Cereus Contamination Research Articles

Control of Bacillus cereus in rice cake and food contact surfaces with novel Becedseptimavirus genus phage BCC348 and its partial SPOR domain-containing endolysin LysBCC348

Here, we investigated the novel bacteriophage BCC348 and its endolysin LysBCC348 as alternative antimicrobials against the major foodborne pathogen Bacillus cereus. The Becedseptimavirus genus phage BCC348 effectively inhibited the growth of B. cereus ATCC 27348 with a remarkable burst size of ∼600 PFU/infected cell. The cation-dependent amidase endolysin LysBCC348 lysed the host B. cereus and Listeria monocytogenes and EDTA-treated Gram-negative pathogens. In a cold storage model of Korean rice cake, Garaetteok, BCC348 significantly reduced artificially contaminated B. cereus counts to undetectable levels within 3 days. Treatment with LysBCC348 also achieved a ∼1.3-log reduction of B. cereus and ∼60% biofilm removal from food contact surfaces. Genes related to DNA modification and sporulation prevention in BCC348, as well as a partial sporulation-related repeat (SPOR) domain in LysBCC348, are thought to enhance the efficacy of BCC348 in controlling B. cereus. These results suggest that BCC348 and LysBCC348 are promising alternative candidates to mitigate B. cereus contamination in the food industry.

Bacillus cereus in rice: A review on food poisoning, antimicrobial resistance, and control measures.

Rice is often associated with Bacillus cereus (B. cereus) food poisoning. This review aims to explore the food poisoning activity, antimicrobial resistance, and control measures of B. cereus in rice from 1974 to October 2023. We searched for eligible studies from the PubMed database based on explicit criteria following the PRISMA checklist. A total of 117 articles were collected, and the final analysis included 29 studies. Quality appraisal was performed using AMSTAR 2, SANRA 2, and Critical Appraisal Tool standards. B. cereus can grow and multiply in food to cause emetic vomiting or diarrheal syndrome. The primary etiology of B. cereus contamination is improper food handling and storage temperature during the cooking, cooling, and reheating stages of rice. The alarming rise of antimicrobial resistance in B. cereus to beta-lactam antibiotics necessitates alternatives from natural antimicrobial preservatives such as carvacrol, chitosan, or trans-cinnamaldehyde to prevent microbial infestation and toxin production. Implementing food safety strategies tailored to specific food settings, such as restaurants and factorymanufactured ready-to-eat rice, is critical for preventing food contamination by B. cereus. Given the heat-resistant spores and intoxication properties of B. cereus, it is important to develop effective interventions and hygienic protocols from farm to fork.

Isolation and characterization of two phages against emetic Bacillus cereus and their potential applications

AbstractBacillus cereus is a common foodborne pathogen capable of producing cereulide and enterotoxin. Consumption of food contaminated with cereulide can even result in fatality. Bacteriophages are increasingly being utilized as biocontrol agents to combat specific pathogens in a variety of food products. However, there are currently no lytic phages available to target cereulide‐producing B. cereus. This study aims to isolate and characterize two novel phages, DC1 and DC2, and assess their potential for use in food substrates. These two phages possessed the widest host range among the reported lytic phages that target B. cereus. The whole genome analysis demonstrated that DC1 and DC2 belonged to the Tsarbombavirus genus of the Bastillevirinae subfamily, which is part of the Herelleviridae family. The one‐step growth curve analysis revealed that DC1 had a latent period of 30 min and a burst size of approximately 39 PFU (plaque‐forming units) per cell. On the other hand, DC2 exhibited a shorter latent period of 15 min and a larger burst size of 124 PFU per cell. Both phages had a burst period of 30 min. Furthermore, DC1 and DC2 displayed excellent stability within a wide range of pH levels and temperatures. After undergoing a brief phage‐soaking treatment, DC1 and DC2 effectively reduced the bacterial count in spiked food samples. Additionally, they inhibited the formation of biofilms and degraded already‐formed biofilms. Collectively, DC1 and DC2 exhibit great potential as biocontrol agents for the prevention and control of B. cereus contamination in foods.

