Claire Dargaignaratz

Sécurité et Qualité des Produits d'Origine Végétale

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Véronique Broussolle

Université d'Avignon et des Pays de Vaucluse

C. Nguyen‐The

Sécurité et Qualité des Produits d'Origine Végétale

Frédéric Carlin

Sécurité et Qualité des Produits d'Origine Végétale

Thierry Clavel

Sécurité et Qualité des Produits d'Origine Végétale

Alizée Guérin

Agence Nationale de Sécurité Sanitaire de l’Alimentation, de l’Environnement et du Travail

Christian Giniès

Université d'Avignon et des Pays de Vaucluse

Hélène Girardin

Sécurité et Qualité des Produits d'Origine Végétale

Julien Brillard

Diversité, génomes et interactions micro-organismes-insectes

Patrick Fach

Agence Nationale de Sécurité Sanitaire de l’Alimentation, de l’Environnement et du Travail

Michel R. Popoff

Institut Pasteur

Cooperative Institutions

Institut National de Recherche pour l'Agriculture, l'Alimentation et l'Environnement

Institut National de la Recherche Agronomique

Sécurité et Qualité des Produits d'Origine Végétale

Université d'Avignon et des Pays de Vaucluse

Centre National de la Recherche Scientifique

Université Paris-Saclay

Institut Pasteur

AgroParisTech

Université de Montpellier

Inserm

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Impact of temperature, pH and oxygen on the fate of Bacillus cereus vegetative cells. Consequences on the safety of new food products for elderly

HAL (Le Centre pour la Communication Scientifique Directe) (2014)

Alizée Guérin Claire Dargaignaratz Véronique Broussolle Thierry Clavel

Impact of temperature, pH and oxygen on the fate of [i]Bacillus cereus[/i] vegetative cells. Consequences on the safety of new food products for elderly. FoodMicro 2014

Cereus

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Effects of porcine bile on survival of Bacillus cereus vegetative cells and Haemolysin BL enterotoxin production in reconstituted human small intestine media

Journal of Applied Microbiology (2007)

Thierry Clavel Frédéric Carlin Claire Dargaignaratz Denis Lairon C. Nguyen‐The

To determine the effects of porcine bile (PB) on Bacillus cereus vegetative cells and Haemolysin BL (HBL) enterotoxin production in reconstituted small intestine media (IM).The effects of PB on the growth of B. cereus vegetative cells in reconstituted IM at PB concentrations ranging between 0 and 3.0 g l(-1) were examined. Four gastric media (GM) named GM-J broth (JB), GM-chicken, GM-milk and GM-pea were prepared by mixing equal volumes of a gastric electrolyte solution containing pepsin with JB, chicken, semi-skimmed milk and pea soup, respectively. Bacillus cereus was inoculated at approx. 2 x 10(4) CFU ml(-1) into each GM at pH 5.0 for 30 min at 37 degrees C, then mixed to the same volume of double-strength JB (IM) and PB to give concentrations of between 0 and 3.0 g of PB per litre at pH 6.5 and incubated at 37 degrees C. The diarrhoeal B. cereus strain F4430/73 grew in IM-JB, IM-chicken and IM-milk at PB concentrations of up to 0.6, 1.5 and 1.2 g l(-1), respectively. Growth was observed in IM-pea at all concentrations tested. The highest PB concentrations allowing a 3 log B. cereus increase in IM-JB, IM-chicken, IM-milk and IM-pea after a 7-10 h incubation period were 0.3, 0.9, 0.9 and 3.0 g l(-1), respectively. The effect of PB on B. cereus cells was strongest in IM-JB, followed by IM-chicken, IM-milk and IM-pea. Haemolysin BL enterotoxin was detectable in IM-chicken, IM-whole milk, IM-semi-skimmed milk and IM-pea up to PB concentrations of only 0.6, 0.6, 0.3 and 0.9 g l(-1), respectively. The diarrhoeal B. cereus strain F4433/73 behaved similarly to B. cereus strain F4430/73, whereas the food strain TZ415 was markedly more susceptible to bile.The tolerance of B. cereus cells to PB strongly depends on the type of food contained in the IM. Bile tolerance is also subject to strain variation.The probability that B. cereus cells will grow in the small intestine, produce toxins and cause diarrhoea is likely to depend on the food they are ingested with, on the bile tolerance of the B. cereus strain, and on bile concentration.

