cytK Genes Research Articles

Molecular screening of potential Bacillus species bacteriocin starter cultures isolated from Nigerian fermented condiments

Traditional fermented food condiments in Nigeria are majorly produced by using protein-rich leguminous seeds via spontaneous fermentation or back slopping. However, health risks such as the production of biogenic amines, presence of toxigenic genes and food borne pathogens remains major concerns of public health significance. Hence, the need for the production of safe condiments using non-pathogenic food-grade starter cultures. Isolation and characterization of organisms from spontaneously fermented condiments made from Parkia biglobosa, Ricinus communis, Pentaclethra macrophylla and Prosopis africana was done using standard methods. Phenotypic and biochemical characterizations was down using established protocols while molecular identification was done using 16S rRNA sequencing. Results obtained showed that the microbial load (cfu/ml) recorded from the spontaneously fermented condiments ranged from: 2.1×107-5.2×1012, 15.2×107-4.4×1010, 4.4×1010-4.4×1012 and 6.4×107-1.6×1012 for P. biglobosa, R. communis, P. macrophylla and P. africana respectively. Identification of isolates revealed Bacillus. However, 22.8% of the Bacillus isolates harboured HblA and HblD genes while 40.9 % showed bands for the presence of HblC genes. In addition, the percentage occurrence of 18.1%, 27.2% and 50% was obtained for the presence of NheA, NheB and NheC genes respectively while none of the Bacillus isolates showed bands for the presence of Cytk and EM1 genes. More so, five Bacillus isolates were identified to be non-toxigenic, showing bands only for Bac, Osbo and Spas genes which are bacteriocin producing genes. Put together, the identified non-toxigenic food-grade Bacillus species recorded in this study can be recommended as potential bacteriocin starter cultures for the fermentation of microbiologically safe food products.

Meat and meat products as potential sources of emerging MDR Bacillus cereus: groEL gene sequencing, toxigenic and antimicrobial resistance

BackgroundBacillus cereus is implicated in severe foodborne infection in humans. This study intended to assess the occurrence, groEL gene sequencing, biofilm production, and resistance profiles of emerged multidrug resistant (MDR) B. cereus in meat and meat product samples. Moreover, this work highlights the virulence and toxigenic genes (hblABCD complex, nheABC complex, cytK, ces, and pc-plc) and antimicrobial resistance genes (bla1, tetA, bla2, tetB, and ermA).MethodsConsequently, 200 samples (sausage, minced meat, luncheon, beef meat, and liver; n = 40 for each) were indiscriminately collected from commercial supermarkets in Port Said Province, Egypt, from March to May 2021. Subsequently, food samples were bacteriologically examined. The obtained isolates were tested for groEL gene sequence analysis, antibiotic susceptibility, biofilm production, and PCR screening of toxigenic and resistance genes.ResultsThe overall prevalence of B. cereus among the inspected food samples was 21%, where the highest predominance was detected in minced meat (42.5%), followed by beef meat (30%). The phylogenetic analysis of the groEL gene exposed that the examined B. cereus strain disclosed a notable genetic identity with other strains from the USA and China. Moreover, the obtained B. cereus strains revealed β-hemolytic activity, and 88.1% of the recovered strains tested positive for biofilm production. PCR evidenced that the obtained B. cereus strains usually inherited the nhe complex genes (nheA and nheC: 100%, and nheB: 83.3%), followed by cytK (76.2%), hbl complex (hblC and hblD: 59.5%, hblB: 16.6%, and hblA: 11.9%), ces (54.7%), and pc-plc (30.9%) virulence genes. Likewise, 42.9% of the examined B. cereus strains were MDR to six antimicrobial classes and encoded bla1, bla2, ermA, and tetA genes.ConclusionIn summary, this study highlights the presence of MDR B. cereus in meat and meat products, posing a significant public health risk. The contamination by B. cereus is common in minced meat and beef meat. The molecular assay is a reliable fundamental tool for screening emerging MDR B. cereus strains in meat and meat products.

