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Ehling-Schulz M, Guinebretiere MH, Monthán A, Berge O, Fricker M, Svensson B. Toxin gene profiling of enterotoxic and emetic Bacillus cereus. FEMS Microbiol Lett 2006; 260:232-40. [PMID: 16842349 DOI: 10.1111/j.1574-6968.2006.00320.x] [Citation(s) in RCA: 144] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Very different toxins are responsible for the two types of gastrointestinal diseases caused by Bacillus cereus: the diarrhoeal syndrome is linked to nonhemolytic enterotoxin NHE, hemolytic enterotoxin HBL, and cytotoxin K, whereas emesis is caused by the action of the depsipeptide toxin cereulide. The recently identified cereulide synthetase genes permitted development of a molecular assay that targets all toxins known to be involved in food poisoning in a single reaction, using only four different sets of primers. The enterotoxin genes of 49 strains, belonging to different phylogenetic branches of the B. cereus group, were partially sequenced to encompass the molecular diversity of these genes. The sequence alignments illustrated the high molecular polymorphism of B. cereus enterotoxin genes, which is necessary to consider when establishing PCR systems. Primers directed towards the enterotoxin complex genes were located in different CDSs of the corresponding operons to target two toxin genes with one single set of primers. The specificity of the assay was assessed using a panel of B. cereus strains with known toxin profiles and was successfully applied to characterize strains from food and clinical diagnostic labs as well as for the toxin gene profiling of B. cereus isolated from silo tank populations.
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Affiliation(s)
- Monika Ehling-Schulz
- Microbial Ecology Group, Department of Biosciences, WZW, Technische Universität München, Freising, Germany.
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Hu X, Hansen BM, Hendriksen NB, Yuan Z. Detection and phylogenic analysis of one anthrax virulence plasmid pXO1 conservative open reading frame ubiquitous presented within Bacillus cereus group strains. Biochem Biophys Res Commun 2006; 349:1214-9. [PMID: 16978581 DOI: 10.1016/j.bbrc.2006.08.125] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2006] [Accepted: 08/22/2006] [Indexed: 11/15/2022]
Abstract
The presence of one of the anthrax virulence plasmid pXO1 conserved fragments was analyzed in 24 Bacillus cereus and B. thuringiensis strains, including 6 B. thuringiensis subspecies, by polymerase chain reactions. Twelve out of 24 strains showed PCR-positive for an ORF101 homologous sequence. Two pXO1-ORF101-like fragments from a B. cereus B-4ac and a commercial B. thuringiensis kurstaki HD1 were cloned, sequenced and expressed in Escherichia coli. Toxicity assays revealed that the product encoded by the pXO1-ORF101-like fragment had no impact on either Vero cells or Chinese Hamster Ovary cells, suggesting that this fragment probably not contribute to enterotoxic activity. Sequence alignment of the pXO1-ORF101 from three Bacillus anthracis and ORF101-like fragments from other 12 B. cereus group isolates indicated high identity (more than 90%) and the presence of subgroup- and strain-specific SNPs among these fragments.
