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Virulence Dec 2022The genes , and encode the components Hbl L2, L1 and B of the pore forming enterotoxin haemolysin BL of . Two variants of the operon existand the more common one...
The genes , and encode the components Hbl L2, L1 and B of the pore forming enterotoxin haemolysin BL of . Two variants of the operon existand the more common one additionally contains downstream of . Up to now, it was completely unclear whether the corresponding protein, Hbl B', is widely expressed among strains and if it has a distinct function. In the present study, it was shown that the gene is indeed expressed and the Hbl B' protein is secreted by nearly all analysed strains. For the latter, a detection system was developed based on monoclonal antibody 11A5. Further, a distinct reduction of cytotoxic and haemolytic activity was observed when recombinant (r)Hbl B' was applied simultaneously with L2, L1 and B. This effect was due to direct interaction of rHbl B' with L1. Altogether, we present the first simple tool for the detection of Hbl B' in culture supernatants. Moreover, an important regulatory function of Hbl B' in the mechanism of Hbl was determined, which is best described as an additional control of complex formation, balancing the amounts of Hbl B-L1 complexes and the corresponding free subunits.
Topics: Bacillus cereus; Bacterial Proteins; Enterotoxins; Hemolysin Proteins; Operon
PubMed: 35291913
DOI: 10.1080/21505594.2022.2046951 -
Ultrasonics Sonochemistry Oct 2021This study was aimed at providing new insights on the proteomic response of bacterial spores to ultrasound. Data-independent-acquisition method was used to quantify the...
This study was aimed at providing new insights on the proteomic response of bacterial spores to ultrasound. Data-independent-acquisition method was used to quantify the proteome change of Bacillus cereus spores after ultrasound treatment (200 W). This study revealed that 2485 proteins were extracted from Bacillus cereus spores, most of them were related to metabolism. After ultrasound treatment, the expression of 340 proteins were significantly changed (the fold change ≥ 2 and p < 0.05), of which 207 proteins were significantly down-regulated. KEGG pathway analysis showed that differentially expressed proteins mainly distributed in metabolism pathway, cell process pathway and genetic information processing pathway after ultrasound treatment. Furthermore, this study analyzed the differentially expressed proteins in significant enrichment pathways. In particular, the expression of key proteins in the phosphorylation reaction of spores was significantly decreased after ultrasound treatment. Thus, ATP synthesis rate decreased and the phosphorylation reaction inhibited. Also, the decrease of the expression of key proteins related to the tricarboxylic acid cycle led to the decrease of nutrients metabolism of spores. Ultrasound treatment induced the down-regulation of fatty acid synthetase expression and promoted fatty acid metabolism at the same time. The content of fatty acids decreased in spores consequently.
Topics: Bacillus cereus; Proteome; Proteomics; Spores, Bacterial; Ultrasonic Waves
PubMed: 34474268
DOI: 10.1016/j.ultsonch.2021.105732 -
Journal of Microbiology and... Jan 2016Bacillus cereus is a gram-positive, rod-shaped, spore-forming bacterium that has been isolated from contaminated fermented soybean food products and from the...
Bacillus cereus is a gram-positive, rod-shaped, spore-forming bacterium that has been isolated from contaminated fermented soybean food products and from the environment. B. cereus produces diarrheal and emetic toxins and has caused many outbreaks of foodborne diseases. In this study, we investigated whether B. amyloliquefaciens RD7-7, isolated from rice doenjang (Korean fermented soybean paste), a traditional Korean fermented soybean food, shows antimicrobial activity against B. cereus and regulates its toxin gene expression. B. amyloliquefaciens RD7-7 exhibited strong antibacterial activity against B. cereus and inhibited the expression of B. cereus toxin-related genes (groEL, nheA, nheC, and entFM). We also found that addition of water extracts of soybean and buckwheat soksungjang (Korean fermented soybean paste made in a short time) fermented with B. amyloliquefaciens RD7-7 significantly reduced the growth and toxin expression of B. cereus. These results indicate that B. amyloliquefaciens RD7-7 could be used to control B. cereus growth and toxin production in the fermented soybean food industry. Our findings also provide a basis for the development of candidate biological control agents against B. cereus to improve the safety of fermented soybean food products.
