Production of Bacillus cereus emetic toxin (cereulide) in various foods

Agata, Norio; Ohta, Michio; Yokoyama, Keiko

doi:10.1016/s0168-1605(01)00692-4

Cited by 229 publications

(152 citation statements)

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“…The global transition state factor AbrB was identified as one factor repressing cereulide production in early exponential phase (38). Although B. cereus enterotoxins and the emetic toxin cereulide seem to belong to completely different regulatory networks, production of both types of toxins depends substantially on nutritional and environmental factors (3,46,55), and it is expected that great effort is required to unravel in detail the intrinsic and extrinsic factors and mechanisms controlling toxin expression in B. cereus.Cereulide, which is produced by specific subgroups of B. cereus (20,62) and a few Bacillus weihenstephanensis isolates (60), is a small, acid-and proteolytically stable cyclic dodecadepsipeptide that is structurally related to the potassium ionophore valinomycin (2). It is toxic to mitochondria and has been implicated in severe forms of food poisoning resulting in acute liver failures (14,41,48)…”

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“…It is toxic to mitochondria and has been implicated in severe forms of food poisoning resulting in acute liver failures (14,41,48). The peptide toxin [D-O-Leu-D-Ala-L-O-Val-L-Val] 3 is synthesized enzymatically by a nonribosomal peptide synthetase (NRPS) (21).…”

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Identification of the Main Promoter Directing Cereulide Biosynthesis in Emetic Bacillus cereus and Its Application for Real-Time Monitoring of ces Gene Expression in Foods

Dommel

Frenzel

Strasser

et al. 2010

Appl Environ Microbiol

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Cereulide, the emetic Bacillus cereus toxin, is synthesized by cereulide synthetase via a nonribosomal peptide synthetase (NRPS) mechanism. Previous studies focused on the identification, structural organization, and biochemical characterization of the ces gene locus encoding cereulide synthetase; however, detailed information about the transcriptional organization of the ces genes was lacking. The present study shows that the ces-PTABCD genes are transcribed as a 23-kb polycistronic transcript, while cesH, encoding a putative hydrolase, is transcribed from its own promoter. Transcription initiation was mapped by primer extension and rapid amplification of cDNA ends (RACE). Deletion analysis of promoter elements revealed a main promoter located upstream of the cesP coding sequence, encoding a 4-phosphopantetheinyl transferase. This promoter drives transcription of cesPTABCD. In addition, intracistronic promoter regions in proximity to the translational start sites of cesB and cesT were identified but were only weakly active under the chosen assay conditions. The identified main promoter was amplified from the emetic reference strain B. cereus F4810/72 and fused to luciferase genes in order to study promoter activity in complex environments and to establish a biomonitoring system to assess cereulide production in different types of foods. ces promoter activity was strongly influenced by the food matrix and varied by 5 orders of magnitude. The amount of cereulide toxin extracted from spiked foods correlated well with the bioluminescence data, thus illustrating the potential of the established reporter system for monitoring of ces gene expression in complex matrices.Bacillus cereus is the causative agent of two types of food poisoning: diarrhea and emesis. The toxicoinfection referred to as diarrheal disease occurs after consumption of B. cereus spores or vegetative cells, most likely due to the action of heat-labile enterotoxins, which are produced by cells multiplying in the small intestine (4,22,30,39). Contrarily, the emetic type of food-borne illness is caused by intoxication with the heat-stable peptide cereulide, which is preformed in foods and elicits vomiting a few hours after ingestion (18,51,58).Regulation of enterotoxin expression of B. cereus has been studied in some detail (e.g., references 16, 29, and 46; for a review, see reference 58), revealing a major role of the pleiotropic transcription regulator PlcR in activation of enterotoxin genes and other virulence factors (1,29,45). Cereulide synthesis in emetic B. cereus, in contrast to synthesis of B. cereus enterotoxins, is not controlled by PlcR but by the Spo0A phosphorelay. The global transition state factor AbrB was identified as one factor repressing cereulide production in early exponential phase (38). Although B. cereus enterotoxins and the emetic toxin cereulide seem to belong to completely different regulatory networks, production of both types of toxins depends substantially on nutritional and environmental factors (3,46,55), and it is expe...

