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28
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Lotte R, Hérissé AL, Berrouane Y, Lotte L, Casagrande F, Landraud L, Herbin S, Ramarao N, Boyer L, Ruimy R. Virulence Analysis of Bacillus cereus Isolated after Death of Preterm Neonates, Nice, France, 2013. Emerg Infect Dis 2017; 23:845-848. [PMID: 28418291 PMCID: PMC5403044 DOI: 10.3201/eid2305.161788] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
After the deaths of 2 preterm neonates with Bacillus cereus systemic infection in the same intensive care unit, we investigated the pathogenic potential of this bacterium. Genetic and virulence analysis indicated the neonates were infected with 2 different strains with a virulence potential similar to environmental strains, indicating likely patient immune response failure.
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29
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Glasset B, Herbin S, Guillier L, Cadel-Six S, Vignaud ML, Grout J, Pairaud S, Michel V, Hennekinne JA, Ramarao N, Brisabois A. Bacillus cereus-induced food-borne outbreaks in France, 2007 to 2014: epidemiology and genetic characterisation. ACTA ACUST UNITED AC 2017; 21:30413. [PMID: 27934583 PMCID: PMC5388111 DOI: 10.2807/1560-7917.es.2016.21.48.30413] [Citation(s) in RCA: 85] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Accepted: 07/16/2016] [Indexed: 11/20/2022]
Abstract
The aim of this study was to identify and characterise Bacillus cereus from a unique national collection of 564 strains associated with 140 strong-evidence food-borne outbreaks (FBOs) occurring in France during 2007 to 2014. Starchy food and vegetables were the most frequent food vehicles identified; 747 of 911 human cases occurred in institutional catering contexts. Incubation period was significantly shorter for emetic strains compared with diarrhoeal strains A sub-panel of 149 strains strictly associated to 74 FBOs and selected on Coliphage M13-PCR pattern, was studied for detection of the genes encoding cereulide, diarrhoeic toxins (Nhe, Hbl, CytK1 and CytK2) and haemolysin (HlyII), as well as panC phylogenetic classification. This clustered the strains into 12 genetic signatures (GSs) highlighting the virulence potential of each strain. GS1 (nhe genes only) and GS2 (nhe, hbl and cytK2), were the most prevalent GS and may have a large impact on human health as they were present in 28% and 31% of FBOs, respectively. Our study provides a convenient molecular scheme for characterisation of B. cereus strains responsible for FBOs in order to improve the monitoring and investigation of B. cereus-induced FBOs, assess emerging clusters and diversity of strains.
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Affiliation(s)
- Benjamin Glasset
- Université Paris-Est, ANSES, Laboratory for Food Safety, Maisons-Alfort Cedex, France.,Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France
| | - Sabine Herbin
- Université Paris-Est, ANSES, Laboratory for Food Safety, Maisons-Alfort Cedex, France.,These authors contributed equally to this work
| | - Laurent Guillier
- Université Paris-Est, ANSES, Laboratory for Food Safety, Maisons-Alfort Cedex, France
| | - Sabrina Cadel-Six
- Université Paris-Est, ANSES, Laboratory for Food Safety, Maisons-Alfort Cedex, France
| | - Marie-Léone Vignaud
- Université Paris-Est, ANSES, Laboratory for Food Safety, Maisons-Alfort Cedex, France
| | - Joel Grout
- Université Paris-Est, ANSES, Laboratory for Food Safety, Maisons-Alfort Cedex, France
| | - Sylvie Pairaud
- Université Paris-Est, ANSES, Laboratory for Food Safety, Maisons-Alfort Cedex, France
| | | | | | - Nalini Ramarao
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, Jouy-en-Josas, France.,These authors contributed equally to this work
| | - Anne Brisabois
- Université Paris-Est, ANSES, Laboratory for Food Safety, Maisons-Alfort Cedex, France.,These authors contributed equally to this work
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30
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Chau ML, Aung KT, Hapuarachchi HC, Lee PSV, Lim PY, Kang JSL, Ng Y, Yap HM, Yuk HG, Gutiérrez RA, Ng LC. Microbial survey of ready-to-eat salad ingredients sold at retail reveals the occurrence and the persistence of Listeria monocytogenes Sequence Types 2 and 87 in pre-packed smoked salmon. BMC Microbiol 2017; 17:46. [PMID: 28245788 PMCID: PMC5331722 DOI: 10.1186/s12866-017-0956-z] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Accepted: 02/14/2017] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND As the preparation of salads involves extensive handling and the use of uncooked ingredients, they are particularly vulnerable to microbial contamination. This study aimed to determine the microbial safety and quality of pre-packed salads and salad bar ingredients sold in Singapore, so as to identify public health risks that could arise from consuming salads and to determine areas for improvement in the management of food safety. RESULTS The most frequently encountered organism in pre-packed salad samples was B. cereus, particularly in pasta salads (33.3%, 10/30). The most commonly detected organism in salad bar ingredients was L. monocytogenes, in particular seafood ingredients (44.1%, 15/34), largely due to contaminated smoked salmon. Further investigation showed that 21.6% (37/171) of the pre-packed smoked salmon sold in supermarkets contained L. monocytogenes. Significantly higher prevalence of L. monocytogenes and higher Standard Plate Count were detected in smoked salmon at salad bars compared to pre-packed smoked salmon in supermarkets, which suggested multiplication of the organism as the products move down the supply chain. Further molecular analysis revealed that L. monocytogenes Sequence Type (ST) 2 and ST87 were present in a particular brand of pre-packed salmon products over a 4-year period, implying a potential persistent contamination problem at the manufacturing level. CONCLUSIONS Our findings highlighted a need to improve manufacturing and retail hygiene processes as well as to educate vulnerable populations to avoid consuming food prone to L. monocytogenes contamination.