Characterization of Bacillus cereus isolated from contaminated foods with sequencing of virulence genes in Egypt.

The current study describes the presence of Bacillus cereus (B. cereus) in contaminated foods of animal source and ready for human consumption with highlighting on their virulence contributing factors by detection of its virulence genes in addition to identification of their sequencing. Three hundred sixty food samples categorized as (228) meat products and (132) milk products were examined for B. cereus isolation and all of these isolates were confirmed by biochemical tests. Eighteen strains obtained from different food samples were examined for the attendance of a number of virulence genes (nheA, cytK, entFM, bceT and hblC genes) using uniplex PCR method. Furthermore, the B. cereus strains were valued for the sequencing of described genes. Generally 24.44% (88/360) food samples classified as 11.11% (40/360) meat products and 13.33% (48/360) milk products carried B. cereus according to cultural and biochemical properties, with geometric mean (1.5×107±0.15 CFU/g or mL) . The highest counts (above 105 CFU/g or mL) were originated from milk products (with geometric mean 2.2×107±0.22 CFU/g or mL) more than meat products (with geometric mean 1×107±0.19 CFU/g or mL). The results revealed that all of our isolates had one or more virulence (enterotoxin) genes. In our research, the most predominant genes were nheA (100%), followed by cytK (61.11%), entFM (33.33%), bceT (11.11%) then hblC (5.56%). Molecular method detected that overall, 5 strains (27.78%) harbored only 1 gene (nheA), 7 strains (38.88%) harbored 2 genes which classified as 5 strains (27.78%) (nheA and cytK), 2 strains (11.11%) have (nheA and entFM). Moreover, 5 strains (27.78%) have 3 genes classified as 3 strains (16.67%) harbored (nheA, cytK and entFM), 1 strain (5.56%) had (nheA, cytK and hblC), and 1 strain (5.56%) had (nheA, cytK and bceT). Only 1 strain (5.56%) carried 4 tested virulence genes (nheA, cytK, entFM and bceT) genes. The most prevalent gene in meat and dairy foods was nheA (100%). The nucleotide sequences of (bceT, cytK, entFM, hblC and nheA genes) of B. cereus strains were deposited in GenBank under accession no. (MW911824, MW911825, MW911826, MW911827 and MW911828), respectively. Our study was established to indicate the presence of virulent B. cereus in meat and milk products ready for human consumption as a result of deficient hygienic actions. So, a plain for good hygienic measures should be modified to avoid causing serious health problems to human due to ingestion of such products.

Characterization of the Toxigenic Potential of Bacillus cereus sensu lato Isolated from Raw Berries and Their Products.

Bacillus cereus is estimated to be responsible for 1.4-12% of all food poisoning outbreaks worldwide. The objective of this study was to investigate the toxigenic potential of 181 isolates of B. cereus previously recovered from different types of berries and berry products (strawberries, raspberries, blackberries, and blueberries) by assessing the presence of enterotoxin genes (hblA, hblC, hblD, nheA, nheB, nheC, and cytK) and an emetic toxin cereulide synthetase gene (ces). The cytotoxic activity on Caco-2 cells was also evaluated for the two isolates containing the gene cytK. Twenty-three toxigenic profiles were found. The nheABC (91.7%) and hblACD (89.0%) complexes were the most prevalent among the isolates, while the cytK and ces genes were detected in low percentages, 1.1% and 3.3%, respectively. In addition, the nheABC/hblACD complex and ces genes were detected in isolates recovered throughout the production process of blackberries and strawberries. The cytotoxic activity on Caco-2 cells was also observed to be greater than 60% for isolates containing the cytK gene.

Prevalence, distribution, enterotoxin profiles, antimicrobial resistance, and genetic diversity of Bacillus cereus group isolates from lettuce farms in Korea.