Topics: Antibiosis; Bacillus; Bacillus cereus; Bacterial Toxins; Fagopyrum; Fermentation; Food Microbiology; Glycine max
PubMed: 26528531
DOI: 10.4014/jmb.1509.09090 -
Toxins Feb 2021is a human pathogenic bacterium found in foods with the potential to cause emesis and diarrhea. This study estimated the presence, toxigenic and genomic diversity of...
is a human pathogenic bacterium found in foods with the potential to cause emesis and diarrhea. This study estimated the presence, toxigenic and genomic diversity of obtained from cassava starch samples collected in bakeries and powdered food companies in Medellín (Colombia). was found in 43 of 75 (57%) cassava starch samples and 98 isolates were obtained. The , , , and toxin genes were detected by multiplex PCR and the most frequent operon was , whereas gene was not found. Twelve toxigenic profiles were determined by the detection of toxin genes, and the most frequent profiles harbored all enterotoxin genes. A broad genomic diversity was detected according to GTG-PCR fingerprinting results with 76 grouped in sixteen clusters and the 22 isolates clustering separately. No relationship was observed between genomic background and toxigenic profiles. In general, the results showed a high genomic and enterotoxigenic diversity in found in cassava starch. These results should incentive future studies to understand the distribution of isolated on raw materials in comparison with finished products.
Topics: Bacillus cereus; Bacterial Proteins; Bacterial Toxins; Enterotoxins; Food Handling; Food Microbiology; Gene Expression Regulation, Bacterial; Genotype; Hemolysin Proteins; Manihot; Starch
PubMed: 33578634
DOI: 10.3390/toxins13020131 -
BMC Microbiology Nov 2019This study aimed to evaluate the safety of raw vegetable products present on the German market regarding toxin-producing Bacillus cereus sensu lato (s.l.) group bacteria.
BACKGROUND
This study aimed to evaluate the safety of raw vegetable products present on the German market regarding toxin-producing Bacillus cereus sensu lato (s.l.) group bacteria.
RESULTS
A total of 147 B. cereus s.l. group strains isolated from cucumbers, carrots, herbs, salad leaves and ready-to-eat mixed salad leaves were analyzed. Their toxinogenic potential was assessed by multiplex PCR targeting the hemolysin BL (hbl) component D (hblD), non-hemolytic enterotoxin (nhe) component A (nheA), cytotoxin K-2 (cytK-2) and the cereulide (ces) toxin genes. In addition, a serological test was used to detect Hbl and Nhe toxins. On the basis of PCR and serological results, none of the strains were positive for the cereulide protein/genes, while 91.2, 83.0 and 37.4% were positive for the Hbl, Nhe and CytK toxins or their genes, respectively. Numerous strains produced multiple toxins. Generally, strains showed resistance against the β-lactam antibiotics such as penicillin G and cefotaxim (100%), as well as amoxicillin/clavulanic acid combination and ampicillin (99.3%). Most strains were susceptible to ciprofloxacin (99.3%), chloramphenicol (98.6%), amikacin (98.0%), imipenem (93.9%), erythromycin (91.8%), gentamicin (88.4%), tetracycline (76.2%) and trimethoprim/sulfamethoxazole combination (52.4%). The genomes of eight selected strains were sequenced. The toxin gene profiles detected by PCR and serological test mostly agreed with those from whole-genome sequence data.
CONCLUSIONS
Our study showed that B. cereus s.l. strains encoding toxin genes occur in products sold on the German market and that these may pose a health risk to the consumer if present at elevated levels. Furthermore, a small percentage of these strains harbor antibiotic resistance genes. The presence of these bacteria in fresh produce should, therefore, be monitored to guarantee their safety.