Antimicrobial mechanism of morusin against Bacillus cereus and its potential as an antimicrobial agent

Bacillus cereus, a food-borne pathogen, threatens human health and food safety. The quest for biologically active substances from natural sources acting as antimicrobial agents for the replacement of antibiotics and chemical additives has received increasing attention. In this study, the antimicrobial mechanism of morusin against B. cereus was outlined, as well as its function as a food supplement to extend the shelf-life of skimmed milk was assessed. Our findings demonstrated that the minimum inhibitory concentration (MIC) value of morusin against B. cereus was 2.25 μg/mL, inhibiting biofilm formation and reducing intracellular ATP and membrane depolarization by disturbing the permeability of the B. cereus cytoplasmic membrane. Damage or collapse of B. cereus cell membranes produced by morusin was identified using the field gun scanning electron microscope (FEG-SEM). Transcriptomic assessment indicated that the two-component system of B. cereus (narG, narH, narI, phoP, phoR, motA) responded positively to morusin within an adverse environment. Moreover, several genes associated with cell membrane and cell wall generation (murA, murB, ddlB) and amino acid metabolism (argF, argH, BCN_RS02850) were significantly downregulated, potentially accelerating the death of B. cereus. In addition, metabolomic investigation suggested that morusin restricted pyruvate metabolism, cysteine and methionine metabolic pathways, and disturbed the intracellular amino acid metabolism of B. cereus. Ultimately, 4.5 μg/mL of morusin was determined to significantly inhibit the growth of B. cereus within skimmed milk. Overall, morusin can be utilized as a natural antimicrobial agent for regulating B. cereus contamination in skimmed milk.

Synergistic antibacterial activity of cell wall hydrolase Lys14579 combined with cinnamaldehyde against emetic Bacillus cereus and their application in foods

Synergistic antibacterial effect as a promising strategy against foodborne pathogens is compelling since the development of novel antibacterial agents is not so easy. Here we investigated the synergistic effect of cell wall hydrolase Lys14579 and cinnamaldehyde (CAL) against emetic Bacillus cereus. The MICs of Lys14579 and CAL against emetic B. cereus were 25 and 200 μg/mL, respectively. The combination of Lys14579 and CAL displayed a synergistic antimicrobial effect with a Fractional Inhibitory Concentration Index (FICI) of 0.375. Bactericidal assays revealed that this combination had better bactericidal performance than either substance alone. Furthermore, the combination of Lys14579 and CAL effectively inhibited the biofilm formation of emetic B. cereus at the concentrations of 6.25 and 50 μg/mL, respectively. Additionally, it down-regulated the cereulide synthetase gene (cesB) expression at the transcription level and reduced swarming motility by 55%. Scanning electron microscope and PI uptake assays further demonstrated that the combination accelerated the disruption of emetic B. cereus cells. Finally, the synergistic preservative effect of this combinational was observed in boiled rice and fresh lean beef. Thus, the combination of Lys14579 and CAL represents a potential synergistic strategy for controlling emetic B. cereus contamination in the food industry.

Isolation and characterization of Bacillus cereus virulent phage CA1

Infection of Bacillus cereus can lead to massive mortality of Chinese soft- shelled turtles (Pelodiscus sinensis). Phage has shown promising effects in the treatment of bacterial infections. A virulent phage CA1 was obtained from pond water of a P. sinensis aquaculture farm. The characteristics of CA1 and its protective effect on P. sinensis were analyzed, and whole genome were sequenced. The phage CA1, with a long tail and a hexagonal head could specifically lyse B. cereus. The CA1 latent phase was 40 min, and the rise phase was 40–160 min. The optimal growth temperature for CA1 was 45 °C, the optimal pH was 7.0, and the multiplicity of infection (MOI) was 0.1. Its whole genome was 45,902 bp linear double-stranded DNA molecule with an average GC of 38.30%, and contained 74 predicted open reading frames. After infection of P. sinensis with B. cereus (1.0 × 107 CFU/g), the protection rate was 54% at the phage MOI of 0.1. The above findings demonstrate that CA1 exhibits typical traits of phage-based disinfectants, suggesting its potential application in the prevention and management of B. cereus contamination within aquaculture environments.