Lettuce wraps are popular in Korean cuisine for their high nutritional value and versatility as healthy additions to multiple dishes. Microbial contamination of lettuce is a major concern, as lettuce is consumed fresh without cooking. Among foodborne pathogens, the spore-forming, facultative anaerobic bacterium, Bacillus cereus is one of the frequently detected pathogen in lettuce in Korea. In this study, we investigated the prevalence and distribution of Bacillus cereus strains in lettuce production farms and further evaluated the enterotoxin gene profiles, antibiotic susceptibility, multidrug resistance pattern, and genetic differences among the B. cereus group isolates. Of the 140 samples isolated from 10 lettuce production farms, 30 samples (21.42%) were positive for B. cereus in which 19 (31.6%) and 10 (23.25%) were from soil and lettuce, respectively. The enterotoxin patterns A (hblCDA, nheABC, entFM, and cytK genes) and B (hblCDA, nheABC, and entFM genes) accounted for 50% and 20% of all the isolates, whereas the emetic gene cesB was not detected in any of the B. cereus group isolates. Antibiotic susceptibility testing of the B. cereus group isolates revealed that all the strains were predominantly resistant to β-lactam antibiotics except imipenem and generally susceptible to most of the non β-lactam antibiotics, including gentamycin, streptomycin, chloramphenicol, and tetracycline. ERIC-PCR and MLST analysis revealed high genetic diversity among the 30 B. cereus group isolates, which belonged to 26 different sequence types (STs) and seven new STs. Moreover, isolates with identical STs exhibited similar patterns of antibiotic resistance and enterotoxin profiles. Results of this study indicate a high prevalence of B. cereus group isolates in lettuce production farms in the Republic of Korea.

Newly Emerging MDR B. cereus in Mugil seheli as the First Report Commonly Harbor nhe, hbl, cytK, and pc-plc Virulence Genes and bla1, bla2, tetA, and ermA Resistance Genes.

BackgroundBacillus cereus is a common food poisoning pathogen in humans. This study aimed to investigate the prevalence, molecular typing, antibiogram profile, pathogenicity, dissemination of virulence and antibiotic resistance genes associated with natural B. cereus infection among Mugil seheli.MethodsConsequently, 120 M. seheli (40 healthy and 80 diseased) were obtained from private fish farms in Port-said Governorate, Egypt. Afterward, samples were processed for clinical, post-mortem, and bacteriological examinations. The recovered isolates were tested for antimicrobial susceptibility, phenotypic assessment of virulence factors, pathogeneicity, and PCR-based detection of virulence and antibiotic resistance genes.ResultsB. cereus was isolated from 30 (25%) examined fish; the highest prevalence was noticed in the liver (50%). The phylogenetic and sequence analyses of the gyrB gene revealed that the tested B. cereus isolate displayed a high genetic similarity with other B. cereus strains from different origins. All the recovered B. cereus isolates (n =60, 100%) exhibited β-hemolytic and lecithinase activities, while 90% (54/60) of the tested isolates were biofilm producers. Using PCR, the tested B. cereus isolates harbor nhe, hbl, cytK, pc-plc, and ces virulence genes with prevalence rates of 91.6%, 86.6%, 83.4%, 50%, and 33.4%, respectively. Moreover, 40% (24/60) of the tested B. cereus isolates were multidrug-resistant (MDR) to six antimicrobial classes and carried the bla1, bla2, tetA, and ermA genes. The experimentally infected fish with B. cereus showed variable mortality in direct proportion to the inoculated doses.ConclusionAs far as we know, this is the first report that emphasized the existence of MDR B. cereus in M. seheli that reflects a threat to the public health and the aquaculture sector. Newly emerging MDR B. cereus in M. seheli commonly carried virulence genes nhe, hbl, cytK, and pc-plc, as well as resistance genes bla1, bla2, tetA, and ermA.