Topics: Anti-Bacterial Agents; Bacillus cereus; Bacterial Toxins; Drug Resistance, Microbial; Food Contamination; Food Microbiology; Gene Expression Regulation, Bacterial; Genome, Bacterial; Germany; Phylogeny; Vegetables; Whole Genome Sequencing
PubMed: 31706266
DOI: 10.1186/s12866-019-1632-2 -
MSphere Nov 2020Gram-positive, spore-forming members of the group species complex are widespread in natural environments and display various degrees of pathogenicity. Recently, group...
Gram-positive, spore-forming members of the group species complex are widespread in natural environments and display various degrees of pathogenicity. Recently, group strain Flugge ATCC 21929 was found to represent a novel lineage within the species complex, sharing a relatively low degree of genomic similarity with all group genomes (average nucleotide identity [ANI] < 88). ATCC 21929 has been previously associated with the production of a patented antibiotic, antibiotic 60-6 (i.e., cerexin A); however, the virulence potential and growth characteristics of this lineage have never been assessed. Here, we provide an extensive genomic and phenotypic characterization of ATCC 21929, and we assess its pathogenic potential ATCC 21929 most closely resembles NH24A2 (ANI and DNA-DNA hybridization values of 86.70 and 34.10%, respectively). Phenotypically, ATCC 21929 does not possess cytochrome oxidase activity and is able to grow at a range of temperatures between 15 and 43°C and a range of pH between 6 and 9. At 32°C, ATCC 21929 shows weak production of diarrheal enterotoxin hemolysin BL (Hbl) but no production of nonhemolytic enterotoxin (Nhe); at 37°C, neither Hbl nor Nhe is produced. Additionally, at 37°C, ATCC 21929 does not exhibit cytotoxic effects toward HeLa cells. With regard to fatty acid composition, ATCC 21929 has iso-C17:0 present in highest abundance. Based on the characterization provided here, ATCC 21929 (= PS00077A = PS00077B = PSU-0922 = BHP) represents a novel effective group species, which we propose as effective species "" The group comprises numerous closely related lineages with various degrees of pathogenic potential and industrial relevance. Species-level taxonomic classification of group strains is important for risk evaluation and communication but remains challenging. Biochemical and phenotypic assays are often used to assign group strains to species but are insufficient for accurate taxonomic classification on a genomic scale. Here, we show that antibiotic-producing ATCC 21929 represents a novel lineage within the group that, by all metrics used to delineate prokaryotic species, exemplifies a novel effective species. Furthermore, we show that ATCC 21929 is incapable of producing enterotoxins Hbl and Nhe or exhibiting cytotoxic effects on HeLa cells at human body temperature These results provide greater insight into the genomic and phenotypic diversity of the group and may be leveraged to inform future public health and food safety efforts.
Topics: Anti-Bacterial Agents; Bacillus cereus; Genome, Bacterial; HeLa Cells; Humans; Phylogeny; Soil Microbiology
PubMed: 33148822
DOI: 10.1128/mSphere.00882-20 -
BMC Microbiology Aug 2019Despite the importance of the B. cereus group as major foodborne pathogens that may cause diarrheal and/or emetic syndrome(s), no study in Tunisia has been conducted in...
BACKGROUND
Despite the importance of the B. cereus group as major foodborne pathogens that may cause diarrheal and/or emetic syndrome(s), no study in Tunisia has been conducted in order to characterize the pathogenic potential of the B. cereus group. The aim of this study was to assess the sanitary potential risks of 174 B. cereus group strains isolated from different foodstuffs by detecting and profiling virulence genes (hblA, hblB, hblC, hblD, nheA, nheB, nheC, cytK, bceT and ces), testing the isolates cytotoxic activity on Caco-2 cells and antimicrobial susceptibility towards 11 antibiotics.