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Affiliation(s)
- Man Ling Chau
- Environmental Health Institute, National Environment Agency, 11 Biopolis Way, #04-03/04, Helios Block, Singapore, 138667 Singapore
| | - Kyaw Thu Aung
- Environmental Health Institute, National Environment Agency, 11 Biopolis Way, #04-03/04, Helios Block, Singapore, 138667 Singapore
| | | | - Pei Sze Valarie Lee
- Department of Chemistry, Food Science and Technology Programme, National University of Singapore, 3 Science Drive 3, Singapore, 117543 Singapore
| | - Pei Ying Lim
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore, 637551 Singapore
| | - Joanne Su Lin Kang
- Environmental Health Institute, National Environment Agency, 11 Biopolis Way, #04-03/04, Helios Block, Singapore, 138667 Singapore
| | - Youming Ng
- Environmental Health Institute, National Environment Agency, 11 Biopolis Way, #04-03/04, Helios Block, Singapore, 138667 Singapore
| | - Hooi Ming Yap
- Environmental Health Institute, National Environment Agency, 11 Biopolis Way, #04-03/04, Helios Block, Singapore, 138667 Singapore
| | - Hyun-Gyun Yuk
- Department of Chemistry, Food Science and Technology Programme, National University of Singapore, 3 Science Drive 3, Singapore, 117543 Singapore
| | - Ramona Alikiiteaga Gutiérrez
- Environmental Health Institute, National Environment Agency, 11 Biopolis Way, #04-03/04, Helios Block, Singapore, 138667 Singapore
| | - Lee Ching Ng
- Environmental Health Institute, National Environment Agency, 11 Biopolis Way, #04-03/04, Helios Block, Singapore, 138667 Singapore
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore, 637551 Singapore
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Horn S, Pieters R, Bezuidenhout C. Pathogenic features of heterotrophic plate count bacteria from drinking-water boreholes. JOURNAL OF WATER AND HEALTH 2016; 14:890-900. [PMID: 27959868 DOI: 10.2166/wh.2016.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Evidence suggests that heterotrophic plate count (HPC) bacteria may be hazardous to humans with weakened health. We investigated the pathogenic potential of HPC bacteria from untreated borehole water, consumed by humans, for: their haemolytic properties, the production of extracellular enzymes such as DNase, proteinase, lipase, lecithinase, hyaluronidase and chondroitinase, the effect simulated gastric fluid has on their survival, as well as the bacteria's antibiotic-susceptible profile. HuTu-80 cells acted as model for the human intestine and were exposed to the HPC isolates to determine their effects on the viability of the cells. Several HPC isolates were α- or β-haemolytic, produced two or more extracellular enzymes, survived the SGF treatment, and showed resistance against selected antibiotics. The isolates were also harmful to the human intestinal cells to varying degrees. A novel pathogen score was calculated for each isolate. Bacillus cereus had the highest pathogen index: the pathogenicity of the other bacteria declined as follows: Aeromonas taiwanensis > Aeromonas hydrophila > Bacillus thuringiensis > Alcaligenes faecalis > Pseudomonas sp. > Bacillus pumilus > Brevibacillus sp. > Bacillus subtilis > Bacillus sp. These results demonstrated that the prevailing standards for HPCs in drinking water may expose humans with compromised immune systems to undue risk.
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Affiliation(s)
- Suranie Horn
- Unit for Environmental Sciences and Management, Potchefstroom Campus, North-West University, Private Bag X6001, Potchefstroom 2520, South Africa E-mail:
| | - Rialet Pieters
- Unit for Environmental Sciences and Management, Potchefstroom Campus, North-West University, Private Bag X6001, Potchefstroom 2520, South Africa E-mail:
| | - Carlos Bezuidenhout
- Unit for Environmental Sciences and Management, Potchefstroom Campus, North-West University, Private Bag X6001, Potchefstroom 2520, South Africa E-mail:
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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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Darrigo C, Guillemet E, Dervyn R, Ramarao N. The Bacterial Mfd Protein Prevents DNA Damage Induced by the Host Nitrogen Immune Response in a NER-Independent but RecBC-Dependent Pathway. PLoS One 2016; 11:e0163321. [PMID: 27711223 PMCID: PMC5053507 DOI: 10.1371/journal.pone.0163321] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Accepted: 09/07/2016] [Indexed: 11/28/2022] Open
Abstract
Production of reactive nitrogen species is an important component of the host immune defence against bacteria. Here, we show that the bacterial protein Mfd (Mutation frequency decline), a highly conserved and ubiquitous bacterial protein involved in DNA repair, confers bacterial resistance to the eukaryotic nitrogen response produced by macrophage cells and during mice infection. In addition, we show that RecBC is also necessary to survive this stress. The inactivation of recBC and mfd genes is epistatic showing that Mfd follows the RecBC repair pathway to protect the bacteria against the genotoxic effect of nitrite. Surprisingly given the role of Mfd in transcription-coupled repair, UvrA is not necessary to survive the nitrite response. Taken together, our data reveal that during the eukaryotic nitrogen response, Mfd is required to maintain bacterial genome integrity in a NER-independent but RecBC-dependent pathway.