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Affiliation(s)
- Xiaomin Hu
- Wuhan Institute of Virology, Chinese Academy of Science, Wuhan 430071, China
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53
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Gray KM, Banada PP, O'Neal E, Bhunia AK. Rapid Ped-2E9 cell-based cytotoxicity analysis and genotyping of Bacillus species. J Clin Microbiol 2005; 43:5865-72. [PMID: 16333068 PMCID: PMC1317164 DOI: 10.1128/jcm.43.12.5865-5872.2005] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2005] [Revised: 05/22/2005] [Accepted: 09/25/2005] [Indexed: 11/20/2022] Open
Abstract
Bacillus species causing food-borne disease produce multiple toxins eliciting gastroenteritis. Toxin assays with mammalian cell cultures are reliable but may take 24 to 72 h to complete and also lack sensitivity. Here, a sensitive and rapid assay was developed using a murine hybridoma Ped-2E9 cell model. Bacillus culture supernatants containing toxins were added to a Ped-2E9 cell line and analyzed for cytotoxicity with an alkaline phosphatase release assay. Most Bacillus cereus strains produced positive cytotoxicity results within 1 h, and data were comparable to those obtained with the standard Chinese hamster ovary (CHO)-based cytotoxicity assay, which took about 72 h to complete. Moreover, the Ped-2E9 cell assay had 25- to 58-fold-higher sensitivity than the CHO assay. Enterotoxin-producing Bacillus thuringiensis also gave positive results with Ped-2E9 cells, while several other Bacillus species were negative. Eight isolates from food suspected of Bacillus contamination were also tested, and only one strain, which was later confirmed as B. cereus, gave a positive result. In comparison with two commercial diarrheal toxin assay kits (BDE-VIA and BCET-RPLA), the Ped-2E9 assay performed more reliably. Toxin fractions of >30 kDa showed the highest degree of cytotoxicity effects, and heat treatment significantly reduced the toxin activity, indicating the involvement of a heat-labile high-molecular-weight component in Ped-2E9 cytotoxicity. PCR results, in most cases, were in agreement with the cytotoxic potential of each strain. Ribotyping was used to identify cultures and indicated differences for several previously reported isolates. This Ped-2E9 cell assay could be used as a rapid (approximately 1-h) alternative to current methods for sensitive detection of enterotoxins from Bacillus species.
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Affiliation(s)
- Kristen M Gray
- Molecular Food Microbiology Laboratory, Department of Food Science, Purdue University, 745 Agriculture Mall Drive, West Lafayette, IN 47907, USA
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Dietrich R, Moravek M, Bürk C, Granum PE, Märtlbauer E. Production and characterization of antibodies against each of the three subunits of the Bacillus cereus nonhemolytic enterotoxin complex. Appl Environ Microbiol 2005; 71:8214-20. [PMID: 16332805 PMCID: PMC1317347 DOI: 10.1128/aem.71.12.8214-8220.2005] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2005] [Accepted: 08/15/2005] [Indexed: 11/20/2022] Open
Abstract
The nonhemolytic enterotoxin (Nhe) is one of the two three-component enterotoxins which are responsible for diarrheal food poisoning syndrome caused by Bacillus cereus. To facilitate the detection of this toxin, consisting of the subunits NheA, NheB, and NheC, a complete set of high-affinity antibodies against each of the three components was established and characterized. A rabbit antiserum specific for the C-terminal part (15 amino acids) of NheC was produced using a respective synthetic peptide coupled to a protein carrier for immunization. Using purified B. cereus exoprotein preparations as immunogens, one monoclonal antibody against NheA and several antibodies against NheB were obtained. No cross-reactivity with other proteins produced by different strains of B. cereus was observed. Antibodies against the NheB component were able to neutralize the cytotoxic activity (up to 98%) of Nhe. Based on indirect enzyme immunoassays, the antibodies developed in this study were successfully used in the characterization of the enterotoxic activity of several B. cereus strains. For the first time, it could be shown that strains carrying the nhe genes usually express the complete set of the three components, including NheC. However, the amount of toxin produced varies considerably between the different strains.
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Affiliation(s)
- Richard Dietrich
- Institut für Hygiene und Technologie der Lebensmittel tierischen Ursprungs, Tierärztliche Fakultät, Universität München, Schönleutnerstrasse 8, 85764 Oberschleissheim, Germany.