Profiling of Bacillus cereus enterotoxigenic genes from retailed foods and detection of the nhe and hbl toxins with immunological assay

Bacillus cereus produces pore-forming toxins responsible for diarrhoea; therefore, rapidly detecting these toxins in food retailed for consumption is needed. The genomic DNA of 100 B. cereus isolates recovered from some retailed foods was extracted and used as a template for enterotoxin detection. The detection of genes of non-haemolyticnonhemolytic enterotoxin (nheA, nheB, nheC), hemolysin BL (hblA, hblC, hblD), entFM, cytK and bceT by the isolates was carried out with PCR using primers specific for the targeted genes, while the production of Nhe and Hbl enterotoxins in fifty of the randomly chosen isolates was detected with a Duopath Cereus Enterotoxin kit. Ninety-five percent of the isolates carried one or more components of the NHE complex, while 56% had one or more components of HBL. Sixteen out of the 100 isolates carried all the genes for NHE and HBL complex genes. The entFM, cytK and bceT genes were detected in 85%, 74% and 60% of B. cereus isolates, respectively. Starchy foods had the highest incidence of the HBL complex, while nheA and nheC occurred mostly in protein foods with 90% and 87% incidence, respectively. The immunological kit was able to detect the production of nonhemolytic enterotoxin (Nhe) in all the B. cereus isolates, while 28 B. cereus isolates produced hemolysin (hbl). Nineteen isolates that carried one or more genes encoding hbl did not produce the toxin. This study clearly showed that retailed foods sold in Ogun State, Nigeria, harbor B. cereus enterotoxigenic genes responsible for diarrhoea. These toxins can be rapidly detected in foods using both molecular and immunological methods.

Potential risk of Bacillus cereus in spices in Turkey

Spices are widely used all over the world in food preparation to give taste, smell and color as well as to preserve food products. Bacillus cereus is a common contaminant in spices which can cause food poisoning due to its toxins. This study focused on determining the presence of B. cereus as well as the toxin profiles of the strains. A total of 203 packaged and unpackaged spice samples were collected during the study. B. cereus prevalence was determined as 31.5%. Also, B. thuringiensis was identified in five samples (2.5%). The prevalence of B. cereus in non-irradiated spices (41.5%) was found significantly higher than the irradiated ones (20.7%) (p < 0.05). Moreover, the isolates were examined for nine toxin genes, and entFM (94%) was found as the most abundant gene, followed by cytK (60%) and hblD (60%) genes. No cesB gene was found in isolates. Among the strains only a B. thurgiensis isolate was found to have eight toxin genes. The results show that B. cereus is a potential public health risk in spices. Considering the possibility of contamination of foods by B. cereus via spices, effective decontamination methods should be applied and precautions should be taken to control growing of B. cereus and forming toxins during food preparation and pre-serving stages. • Prevalence of B. cereus in spices was 31.5%. • B. thuringiensis was identified in 5 of 203 (2.5%) spice samples. • EntFM (94%), cytK (60%) and hblD (60%) were the most abundant toxin genes. • No cesB gene was found in isolates (0/89). • The contamination in non-irradiated spices was significantly higher (p < 0.05).

Psychrotrophic properties, toxigenic characteristics, and PFGE profiles of Bacillus cereus isolated from different foods and spices

ABSTRACT: Bacillus cereus is an aerobic and facultatively anaerobic, spore-forming bacterium, and it is found naturally in soil and poses a risk factor for the contamination of food and foodstuffs including cereals, vegetables, spices, ready-to-eat (RTE) foods, meats, milk, and dairy products. This study determined the prevalence of B. cereus in raw poultry meat, raw cow’s milk, cheese, spices, and RTE foods in Hatay province. The study also analysed the psychrotrophic properties, toxigenic characteristics, and pulsed-field gel electrophoresis (PFGE) profiles of the isolates. The levels of contamination with B. cereus determined for cheese, raw milk, RTE foods, spices, and raw poultry meat were 16.6%, 34.2%, 42.8%, 49%, and 55.5%, respectively. B. cereus was isolated from 84 (42%) of the 200 samples analysed and the 84 isolates were verified by PCR analysis targeting the haemolysin gene specific for B. cereus. Of the total isolates, 64 (76.1%) were psychrotrophic. The toxin gene profiling of B. cereus isolates was determined by amplifying the four genes nhe, hbl, cytK, and ces. The nhe and cytK genes were most frequently detected in the isolates, while the hbl and ces genes were not found. In addition, a high genetic relationship between the isolates was detected at a 92% similarity level by PFGE analysis. In conclusion, the occurrence of both psychrotrophic and toxigenic B. cereus strains in this study indicated a potential risk for food spoilage and food poisoning.

