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Su J, Chandross-Cohen T, Qian C, Carroll L, Kimble K, Yount M, Wiedmann M, Kovac J. Assessment of the exposure to cytotoxic Bacillus cereus group genotypes through HTST milk consumption. J Dairy Sci 2024:S0022-0302(24)00896-8. [PMID: 38851576 DOI: 10.3168/jds.2024-24703] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Accepted: 05/02/2024] [Indexed: 06/10/2024]
Abstract
This study addresses the limited tools available for assessing food safety risks from cytotoxic Bacillus cereus group strains in contaminated food. We quantified the growth, in skim milk broth, of 17 cytotoxic B. cereus strains across 6 phylogenetic groups with various virulence gene profiles. The strains did not grow in HTST milk at 4 or 6°C. At 10°C, 15 strains exhibited growth; at 8°C, one strain grew; and all strains grew at temperatures ≥ 14°C. Using growth data from 16 strains, we developed linear secondary growth models and an exposure assessment model. This model, simulating a 5-stage HTST milk supply chain and up to 35 d of consumer storage with an initial contamination of 100 cfu/mL, estimated that 2.81 ± 0.66% and 4.13 ± 2.53% of milk containers would surpass 105 cfu/mL of B. cereus by d 21 and 35, respectively. A sensitivity analysis identified the initial physiological state of cells (Q0) as the most influential variable affecting predictions for specific isolates. What-if scenarios indicated that increases in mean and variability of consumer storage temperatures significantly affected the predicted B. cereus concentrations in milk. This model serves as an initial tool for risk-based food safety decision making regarding low-level B. cereus contamination.
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Affiliation(s)
- Jun Su
- Department of Food Science, Cornell University, Ithaca, NY 14850
| | - Tyler Chandross-Cohen
- Department of Food Science, The Pennsylvania State University, University Park, PA 16802
| | - Chenhao Qian
- Department of Food Science, Cornell University, Ithaca, NY 14850
| | - Laura Carroll
- Department of Clinical Microbiology, SciLifeLab, Umeå University, Umeå, Sweden; Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Umeå, Sweden; Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden; Integrated Science Lab (IceLab), Umeå University, Umeå, Sweden
| | - Kayla Kimble
- Department of Food Science, The Pennsylvania State University, University Park, PA 16802
| | - Mackenna Yount
- Department of Food Science, The Pennsylvania State University, University Park, PA 16802
| | - Martin Wiedmann
- Department of Food Science, Cornell University, Ithaca, NY 14850
| | - Jasna Kovac
- Department of Food Science, The Pennsylvania State University, University Park, PA 16802
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2
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Huang L, Ahmad NH, Juneja V, Stapp-Kamotani E, Gabiola J, Minocha U, Phillips R, Hooker M, Walls I, Cook K, Lindsay J. Growth kinetics of Bacillus cytotoxicus in liquid Egg yolk during treatment with phospholipase A 2 - A one-step global dynamic analysis. Food Microbiol 2024; 118:104420. [PMID: 38049265 DOI: 10.1016/j.fm.2023.104420] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Revised: 10/17/2023] [Accepted: 10/30/2023] [Indexed: 12/06/2023]
Abstract
During commercial production of liquid egg yolk (LEY), phospholipase A2 (PLA2) is used to improve its emulsification capacity and thermal stability. The enzymatic treatment may occur at elevated temperatures such as 50 °C, potentially allowing foodborne pathogens, such as Bacillus cereus, to grow. Little knowledge is available concerning growth of B. cereus in LEY during PLA2 treatment. Therefore, the objective of this study was to investigate the growth kinetics of B. cereus during PLA2 treatment using pathogenic B. cytotoxicus NVH391-98, the most thermotolerant member in the B. cereus group, as a surrogate. Inoculated LEY samples were placed in precision programmable incubators to observe the growth of B. cytotoxicus NVH391-98 under multiple isothermal and dynamic temperature conditions between 20 and 53 °C. The bacterial growth was described using the differential Baranyi model coupled with two different secondary models. The kinetic parameters were determined using one-step dynamic inverse analysis of multiple growth curves. The least square method was used in combination with the 4th order Runge-Kutta method to solve the differential Baranyi model using multiple growth curves to determine the cardinal kinetic parameters. The results showed that B. cytotoxicus NVH391-98 can grow prolifically at 50 °C. The estimated minimum, optimum and maximum temperatures were 16.7 or 18.5, 47.8 or 48.1, and 52.1 or 52.4 °C, respectively, depending on the secondary models, with an optimum growth rate of 2.1 log colony-forming-unit (CFU)/g per hour. The dynamic model is validated using isothermal curves with reasonable accuracy. B. cytotoxicus died off slowly at 15 °C. At 55 °C, thermal inactivation was observed, with a D value of approximately 2.7 h. Holding at 55 °C or below 15 °C can effectively prevent the growth of B. cytotoxicus in egg yolk.