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55
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Ehling-Schulz M, Vukov N, Schulz A, Shaheen R, Andersson M, Märtlbauer E, Scherer S. Identification and partial characterization of the nonribosomal peptide synthetase gene responsible for cereulide production in emetic Bacillus cereus. Appl Environ Microbiol 2005; 71:105-13. [PMID: 15640177 PMCID: PMC544239 DOI: 10.1128/aem.71.1.105-113.2005] [Citation(s) in RCA: 194] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cereulide, a depsipeptide structurally related to valinomycin, is responsible for the emetic type of gastrointestinal disease caused by Bacillus cereus. Due to its chemical structure, (D-O-Leu-D-Ala-L-O-Val-L-Val)(3), cereulide might be synthesized nonribosomally. Therefore, degenerate PCR primers targeted to conserved sequence motifs of known nonribosomal peptide synthetase (NRPS) genes were used to amplify gene fragments from a cereulide-producing B. cereus strain. Sequence analysis of one of the amplicons revealed a DNA fragment whose putative gene product showed significant homology to valine activation NRPS modules. The sequences of the flanking regions of this DNA fragment revealed a complete module that is predicted to activate valine, as well as a putative carboxyl-terminal thioesterase domain of the NRPS gene. Disruption of the peptide synthetase gene by insertion of a kanamycin cassette through homologous recombination produced cereulide-deficient mutants. The valine-activating module was highly conserved when sequences from nine emetic B. cereus strains isolated from diverse geographical locations were compared. Primers were designed based on the NRPS sequence, and the resulting PCR assay, targeting the ces gene, was tested by using a panel of 143 B. cereus group strains and 40 strains of other bacterial species showing PCR bands specific for only the cereulide-producing B. cereus strains.
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Affiliation(s)
- Monika Ehling-Schulz
- Microbial Ecology Group, Department of Biosciences, WZW, Technische Universität München, D-85354 Freising, Germany
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Abstract
The genus Bacillus includes members that demonstrate a wide range of diversity from physiology and ecological niche to DNA sequence and gene regulation. The species of most interest tend to be known for their pathogenicity and are closely linked genetically. Bacillus anthracis causes anthrax, and Bacillus thuringiensis is widely used for its insecticidal properties but has also been associated with foodborne disease. Bacillus cereus causes two types of food poisoning, the emetic and diarrheal syndromes, and a variety of local and systemic infections. Although in this review we provide information on the genus and a variety of species, the primary focus is on the B. cereus strains and toxins that are involved in foodborne illness. B. cereus produces a large number of potential virulence factors, but for the majority of these factors their roles in specific infections have not been established. To date, only cereulide and the tripartite hemolysin BL have been identified specifically as emetic and diarrheal toxins, respectively. Nonhemolytic enterotoxin, a homolog of hemolysin BL, also has been associated with the diarrheal syndrome. Recent findings regarding these and other putative enterotoxins are discussed.
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Affiliation(s)
- Jean L Schoeni
- Department of Food Microbiology and Toxicology, Food Research Institute, University of Wisconsin, Madison, Wisconsin 53706, USA
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Ehling-Schulz M, Fricker M, Scherer S. Bacillus cereus, the causative agent of an emetic type of food-borne illness. Mol Nutr Food Res 2004; 48:479-87. [PMID: 15538709 DOI: 10.1002/mnfr.200400055] [Citation(s) in RCA: 232] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Bacillus cereus is the causative agent of two distinct forms of gastroenteritic disease connected to food-poisoning. It produces one emesis-causing toxin and three enterotoxins that elicit diarrhea. Due to changing lifestyles and eating habits, B. cereus is responsible for an increasing number of food-borne diseases in the industrial world. In the past, most studies concentrated on the diarrhoeal type of food-borne disease, while less attention has been given to the emetic type of the disease. The toxins involved in the diarrhoeal syndrome are well-known and detection methods are commercially available, whereas diagnostic methods for the emetic type of disease have been limited. Only recently, progress has been made in developing identification methods for emetic B. cereus and its corresponding toxin. We will summarize the data available for the emetic type of the disease and discuss some new insights in emetic strain characteristics, diagnosis, and toxin synthesis.