Cereus

Tryptic soy broth

10.1111/j.1365-2672.2007.03410.x

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Citations (30)

Spores of Bacillus cereus strain KBAB4 produced at 10 degrees C and 30 degrees C display variations in their properties

HAL (Le Centre pour la Communication Scientifique Directe) (2011)

S Tichit-Planchon Claire Dargaignaratz Christopher Lew Christian Giniès Véronique Broussolle

Strain (injury)

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Interactions entre la microflore saprophyte des produits pasteurisés réfrigérés et Clostridium botulinum

HAL (Le Centre pour la Communication Scientifique Directe) (1999)

Hélène Girardin Claire Dargaignaratz Guy Albagnac Frédéric Carlin C. Nguyen‐The

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Impact of temperature and oxygen on the fate of Bacillus weihenstephanensis in a food-based medium

Food Microbiology (2019)

Alizée Guérin Claire Dargaignaratz Thierry Clavel Véronique Broussolle C. Nguyen‐The

Cereus

10.1016/j.fm.2019.05.011

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Citations (1)

The YvfTU Two-component System is involved in plcR expression in Bacillus cereus

BMC Microbiology (2008)

Julien Brillard Kim A. Susanna Caroline Michaud Claire Dargaignaratz Michel Gohar

Most extracellular virulence factors produced by Bacillus cereus are regulated by the pleiotropic transcriptional activator PlcR. Among strains belonging to the B. cereus group, the plcR gene is always located in the vicinity of genes encoding the YvfTU two-component system. The putative role of YvfTU in the expression of the PlcR regulon was therefore investigated. Expression of the plcR gene was monitored using a transcriptional fusion with a lacZ reporter gene in a yvfTU mutant and in its B. cereus ATCC 14579 parental strain. Two hours after the onset of the stationary phase, a stage at which the PlcR regulon is highly expressed, the plcR expression in the yvfTU mutant was only 50% of that of its parental strain. In addition to the reduced plcR expression in the yvfTU mutant, a few members of the PlcR regulon showed a differential expression, as revealed by transcriptomic and proteomic analyses. The virulence of the yvfTU mutant in a Galleria mellonella insect model was slightly lower than that of the parental strain. The YvfTU two-component system is not required for the expression of most of the virulence factors belonging to the PlcR regulon. However, YvfTU is involved in expression of plcR, a major regulator of virulence in B. cereus.

Regulon

10.1186/1471-2180-8-183

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Citations (35)

Behaviour of psychrotrophic Bacillus cereus during the life cycle of food products for elderly people

HAL (Le Centre pour la Communication Scientifique Directe) (2016)

Alizée Guérin Claire Dargaignaratz Véronique Broussolle Thierry Clavel

The aim of the FP7-OPTIFEL project is to create new food products based on fruits and vegetables, supplemented with specific nutrients to fight elderlies’ nutritional deficiencies. The microbial safety of these products is of great importance due to the high risk of foodborne disease in the elderly population. The foodborne pathogen Bacillus cereus can resist to pasteurization treatments, psychrotrophic strains can multiply during food storage at low temperatures, and some may produce the heat resistant emetic toxin cereulide.

Pasteurization

Food Products

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Growth and Germination of Proteolytic Clostridium botulinum in Vegetable-Based Media

Journal of Food Protection (2003)

Agnès Braconnier Véronique Broussolle Claire Dargaignaratz C. Nguyen‐The Frédéric Carlin

Clostridium botulinum

Spore germination

10.4315/0362-028x-66.5.833

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Citations (9)

Contamination flows of Bacillus cereus and spore-forming aerobic bacteria in a cooked, pasteurized and chilled zucchini purée processing line

International Journal of Food Microbiology (2003)

M.H. Guinebretière H Girardin Claire Dargaignaratz Frédéric Carlin C. Nguyen‐The

Cereus

Pasteurization

Aerobic bacteria

Food microbiology

10.1016/s0168-1605(02)00307-0

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Citations (88)

Identification of Bacillus cereus Genes Specifically Expressed during Growth at Low Temperatures

Applied and Environmental Microbiology (2010)

Julien Brillard Isabelle Jéhanno Claire Dargaignaratz Isabelle Barbosa Christian Giniès

ABSTRACT The mechanisms involved in the ability of Bacillus cereus to multiply at low temperatures were investigated. It was assumed that many genes involved in cold acclimation would be upregulated at low temperatures. Recombinase-based in vivo expression technology (IVET) was adapted to the detection of the transient activation of B. cereus promoters during growth at 10°C. Four independent screenings of a promoter library from type strain ATCC 14579 were performed, and 17 clones were isolated. They corresponded to 17 promoter regions that displayed reproducibly elevated expression at 10°C relative to expression at 30°C. This analysis revealed several genes that may be important for B. cereus to grow successfully under the restrictive conditions of cold habitats. Among them, a locus corresponding to open reading frames BC5402 to BC5398, harboring a lipase-encoding gene and a putative transcriptional regulator, was identified three times. While a mutation in the putative regulator-encoding gene did not cause any particular phenotype, a mutant deficient in the lipase-encoding gene showed reduced growth abilities at low temperatures compared with the parental strain. The mutant did not change its fatty acid profiles in the same way as the wild type when grown at 12°C instead of 37°C. This study demonstrates the feasibility of a promoter trap strategy for identifying cold-induced genes. It outlines a first picture of the different processes involved in B. cereus cold acclimation.

Cereus

Wild type

10.1128/aem.02348-09

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Citations (37)