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Affiliation(s)
- Lihan Huang
- USDA-Agriculture Research Service, Wyndmoor, PA, USA.
| | - Nurul Hawa Ahmad
- ORISE Postdoctoral Research Fellow, Universiti Putra Malaysia, Malaysia
| | - Vijay Juneja
- USDA-Agriculture Research Service, Wyndmoor, PA, USA
| | | | - Jose Gabiola
- USDA-Food Safety and Inspection Service, Washington, DC, USA
| | - Udit Minocha
- USDA-Food Safety and Inspection Service, Washington, DC, USA
| | | | - Marie Hooker
- USDA-Food Safety and Inspection Service, Athens, GA, USA
| | - Isabel Walls
- USDA-Food Safety and Inspection Service, Washington, DC, USA
| | - Kim Cook
- USDA-Agriculture Research Service, Beltsville, MD, USA
| | - James Lindsay
- USDA-Agriculture Research Service, Beltsville, MD, USA
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3
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Etter D, Biggel M, Greutmann M, Cernela N, Johler S. New insights into Bacillus cytotoxicus sources, screening, toxicity, and persistence in food production facilities. Food Microbiol 2024; 117:104399. [PMID: 37919007 DOI: 10.1016/j.fm.2023.104399] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Revised: 10/03/2023] [Accepted: 10/06/2023] [Indexed: 11/04/2023]
Abstract
Bacillus cytotoxicus is a thermotolerant member of the Bacillus cereus group. It has been linked to rare, but at times fatal cases of diarrheal disease and might be missed at routine diagnostic screening temperatures commonly used for the B. cereus group. The pathogen is mostly found on dehydrated foods containing potato starch or insects. How it enters the food chain or whether it persists in food producing environments is largely unknown. Increased consumption of insects and convenience foods in Europe and the lack of information on the persistence of B. cytotoxicus in food environments and its virulence demand for further characterization. In this study, we aimed to obtain a better understanding of i) the food sources of B. cytotoxicus, ii) screening temperatures needed for its isolation from food matrices, iii) cytotoxicity of the organism, and iv) its ecological niche and potential epidemiological links. To this end, 112 food samples were collected, with a focus on foods exhibiting low water activity. The samples were screened for B. cytotoxicus at 42 °C and at 50 °C. Presumptive isolates were characterized by cytK-1 toxin gene PCR for differentiation of B. cytotoxicus from other B. cereus group members. Vero cell cytotoxicity assays were performed, and selected isolates were sequenced. Our results show that screening at 42 °C might be insufficient for detecting B. cytotoxicus in foods that harbor other less thermophilic Bacillus species. When screening at 50 °C, B. cytotoxicus was detected in 23% of the food samples (n = 26 isolates). The highest prevalence was detected in mashed potato products (82%) and potato flakes (67%). In contrast, a wide range of products not containing any potato ingredients did not yield B. cytotoxicus isolates. All B. cytotoxicus isolates exhibited either low or no detectable cytotoxicity. WGS analysis revealed that a highly toxic isolate is closely related to the French outbreak strain NVH 391-98. In addition, we could show that two isolates sampled 5 years apart from the same production facility only differed by seven SNPs, making it likely that B. cytotoxicus is able to persist in production facilities over a long time. Interestingly, the reoccurring strain possessed an additional plasmid and did not show cytotoxic potential when re-isolated after 5 years.
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Affiliation(s)
- Danai Etter
- Institute for Food Safety and Hygiene, University of Zurich, Zurich, Switzerland
| | - Michael Biggel
- Institute for Food Safety and Hygiene, University of Zurich, Zurich, Switzerland
| | - Mariella Greutmann
- Institute for Food Safety and Hygiene, University of Zurich, Zurich, Switzerland
| | - Nicole Cernela
- Institute for Food Safety and Hygiene, University of Zurich, Zurich, Switzerland
| | - Sophia Johler
- Institute for Food Safety and Hygiene, University of Zurich, Zurich, Switzerland.