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Moravek M, Wegscheider M, Schulz A, Dietrich R, Bürk C, Märtlbauer E. Colony immunoblot assay for the detection of hemolysin BL enterotoxin producingBacillus cereus. FEMS Microbiol Lett 2004. [DOI: 10.1111/j.1574-6968.2004.tb09744.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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Duport C, Thomassin S, Bourel G, Schmitt P. Anaerobiosis and low specific growth rates enhance hemolysin BL production by Bacillus cereus F4430/73. Arch Microbiol 2004; 182:90-5. [PMID: 15205890 DOI: 10.1007/s00203-004-0688-y] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2003] [Revised: 04/21/2004] [Accepted: 05/17/2004] [Indexed: 10/26/2022]
Abstract
Bacillus cereus F4430/73 produced the highest levels of hemolysin BL (HBL) when grown under anaerobiosis in MOD medium. Anaerobic cells grown in a chemostat at low specific growth rate (0.1-0.2 h(-1)) expressed up to sevenfold more HBL than did cells held at a faster growth rate. At 0.2 h(-1), the presence of 90 mM glucose resulted in inhibition of HBL production. Glucose was found to repress HBL induction at the mRNA level, indicating the potential involvement of catabolite repression in the regulation of HBL. Based on these data, it is suggested that growth rate could be an effector of catabolite regulation of HBL.
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Affiliation(s)
- Catherine Duport
- UMR A408 Sécurité et Qualité des Produits d'Origine Végétale, INRA/Université d'Avignon, INRA Domaine St Paul, 84914, Avignon cedex 9, France
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60
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Cherif A, Chehimi S, Limem F, Hansen BM, Hendriksen NB, Daffonchio D, Boudabous A. Detection and characterization of the novel bacteriocin entomocin 9, and safety evaluation of its producer, Bacillus thuringiensis ssp. entomocidus HD9. J Appl Microbiol 2004; 95:990-1000. [PMID: 14633027 DOI: 10.1046/j.1365-2672.2003.02089.x] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
AIMS To identify and characterize new bacteriocins from a collection of 41 strains belonging to 27 subspecies of Bacillus thuringiensis, and to evaluate the safety of the producers. METHODS AND RESULTS Bacillus thuringiensis ssp. entomocidus HD9 produced in the culture supernatant an antimicrobial activity against Gram-positive bacteria including Listeria monocytogenes, one of four pathogenic Pseudomonas aeruginosa and several fungi. Production of the antibacterial activity, named entomocin 9, started during mid-logarithmic growth reaching its maximum at the early stationary phase. Entomocin 9 retained more than 72% of activity after incubation for 20 min at 121 degrees C. Activity was lost after proteinase K treatment, it was stable in a pH range between 3 and 9, and resistant to lyophilization. After partial purification with ammonium sulphate precipitation followed by gel-filtration and anion-exchange chromatography, an active protein of ca 12.4 kDa was isolated. The mode of action of entomocin 9 was bactericidal and caused cell lysis of growing cells. Despite the presence of a range of virulence related genes, including haemolysin BL, nonhaemolytic enterotoxin, cytotoxin K and several hydrolytic activities, B. thuringiensis HD9 was not toxic against Vero cells. CONCLUSIONS Entomocin 9 is a novel heat-stable, bacteriocin produced by B. thuringiensis HD9. The absence of toxicity against Vero cells suggests the suitability of strain HD9 for a safe application in antimicrobial treatments. SIGNIFICANCE AND IMPACT OF THE STUDY New finding on entomocin 9 would make B. thuringiensis attractive in biotechnological applications as an antimicrobial agent in agriculture and food industry.
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Affiliation(s)
- A Cherif
- Laboratoire de Microbiologie, Département de Biologie, Faculté des Sciences de Tunis, Campus Universitaire, Tunis, Tunisia.