Reuterin formed by poultry-derived Limosilactobacillus reuteri HLRE05 inhibits the growth of enterotoxigenic Bacillus cereus in in vitro and fermented milk

The problem of food safety caused by Bacillus cereus contamination has been widely concerned, particularly in milk and its products, while effective prevention and control measures have not been implemented. Reuterin is a special broad-spectrum antibacterial substance produced by Limosilactobacillus reuteri via glycerol fermentation and is considered as a viable alternative to preservatives. In this study, a health poultry-derived L. reuteri HLRE05 (lineage VI strain in the evolutionary branch) was used to confirm its ability to produce reuterin, and then its basic biological activity and inhibitory capacity against foodborne pathogens were evaluated by glycerol fermentation in in vitro and fermented milk. Results showed that L. reuteri HLRE05 exhibited high resistance to hydrogen peroxide and intestinal fluids, and its adhesion rate to intestinal epithelial cells (Caco-2) reached about 80%. The content of reuterin produced by glycerol fermentation in vitro reached to 9.98 mg/mL, and the addition of glycerol to the fermentation broth could significantly improve the ability of supernatant to inhibit common foodborne pathogens. In addition, reuterin inhibited enterotoxigenic B. cereus HN001 with concentration dependent manner and restricted its adhesion rate to intestinal epithelial cells. Furthermore, L. reuteri HLRE05 produced reuterin during milk fermentation and eradicated B. cereus HN001 in a short period of time. This study highlights the potential application of natural-sourced antimicrobial approach with specific L. reuteri HLRE05 to control the safety of dairy products.

Safety and quality assessment of hot-drinks vending machines in Southern Italy

Vending machines (VMs) are common and convenient sources of various food and beverage items. Due to limited available information, concerns have been raised about the hygiene and safety of products dispensed by VMs. This study aims to assess the microbiological contamination of VMs in the Campania region (Italy), by combining microbiological and molecular biology analyses. The results revealed notable microbial contamination in VMs. Total Viable Count exceeded acceptable limits in VMs components, particularly in the inner walls of beverage dispensing nozzles and in the hot-drink product. Coffee and ginseng powders exhibited comparatively lower Total Viable Count values, while chocolate displayed none. Regarding pathogens, Listeria monocytogenes and Salmonella spp. were not detected in any of the samples subjected to analysis. Bacillus cereus (B. cereus) and Staphylococcus aureus (S. aureus) were detected in various VMs components. B. cereus contamination was prevalent, exceeding 80% in some surface swabs (water intake pipe, mixer bowl, and dispensing nozzle), and coincided with a high occurrence in the hot-drink final product. S. aureus was frequently found in milk powder, dispensing nozzles, and cappuccino samples. This research offers valuable insights into VM hygiene and safety, emphasizing the importance of multifaceted approaches to address microbiological contamination and promote public health. Regulatory compliance with cleaning procedures and proactive measures, such as robust self-monitoring plans and adherence to Good Manufacturing Practices, are crucial in mitigating contamination hazards and safeguarding product quality.

Evaluation of the ability to detect Bacillus cereus in food of chromogenic agar media RAPID’B.cereus according to ISO 7932:2004

In this study, the ability to detect Bacillus cereus of the new chromogenic agar media RAPID’B.cereus (RBC) was compared with the standard selective culture media Mannitol Egg Yolk Polymyxin (MYP) recommended by food authorities for isolation, identification, and quantification of Bacillus cereus. Two types of media were used to conduct the assessment on five categories of food, including cereals and cereal products; flour and starch; vegetables and vegetable products; milk and dairy products; and confectionery (n = 164). The results of the survey Bacillus cereus contamination on RBC (75.61%), MYP (70.12%), of which 46.09% of the samples didn’t meet the standards of the Ministry of Health on the maximum allowable limit of Bacillus cereus in food. Conducting performance testing of RBC according to ISO 16140-2:2016 with parameters: growth, selectivity, specificity, relative trueness and accuracy profile, the analysis results all met the criteria according to the standard: the development (PR) of the two media were 0.97 and 0.81 respectively; a high level of background microflora was present on the MYP plates while if it was not the case on the RBC plates; both media allowed the detection of Bacillus cereus with a difference of 0.14.  Compared with the acceptance criteria as prescribed, the categories used in the study were all suitable for assessment in the new media with the accuracy between the two methods being equivalent.

Risk assessment of Bacillus cereus in lettuce grown in open-field and greenhouse farming systems in China: A comparative study