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Defaix R, Lokesh J, Frohn L, Le Bechec M, Pigot T, Véron V, Surget A, Biasutti S, Terrier F, Skiba-Cassy S, Roy J, Panserat S, Ricaud K. Exploring the effects of dietary inulin in rainbow trout fed a high-starch, 100% plant-based diet. J Anim Sci Biotechnol 2024; 15:6. [PMID: 38247008 PMCID: PMC10802069 DOI: 10.1186/s40104-023-00951-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Accepted: 10/16/2023] [Indexed: 01/23/2024] Open
Abstract
BACKGROUND High dietary carbohydrates can spare protein in rainbow trout (Oncorhynchus mykiss) but may affect growth and health. Inulin, a prebiotic, could have nutritional and metabolic effects, along with anti-inflammatory properties in teleosts, improving growth and welfare. We tested this hypothesis in rainbow trout by feeding them a 100% plant-based diet, which is a viable alternative to fishmeal and fish oil in aquaculture feeds. In a two-factor design, we examined the impact of inulin (2%) as well as the variation in the carbohydrates (CHO)/plant protein ratio on rainbow trout. We assessed the influence of these factors on zootechnical parameters, plasma metabolites, gut microbiota, production of short-chain fatty acids and lactic acid, as well as the expression of free-fatty acid receptor genes in the mid-intestine, intermediary liver metabolism, and immune markers in a 12-week feeding trial. RESULTS The use of 2% inulin did not significantly change the fish intestinal microbiota, but interestingly, the high CHO/protein ratio group showed a change in intestinal microbiota and in particular the beta diversity, with 21 bacterial genera affected, including Ralstonia, Bacillus, and 11 lactic-acid producing bacteria. There were higher levels of butyric, and valeric acid in groups fed with high CHO/protein diet but not with inulin. The high CHO/protein group showed a decrease in the expression of pro-inflammatory cytokines (il1b, il8, and tnfa) in liver and a lower expression of the genes coding for tight-junction proteins in mid-intestine (tjp1a and tjp3). However, the 2% inulin did not modify the expression of plasma immune markers. Finally, inulin induced a negative effect on rainbow trout growth performance irrespective of the dietary carbohydrates. CONCLUSIONS With a 100% plant-based diet, inclusion of high levels of carbohydrates could be a promising way for fish nutrition in aquaculture through a protein sparing effect whereas the supplementation of 2% inulin does not appear to improve the use of CHO when combined with a 100% plant-based diet.
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Affiliation(s)
- Raphaël Defaix
- Université de Pau Et Des Pays de L'Adour, E2S UPPA, INRAE, NUMEA, Saint-Pée-Sur-Nivelle, France
| | - Jep Lokesh
- Université de Pau Et Des Pays de L'Adour, E2S UPPA, INRAE, NUMEA, Saint-Pée-Sur-Nivelle, France
| | - Laura Frohn
- Université de Pau Et Des Pays de L'Adour, E2S UPPA, INRAE, NUMEA, Saint-Pée-Sur-Nivelle, France
| | - Mickael Le Bechec
- Université de Pau Et Des Pays de L'Adour, E2S UPPA, CNRS, IMT Mines Ales, IPREM, Pau, France
| | - Thierry Pigot
- Université de Pau Et Des Pays de L'Adour, E2S UPPA, CNRS, IMT Mines Ales, IPREM, Pau, France
| | - Vincent Véron
- Université de Pau Et Des Pays de L'Adour, E2S UPPA, INRAE, NUMEA, Saint-Pée-Sur-Nivelle, France
| | - Anne Surget
- Université de Pau Et Des Pays de L'Adour, E2S UPPA, INRAE, NUMEA, Saint-Pée-Sur-Nivelle, France
| | - Sandra Biasutti
- Université de Pau Et Des Pays de L'Adour, E2S UPPA, IUT des Pays de l'Adour, Département Génie Biologique, Mont de Marsan, France
| | - Frédéric Terrier
- Université de Pau Et Des Pays de L'Adour, E2S UPPA, INRAE, NUMEA, Saint-Pée-Sur-Nivelle, France
| | - Sandrine Skiba-Cassy
- Université de Pau Et Des Pays de L'Adour, E2S UPPA, INRAE, NUMEA, Saint-Pée-Sur-Nivelle, France
| | - Jérôme Roy
- Université de Pau Et Des Pays de L'Adour, E2S UPPA, INRAE, NUMEA, Saint-Pée-Sur-Nivelle, France
| | - Stéphane Panserat
- Université de Pau Et Des Pays de L'Adour, E2S UPPA, INRAE, NUMEA, Saint-Pée-Sur-Nivelle, France
| | - Karine Ricaud
- Université de Pau Et Des Pays de L'Adour, E2S UPPA, INRAE, NUMEA, Saint-Pée-Sur-Nivelle, France.