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61
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Bürk C, Dietrich R, Açar G, Moravek M, Bülte M, Märtlbauer E. Identification and characterization of a new variant of Shiga toxin 1 in Escherichia coli ONT:H19 of bovine origin. J Clin Microbiol 2003; 41:2106-12. [PMID: 12734256 PMCID: PMC154714 DOI: 10.1128/jcm.41.5.2106-2112.2003] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2002] [Revised: 12/27/2002] [Accepted: 01/25/2003] [Indexed: 01/08/2023] Open
Abstract
A new variant of Shiga toxin 1 (Stx1), designated Stx1d, which deviates considerably more than any other known variant from Stx1 encoded by phage 933J, was identified in an Escherichia coli strain, ONT:H19, isolated from bovine feces. The complete stx(1) gene of this strain was amplified and sequenced. Nucleotide sequence homology with stx(1) from phage 933J was only 91%, resulting in the substitution of 20 amino acids in the A subunit and 7 amino acids in the B subunit of the protein. Cell culture supernatant of this strain, which was negative for stx(2) by PCR testing, was cytotoxic to Vero cells and gave positive results in two commercial enzyme-linked immunosorbent assays for Stx. PCR primers were constructed for the specific detection of the new variant. The findings of this study suggest that Stx1 is not as conserved as thought before and that there might be more variants which cannot be detected by commonly used PCR methods.
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Affiliation(s)
- Christine Bürk
- Institute for Hygiene and Technology of Food of Animal Origin, Veterinary Faculty, Ludwig-Maximilians-Universität, 80539 Munich, Germany.
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62
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Choma C, Granum PE. The enterotoxin T (BcET) from Bacillus cereus can probably not contribute to food poisoning. FEMS Microbiol Lett 2002; 217:115-9. [PMID: 12445654 DOI: 10.1111/j.1574-6968.2002.tb11464.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
A polymerase chain reaction (PCR) fragment from strain NVH 38 (containing bceT) was cloned, sequenced and expressed in Escherichia coli. This sequence showed 50-60% identity to the original. When this bceT clone was expressed in E. coli no biological activity was found in either supernatants or cell extracts. Cell extracts from the Bacillus cereus strains (NVH 38 and B-4ac) were also negative on Vero cells. Neutralisation of supernatant from B. cereus B-4ac using a monoclonal antibody (reacting with NheB and HblD) abolished the activity. A test for cytotoxic enterotoxins was negative for both cell extracts and supernatants. Our data suggest that BcET either has an unknown type enterotoxic action or non at all.
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Affiliation(s)
- Caroline Choma
- Norwegian School of Veterinary Science, Department of Pharmacology Microbiology and Food Hygiene, PO Box 8146, 0033, Oslo, Norway
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63
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Gohar M, Økstad OA, Gilois N, Sanchis V, Kolstø AB, Lereclus D. Two-dimensional electrophoresis analysis of the extracellular proteome of Bacillus cereus reveals the importance of the PlcR regulon. Proteomics 2002; 2:784-91. [PMID: 12112862 DOI: 10.1002/1615-9861(200206)2:6<784::aid-prot784>3.0.co;2-r] [Citation(s) in RCA: 154] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Many virulence factors are secreted by the gram-positive, spore forming bacterium Bacillus cereus. Most of them are regulated by the transcriptional activator, PlcR, which is maximally expressed at the beginning of the stationary phase. We used a proteomic approach to study the impact of the PlcR regulon on the secreted proteins of B. cereus, by comparing the extracellular proteomes of strains ATCC 14579 and ATCC 14579 Delta plcR, in which plcR has been disrupted. Our study indicated that, quantitatively, most of the proteins secreted at the onset of the stationary phase are putative virulence factors, all of which are regulated, directly or indirectly, by PlcR. The inactivation of plcR abolished the secretion of some of these virulence factors, and strongly decreased that of others. The genes encoding proteins that are not secreted in the DeltaplcR mutant possessed a regulatory sequence, the PlcR box, upstream from their coding sequence. These proteins include collagenase, phospholipases, haemolysins, proteases and enterotoxins. Proteins for which the secretion was strongly decreased, but not abolished, in the DeltaplcR mutant did not display the PlcR box upstream from their genes. These proteins include flagellins and InhA2. InhA2 is a homologue of InhA, a Bacillus thuringiensis metalloprotease that specifically degrades antibacterial peptides. The mechanism by which PlcR affects the production of flagellins and InhA2 is not known.