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Affiliation(s)
- Claire Darrigo
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France
| | - Elisabeth Guillemet
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France
| | - Rozenn Dervyn
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France
| | - Nalini Ramarao
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France
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The bacterial DNA repair protein Mfd confers resistance to the host nitrogen immune response. Sci Rep 2016; 6:29349. [PMID: 27435260 PMCID: PMC4951645 DOI: 10.1038/srep29349] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Accepted: 06/17/2016] [Indexed: 01/23/2023] Open
Abstract
Production of reactive nitrogen species (NO) is a key step in the immune response following infections. NO induces lesions to bacterial DNA, thus limiting bacterial growth within hosts. Using two pathogenic bacteria, Bacillus cereus and Shigella flexneri, we show that the DNA-repair protein Mfd (Mutation-Frequency-Decline) is required for bacterial resistance to the host-NO-response. In both species, a mutant deficient for mfd does not survive to NO, produced in vitro or by phagocytic cells. In vivo, the ∆mfd mutant is avirulent and unable to survive the NO-stress. Moreover, NO induces DNA-double-strand-breaks and point mutations in the Δmfd mutant. In overall, these observations demonstrate that NO damages bacterial DNA and that Mfd is required to maintain bacterial genomic integrity. This unexpected discovery reveals that Mfd, a typical housekeeping gene, turns out to be a true virulence factor allowing survival and growth of the pathogen in its host, due to its capacity to protect the bacterium against NO, a key molecule of the innate immune defense. As Mfd is widely conserved in the bacterial kingdom, these data highlight a mechanism that may be used by a large spectrum of bacteria to overcome the host immune response and especially the mutagenic properties of NO.
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Gélis-Jeanvoine S, Canette A, Gohar M, Caradec T, Lemy C, Gominet M, Jacques P, Lereclus D, Slamti L. Genetic and functional analyses of krs, a locus encoding kurstakin, a lipopeptide produced by Bacillus thuringiensis. Res Microbiol 2016; 168:356-368. [PMID: 27353188 DOI: 10.1016/j.resmic.2016.06.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Revised: 05/23/2016] [Accepted: 06/06/2016] [Indexed: 11/17/2022]
Abstract
Bacteria of the Bacillus genus are able to synthesize several families of lipopeptides. These small molecules are the product of non-ribosomal peptide synthetases. In 2000, it was found that Bacillus thuringiensis, an entomopathogenic bacterium of the Bacillus cereus group, produced a previously unknown lipopeptide: kurstakin. Genomic analyses reveal that the krs locus, encoding the kurstakin synthetases, is specific to the B. cereus group, but is unevenly distributed within this group. Previous work showed that krs transcription requires the necrotrophism quorum-sensor NprR. Here, we demonstrated that the genes of the krs locus form an operon and we defined its transcription start site. Following krs transcription at the population and single-cell levels in multiple culture conditions, we depicted a condition-dependent transcription pattern, indicating that production of kurstakin is subject to environmental regulation. Consistent with this idea, we found krs transcription to be regulated by another master regulator, Spo0A, suggesting that krs expression is fine-tuned by integrating multiple signals. We also reported an unknown DNA palindrome in the krs promoter region that modulates krs expression. Due to their surfactant properties, lipopeptides could play several physiological roles. We showed that the krs locus was required for proper biofilm structuration.
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Affiliation(s)
| | - Alexis Canette
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France.
| | - Michel Gohar
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France.
| | - Thibault Caradec
- University of Lille, EA 7394, ICV-Institut Charles Viollette, ProBioGEM Team, Polytech'Lille, Avenue Langevin, 59655 Villeneuve d'Ascq, France.
| | - Christelle Lemy
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France.
| | - Myriam Gominet
- Institut Pasteur, CNRS URA 2172, Unité de Biologie des Bactéries Pathogènes à Gram positif, 75015 Paris, France.
| | - Philippe Jacques
- University of Lille, EA 7394, ICV-Institut Charles Viollette, ProBioGEM Team, Polytech'Lille, Avenue Langevin, 59655 Villeneuve d'Ascq, France.
| | - Didier Lereclus
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France.
| | - Leyla Slamti
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France.