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Li X, Lin Y, Chen Y, Sui H, Chen J, Li J, Zhang G, Yan Y. The effects of race and probiotic supplementation on the intestinal microbiota of 10-km open-water swimmers. Heliyon 2023; 9:e22735. [PMID: 38144321 PMCID: PMC10746432 DOI: 10.1016/j.heliyon.2023.e22735] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Revised: 11/16/2023] [Accepted: 11/17/2023] [Indexed: 12/26/2023] Open
Abstract
This study collected the stools of 10-km open-water swimmers after race and probiotic supplementation, and 16S rRNA sequencing and metabolomic analysis were performed to clarify their intestinal microbiota characteristics. The findings revealed a relatively high proportion of Firmicutes in all the athletes. Firmicutes in female athletes were significantly higher after probiotic supplementation. The intestinal microbiota of athletes was closely associated with the pathways of exercise against cancer, exercise against aging, exercise for improving cognition, sphingolipid metabolism and endocrine resistance. Future research should focus on the relationship between Firmicutes and Proteobacteria with super class metabolites in athletes. This report initially explored the changes in intestinal microbiota involved in metabolic pathways in athletes after race and after probiotic supplementation and provided a theoretical basis for the further improvement of the monitoring of their physical function after race and selection of nutritional strategies during exercise training.
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Affiliation(s)
- Xuehan Li
- Sport Science School, Beijing Sport University, Beijing, China
| | - Yihsuan Lin
- Sport Science School, Beijing Sport University, Beijing, China
| | - Yue Chen
- Sport Science School, Beijing Sport University, Beijing, China
| | - Hongtao Sui
- Sport Science School, Beijing Sport University, Beijing, China
| | - Jianhao Chen
- Sport Science School, Beijing Sport University, Beijing, China
| | - Jiaqi Li
- Sport Science School, Beijing Sport University, Beijing, China
| | - Guoqing Zhang
- Shandong Swimming Sports Management Center, Shandong, China
| | - Yi Yan
- Sport Science School, Beijing Sport University, Beijing, China
- Key Laboratory of Exercise and Physical Fitness (Beijing Sport University), Ministry of Education, Beijing, China
- Laboratory of Sports Stress and Adaptation of General Administration of Sport, Beijing, China
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6
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Yadav A, Kumari P, Devi P, Adjele JJB, Budhiraja S, Tarai B, Pandey R. Dual RNA-Seq reveals transcriptionally active microbes (TAMs) dynamics in the serum of dengue patients associated with disease severity. Front Microbiol 2023; 14:1307859. [PMID: 38107870 PMCID: PMC10723774 DOI: 10.3389/fmicb.2023.1307859] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2023] [Accepted: 11/13/2023] [Indexed: 12/19/2023] Open
Abstract
Introduction Dengue virus (DENV) is a flavivirus that has emerged as a global health threat, characterized by either asymptomatic or mild self-limiting febrile illness, but a subset of DENV outbreaks have been associated with severe disease. Studies have looked into the host immune response and dengue viral load during infection. However, it remains unknown how the active microbial isolates modulate the dengue viral infection. In this study, we demonstrate the significance of in-depth analysis of microbiota composition in the serum samples of dengue-infected patients. Materials and methods RNA was extracted from the serum samples collected from 24 dengue positive patients. The human mapped reads generated through RNA-Sequencing (RNA-Seq) were removed, while the unmapped (non-human) reads were employed for microbial taxonomic classification using Kraken2 and Bracken2. Further, we assessed the initial blood parameters analyzing the complete blood count (CBC) profile of the patients. Results Findings revealed differential abundance of commensals and pathogenic microbes in the early febrile period of hospitalized dengue patients, segregated into, High Viral Reads (HVR) and Low Viral Reads (LVR). The Campylobacter genus was abundant in the HVR whereas Lactobacillus dominated the LVR patients. At species level, the microbiota of HVR exhibited higher abundance of unique potential opportunistic microbes, compared to the commensal microbes' enrichment in the LVR patients'. We hypothesize that the DENV might alter the microbiota composition as observed by the increase in preponderance of opportunistic pathogens and an absence of commensals in the HVR. The presence of commensals in the LVR might explain, i) overall lower dengue viral reads compared to the HVR, and ii) shift in lymphocytes (high) and neutrophils (low) counts; resulting in a comparatively milder clinical manifestation in this group. Our findings may help in understanding the co-infection aspect that will be important to develop dengue therapeutics and vaccines. Discussion This study highlights the potential of the unexplored roles of the TAMs in modulating the dengue disease severity using the metatranscriptomic sequencing. This study serves to enhance our understanding of the distinctive microbial and hematologic signatures in the early infection stage that differentiate patients with high viral reads patients from those with low dengue viral reads.