Comprehensive Study about the Identification of Bacillus Cereus Isolated from Chicken Farms

Bacillus cereus is one of the opportunistic foodborne bacteria producing food poisoning producing severe economic loss and representing a high risk to the human. The contamination of poultry feed with Bacillus cereus produces gastric damage and facilitates other bacterial infections. For these reasons, fresh fecal matters were collected from poultry farms located in 3 Egyptian Governorates (Giza, Gharbia, and Dakahlia) to isolate and identify Bacillus cereus, determine their susceptibility to different antimicrobial agents, and examine their virulence and resistance factors. Eleven B. Cereus out of 50 examined samples was isolated with a percentage of (11/50, 22%) and subjected to confirmation using the VITEK2 instrument. Disc diffusion tests showed that all isolates were resistant to trimethoprim-sulfamethoxazole, imipenem, cefotaxime, ampicillin, amoxicillin/clavulanic acid, and penicillin G and sensitive to chloramphenicol, gentamicin, and ciprofloxacin. The molecular characterizations of virulence and resistance factors revealed the detection of targeting the groEL gene in all isolates (100%). The toxin gene profiling showed the existence of the nhe gene (90.9%) and the hbl genes (18.18%). The ces and cytk genes were not detected in the examined isolates. Two antimicrobial resistance genes were detected in the examined isolates with (33.33%) for the tetA gene and (45.45%) for bla gene. Therefore, it was concluded that the isolation of B. cereus carrying genes responsible for antimicrobial resistance and toxins production in broiler farms, represents major threats for human health and poultry industry. So that control programs of biosecurity should be implemented in poultry farms to mitigate the losses of B. cereus infection.

Bacillus Cereus in Eggshell: Enterotoxigenic Profiles and Biofilm Production

A study was carried out with the objective of determining the presence of Bacillus cereus in eggshells commercialized in Mexico, the enterotoxigenic profile of the isolated strains, and the production of biofilms in different materials as well as in the eggshell. 1000 chicken eggs from four commercial brands were collected from markets and supermarkets located in the city of Chilpancingo, Mexico. Bacillus cereus was isolated from the eggshell. The molecular identification was by amplification of the gyrB gene and the enterotoxigenic profiles by the amplification of the cytK, ces, nheABC, and hblABD genes, in addition to the amplification of the tasA and sipW genes associated with the production of biofilms. In different materials and in eggshells, the production of biofilms was evaluated. The microbiological and molecular analysis of B. cereus yielded a frequency of 5.5% (55/1000), this was higher in brand III (11.6%, p=0.0001) and white eggshell (7.6%, 38/500, p≤0.001) and by marketing source, it was similar between market (5.2% / 26/500) and supermarket (5.8%, 29/500). The most common was the toxigenic profile A (23/55). Biofilm production is high in PVC in relation to other materials (p<0.0001), and the frequency of the related genes tasA and sipW was 72.7% and 40% respectively; the highest production was related to the tasA gene; in eggshell, most of the strains (54/55) were able to produce biofilm. Strains of B. cereus with toxigenic potential circulate and persist in this product, which shows the need for sanitary regulation in the country.