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Massive horizontal gene transfer, strictly vertical inheritance and ancient duplications differentially shape the evolution of Bacillus cereus enterotoxin operons hbl, cytK and nhe. BMC Evol Biol 2015; 15:246. [PMID: 26555390 PMCID: PMC4641410 DOI: 10.1186/s12862-015-0529-4] [Citation(s) in RCA: 84] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Accepted: 10/30/2015] [Indexed: 11/10/2022] Open
Abstract
Background Bacillus cereus sensu lato comprises eight closely related species including the human pathogens Bacillus anthracis and Bacillus cereus. Within B. cereus sensu lato, chromosomally and plasmid-encoded toxins exist. While plasmid-mediated horizontal gene transfer of the emetic toxin, anthrax and insecticidal toxins is known, evolution of enterotoxin genes within the group has not been studied. Results We report draft genome assemblies of 25 strains, a phylogenetic network of 142 strains based on ANI derived from genome sequences and a phylogeny based on whole-genome SNP analysis. The data clearly support subdivision of B. cereus sensu lato into seven phylogenetic groups. While group I, V and VII represent B. pseudomycoides, B. toyonensis and B. cytotoxicus, which are distinguishable at species level (ANI border ≥ 96 %), strains ascribed to the other five species do not match phylogenic groups. The chromosomal enterotoxin operons nheABC and hblCDAB are abundant within B. cereus both isolated from infections and from the environment. While the duplicated hbl variant hbla is present in 22 % of all strains investigated, duplication of nheABC is extremely rare (0.02 %) and appears to be phylogenetically unstable. Distribution of toxin genes was matched to a master tree based on seven concatenated housekeeping genes, which depicts species relationships in B. cereus sensu lato as accurately as whole-genome comparisons. Comparison to the phylogeny of enterotoxin genes uncovered ample evidence for horizontal transfer of hbl, cytK and plcR, as well as frequent deletion of both toxins and duplication of hbl. No evidence for nhe deletion was found and stable horizontal transfer of nhe is rare. Therefore, evolution of B. cereus enterotoxin operons is shaped unexpectedly different for yet unknown reasons. Conclusions Frequent exchange of the pathogenicity factors hbl, cytK and plcR in B. cereus sensu lato appears to be an important mechanism of B. cereus virulence evolution, including so-called probiotic or non-pathogenic species, which might have consequences for risk assessment procedures. In contrast, exclusively vertical inheritance of nhe was observed, and since nhe-negative strains appear to be extremely rare, we suggest that fitness loss may be associated with deletion or horizontal transfer of the nhe operon. Electronic supplementary material The online version of this article (doi:10.1186/s12862-015-0529-4) contains supplementary material, which is available to authorized users.
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Didier A, Jeßberger N, Krey V, Dietrich R, Scherer S, Märtlbauer E. The mutation Glu151Asp in the B-component of the Bacillus cereus non-hemolytic enterotoxin (Nhe) leads to a diverging reactivity in antibody-based detection systems. Toxins (Basel) 2015; 7:4655-67. [PMID: 26569304 PMCID: PMC4663526 DOI: 10.3390/toxins7114655] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Revised: 10/29/2015] [Accepted: 11/02/2015] [Indexed: 11/17/2022] Open
Abstract
The ability of Bacillus cereus to cause foodborne toxicoinfections leads to increasing concerns regarding consumer protection. For the diarrhea-associated enterotoxins, the assessment of the non-hemolytic enterotoxin B (NheB) titer determined by a sandwich enzyme immunoassay (EIA) correlates best with in vitro cytotoxicity. In general, the regulation of enterotoxin expression of B. cereus is a coordinately-regulated process influenced by environmental, and probably also by host factors. As long as these factors are not completely understood, the currently-applied diagnostic procedures are based on indirect approaches to assess the potential virulence of an isolate. To date, sandwich EIA results serve as a surrogate marker to categorize isolates as either potentially low or highly toxic. Here, we report on a single amino acid exchange in the NheB sequence leading to an underestimation of the cytotoxic potential in a limited number of strains. During the screening of a large panel of B. cereus isolates, six showed uncommon features with low sandwich EIA titers despite high cytotoxicity. Sequence analysis revealed the point-mutation (Glu)151(Asp) in the potential binding region of the capture antibody. Application of this antibody also results in low titers in an indirect EIA format and shows variable detection intensities in Western-immunoblots. A commercially-available assay based on a lateral flow device detects all strains correctly as NheB producers in a qualitative manner. In conclusion, isolates showing low NheB titers should additionally be assayed in an indirect EIA or for their in vitro cytotoxicity to ensure a correct classification as either low or highly toxic.