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Affiliation(s)
- Aanchal Yadav
- Division of Immunology and Infectious Disease Biology, INtegrative GENomics of HOst-PathogEn (INGEN-HOPE) Laboratory, CSIR-Institute of Genomics and Integrative Biology (CSIR-IGIB), Delhi, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
| | - Pallawi Kumari
- Division of Immunology and Infectious Disease Biology, INtegrative GENomics of HOst-PathogEn (INGEN-HOPE) Laboratory, CSIR-Institute of Genomics and Integrative Biology (CSIR-IGIB), Delhi, India
- Indraprastha Institute of Information Technology Delhi, New Delhi, India
| | - Priti Devi
- Division of Immunology and Infectious Disease Biology, INtegrative GENomics of HOst-PathogEn (INGEN-HOPE) Laboratory, CSIR-Institute of Genomics and Integrative Biology (CSIR-IGIB), Delhi, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
| | - Jorelle Jeanne B. Adjele
- Division of Immunology and Infectious Disease Biology, INtegrative GENomics of HOst-PathogEn (INGEN-HOPE) Laboratory, CSIR-Institute of Genomics and Integrative Biology (CSIR-IGIB), Delhi, India
- Centre for Food, Food Security, and Nutrition Research, Institute of Medical Research and Medicinal Plant Studies, Yaounde, Cameroon
| | - Sandeep Budhiraja
- Max Super Speciality Hospital (A Unit of Devki Devi Foundation), Max Healthcare, Delhi, India
| | - Bansidhar Tarai
- Max Super Speciality Hospital (A Unit of Devki Devi Foundation), Max Healthcare, Delhi, India
| | - Rajesh Pandey
- Division of Immunology and Infectious Disease Biology, INtegrative GENomics of HOst-PathogEn (INGEN-HOPE) Laboratory, CSIR-Institute of Genomics and Integrative Biology (CSIR-IGIB), Delhi, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
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Rizzotto F, Marin M, Péchoux C, Auger S, Vidic J. Colorimetric aptasensor for detection of Bacillus cytotoxicus spores in milk and ready-to-use food. Heliyon 2023; 9:e17562. [PMID: 37449120 PMCID: PMC10336431 DOI: 10.1016/j.heliyon.2023.e17562] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 05/09/2023] [Accepted: 06/21/2023] [Indexed: 07/18/2023] Open
Abstract
The high incidence of foodborne diseases caused by pathogenic bacteria raises concerns worldwide and imposes considerable public healthcare challenges. This is especially observed with dormant spores of Bacilli, which can often survive treatments used by the food industry to kill growing bacteria. The early and rapid detection of bacterial spores is essential to ensure food safety. Commercial availability of such a test will present a high potential for food sector. We present a point-of-need colorimetric assay for detection of Bacillus cytotoxicus spores in food. The detection principle is based on spore-enhanced peroxidase-like catalytic activity of gold nanoparticles. The sensing platform consists of a microtube containing gold nanoparticles (AuNPs), and magnetic particles (MPs), both conjugated with specific aptamer BAS6R that recognize B. cytotoxicus spores. Upon the addition of the sample, spores were determined as present by the enhanced color change of the solution, due to the oxidation of tetramethylbenidine (TMB) with H2O2. The assay was evaluated by the naked eye (on/off) and quantitatively with use of a spectrophotometer. BAS6R@AuNPs aptasensor coupled to BAS6R@MPs proved to be highly sensitive, achieving the naked-eye limit of detection as low as 102 cfu/mL in water and milk, and 104 cfu/mL in mashed potatoes. Moreover, discrimination between spores of B. cytotoxicus and B. subtilis as well as bacterial vegetative cells was achieved in contaminated food samples, providing a good selectivity. This work provides a promising proof of concept for the development of instrument-free, low-cost and rapid assay for Bacillus cytotoxicus spore detection, which is able to compete in sensitivity with conventional costly and time-consuming laboratory analyses.