Abstract Objectives Bacillus cereus isolates from vegetables can cause diarrheal syndrome food poisoning. Lettuce, the most highly consumed ready-to-eat vegetable, poses a significant risk of B. cereus exposure. Hence, B. cereus monitoring and evaluation during cultivation are essential for preventing foodborne illnesses caused by this food–pathogen combination. However, the impact of different cultivation practices on B. cereus contamination in lettuce currently remains unclear. Furthermore, a validity indicator for the experimental models cannot be effectively validated under field conditions. Materials and Methods Herein, we assessed the risk of B. cereus exposure using lettuce grown under two different cultivation farming systems in China (open-field versus greenhouse) using a quantitative microbial risk assessment model. Tukey’s mean comparison method and kernel density estimation frequency distribution statistics were used for model validation using environmental samples and lettuce. Results The mean concentration of B. cereus in open-field-grown lettuce was significantly higher than that in greenhouse-grown lettuce (P<0.05). No significant differences were observed between measured, formula-calculated, and risk assessment values in environmental samples or lettuce (P>0.05), verifying the accuracy of the risk model. Conclusion Soil solarization, complete manure treatment, usage of mulch films, and irrigation water quality should be considered in agricultural practices to control B. cereus concentrations in lettuce. Overall, we found that B. cereus was more abundant in open-field-grown lettuce, and we provide a risk evaluation framework that can guide farmers and policy-makers to control B. cereus contamination in farm-to-fork lettuce chains in China.

Contamination of Plant Foods with Bacillus cereus in a Province and Analysis of Its Traceability.

Bacillus cereus is an important zoonotic foodborne conditional pathogen. It is found in vegetables, dairy products, rice, and other foods, thereby greatly endangering human health. Investigations on B. cereus contamination in China primarily focus on raw milk, dairy products, meat, and others, and limited research has been conducted on plant-based foodstuffs. The rapid development of sequencing technology and the application of bioinformatics-related techniques means that analysis based on whole-genome sequencing has become an important tool for the molecular-epidemiology investigation of B. cereus. In this study, we investigated the contamination of B. cereus in six types of commercially available plant foods from eight regions of a province. The molecular epidemiology of the isolated B. cereus was analyzed by whole-genome sequencing. We aimed to provide fundamental data for the surveillance and epidemiology analysis of B. cereus in food products in China. The rapid traceability system of B. cereus established in this study can provide a basis for rapid molecular epidemiology analysis of B. cereus, as well as for the prevention and surveillance of B. cereus. Moreover, it can also be expanded to monitoring and rapid tracing of more foodborne pathogens.

Emetic and Diarrheal Toxins Detection and Typing of Bacillus cereus in Food and Human Milk in Italy

Abstract Background Bacillus cereus, responsible for 1.4%-12% of all food poisoning outbreaks worldwide, produces several virulence factors, including toxins which are mainly found in raw and processed food, as starch-based and dairy products. It can cause two types of gastrointestinal diseases: emetic form, with nausea and vomiting which appears as soon as after food consumption, and diarrheal form, with abdominal cramps, which occurs after 8-16 h. Moreover, B. cereus is the most common pathogen in pasteurized human milk, a precious aid in neonatal care. The aim of this study was to investigate the prevalence of B. cereus toxins kinds using WGS and to detect in silico sequence types (ST) in isolates from food and human milk. Methods During B. cereus routine surveillance in Lombardy (Italy), a total of 41 isolates were collected from food (n = 16) and donor breast milk (n = 25) between 2022-2023, and then analysed with WGS. Libraries were prepared using the Illumina DNA Prep Kit and WGS was performed on the Illumina MiSeq. Using the BTyper tool, for each sample emetic and diarrheal toxins were identified and ST was assigned. Results All 41 isolates had at least one diarrheal toxin, specifically the nonhemolytic enterotoxin was found in all the isolates, the cytotoxin K was detected in 37% of isolates, and the hemolysin BL in 32%. Instead, the emetic toxin was found in only 3 samples isolated from food. Using in silico MLST, different STs were found with a higher prevalence of ST26 and ST144. Conclusions Diarrheal toxins were detected in all samples underling that B. cereus food infections play an important role in the public health and in the food industry. These aspects are even more significant when the pathogen is isolated from human breast milk, as it can induce severe infections in newborns. Key messages • The presence of B. cereus toxins in food and human milk underlines the importance of its ongoing monitoring and analysis. • Human breast milk has a high risk of B. cereus contamination which is the most frequent cause for its discarding.