Prevalence of virulence genes and antibiotic susceptibility of Bacillus used in commercial aquaculture probiotics in China

Disease is a significant constraint faced by aquaculture, and its prevention and control bring together a hub of recent research. Several resources and resorts have been applied to prevent diseases in aquaculture. Probiotics are known to be beneficial natural derivatives that have several benefits in aquaculture. Currently, several commercial probiotics are used in the aquaculture industry that contains one or more live microorganisms. In the aquaculture industry, Bacillus species is one of the most widely used probiotic organisms. They are considered distinctive and are found to be natural members of the gut microbiota of some fish species. The safety of beneficial microorganisms is essential since some of these organisms are reported to harbor traits that might be transferable to their hosts. In this study, the safety of some Bacillus-based commercial probiotics used in aquaculture in terms of virulence and drug resistance were assessed. Commercial Bacillus species after isolation were screened for the presence of virulence genes (nheA, nheB, nheC, hblA, hblC, hblD, cytK, and entFM) and one emetic gene (ces), as well as their resistance to some antibiotics. Most isolates did not possess any of the virulence genes assessed. Nonetheless, three isolates harbored the nheABC and entFM enterotoxin genes, while two had the hblA, hblC, hblD, cytK genes. None of the isolates possessed the ces emetic gene. Antibiotic resistance assessment revealed most of the isolates to be resistant to β-lactam antibiotics, including penicillin, ampicillin, oxacillin, cefuroxime, and ceftriaxone, and also to minocycline.

Detection of Bacillus cereus genes responsible for diarrheal and emetic toxins

Bacillus cereus isolated from different food sources. The diarrheal toxin genes such as cytK, hemolytic enterotoxin (hblA, hblC and hblD), non-hemolytic enterotoxin (nheA, nheB and nheC), bceT and entFM in addition to emetic toxin gene were detected by PCR. The cyt K gene was observed in 94.87 % of the isolates. entFM and emetic toxin gene were found very rare in all food samples at the percentage 2.56% and 7.69% respectively. Uncooked rice which has a highest number of bacterial isolation, also showed relatively high percentage of the cytK and bceT genes (90%). These two genes present in 100% of Bacillus cereus isolates in most food samples. Bacteria isolated from burger meat contain all investigated genes.

Multi-locus sequence typing and virulence profile in Bacillus cereus sensu lato strains isolated from dairy products.

Members of Bacillus cereus group are important food contaminants and they are of relevant interest in food safety and public heath due to their ability to cause two distinct forms of food poisoning, emetic and diarrhoeal syndrome. In the present study, 90 strains of B. cereus isolated from dairy products, have been typed using Multilocus Sequence Typing (MLST) analysis and investigated for the occurrence of 10 enterotoxigenic genes (hblA, hblC, hblD, nheA, nheB, nheC, cytK, entFM, entS and bceT) and one emetogenic gene (ces), to determine their genetic diversity. A total of 58 sequence types were identified and among these 17 were signalled as new profiles. Among the virulence genes, the majority of our strains carried the entS (92%), entFM (86%), nhe (82%) and cytK (72%) genes. All remaining genes were identified in at least one strain with different prevalence, stressing the genetic diversity, how even the different grade of pathogenicity of B. cereus isolated from dairy products.

Multiplex Polymerase Chain Reaction for Detection of Toxin Genes of Bacillus cereus Group Isolated from Meat and Chicken Products

Bacillus cereus sensu lato (B. cereus s. l.) is a significant cause of food spoilage issue owing to the activity of certain hydrolytic enzymes. This study aimed to detect the incidence and contamination level of meat and chicken products with B. cereus group in Sharkia Governorate, Egypt, with reference to their enterotoxin genes` profiles. Overall, 43 out of 200 (21.5%) examined samples were contaminated by B. cereus group, with identification of only one species, B. cereus. B. cereus group isolates were frequent in chicken samples (25.71%), with the highest incidence in chicken meat (30%) followed by chicken sausage and chicken luncheon (25% each). Meanwhile, they were isolated from 19.23% of examined meat products, which predominated in meat burger (25%), followed by each of meat kofta, shawarma, and luncheon (20% each), minced meat (17.14%) and meat sausage (15%). Of interest, the highest B. cereus count (>104 colony forming units (CFU)/ g) was found in 2% of positive samples, with a higher percent in meat sausage (33.33%). Whereas 15.5% of positive samples harbored B. cereus with counts ranging from >1x103-104 CFU/g. Molecular analysis of B. cereus enterotoxin genes using multiplex polymerase chain reaction (PCR) revealed that both ces and nhe genes were detected in 100% of the examined isolates, while cytk and hbl genes were present only in 9.52% and 23.8% of analyzed isolates, respectively. These findings, involving a higher occurrence of B. cereus and their toxin genes in meat and chicken products represent a serious public health concern in Egypt.