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Affiliation(s)
- Francesco Rizzotto
- Micalis Institute, INRAE, AgroParisTech, Université Paris-Saclay, 78350 Jouy en Josas, France
| | - Marco Marin
- Micalis Institute, INRAE, AgroParisTech, Université Paris-Saclay, 78350 Jouy en Josas, France
| | - Christine Péchoux
- INRAE, AgroParisTech, Université Paris-Saclay, GABI, 78350 Jouy-en-Josas, France
| | - Sandrine Auger
- Micalis Institute, INRAE, AgroParisTech, Université Paris-Saclay, 78350 Jouy en Josas, France
| | - Jasmina Vidic
- Micalis Institute, INRAE, AgroParisTech, Université Paris-Saclay, 78350 Jouy en Josas, France
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8
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Jovanovic J, Tretiak S, Begyn K, Rajkovic A. Detection of Enterotoxigenic Psychrotrophic Presumptive Bacillus cereus and Cereulide Producers in Food Products and Ingredients. Toxins (Basel) 2022; 14:toxins14040289. [PMID: 35448897 PMCID: PMC9030337 DOI: 10.3390/toxins14040289] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2022] [Revised: 04/07/2022] [Accepted: 04/13/2022] [Indexed: 02/04/2023] Open
Abstract
In the last decade, foodborne outbreaks and individual cases caused by bacterial toxins showed an increasing trend. The major contributors are enterotoxins and cereulide produced by Bacillus cereus, which can cause a diarrheal and emetic form of the disease, respectively. These diseases usually induce relatively mild symptoms; however, fatal cases have been reported. With the aim to detected potential toxin producers that are able to grow at refrigerator temperatures and subsequently produce cereulide, we screened the prevalence of enterotoxin and cereulide toxin gene carriers and the psychrotrophic capacity of presumptive B. cereus obtained from 250 food products (cereal products, including rice and seeds/pulses, dairy-based products, dried vegetables, mixed food, herbs, and spices). Of tested food products, 226/250 (90.4%) contained presumptive B. cereus, which communities were further tested for the presence of nheA, hblA, cytK-1, and ces genes. Food products were mainly contaminated with the nheA B. cereus carriers (77.9%), followed by hblA (64.8%), ces (23.2%), and cytK-1 (4.4%). Toxigenic B. cereus communities were further subjected to refrigerated (4 and 7 °C) and mild abuse temperatures (10 °C). Overall, 77% (94/121), 86% (104/121), and 100% (121/121) were able to grow at 4, 7, and 10 °C, respectively. Enterotoxin and cereulide potential producers were detected in 81% of psychrotrophic presumptive B. cereus. Toxin encoding genes nheA, hblA, and ces gene were found in 77.2, 55, and 11.7% of tested samples, respectively. None of the psychrotrophic presumptive B. cereus were carriers of the cytotoxin K-1 encoding gene (cytK-1). Nearly half of emetic psychrotrophic B. cereus were able to produce cereulide in optimal conditions. At 4 °C none of the examined psychrotrophs produced cereulide. The results of this research highlight the high prevalence of B. cereus and the omnipresence of toxin gene harboring presumptive B. cereus that can grow at refrigerator temperatures, with a focus on cereulide producers.
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Affiliation(s)
- Jelena Jovanovic
- Department of Food Technology, Safety, and Health, Ghent University, Coupure Links 653, 9000 Ghent, Belgium; (J.J.); (K.B.)
| | - Svitlana Tretiak
- Department of Pathobiology, Pharmacology and Zoological Medicine, Ghent University, Salisburylaan 133, D5 Ingang 78, 9820 Merelbeke, Belgium;
- Impextraco nv, Wiekevorstsesteenweg 38, 2220 Heist-op-den-Berg, Belgium
| | - Katrien Begyn
- Department of Food Technology, Safety, and Health, Ghent University, Coupure Links 653, 9000 Ghent, Belgium; (J.J.); (K.B.)
| | - Andreja Rajkovic
- Department of Food Technology, Safety, and Health, Ghent University, Coupure Links 653, 9000 Ghent, Belgium; (J.J.); (K.B.)