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Affiliation(s)
- Michel Gohar
- INRA, Unité de Recherches de Lutte biologique, Guyancourt, France.
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64
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Gohar M, Økstad OA, Gilois N, Sanchis V, Kolst⊘ AB, Lereclus D. Two-dimensional electrophoresis analysis of the extracellular proteome of Bacillus cereusreveals the importance of the PlcR regulon. Proteomics 2002. [DOI: 10.1002/1615-9861(200206)2:6%3c784::aid-prot784%3e3.0.co;2-r] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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65
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Rowan NJ, Deans K, Anderson JG, Gemmell CG, Hunter IS, Chaithong T. Putative virulence factor expression by clinical and food isolates of Bacillus spp. after growth in reconstituted infant milk formulae. Appl Environ Microbiol 2001; 67:3873-81. [PMID: 11525980 PMCID: PMC93104 DOI: 10.1128/aem.67.9.3873-3881.2001] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2000] [Accepted: 05/30/2001] [Indexed: 11/20/2022] Open
Abstract
Forty-seven strains representing 14 different Bacillus species isolated from clinical and food samples were grown in reconstituted infant milk formulae (IMF) and subsequently assessed for adherence to, invasion of, and cytotoxicity toward HEp-2 and Caco-2 cells. Cell-free supernatant fluids from 38 strains (81%) were shown to be cytotoxic, 43 strains (91%) adhered to the test cell lines, and 23 strains (49%) demonstrated various levels of invasion. Of the 21 Bacillus cereus strains examined, 5 (24%) were invasive. A larger percentage of clinically derived Bacillus species (20%) than of similar species tested from the food environment were invasive. Increased invasion occurred after growth of selected Bacillus species in reconstituted IMF containing glucose. While PCR primer studies revealed that many different Bacillus species contained DNA sequences encoding the hemolysin BL (HBL) enterotoxin complex and B. cereus enterotoxin T, not all of these isolates expressed these diarrheagenic genes after growth in reconstituted IMF. Of the 47 Bacillus isolates examined, 3 isolates of B. cereus and 1 isolate of B. subtilis produced the HBL enterotoxin after 18 h of growth in brain heart infusion broth. However, eight isolates belonging to the species B. cereus, B. licheniformis, B. circulans, and B. megaterium were found to produce this enterotoxin after growth in reconstituted IMF when assessed with the B. cereus enterotoxin (diarrheal type) reversed passive latex agglutination (RPLA) kit. It is concluded that several Bacillus species occurring occasionally in clinical specimens and food samples are of potential medical significance due to the expression of putative virulence factors.
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Affiliation(s)
- N J Rowan
- Department of Bioscience, University of Strathclyde, Glasgow, Scotland.
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66
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Tsen HY, Chen ML, Hsieh YM, Sheu SJ, Chen YL. Bacillus cereus group strains, their hemolysin BL activity, and their detection in foods using a 16S RNA and hemolysin BL gene-targeted multiplex polymerase chain reaction system. J Food Prot 2000; 63:1496-502. [PMID: 11079690 DOI: 10.4315/0362-028x-63.11.1496] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Hemolysin BL (HBL) is a major virulence factor for Bacillus cereus group strains. It is also a target enterotoxin for the most commonly used B. cereus detection kit, i.e., the B. cereus enterotoxin (diarrheal type) reversed passive latex agglutination (BCET-RPLA) test kit. A survey of the HBL activities and the cytotoxicities to the Chinese hamster ovary (CHO) cells for the B. cereus group strains, however, showed that although only part of the B. cereus group strains are HBL active, all strains show cytotoxicity to the CHO cells. Thus, methods that allow the detection of not only the HBL but also of the B. cereus group strains are important. In this study, by comparison of the gene sequences of the 16S rRNA for B. cereus group and other bacteria strains, we designed primers B16S1 and B16S2 specific to all the B. cereus group strains. In addition, because HBL is a major enterotoxin, we also designed HBL gene-specific polymerase chain reaction (PCR) primers, i.e., Hm1 and Hm2, that generated the same results as those of the hemolysis and BCET-RPLA assays. Primers B16S1/B16S2 and Hm1/Hm2 could be combined into a multiplex PCR system for the simultaneous detection of B. cereus group cells and the possible presence of their HBL enterotoxins. Also, all these PCR systems allowed the detection of n x 10(0) CFU B. cereus cells per g of food sample if an 8-h enrichment step was performed prior to the PCR.