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Affiliation(s)
- Andrea Didier
- Department of Veterinary Science, Faculty of Veterinary Medicine, Ludwig-Maximilians Universität München, 85763 Oberschleißheim, Germany.
| | - Nadja Jeßberger
- Department of Veterinary Science, Faculty of Veterinary Medicine, Ludwig-Maximilians Universität München, 85763 Oberschleißheim, Germany.
| | - Victoria Krey
- Lehrstuhl für Mikrobielle Ökologie, Zentralinstitut für Ernährungs-und Lebensmittelforschung, Wissenschaftszentrum Weihenstephan, Technische Universität München, 85354 Freising, Germany.
| | - Richard Dietrich
- Department of Veterinary Science, Faculty of Veterinary Medicine, Ludwig-Maximilians Universität München, 85763 Oberschleißheim, Germany.
| | - Siegfried Scherer
- Lehrstuhl für Mikrobielle Ökologie, Zentralinstitut für Ernährungs-und Lebensmittelforschung, Wissenschaftszentrum Weihenstephan, Technische Universität München, 85354 Freising, Germany.
| | - Erwin Märtlbauer
- Department of Veterinary Science, Faculty of Veterinary Medicine, Ludwig-Maximilians Universität München, 85763 Oberschleißheim, Germany.
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Jeßberger N, Krey VM, Rademacher C, Böhm ME, Mohr AK, Ehling-Schulz M, Scherer S, Märtlbauer E. From genome to toxicity: a combinatory approach highlights the complexity of enterotoxin production in Bacillus cereus. Front Microbiol 2015; 6:560. [PMID: 26113843 PMCID: PMC4462024 DOI: 10.3389/fmicb.2015.00560] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Accepted: 05/21/2015] [Indexed: 01/30/2023] Open
Abstract
In recent years Bacillus cereus has gained increasing importance as a food poisoning pathogen. It is the eponymous member of the B. cereus sensu lato group that consists of eight closely related species showing impressive diversity of their pathogenicity. The high variability of cytotoxicity and the complex regulatory network of enterotoxin expression have complicated efforts to predict the toxic potential of new B. cereus isolates. In this study, comprehensive analyses of enterotoxin gene sequences, transcription, toxin secretion and cytotoxicity were performed. For the first time, these parameters were compared in a whole set of B. cereus strains representing isolates of different origin (food or food poisoning outbreaks) and of different toxic potential (enteropathogenic and apathogenic) to elucidate potential starting points of strain-specific differential toxicity. While toxin gene sequences were highly conserved and did not allow for differentiation between high and low toxicity strains, comparison of nheB and hblD enterotoxin gene transcription and Nhe and Hbl protein titers revealed not only strain-specific differences but also incongruence between toxin gene transcripts and toxin protein levels. With one exception all strains showed comparable capability of protein secretion and so far, no secretion patterns specific for high and low toxicity strains were identified. These results indicate that enterotoxin expression is more complex than expected, possibly involving the orchestrated interplay of different transcriptional regulator proteins, as well as posttranscriptional and posttranslational regulatory mechanisms plus additional influences of environmental conditions.
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Affiliation(s)
- Nadja Jeßberger
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität München Oberschleißheim, Germany
| | - Viktoria M Krey
- Lehrstuhl für Mikrobielle Ökologie, Zentralinstitut für Ernährungs- und Lebensmittelforschung, Wissenschaftszentrum Weihenstephan, Technische Universität München Freising, Germany
| | - Corinna Rademacher
- Functional Microbiology, Department of Pathobiology, Institute of Microbiology, University of Veterinary Medicine Vienna Vienna, Austria
| | - Maria-Elisabeth Böhm
- Lehrstuhl für Mikrobielle Ökologie, Zentralinstitut für Ernährungs- und Lebensmittelforschung, Wissenschaftszentrum Weihenstephan, Technische Universität München Freising, Germany
| | - Ann-Katrin Mohr
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität München Oberschleißheim, Germany
| | - Monika Ehling-Schulz
- Functional Microbiology, Department of Pathobiology, Institute of Microbiology, University of Veterinary Medicine Vienna Vienna, Austria
| | - Siegfried Scherer
- Lehrstuhl für Mikrobielle Ökologie, Zentralinstitut für Ernährungs- und Lebensmittelforschung, Wissenschaftszentrum Weihenstephan, Technische Universität München Freising, Germany
| | - Erwin Märtlbauer
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität München Oberschleißheim, Germany
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A case of intoxication due to a highly cytotoxic Bacillus cereus strain isolated from cooked chicken. Food Microbiol 2015; 46:195-199. [DOI: 10.1016/j.fm.2014.08.005] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Revised: 08/11/2014] [Accepted: 08/14/2014] [Indexed: 12/12/2022]
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40
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Kholodkov OA, Budarina ZI, Andreeva-Kovalevskaya ZI, Siunov AV, Solonin AS. Effect of Bacillus cereus hemolysin II on hepatocyte cells. APPL BIOCHEM MICRO+ 2015. [DOI: 10.1134/s000368381502009x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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41
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Kong L, Lu A, Guan J, Yang B, Li M, Hillyer JF, Ramarao N, Söderhäll K, Liu C, Ling E. Thermolysin damages animal life through degradation of plasma proteins enhanced by rapid cleavage of serpins and activation of proteases. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2015; 88:64-84. [PMID: 25042057 DOI: 10.1002/arch.21178] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Thermolysin, a metallopeptidase secreted by pathogenic microbes, is concluded as an important virulence factor due to cleaving purified host proteins in vitro. Using the silkworm Bombyx mori as a model system, we found that thermolysin injection into larvae induces the destruction of the coagulation response and the activation of hemolymph melanization, which results in larval death. Thermolysin triggers the rapid degradation of insect and mammalian plasma proteins at a level that is considerably greater than expected in vitro and/or in vivo. To more specifically explore the mechanism, thermolysin-induced changes to key proteins belonging to the insect melanization pathway were assessed as a window for observing plasma protein cleavage. The application of thermolysin induced the rapid cleavage of the melanization negative regulator serpin-3, but did not directly activate the melanization rate-limiting enzyme prophenoloxidase (PPO) or the terminal serine proteases responsible for PPO activation. Terminal serine proteases of melanization are activated indirectly after thermolysin exposure. We hypothesize that thermolysin induces the rapid degradation of serpins and the activation of proteases directly or indirectly, boosting uncontrolled plasma protein degradation in insects and mammalians.