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Identification of the Main Promoter Directing Cereulide Biosynthesis in Emetic Bacillus cereus and Its Application for Real-Time Monitoring of ces Gene Expression in Foods

Dommel

Frenzel

Strasser

et al. 2010

Appl Environ Microbiol

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“…In order to assess biological activity, a number of eukaryotic-cell-based assays have been employed (5,11,27). The emetic toxin is traditionally assessed using a HEp-2 tissue culture assay by observing vacuole formation (3,26,51) or colorimetrically, by using the 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide (MTT) metabolic staining assay (15,47). Another bioassay, based on the loss of motility of boar spermatozoa, has also been developed (4).…”

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Rapid Ped-2E9 Cell-Based Cytotoxicity Analysis and Genotyping of Bacillus Species

et al. 2005

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Bacillus species causing food-borne disease produce multiple toxins eliciting gastroenteritis. Toxin assays with mammalian cell cultures are reliable but may take 24 to 72 h to complete and also lack sensitivity. Here, a sensitive and rapid assay was developed using a murine hybridoma Ped-2E9 cell model. Bacillus culture supernatants containing toxins were added to a Ped-2E9 cell line and analyzed for cytotoxicity with an alkaline phosphatase release assay. Most Bacillus cereus strains produced positive cytotoxicity results within 1 h, and data were comparable to those obtained with the standard Chinese hamster ovary (CHO)-based cytotoxicity assay, which took about 72 h to complete. Moreover, the Ped-2E9 cell assay had 25-to 58-fold-higher sensitivity than the CHO assay. Enterotoxin-producing Bacillus thuringiensis also gave positive results with Ped-2E9 cells, while several other Bacillus species were negative. Eight isolates from food suspected of Bacillus contamination were also tested, and only one strain, which was later confirmed as B. cereus, gave a positive result. In comparison with two commercial diarrheal toxin assay kits (BDE-VIA and BCET-RPLA), the Ped-2E9 assay performed more reliably. Toxin fractions of >30 kDa showed the highest degree of cytotoxicity effects, and heat treatment significantly reduced the toxin activity, indicating the involvement of a heat-labile high-molecularweight component in Ped-2E9 cytotoxicity. PCR results, in most cases, were in agreement with the cytotoxic potential of each strain. Ribotyping was used to identify cultures and indicated differences for several previously reported isolates. This Ped-2E9 cell assay could be used as a rapid (ϳ1-h) alternative to current methods for sensitive detection of enterotoxins from Bacillus species.

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“…The common practice in these restaurants is that the boiled rice is stored overnight usually at room temperature and B. cereus is then able to multiply. Once formed, t h e emetic toxin in rice is heat stable and cannot be inactivated during the subsequent reheating (Agata et al 2002;Kotiranta et al 2000). Thus, makes the chilling of cooked rice as an important food safety point.…”

Section: Resultsmentioning

confidence: 99%

CHILLING RATE OF COOKED RICE AND RISK OF Bacillus cereus GROWTH IN RESTAURANT OPERATION

Müftügil¹

2016

J Food Health Sci

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Abstract:The emetic syndrome of B. cereus food poisoning is often connected with consumption of rice. When cooked rice is cooled slowly and stored between 10°C to 50°C B. cereus spores germinate and reach numbers high enough to cause illness.Cooked rice is often slowly chilled in most of the restaurants. In the absence of rapid cooling instruments such as blast chiller and cold room, cooked rice, as a common practice is kept at room temperature for cooling for a long time before putting into a refrigerator.In this study, cooked rice in 10 cm deep in a pan was chilled in a blast chiller, cold room, refrigerator and at ambient and the cooling rates between the temperature zone of 50ºC to 10ºC were determined. Except the chilling in a blast chiller, in no other chilling methods the instructed/recommended four hours chilling time was achieved. Chilling of rice from 50ºC to 10ºC in a refrigerator took 12.5-13.5 hours. Chilling time came down to around 10 hours when thickness of rice in the pan was reduced to 5 cm. Chilling time was much longer (15.5-16.5 hours) when the rice was held at ambient until the centre temperature was 30 ºC before putting into the refrigerator. It is obvious that the commonly applied rice chilling in the restaurants is not safe. Some other practical ways other than reducing the thickness of rice should also be applied.

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Production of Bacillus cereus emetic toxin (cereulide) in various foods

Cited by 229 publications

References 7 publications

Identification of the Main Promoter Directing Cereulide Biosynthesis in Emetic Bacillus cereus and Its Application for Real-Time Monitoring of ces Gene Expression in Foods

Identification of the Main Promoter Directing Cereulide Biosynthesis in Emetic Bacillus cereus and Its Application for Real-Time Monitoring of ces Gene Expression in Foods

Rapid Ped-2E9 Cell-Based Cytotoxicity Analysis and Genotyping of Bacillus Species

CHILLING RATE OF COOKED RICE AND RISK OF Bacillus cereus GROWTH IN RESTAURANT OPERATION

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