RESULTS
The entertoxin genes detected among B. cereus isolates were, in decreasing order, nheA (98.9%), nheC (97.7%) and nheB (86.8%) versus hblC (54.6%), hblD (54.6%), hblA (29.9%) and hblB (14.9%), respectively encoding for Non-hemolytic enterotoxin (NHE) and Hemolysin BL (HBL). The isolates are multi-toxigenic, harbouring at least one gene of each NHE and HBL complexes associated or not to bceT, cytK-2 and ces genes. Based on the incidence of virulence genes, the strains were separated into 12 toxigenic groups. Isolates positive for cytK (37,9%) harbored the cytK-2 variant. The detection rates of bceT and ces genes were 50.6 and 4%, respectively. When bacteria were incubated in BHI-YE at 30 °C for 18 h and for 5 d, 70.7 and 35% of the strains were shown to be cytotoxic to Caco-2 cells, respectively. The cytotoxicity of B. cereus strains depended on the food source of isolation. The presence of virulence factors is not always consistent with cytotoxicity. However, different combinations of enterotoxin genetic determinants are significantly associated to the cytotoxic potential of the bacteria. All strains were fully sensitive to rifampicin, chloramphenicol, ciprofloxacin, and gentamycin. The majority of the isolates were susceptible to streptomycin, kanamycin, erythromycin, vancomycin and tetracycline but showed resistance to ampicillin and novobiocin.
CONCLUSION
Our results contribute data that are primary to facilitate risk assessments in order to prevent food poisoning due to B. cereus group.
Topics: Anti-Bacterial Agents; Bacillus cereus; Bacterial Proteins; Caco-2 Cells; Enterotoxins; Food Contamination; Food Microbiology; Foodborne Diseases; Humans; Phylogeny; Tunisia; Virulence Factors
PubMed: 31445510
DOI: 10.1186/s12866-019-1571-y -
Microbiology (Reading, England) Feb 2005A homologue of the Bacillus subtilis fur gene was identified in Bacillus cereus and characterized. The predicted amino acid sequence of the cloned gene was found to be...
A homologue of the Bacillus subtilis fur gene was identified in Bacillus cereus and characterized. The predicted amino acid sequence of the cloned gene was found to be highly similar to other members of the Fur family of transcriptional regulators. The B. cereus fur gene was shown to partially complement an Escherichia coli fur mutant. Purified B. cereus Fur bound specifically to a 19 bp DNA sequence homologous to the B. subtilis Fur box in a metal-dependent manner. Analysis of the available B. cereus genome data identified a number of genes which contain predicted Fur box sequences in the promoter region. Many of these genes are predicted to play a role in bacterial iron uptake and metabolism, but several have also been implicated as having a role in virulence. Fur and iron regulation of a siderophore biosynthesis operon was confirmed in a beta-galactosidase assay. A B. cereus fur null strain was constructed by allelic replacement of the chromosomal gene with a copy disrupted with a kanamycin resistance cassette. The Deltafur mutant was found to constitutively express siderophores, to accumulate iron intracellularly to a level approximately threefold greater than the wild-type, and to be hypersensitive to hydrogen peroxide. In an insect infection model, the virulence of the fur null strain was found to be significantly attenuated, highlighting the essential role played by Fur in the virulence of this pathogen.
Topics: Amino Acid Sequence; Animals; Bacillus cereus; Bacterial Proteins; Base Sequence; Gene Expression Regulation, Bacterial; Humans; Iron; Larva; Manduca; Molecular Sequence Data; Repressor Proteins; Sequence Analysis, DNA; Transcription, Genetic; Virulence
PubMed: 15699205
DOI: 10.1099/mic.0.27744-0 -
Journal of Food Protection Oct 2018Bacillus cereus has long been recognized as an important pathogen in foodborne poisoning worldwide. Fresh vegetables are often contaminated with enterotoxigenic B....