Prevalence of ces and cytk Genes of Bacillus cereus Isolated From Raw Milk in Tabriz, Iran

Background: Bacillus cereus is a gram-positive and spore-forming bacterium which is widespread in nature. It also has been known as a major foodborne pathogen that often plays a role in the contamination of ready-to-eat and dairy products. It causes two different types of food poisoning in human: the diarrheal type and the emetic type. Objective: The current study was planned to determine the prevalence of ces and cytk genes of Bacillus cereus isolated from raw milk in Tabriz, Iran. Materials and Methods: In this study, 40 B. cereus strains isolated from cow raw milk, that had already been identified phenotypically, were assessed for molecular confirmation by polymerase chain reaction (PCR) method. Then, they were evaluated for presence of ces and cytK genes by specific primers. Results: Of 40 B. cereus strains, 39 strains were confirmed molecularly. The frequency of cytK and ces genes was reported 38 (97.43%) and 0 (0%), respectively. Conclusion: The results of present study showed that B. cereus strains isolated from raw milk had high potential in causing diarrhea poisoning. Therefore, using procedures to reduce the bacterial contamination during the processing of dairy product is essential.

Identification and Pathogenic Potential of Bacillus cereus Strains Isolated from a Dairy Processing Plant Producing PDO Taleggio Cheese.

Low levels of contamination by Bacillus cereus at the cheese farm is essential for reducing any opportunity for growth prior consumption. In this study, B. cereus distribution in a plant producing Protected Designation of Origin Taleggio cheese was investigated and the virulence potential of the isolates was evaluated. Seventy-four samples were collected from Food and Non Food Contact Surfaces (FCS, NFCS), saline curd, and Taleggio. The eleven isolates were identified, typified, and clustered. Strains were tested for the production of hemolysins, hemolysin BL (HBL), phosphatidylcholine-specific phospholipase C (PC-PLC), proteases, and biofilm, and for the presence of chromosomal toxin-encoding genes (sph, plcA, cytK, entFM, bcet, entS, nheA, nheB, nheC). B. cereus was detected on NFCS, FCS, and curd, but not in Taleggio. The isolates were grouped into six clusters, and all produced PC-PLC, hemolysins, and proteases, and most of them HBL (66.7%). All the clusters harbored the nheA, sph, plcA, entFM, and cytK genes, and some also nheB (83.3%), nheC (66.7%), bcet (50.0%), and entS (66.7%). All strains showed biofilm-forming ability. Our data reveal possible contamination of production plants and cheese curd by potentially virulent B. cereus, but bacterial absence in Taleggio highlights the efficacy of a proper management of the production phases in assuring consumer’s protection.

Prevalence, molecular characterization, and antibiotic susceptibility of Bacillus cereus isolated from dairy products in China

