An aerobic endospore-forming bacillus ) was isolated during a severe food poisoning outbreak in France in 1998, and four other similar strains have since been isolated, also mostly from food poisoning cases. Based on 16S rRNA gene sequence similarity, these strains were shown to belong to the Bacillus cereus Group (over 97 % similarity with the current Group species) and phylogenetic distance from other validly described species of the genus Bacillus was less than 95 %. Based on 16S rRNA gene sequence similarity and MLST data, these novel strains were shown to form a robust and well-separated cluster in the B. cereus Group, and constituted the most distant cluster from species of this Group. Major fatty acids (iso-C 15 : 0 , C 16 : 0 , iso-C 17 : 0 , anteiso-C 15 : 0 , iso-C 16 : 0 , iso-C 13 : 0 ) supported the affiliation of these strains to the genus Bacillus, and more specifically to the B. cereus Group. NVH 391-98 T taxon was more specifically characterized by an abundance of iso-C 15 : 0 and low amounts of iso-C 13 : 0 compared with other members of the B. cereus Group. Genome similarity together with DNA-DNA hybridization values and physiological and biochemical tests made it possible to genotypically and phenotypically differentiate NVH 391-98 T taxon from the six current B. cereus Group species.NVH 391-98 T therefore represents a novel species, for which the name Bacillus cytotoxicus sp. Abbreviations: DDH, DNA-DNA hybridization; MLST, multilocus sequence typing.The GenBank/EMBL/DDBJ accession numbers for the 16S rRNA gene of strains are described in Tables 1 and S1. The sequences of the MLST genes can be found at http://mlstoslo.uio.no/index.html.A supplementary figure and three supplementary tables are available with the online version of this paper.
Corynebacterium ulcerans may cause diphtheria in humans and caseous lymphadenitis in animals. We isolated nontoxigenic tox-bearing C. ulcerans from 13 game animals in Germany. Our results indicate a role for game animals as reservoirs for zoonotic C. ulcerans.
While the relevance of Bacillus (B.) cereus as a major cause of gastroenteritis is undisputed, the role of the closely related B. thuringiensis in foodborne disease is unclear. B. thuringiensis strains frequently harbor enterotoxin genes. However, the organism has only very rarely been associated with foodborne outbreaks, possibly due to the fact that during outbreak investigations, B. cereus is routinely not differentiated from B. thuringiensis. A recent EFSA scientific opinion stresses the urgent need for further data allowing for improved risk assessment, in particular as B. thuringiensis is a commonly used biopesticide. Therefore, the aim of this study was to gain further insights into the hazardous potential of B. thuringiensis. To this end, 39 B. thuringiensis isolates obtained from commercially used biopesticides, various food sources, as well as from foodborne outbreaks were characterized by panC typing, panC-based SplitsTree analysis, toxin gene profiling, FTIR spectroscopic analysis, a cytotoxicity assay screening for enterotoxic activity, and a sphingomyelinase assay. The majority of the tested B. thuringiensis isolates exhibited low (23%, n = 9) or mid level enterotoxicity (74%, n = 29), and produced either no (59%, n = 23) or low levels (33%, n = 13) of sphingomyelinase, which is reported to act synergistically with enterotoxins Nhe and Hbl. One strain isolated from rosemary was however classified as highly enterotoxic surpassing the cytotoxic activity of the high-level reference strain by a factor of 1.5. This strain also produced vast amounts of sphingomyelinase. Combining all results obtained in this study into a fingerprint pattern, several enterotoxic biopesticide strains were indistinguishable from those of isolates from foods or collected in association with outbreaks. Our study shows that many B. thuringiensis biopesticide strains exhibit mid-level cytotoxicity in a Vero cell assay and that some of these strains cannot be differentiated from isolates collected from foods or in association with outbreaks. Thus, we demonstrate that the use of B. thuringiensis strains as biopesticides can represent a food safety risk, underpinning the importance of assessing the hazardous potential of each strain and formulation used.
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