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Affiliation(s)
- Lulu Kong
- College of Life Science, Anhui Agricultural University, Changjiang, People's Republic of China; College of Agriculture and Biology, Shanghai Jiaotong University, Dongchuan, Shanghai, People's Republic of China; Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, People's Republic of China
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42
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Guidance on the assessment of the toxigenic potential of Bacillus species used in animal nutrition. EFSA J 2014. [DOI: 10.2903/j.efsa.2014.3665] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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Techer C, Baron F, Delbrassinne L, Belaïd R, Brunet N, Gillard A, Gonnet F, Cochet MF, Grosset N, Gautier M, Andjelkovic M, Lechevalier V, Jan S. Global overview of the risk linked to the Bacillus cereus group in the egg product industry: identification of food safety and food spoilage markers. J Appl Microbiol 2014; 116:1344-58. [PMID: 24484429 DOI: 10.1111/jam.12462] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2013] [Revised: 01/10/2014] [Accepted: 01/26/2014] [Indexed: 11/28/2022]
Abstract
AIMS To evaluate the food safety and spoilage risks associated with psychrotrophic Bacillus cereus group bacteria for the egg product industry and to search for relevant risk markers. METHODS AND RESULTS A collection of 68 psychrotrophic B. cereus group isolates, coming from pasteurized liquid whole egg products, was analysed through a principal component analysis (PCA) regarding their spoilage and food safety risk potentials. The principal component analysis showed a clear differentiation between two groups within the collection, one half of the isolates representing a safety risk and the other half a spoilage risk. CONCLUSIONS Relevant risk markers were highlighted by PCA, that is (i) for the food safety risk, the presence of the specific 16S rDNA-1m genetic signature and the ability to grow at 43°C on solid medium and (ii) for the spoilage risk, the presence of the cspA genetic signature. SIGNIFICANCE AND IMPACT OF THE STUDY This work represents a first step in the development of new diagnostic technologies for the assessment of the microbiological quality of foods likely to be contaminated with psychrotrophic B. cereus group bacteria.
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Affiliation(s)
- C Techer
- Equipe Microbiologie de l'Œuf et des Ovoproduits (MICOV), Agrocampus Ouest, INRA, UMR1253 Science et Technologie du Lait et de l'Œuf, Rennes, France
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Jeßberger N, Dietrich R, Bock S, Didier A, Märtlbauer E. Bacillus cereus enterotoxins act as major virulence factors and exhibit distinct cytotoxicity to different human cell lines. Toxicon 2013; 77:49-57. [PMID: 24211313 DOI: 10.1016/j.toxicon.2013.10.028] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Accepted: 10/29/2013] [Indexed: 11/17/2022]
Abstract
A comparative analysis on the relevance of the Bacillus cereus enterotoxins Nhe (nonhemolytic enterotoxin), HBL (haemolysin BL) and CytK (cytotoxin K) was accomplished, concerning their toxic activity towards different target cell lines. Overall, among the components secreted by the reference strains for Nhe and HBL, the enterotoxin complexes accounted for over 90% of the total toxicity. Vero and primary endothelial cells (HUVEC) were highly susceptible to Nhe, whereas Hep-G2, Vero and A549 reacted most sensitive to Nhe plus HBL. For CytK the highest toxicity was observed on CaCo-2 cells. As HBL positive strains always produce Nhe in parallel, the specific contribution of both enterotoxin complexes to the overall observed cytotoxic effects was determined by consecutively removing their single components. While in most cell lines Nhe and HBL contributed more or less equally (40-60%) to cytotoxicity, the relative activity of Nhe was approximately 90% in HUVEC, and that of HBL 75% in A549 cells. With U937, a nearly Nhe resistant cell line was identified for the first time. This distinct susceptibility of cell lines was confirmed by investigating a set of 37 B. cereus strains. Interestingly, whereas Nhe is the enterotoxin mainly responsible for cell death as determined by WST-1 bioassays, more rapid pore formation was observed when HBL was present, pointing to a different mode of action of the two enterotoxin complexes. Furthermore, correlation was observed between cytotoxicity of solely Nhe producing strains and NheB. Cytotoxicity of Nhe/HBL producing isolates correlated with the expression of HBL L1, NheB and HBL B. In conclusion, the observed susceptibilities of target cell lines of different histological origin underline that B. cereus enterotoxins represent major virulence factors and that toxicity is not restricted to gastrointestinal infections. The varying contribution of Nhe and HBL to total cytotoxicity strongly indicates that Nhe as well as HBL specific B. cereus enterotoxin receptors exist.