This study was conducted to reveal the prevalence, molecular characterization, and antibiotic susceptibility of Bacillus cereus isolated from dairy products including powdered infant formula, raw milk, pasteurized milk, ultra-high-temperature milk, and cheese. Five hundred samples collected from 5 provinces in China were analyzed in overall experiments. Multilocus sequence typing, distribution of toxin genes, and antibiotic susceptibility of the isolates were analyzed. Fifty-four B. cereus strains were detected; of these, 13 isolates (26%) were from raw milk, 12 isolates (12%) from pasteurized milk, 10 isolates (10%) from cheese, 12 isolates (8%) from ultra-high-temperature milk, and 7 isolates (7%) from powdered infant formula. These isolates were divided into 24 sequence types (ST); among them, ST24, ST26, ST82, ST142, ST377, ST857, and ST1046 were the main dominant ST. The results of detection of toxin genes (hblA, hblC, hblD, nheA, nheB, nheC, cytK, entFM, bceT, hlyII, and cesB) showed that 94.4% isolates carried nheABC genes, whereas only 11.1% of the isolates contained the hblACD gene cluster. In addition, detection rates of cytK, bceT, entFM, hlyII, and cesB genes were 75.9, 77.8, 85.2, 53.7, and 11.1%, respectively. The antibiotic susceptibility test indicated that most of B. cereus isolates were resistant to ampicillin, penicillin, cefepime, cephalothin, and oxacillin, and were susceptible to gentamicin, chloramphenicol, imipenem, tetracycline, ciprofloxacin, trimethoprim-sulfamethoxazole, erythromycin, kanamycin, and cefotetan. Therefore, this study revealed the prevalence and characteristics of B. cereus isolated from dairy products in China, indicating the potential risk and contributing to the effective prevention and control of this pathogen.

Enterotoxigenic Profiles of Bacillus Cereus Isolated from Manufacturing Steps of Traditional Soft Cheese Plant

Microbial contamination of soft cheese may originate from various sources such as contaminated equipment or from the workers themselves during cheese production. The study was aimed to characterize Bacillus cereus using culture-based and PCR techniques among 285 samples along Damietta and Kareish cheese producing line in a small cheese plant in Alexandria governorate including raw milk, cheese, whey, rennet, water, and swabs from all contacts surfaces. Overall of 10.90 % and 10 % among raw milk, cheese, whey, rennet, water, and swabs from all contacts surfaces were positive for Bacillus species in Damietta and Kareish cheese producing line. The incidence of Bacillus cereus in receiving raw milk, curd, whey, fresh cheese samples were 6.66, 13.33 and 13.33%, respectively for traditional Damietta cheese plant. Bacillus cereus is found in only 6.66 % in receiving raw milk, pasteurized milk and fresh cheese samples for traditional Kareish cheese plant. Hbl, Nhe and Cytk genes were detected in Bacillus cereus isolated from curd and Damietta cheese. Nhe gene was detected in Bacillus cereus isolated from raw milk, pasteurized milk and Kareish cheese While, Ces gene was detected only in Bacillus cereus isolated from fresh Kareish cheese samples. The prevalence of Eneterotoxigenic virulent B. cereus poses public health threats to consumers. HACCP should be implemented for all steps of manufacture in order to produce a safe and good quality dairy product.

Prevalence of the Strains of Bacillus cereus Group in Artisanal Mexican Cheese.

Bacillus cereus is a microorganism associated with food poisoning. It has been found in products, such as milk and dairy products. The aim of this study was to isolate and identify B. cereus group strains in artisan cheeses sold in southwestern Mexico, as well as its toxigenic profile, its psychrophilic ability, and its biofilm production. B. cereus isolation was performed on Mannitol Yolk Polymyxin (MYP) agar and this was molecularly confirmed by the amplification of the gyrB gene. Polymerase chain reaction was used to determine the toxigenic profile, amplifying conserved regions of hblABD and nheABC operons, which code for the subunits of Hbl and Nhe toxins, respectively, as well as ges and cytK genes, which code for toxin cereulide and cytotoxin K (Cytk). Frequency of B. cereus contamination in artisan cheeses was 29.48% (23/78), and the bacterium was isolated in similar quantities in all types of products. All strains were amylase positive, and 60.86% (14/23) were able to produce biofilm; 91.30% (21/23) of the strains were psychrophilic. In most of the strains, at least one gene related to enterotoxins was identified (21/23). B. cereus strains in this study have a high toxigenic potential, which increases the risk of food poisoning due to the consumption of artisan cheeses made in Mexico.