Comparative Analysis of Microbial and Mycotoxin Contamination in Korean Traditional Soybean Paste and Soy Sauce Production with and without Starter

Doenjang and ganjang are traditional, Korean fermented foods. They are manufactured by fermenting jangs, either through the traditional natural fermentation, using straw, or the commercial inoculating starter cultures. However, both Bacillus cereus and aflatoxins have been detected in jangs, compromising their safety. Aflatoxins have been detected on numerous occasions. However, studies are yet to be conducted on whether these safety issues differ depending on the manufacturing method. In this study, we evaluated whether the manufacturing methods of doenjang and ganjang alter their safety. Samples of traditional and commercial doenjang and ganjang were analyzed for aflatoxin and B. cereus contamination. Microbiome taxonomic profiling was performed to assess microbial composition. The experimental methodology involved sample collection from various stages of production, including the use of starter cultures and natural fermentation processes. Aflatoxin levels were determined using regulatory limits, and B. cereus content was evaluated against specific thresholds. Aflatoxins were detected in both traditional and commercial doenjang and ganjang, with either the total aflatoxin (15 μg/kg) or aflatoxin B1 (10 μg/kg) exceeding the regulatory limits. However, ochratoxin A was not detected in any of the samples. B. cereus was detected in some samples, within the regulatory limit (4 log CFU/g), and was not influenced by the manufacturing method. Analysis at the production stage showed that aflatoxin increased alongside the fermentation time in traditional doenjang. However, in ganjang, no significant differences were associated with the fermentation period. When using starter cultures, the fermentation period did not affect the toxin level in both foods. Both methods showed lower aflatoxin content in the initial doenjang and ganjang samples than in meju. B. cereus was not detected in either method, as its content decreased over the fermentation period. Microbiome taxonomic profiling confirmed that even when using starter cultures, B. cereus was not a dominant species and was considerably affected by the environment. Staphylococcus aureus and Pseudomonas, pathogenic in nature, were detected in products manufactured using the traditional method; hence, the potential risk of this method was higher than that of the commercial method. The experimental methodology employed in this study contributes to understanding the microbial composition and toxin contamination levels in doenjang and ganjang, contributing to the overall knowledge of their safety and quality control.

Beetroot (Beta vulgaris) extract exerts an antibacterial effect by inducing apoptosis-like death in Bacillus cereus

In this study, we assessed the phytochemicals of beetroot (Beta vulgaris) extract (BE), and examined the antibacterial activity and possible mechanism of BE against Bacillus cereus. The phytochemicals in BE were analyzed by UPLC-ESI-MS-based widely targeted metabolomics analysis, and identified a total of 745 phytochemicals. Nine polyphenols and 19 flavonoids with growth-inhibiting activity against B. cereus were identified. The minimum inhibitory concentration (MIC) of BE against B. cereus was 15 mg/mL. The intracellular adenosine 5′-triphosphate (ATP) levels were decreased and the B. cereus exhibited the features of apoptosis-like death (ALD) [cell membrane depolarization, caspase-like protein activation, phosphatidylserine (PS) translocation, and DNA fragmentation] by depleting reactive oxygen species (ROS) after BE treatment. These results suggest BE is rich in bioactive substances and induces ALD in B. cereus. Thus, the phytochemicals diversity makes BE as a source of bioactive ingredients, especially as a promising potential natural preservative to reduce B. cereus contamination.

Quantitative risk assessment of Bacillus cereus in wet rice noodles from raw material to marketing phase

From 2018, several foodborne diseases caused by the consumption of wet rice noodles contaminated with microorganisms have attracted the attention of consumers and surveillance departments. We explored the crucial risk factors for the contamination of Bacillus cereus during the various steps of the wet rice noodles production chain (from raw material to marketing phase). A total of 273 samples were collected in each corresponding production phase. The contamination level was quantitatively detected in the samples, and the corresponding temperature and time were recorded and analyzed using @Risk software. The quantitative detection results of raw material were determined as the initial contamination level in the model to predict the final contamination level and assess the key risk factors for B. cereus contamination in wet rice noodles. The model predicted that the final contamination level of B. cereus was in the range of −3.55 to 4.34 log CFU/g in 95% wet rice noodles at the marketing phase. The highest predicted contamination level was 6.28 log CFU/g, and the risk of exceeding the threshold was 0.80%. The model was verified to be valid for R2 > 0.96, and the predicted results could be used for reference. Moreover, the sensitivity analysis revealed that in addition to raw material, the key control factors were buffering temperature in the packaging delivery phase, transporting temperature and time from factory to marketing phase; their correlation coefficients (r) were 0.18, 0.16, and 0.15, respectively. Therefore, manufacturers need to adjust the current predelivery buffering and transporting mode. It is recommended to reduce the predelivery buffering temperature, and refrigerated trucks are preferred to control the proliferation of B. cereus in transported food, thus reducing the occurrence of foodborne diseases and improving the safety of food.