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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.
| | - Richard Dietrich
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität München, Schönleutnerstr. 8, 85764 Oberschleißheim, Germany
| | - Stefanie Bock
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität München, Schönleutnerstr. 8, 85764 Oberschleißheim, Germany
| | - Andrea Didier
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität München, Schönleutnerstr. 8, 85764 Oberschleißheim, Germany
| | - Erwin Märtlbauer
- Department of Veterinary Sciences, Faculty of Veterinary Medicine, Ludwig-Maximilians-Universität München, Schönleutnerstr. 8, 85764 Oberschleißheim, Germany
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Decousser JW, Ramarao N, Duport C, Dorval M, Bourgeois-Nicolaos N, Guinebretière MH, Razafimahefa H, Doucet-Populaire F. Bacillus cereus and severe intestinal infections in preterm neonates: Putative role of pooled breast milk. Am J Infect Control 2013; 41:918-21. [PMID: 23769834 DOI: 10.1016/j.ajic.2013.01.043] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2012] [Revised: 01/31/2013] [Accepted: 01/31/2013] [Indexed: 01/24/2023]
Abstract
BACKGROUND Bacillus cereus is an environmental pathogen whose spores resist the usual cleaning procedure applied by the food industry and hospitals. We reported a cluster of severe intestinal infections due to B cereus in 2 very low birth weight neonates from a neonatal intensive care unit. METHODS Environmental sampling and bacteriological analysis of pooled breast milk (PBM) were performed. Practices for preparation and administration of milk were observed and additional laboratory experiments performed. Strains were typed using M13-polymerase chain reaction and their virulence tested using cellular and insect models. RESULTS B cereus strains were exclusively isolated from intestinal tracts and PBM. No environmental culture yielded any viable B cereus. Although genotypically diverse, both clinical and food strains exhibited high virulence potency. These findings pointed out the pathogenic potency of B cereus in neonates; the putative role of PBM as a reservoir for pathogenic B cereus and the triggered effect of a defective care procedure, which allowed the growth of bacteria in pasteurized PBM. Well described from dried formula, the presence of pathogenic B cereus strains in PBM was not previously reported. CONCLUSIONS Careful monitoring of conditions during collection, conservation, and administration of PBM should be implemented in high-risk populations such as premature neonates.
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Affiliation(s)
- Jean-Winoc Decousser
- Department of Virology, Bacteriology-Infection Control, Parasitology-Mycology, Assistance Publique-Hôpitaux de Paris, University Hospital Henri Mondor, Créteil, France.
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46
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Tran SL, Ramarao N. Bacillus cereus immune escape: a journey within macrophages. FEMS Microbiol Lett 2013; 347:1-6. [PMID: 23827020 DOI: 10.1111/1574-6968.12209] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2013] [Accepted: 06/28/2013] [Indexed: 12/14/2022] Open
Abstract
During bacterial infection, professional phagocytes are attracted to the site of infection, where they constitute a first line of host cell defense. Their function is to engulf and destroy the pathogens. Thus, bacteria must withstand the bactericidal activity of professional phagocytes, including macrophages to counteract the host immune system. Bacillus cereus infections are characterized by bacteremia despite the accumulation of inflammatory cells at the site of infection. This implies that the bacteria have developed means of resisting the host immune system. Bacillus cereus spores survive, germinate, and multiply in contact with macrophages, eventually producing toxins that kill these cells. However, the exact mechanism by which B. cereus evades immune attack remains unclear. This review addresses the interaction between B. cereus and macrophages, highlighting, in particular, the ways in which the bacteria escape the microbicidal activities of professional phagocytes.
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Affiliation(s)
- Seav-Ly Tran
- INRA, Unité MICALIS, AgroParisTech, UMR-1319, La Minière, Guyancourt, France
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47
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The pore-forming haemolysins of bacillus cereus: a review. Toxins (Basel) 2013; 5:1119-39. [PMID: 23748204 PMCID: PMC3717773 DOI: 10.3390/toxins5061119] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2013] [Revised: 05/22/2013] [Accepted: 05/24/2013] [Indexed: 12/05/2022] Open
Abstract
The Bacillus cereus sensu lato group contains diverse Gram-positive spore-forming bacteria that can cause gastrointestinal diseases and severe eye infections in humans. They have also been incriminated in a multitude of other severe, and frequently fatal, clinical infections, such as osteomyelitis, septicaemia, pneumonia, liver abscess and meningitis, particularly in immuno-compromised patients and preterm neonates. The pathogenic properties of this organism are mediated by the synergistic effects of a number of virulence products that promote intestinal cell destruction and/or resistance to the host immune system. This review focuses on the pore-forming haemolysins produced by B. cereus: haemolysin I (cereolysin O), haemolysin II, haemolysin III and haemolysin IV (CytK). Haemolysin I belongs to the cholesterol-dependent cytolysin (CDC) family whose best known members are listeriolysin O and perfringolysin O, produced by L. monocytogenes and C. perfringens respectively. HlyII and CytK are oligomeric ß-barrel pore-forming toxins related to the α-toxin of S. aureus or the ß-toxin of C. perfringens. The structure of haemolysin III, the least characterized haemolytic toxin from the B. cereus, group has not yet been determined.