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Affiliation(s)
- H Y Tsen
- Department of Food Science, National Chung-Hsing University, Taichung, Taiwan, ROC.
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67
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Gaviria Rivera AM, Granum PE, Priest FG. Common occurrence of enterotoxin genes and enterotoxicity in Bacillus thuringiensis. FEMS Microbiol Lett 2000; 190:151-5. [PMID: 10981706 DOI: 10.1111/j.1574-6968.2000.tb09278.x] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
Seventy-four strains of Bacillus thuringiensis thuringiensis representing 24 serovars were examined for the presence of three enterotoxin genes/operons; the non-haemolytic enterotoxin Nhe, the haemolytic enterotoxin hbl and the Bacillus cereus toxin bceT using polymerase chain reaction. The nheBC genes were found in all strains examined, the hblCD genes in 65 of the 74 strains and bceT in 63 strains. There was little consistency of the distribution of enterotoxin loci among strains of the same serovar in serovars that were well represented in our collection. Culture supernatants from all but one strain inhibited protein synthesis in Vero cells, generally with a toxicity equivalent to that seen in strains of B. cereus isolated from incidents of food poisoning. Microbiological Societies.
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Affiliation(s)
- A M Gaviria Rivera
- Department of Biological Sciences, Heriot-Watt University, Riccarton, Edinburgh, UK
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68
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Prüss BM, Dietrich R, Nibler B, Märtlbauer E, Scherer S. The hemolytic enterotoxin HBL is broadly distributed among species of the Bacillus cereus group. Appl Environ Microbiol 1999; 65:5436-42. [PMID: 10584001 PMCID: PMC91741 DOI: 10.1128/aem.65.12.5436-5442.1999] [Citation(s) in RCA: 144] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The prevalence of the hemolytic enterotoxin complex HBL was determined in all species of the Bacillus cereus group with the exception of Bacillus anthracis. hblA, encoding the binding subunit B, was detected by PCR and Southern analysis and was confirmed by partial sequencing of 18 strains. The sequences formed two clusters, one including B. cereus and Bacillus thuringiensis strains and the other one consisting of Bacillus mycoides, Bacillus pseudomycoides, and Bacillus weihenstephanensis strains. From eight B. thuringiensis strains, the enterotoxin gene hblA could be amplified. Seven of them also expressed the complete HBL complex as determined with specific antibodies against the L(1), L(2), and B components. Eleven of 16 B. mycoides strains, all 3 B. pseudomyoides strains, 9 of 15 B. weihenstephanensis strains, and 10 of 23 B. cereus strains carried hblA. While HBL was not expressed in the B. pseudomycoides strains, the molecular assays were in accordance with the immunological assays for the majority of the remaining strains. In summary, the hemolytic enterotoxin HBL seems to be broadly distributed among strains of the B. cereus group and relates neither to a certain species nor to a specific environment. The consequences of this finding for food safety considerations need to be evaluated.
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Affiliation(s)
- B M Prüss
- Institut für Mikrobiologie, FML Weihenstephan, Technische Universität München, D-85350 Freising, Germany
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