Consumed Foodstuffs Have a Crucial Impact on the Toxic Activity of Enteropathogenic Bacillus cereus

Riol, Claudia Da; Dietrich, Richard; Märtlbauer, Erwin; Jeßberger, Nadja

doi:10.3389/fmicb.2018.01946

Cited by 23 publications

(20 citation statements)

References 59 publications

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“…B. thuringiensis spores were prepared as described previously [ 14 , 31 , 32 ]. Briefly, 100 mL of minimal sporulation medium (1 mM MgCl 2 × 6 H 2 O, 1 mM Ca(NO 3 ) 2 × 4 H 2 O, 12.5 µM ZnCl 2 , 2.5 µM CuCl 2 , 2.5 µM CoCl 2 × 6 H 2 O, 2.5 µM Na 2 MoO 4 × 2 H 2 O, 5 µM (NH 4 ) 2 SO 4 , 0.066 µM MnSO 4 × H 2 O, 1 mM FeSO 4 and 1 M maltose in bacto nutrient broth (Oxoid, Wesel, Northrhine-Westphalia, Germany); pH 7.6) were inoculated with 0.5% overnight culture (see Section 2.1 ) and incubated for three days at 32 °C and 200 rpm.…”

Section: Methodsmentioning

confidence: 99%

Enteropathogenic Potential of Bacillus thuringiensis Isolates from Soil, Animals, Food and Biopesticides

Schwenk

Riegg

Lacroix³

et al. 2020

Foods

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Despite its benefits as biological insecticide, Bacillus thuringiensis bears enterotoxins, which can be responsible for a diarrhoeal type of food poisoning. Thus, all 24 isolates from foodstuffs, animals, soil and commercially used biopesticides tested in this study showed the genetic prerequisites necessary to provoke the disease. Moreover, though highly strain-specific, various isolates were able to germinate and also to actively move, which are further requirements for the onset of the disease. Most importantly, all isolates could grow under simulated intestinal conditions and produce significant amounts of enterotoxins. Cytotoxicity assays classified 14 isolates as highly, eight as medium and only two as low toxic. Additionally, growth inhibition by essential oils (EOs) was investigated as preventive measure against putatively enteropathogenic B. thuringiensis. Cinnamon Chinese cassia showed the highest antimicrobial activity, followed by citral, oregano and winter savory. In all tests, high strain-specific variations appeared and must be taken into account when evaluating the hazardous potential of B. thuringiensis and using EOs as antimicrobials. Altogether, the present study shows a non-negligible pathogenic potential of B. thuringiensis, independently from the origin of isolation. Generally, biopesticide strains were indistinguishable from other isolates. Thus, the use of these pesticides might indeed increase the risk for consumers’ health. Until complete information about the safety of the applied strains and formulations is available, consumers or manufacturers might benefit from the antimicrobial activity of EOs to reduce the level of contamination.

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Section: Methodsmentioning

confidence: 99%

Enteropathogenic Potential of Bacillus thuringiensis Isolates from Soil, Animals, Food and Biopesticides

Schwenk

Riegg

Lacroix³

et al. 2020

Foods

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“…Germination. B. cereus spores were prepared as previously described (69). Media to be tested were inoculated with the spores to an optical density of 1.…”

Section: Methodsmentioning

confidence: 99%

Porcine Gastric Mucin Triggers Toxin Production of Enteropathogenic Bacillus cereus