- Correspondence:
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9
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Fuchs E, Raab C, Brugger K, Ehling-Schulz M, Wagner M, Stessl B. Performance Testing of Bacillus cereus Chromogenic Agar Media for Improved Detection in Milk and Other Food Samples. Foods 2022; 11:foods11030288. [PMID: 35159440 PMCID: PMC8834558 DOI: 10.3390/foods11030288] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 01/05/2022] [Accepted: 01/10/2022] [Indexed: 02/07/2023] Open
Abstract
In this study, the performance of four alternative selective chromogenic B. cereus agar was compared to the reference mannitol-yolk polymyxin (MYP) agar (ISO 7932) using inclusion and exclusion test strains (n = 110) and by analyzing naturally contaminated milk and other food samples (n = 64). Subsequently, the panC group affiliation and toxin gene profile of Bacillus cereus senso lato (s.l.) isolates were determined. Our results corroborate that the overall best performing media CHROMagar™ B. cereus (93.6% inclusivity; 82.7% exclusivity) and BACARA® (98.2% inclusivity, 62.7% exclusivity) are more sensitive and specific compared to Brilliance™ B. cereus, MYP and ChromoSelect Bacillus Agar. Both media allow unequivocal detection of B. cereus with low risks of misidentification. Media containing ß-D-glucosidase for the detection of presumptive B. cereus may form atypical colony morphologies resulting in a false negative evaluation of the sample. Naturally contaminated samples presented high numbers of background flora, while numbers of presumptive B. cereus were below the detection limit (<10 CFU g−1 or mL−1). Recovery after freezing resulted in the highest detection of B. cereus s.l. on BACARA® (57.8%), CHROMagar™ B. cereus (56.3%) and MYP agar (54.7%). The panC/toxin profile combination IV/A was the most abundant (33.0%), followed by III/F (21.7%) and VI/C (10.4%). More panC and toxin combinations were present in 15.6% of samples when reanalyzed after freezing. In order to improve detection and confirmation of B. cereus s.l. in food samples, we recommend the parallel use of two complementary selective media followed by molecular characterization (e.g., panC typing combined with toxin gene profiling). When determining psychrotolerant or thermophilic members of the B. cereus group, the selective agar media should additionally be incubated at appropriate temperatures (5 °C, ≥45 °C). If high-risk toxin genes (e.g., ces or cytK-1) are detected, the strain-specific ability to produce toxin should be examined to decisively assess risk.
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Affiliation(s)
- Eva Fuchs
- Unit of Food Microbiology, Institute of Food Safety, Food Technology and Veterinary Public Health, University of Veterinary Medicine Vienna, 1210 Vienna, Austria; (E.F.); (C.R.); (M.W.)
| | - Christina Raab
- Unit of Food Microbiology, Institute of Food Safety, Food Technology and Veterinary Public Health, University of Veterinary Medicine Vienna, 1210 Vienna, Austria; (E.F.); (C.R.); (M.W.)
| | - Katharina Brugger
- Unit of Veterinary Public Health and Epidemiology, Institute of Food Safety, Food Technology and Veterinary Public Health, University of Veterinary Medicine Vienna, 1210 Vienna, Austria;
| | - Monika Ehling-Schulz
- Functional Microbiology Group, Institute of Microbiology, University of Veterinary Medicine Vienna, 1210 Vienna, Austria;
| | - Martin Wagner
- Unit of Food Microbiology, Institute of Food Safety, Food Technology and Veterinary Public Health, University of Veterinary Medicine Vienna, 1210 Vienna, Austria; (E.F.); (C.R.); (M.W.)
- Austrian Competence Center for Feed and Food Quality, Safety and Innovation (FFOQSI GmbH), 3430 Tulln an der Donau, Austria
| | - Beatrix Stessl
- Unit of Food Microbiology, Institute of Food Safety, Food Technology and Veterinary Public Health, University of Veterinary Medicine Vienna, 1210 Vienna, Austria; (E.F.); (C.R.); (M.W.)
- Correspondence:
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