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48
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Iron regulates Bacillus thuringiensis haemolysin hlyII gene expression during insect infection. J Invertebr Pathol 2013; 113:205-8. [PMID: 23598183 DOI: 10.1016/j.jip.2013.04.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2013] [Revised: 03/29/2013] [Accepted: 04/04/2013] [Indexed: 11/22/2022]
Abstract
Bacillus thuringiensis (Bt) is a spore-forming entomopathogen broadly used in agriculture crop. The haemolysin HlyII is an important Bt virulence factor responsible for insect death. In this work, we focused on the regulation of the hlyII gene throughout the bacterial growth in vitro and in vivo during insect infection. We show that hlyII regulation depends on the global regulator Fur. This regulation occurs independently of HlyIIR, the other known regulator of hlyII gene expression. Moreover, we show that hlyII is highly expressed when iron is depleted in vivo. As HlyII induces haemocyte and macrophage death, which are involved in the sequestration of iron upon infection, HlyII may induce host cell death to allow bacteria to gain access to iron.
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49
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Ceuppens S, Boon N, Uyttendaele M. Diversity of Bacillus cereus group strains is reflected in their broad range of pathogenicity and diverse ecological lifestyles. FEMS Microbiol Ecol 2013; 84:433-50. [PMID: 23488744 DOI: 10.1111/1574-6941.12110] [Citation(s) in RCA: 125] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Revised: 03/06/2013] [Accepted: 03/06/2013] [Indexed: 12/25/2022] Open
Abstract
Bacillus cereus comprises a highly versatile group of bacteria, which are of particular interest because of their capacity to cause disease. Emetic food poisoning is caused by the toxin cereulide produced during the growth of emetic B. cereus in food, while diarrhoeal food poisoning is the result of enterotoxin production by viable vegetative B. cereus cells in the small intestine, probably in the mucus layer and/or attached to the host's intestinal epithelium. The numbers of B. cereus causing disease are highly variable, depending on diverse factors linked to the host (age, diet, physiology and immunology), bacteria (cellular form, toxin genes and expression) and food (nutritional composition and meal characteristics). Bacillus cereus group strains show impressive ecological diversity, ranging from their saprophytic life cycle in soil to symbiotic (commensal and mutualistic) lifestyles near plant roots and in guts of insects and mammals to various pathogenic ones in diverse insect and mammalian hosts. During all these different ecological lifestyles, their toxins play important roles ranging from providing competitive advantages within microbial communities to inhibition of specific pathogenic organisms for their host and accomplishment of infections by damaging their host's tissues.
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Affiliation(s)
- Siele Ceuppens
- Laboratory of Food Microbiology and Food Preservation, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium.
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50
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Dubois T, Perchat S, Verplaetse E, Gominet M, Lemy C, Aumont-Nicaise M, Grenha R, Nessler S, Lereclus D. Activity of the Bacillus thuringiensis NprR-NprX cell-cell communication system is co-ordinated to the physiological stage through a complex transcriptional regulation. Mol Microbiol 2013; 88:48-63. [PMID: 23388036 DOI: 10.1111/mmi.12168] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/31/2013] [Indexed: 12/01/2022]
Abstract
NprR is a quorum sensor of the RNPP family found in bacteria of the Bacillus cereus group. In association with its cognate peptide NprX, NprR controls the expression of genes essential for survival and sporulation of Bacillus thuringiensis during its necrotrophic development in insects. Here, we report that the nprR-nprX genes are not autoregulated and are co-transcribed from a σ(A) -dependent promoter (PA ) located upstream from nprR. The transcription from PA starts at the onset of the stationary phase and is controlled by two transcriptional regulators: CodY and PlcR. The nutritional repressor CodY represses nprR-nprX transcription during the exponential growth phase and the quorum sensor PlcR activates nprR-nprX transcription at the onset of stationary phase. We show that nprX is also transcribed independently of nprR from two promoters, PH and PE , dependent on the sporulation-specific sigma factors, σ(H) and σ(E) respectively. Both promoters ensure nprX transcription during late stationary phase while transcription from PA has decreased. These results show that the activity of the NprR-NprX quorum sensing system is tightly co-ordinated to the physiological stage throughout the developmental process of the Bacillus.
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Affiliation(s)
- Thomas Dubois
- INRA, UMR1319 Micalis, La Minière, F-78280, Guyancourt, France
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