A wide variety of enzymatic pathways that produce specialized metabolites in bacteria, fungi and plants are known to be encoded in biosynthetic gene clusters. Information about these clusters, pathways and metabolites is currently dispersed throughout the literature, making it difficult to exploit. To facilitate consistent and systematic deposition and retrieval of data on biosynthetic gene clusters, we propose the Minimum Information about a Biosynthetic Gene cluster (MIBiG) data standard.

The Bacillus cereus group includes several Bacillus species with closely related phylogeny. The most well-studied members of the group, B. anthracis , B. cereus , and B. thuringiensis , are known for their pathogenic potential. Here, we present the historical rationale for speciation and discuss shared and unique features of these bacteria. Aspects of cell morphology and physiology, and genome sequence similarity and gene synteny support close evolutionary relationships for these three species. For many strains, distinct differences in virulence factor synthesis provide facile means for species assignment. B. anthracis is the causative agent of anthrax. Some B. cereus strains are commonly recognized as food poisoning agents, but strains can also cause localized wound and eye infections as well as systemic disease. Certain B. thuringiensis strains are entomopathogens and have been commercialized for use as biopesticides, while some strains have been reported to cause infection in immunocompromised individuals. In this article we compare and contrast B. anthracis , B. cereus , and B. thuringiensis , including ecology, cell structure and development, virulence attributes, gene regulation and genetic exchange systems, and experimental models of disease.

Summary: The Bacillus cereus Group comprises organisms that are widely distributed in the environment and are of health and economic interest. We demonstrate an ‘ecotypic’ structure of populations in the B. cereus Group using (i) molecular data from Fluorescent Amplified Fragment Length Polymorphism patterns, ribosomal gene sequences, partial panC gene sequences, ‘psychrotolerant’ DNA sequence signatures and (ii) phenotypic and descriptive data from range of growth temperature, psychrotolerance and thermal niches. Seven major phylogenetic groups (I to VII) were thus identified, with ecological differences that provide evidence for a multiemergence of psychrotolerance in the B. cereus Group. A moderate thermotolerant group (VII) was basal to the mesophilic group I, from which in turn distinct thermal lineages have emerged, comprising two mesophilic groups (III, IV), an intermediate group (V) and two psychrotolerant groups (VI, II). This stepwise evolutionary transition toward psychrotolerance was particularly well illustrated by the relative abundance of the ‘psychrotolerant’ rrs signature (as defined by Pruss et al .) copies accumulated in strains that varied according to the phylogenetic group. The ‘psychrotolerant’ cspA signature (as defined by Francis et al .) was specific to group VI and provided a useful way to differentiate it from the psychrotolerant group II. This study illustrates how adaptation to novel environments by the modification of temperature tolerance limits has shaped historical patterns of global ecological diversification in the B. cereus Group. The implications for the taxonomy of this Group and for the human health risk are discussed.

Bacillus cereus is a ubiquitous soil bacterium responsible for two types of food-associated gastrointestinal diseases. While the emetic type, a food intoxication, manifests in nausea and vomiting, food infections with enteropathogenic strains cause diarrhea and abdominal pain. Causative toxins are the cyclic dodecadepsipeptide cereulide, and the proteinaceous enterotoxins hemolysin BL (Hbl), nonhemolytic enterotoxin (Nhe) and cytotoxin K (CytK), respectively. This review covers the current knowledge on distribution and genetic organization of the toxin genes, as well as mechanisms of enterotoxin gene regulation and toxin secretion. In this context, the exceptionally high variability of toxin production between single strains is highlighted. In addition, the mode of action of the pore-forming enterotoxins and their effect on target cells is described in detail. The main focus of this review are the two tripartite enterotoxin complexes Hbl and Nhe, but the latest findings on cereulide and CytK are also presented, as well as methods for toxin detection, and the contribution of further putative virulence factors to the diarrheal disease.

An in-depth polyphasic approach was applied to study the population structure of the human pathogen Bacillus cereus. To assess the intraspecific biodiversity of this species, which is the causative agent of gastrointestinal diseases, a total of 90 isolates from diverse geographical origin were studied by genetic [M13-PCR, random amplification of polymorphic DNA (RAPD), multilocus sequence typing (MLST)] and phenetic [Fourier transform Infrared (FTIR), protein profiling, biochemical assays] methods. The strain set included clinical strains, isolates from food remnants connected to outbreaks, as well as isolates from diverse food environments with a well documented strain history. The phenotypic and genotypic analysis of the compiled panel of strains illustrated a considerable diversity among B. cereus connected to diarrhoeal syndrome and other non-emetic food strains, but a very low diversity among emetic isolates. Using all typing methods, cluster analysis revealed a single, distinct cluster of emetic B. cereus strains. The isolates belonging to this cluster were neither able to degrade starch nor could they ferment salicin; they did not possess the genes encoding haemolysin BL (Hbl) and showed only weak or no haemolysis. In contrast, haemolytic-enterotoxin-producing B. cereus strains showed a high degree of heterogeneity and were scattered over different clusters when different typing methods were applied. These data provide evidence for a clonal population structure of cereulide-producing emetic B. cereus and indicate that emetic strains represent a highly clonal complex within a potentially panmictic or weakly clonal background population structure of the species. It may have originated only recently through acquisition of specific virulence factors such as the cereulide synthetase gene.