The Sources of Bacillus cereus Contamination and their Association with Cereulide Production in Dairy and Cooked Rice Processing Lines

Abstract Bacillus cereus, a spore-forming bacterium and frequent cause of food poisoning, poses a safety threat to dairy and rice industries due to its high contamination rates and ability to produce toxins such as cereulide. Because of widespread presence and thermal resistance of the spores, B. cereus cannot be eliminated from the environment and may survive in processing plants. Surviving spores can develop into vegetative cells, leading to a heightened risk of cereulide production in the processing environment. Both spores and vegetative cells have the ability to adhere to the surfaces of dairy plants and form biofilms, serving as the site for cereulide production and accumulation. Therefore, it is crucial for the food industry to address potential sources and pathways of B. cereus contamination and their connections to cereulide production in processing lines. In this review, sources of contamination of B. cereus, including spores, vegetative cells, and biofilms and their potential role in cereulide production at each stage of dairy and cooked rice processing were analyzed. In addition, control methods to prevent B. cereus contamination and cereulide production in processing lines were proposed, offering valuable insights for improving microbial risk management in the food industry.

Short Communication: Enterotoxin Genes and Antibiotic Susceptibility of Bacillus cereus Isolated from Garlic Chives and Agricultural Environment.

This study aims to investigate the enterotoxin profiles and antibiotic susceptibility of Bacillus cereus isolated from garlic chives and environmental samples. A total of 103 B. cereus isolates were used to identify enterotoxin genes, including hblA, hblC, hblD, nheA, nheB, and nheC. The hemolysin BL enterotoxin complex (hblACD) was detected in 38 isolates (36.9%), and the non-hemolytic enterotoxin complex (nheABC) was detected in 8 (7.8%) isolates. Forty-five isolates (43.7%) had hblACD and nheABC genes. B. cereus was resistant to β-lactam antibiotics and susceptible to non-β-lactam antibiotics. However, some B. cereus strains showed intermediate resistance to β-lactam and non-β-lactam antibiotics. B. cereus isolated from garlic chives showed intermediate resistance to cefotaxime (7.7%), rifampin (15.4%), clindamycin (30.8%), erythromycin (7.7%), and tetracycline (7.7%). B. cereus isolates from the agricultural environment were moderately resistant to cefotaxime (18.9%), rifampin (15.6%), clindamycin (12.2%), erythromycin (4.4%), and tetracycline (5.6%). Moreover, B. cereus isolates from garlic chives and cultivation environments could change their antibiotic resistance profile from susceptible to intermediate-resistant to rifampin, clindamycin, erythromycin, and tetracycline and exhibit multidrug resistance. These results indicate that continuous monitoring of B. cereus contamination in the produce and agricultural environment might be needed to ensure the safety of consuming fresh vegetables.

Physicochemical, Microbial, and Volatile Compound Characteristics of Gochujang, Fermented Red Pepper Paste, Produced by Traditional Cottage Industries.

Gochujang, fermented red pepper paste, is a grain-based Korean traditional food. The quality of gochujang produced by cottage industries is not well-documented. Thus, the present study aimed to analyze the quality of gochujang from 35 traditional cottage industries for physicochemical and microbial characteristics, along with volatile compound contents. In addition to microbial characteristics, salinity, pH, free amino nitrogen, and alcohol content were evaluated. Ethanol was detected as the predominant alcohol and 57% of tested gochujang products harbored >1% of total alcohol content, which was above the recommended level for halal products. Gochujang products contained hexadecanoic and linoleic acids predominantly and several volatile compounds belonging to the classes of alcohols, aldehydes, alkanes, nitrogen-containing compounds, and terpenes. A wide range of aerobic mesophilic bacteria (2.79–8.73 log CFU/g) and yeast counts (1.56–7.15 log CFU/g) was observed. Five distinct yeast species were identified, including Zygosaccharomyces rouxii. Eight gochujang products were found to be contaminated with Bacillus cereus (>4 log CFU/g). This study suggests that there is a need to limit B. cereus contamination in cottage industry products and reduce alcohol content to comply with halal food guidelines.

New genetic biomarkers to differentiate non-pathogenic from clinically relevant Bacillus cereus strains

ObjectivesBacillus 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. MethodsA 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. ResultsSeven 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. ConclusionsThese 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.

New Operating Approach to Limit Bacillus Cereus Contamination of Donor Human Milk.

New Operating Approach to Limit Bacillus Cereus Contamination of Donor Human Milk.