et al. 2019

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Enteropathogenic Bacillus cereus causes foodborne infections due to the production of pore-forming enterotoxins in the intestine. Before that, spores have to be ingested, survive the stomach passage, and germinate. Thus, before reaching epithelial cells, B. cereus comes in contact with the intestinal mucus layer. In the present study, different aspects of this interaction were analyzed. Total RNA sequencing revealed major transcriptional changes of B. cereus strain F837/76 upon incubation with porcine gastric mucin (PGM), comprising genes encoding enterotoxins and further putative virulence factors, as well as proteins involved in adhesion to and degradation of mucin. Indeed, PGM was partially degraded by B. cereus via secreted, EDTA-sensitive proteases. The amount of enterotoxins detectable in culture media supplemented with PGM was also clearly increased. Tests of further strains revealed that enhancement of enterotoxin production upon contact with PGM is broadly distributed among B. cereus strains. Interestingly, evidence was found that PGM can also strain-specifically trigger germination of B. cereus spores and that vegetative cells actively move toward mucin. Overall, our data suggest that B. cereus is well adapted to the host environment due to massive transcriptome changes upon contact with PGM, attributing mucin an important and, thus far, neglected role in pathogenesis.M ucus is a highly complex viscous substance that covers gastrointestinal cells.Besides salts, lipids, and several proteins involved in defense mechanisms, it consists mainly of water (approximately 95%) and the glycoprotein mucin (1, 2). A large number of different mucins has been discovered. These can be divided into membranebound and secretory mucins, which form the mucus layers (3, 4). Mucins have a molecular weight of 0.5 to 20 MDa and consist of ϳ20% proteins and ϳ80% carbohydrates (1). The protein core is organized in tandem repeats of serine-, threonine-, and proline-rich regions, which are mostly O-glycosylated. At the C and N termini, large amounts of cysteine are found. The carbohydrates include N-acetylgalactosamine, N-acetylglucosamine, N-acetylneuraminic acid, fucose, galactose, and mannose. Mucin monomers dimerize and multimerize via disulfide bonds (1).Mucus functions as a lubricant in the gastrointestinal tract, facilitating the passage of food. It is also important for growth, adhesion, and protection of the intestinal microbiota (2). Furthermore, it represents a biophysical barrier between epithelial cells and the environment, including chemical and mechanical insults as well as the commensal microbiota and pathogens (2,5,6). The mucus layer is a reservoir for many antimicrobial molecules, and various mucin oligosaccharides themselves show antimicrobial activity (5). By adhesion to mucin oligosaccharides, pathogens are trapped and removed due to the constant renewal of the mucus layer (5, 6). Cell surface-bound mucins can even initiate intracellular signaling in response to bacteria (5).On the other hand, pathogens, espe...

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“…Most of studies have focused on foodborne and clinical B. cereus s.l. isolates [4,7,[18][19][20][21]], yet strains belonging to this group are present in various natural environments, such as soil [22] or aquatic habitats [23], from which they can be easily transferred to crops and food products [24]. In addition, since B. cereus s.l.…”

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confidence: 99%

Potential Enterotoxicity of Phylogenetically Diverse Bacillus cereus Sensu Lato Soil Isolates from Different Geographical Locations

Drewnowska

Stefanska

Czerniecka

et al. 2020

Appl Environ Microbiol

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Bacillus cereus sensu lato comprises Gram-positive spore-forming bacteria producing toxins associated with foodborne diseases. Three pore-forming enterotoxins, nonhemolytic enterotoxin (Nhe), hemolysin BL (Hbl), and cytotoxin K (CytK), are considered the primary factors in B. cereus sensu lato diarrhea. The aim of this study was to determine the potential risk of enterotoxicity among soil B. cereus sensu lato isolates representing diverse phylogroups and originated from different geographic locations with various climates (Burkina Faso, Kenya, Argentina, Kazakhstan, and Poland). While nheA- and hblA-positive isolates were present among all B. cereus sensu lato populations and distributed across all phylogenetic groups, cytK-2-positive strains predominated in geographic regions with an arid hot climate (Africa) and clustered together on a phylogenetic tree mainly within mesophilic groups III and IV. The highest in vitro cytotoxicity to Caco-2 and HeLa cells was demonstrated by the strains clustered within phylogroups II and IV. Overall, our results suggest that B. cereus sensu lato pathogenicity is a comprehensive process conditioned by many intracellular factors and diverse environmental conditions. IMPORTANCE This research offers a new route for a wider understanding of the dependency between pathogenicity and phylogeny of a natural bacterial population, specifically within Bacillus cereus sensu lato, that is widely distributed around the world and easily transferred into food products. Our study indicates differences in the phylogenetic and geographical distributions of potential enterotoxigenic B. cereus sensu lato strains. Hence, these bacilli possess a risk for human health, and rapid testing methods for their identification are greatly needed. In particular, the detection of the CytK enterotoxin should be a supporting strategy for the identification of pathogenic B. cereus sensu lato.

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Consumed Foodstuffs Have a Crucial Impact on the Toxic Activity of Enteropathogenic Bacillus cereus

Cited by 23 publications

References 59 publications

Enteropathogenic Potential of Bacillus thuringiensis Isolates from Soil, Animals, Food and Biopesticides

Enteropathogenic Potential of Bacillus thuringiensis Isolates from Soil, Animals, Food and Biopesticides

Porcine Gastric Mucin Triggers Toxin Production of Enteropathogenic Bacillus cereus

Potential Enterotoxicity of Phylogenetically Diverse Bacillus cereus Sensu Lato Soil Isolates from Different Geographical Locations

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