Bacillus cereus has long been recognized as an important pathogen in foodborne poisoning worldwide. Fresh vegetables are often contaminated with enterotoxigenic B. cereus and have been implicated as a vehicle for the transmission of this bacterium. This study reports on the occurrence, virulence gene profile, and antibiotic resistance of B. cereus in fresh vegetables. Of 102 examined samples, 48 (47%) of the samples were contaminated with B. cereus (>1 log CFU/g) and 7 (6.8%) of the samples showed more than 3 log CFU/g. In total, 118 B. cereus isolates were examined for the virulence genes nheA, nheB, nheC, hblA, hblC, hblD, cytK, and entFM and for resistance to antibiotics. Of these B. cereus isolates, 70% harbored nheA, nheB, nheC, and cytK. Eighteen (80%) of 21 isolates from bell peppers possessed eight enterotoxin genes. B. cereus isolates were susceptible to imipenem, vancomycin, gentamicin, erythromycin, ciprofloxacin, and chloramphenicol, whereas 22.4% of isolates from garlic chives, 48.7% from perilla leaf, and 40.5% from romaine lettuce showed antibiotic resistance to rifampin and 6% of isolates from garlic chives exhibited resistance to tetracycline. Three isolates from garlic chives were resistant to both tetracycline and rifampin. Raw vegetables were revealed to be major sources of B. cereus containing multiple toxin genes and exhibiting antibiotic resistance. Therefore, the potential health risks of consuming these vegetables raw or undercooked should not be underestimated. This study provides basic information for monitoring the antibiotic resistance and toxigenicity of B. cereus in the food chain during vegetable distribution and for developing food safety management to reduce the contamination with and transmission of B. cereus.
Topics: Bacillus cereus; Drug Resistance, Microbial; Enterotoxins; Food Microbiology; Prevalence; Republic of Korea; Vegetables
PubMed: 30169119
DOI: 10.4315/0362-028X.JFP-18-205 -
International Journal of Molecular... Oct 2021Spores of the bacterium can cause disease in humans due to contamination of raw materials for food manufacturing. These dormant, resistant spores can survive for years...
Spores of the bacterium can cause disease in humans due to contamination of raw materials for food manufacturing. These dormant, resistant spores can survive for years in the environment, but can germinate and grow when their surroundings become suitable, and spore germination proteins play an important role in the decision to germinate. Since germinated spores have lost dormant spores' extreme resistance, knowledge about the formation and function of germination proteins could be useful in suggesting new preservation strategies to control spores. In this study, we confirmed that the GerR germinant receptor's (GR) A, B, and C subunits and GerD co-localize in spore inner membrane (IM) foci termed germinosomes. The interaction between these proteins was examined by using fusions to the fluorescent reporter proteins SGFP2 and mScarlet-I and Förster Resonance Energy Transfer (FRET). This work found that the FRET efficiency was 6% between GerR(A-C-B)-SGFP2 and GerD-mScarlet-I, but there was no FRET between GerD-mScarlet-I and either GerRA-SGFP2 or GerRC-SGFP2. These results and that GerD does not interact with a GR C-subunit in vitro suggest that, in the germinosome, GerD interacts primarily with the GR B subunit. The dynamics of formation of germinosomes with GerR(A-C-B)-SGFP2 and GerD-mScarlet-I was also followed during sporulation. Our results showed heterogeneity in the formation of FRET positive foci of GerR(A-C-B)-SGFP2 and GerD-mScarlet-I; and while some foci formed at the same time, the formation of foci in the FRET channel could be significantly delayed. The latter finding suggests that either the GerR GR can at least transiently form IM foci in the absence of GerD, or that, while GerD is essential for GerR foci formation, the time to attain the final germinosome structure with close contacts between GerD and GerR can be heterogeneous.
Topics: Bacillus cereus; Bacterial Proteins; Cell Membrane; Fluorescence Resonance Energy Transfer; Gene Expression Regulation, Bacterial; Protein Interaction Domains and Motifs; Spores, Bacterial
PubMed: 34681888
DOI: 10.3390/ijms222011230