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.

Minimal standards for describing new taxa within the aerobic endospore-forming bacteria are proposed, following Recommendation 30b of the Bacteriological Code (1990 Revision). These minimal standards are recommended as guidelines to assist authors in the preparation of descriptions for novel taxa. They encourage broad polyphasic characterization and the construction of descriptions that are practically useful in routine diagnostic laboratories. The proposals have been endorsed by the Subcommittee on the Taxonomy of the Genus Bacillus and Related Organisms of the International Committee on Systematics of Prokaryotes.

Bacillus cereus is a well-known cause of food-borne illness, but infection with this organism is not commonly reported because of its usually mild symptoms. A fatal case due to liver failure after the consumption of pasta salad is described and demonstrates the possible severity of the emetic syndrome.

Abstract:  Bacteria in milk have the ability to adhere and aggregate on stainless steel surfaces, resulting in biofilm formation in milk storage tanks and milk process lines. Growth of biofilms in milk processing environments leads to increased opportunity for microbial contamination of the processed dairy products. These biofilms may contain spoilage and pathogenic microorganisms. Bacteria within biofilms are protected from sanitizers due to multispecies cooperation and the presence of extracellular polymeric substances, by which their survival and subsequent contamination of processed milk products is promoted. This paper reviews the most critical factors in biofilm formation, with special attention to pseudomonads, the predominant spoilage bacteria originating from raw milk. Biofilm interactions between pseudomonads and milk pathogens are also addressed, as emerging risks and future research perspectives, specifically related to the milk processing environment.

Campylobacteriosis is the most reported foodborne gastroenteritic disease and poses a serious health burden in industrialized countries. Disease in humans is mainly caused by the zoonotic pathogen Campylobacter jejuni . Due to its wide-spread occurrence in the environment, the epidemiology of Campylobacter remains poorly understood. It is generally accepted, however, that chickens are a natural host for Campylobacter jejuni , and for Campylobacter spp. in general, and that colonized broiler chicks are the primary vector for transmitting this pathogen to humans. Several potential sources and vectors for transmitting C. jejuni to broiler flocks have been identified. Initially, one or a few broilers can become colonized at an age of >2 weeks until the end of rearing, after which the infection will rapidly spread throughout the entire flock. Such a flock is generally colonized until slaughter and infected birds carry a very high C. jejuni load in their gastrointestinal tract, especially the ceca. This eventually results in contaminated carcasses during processing, which can transmit this pathogen to humans. Recent genetic typing studies showed that chicken isolates can frequently be linked to human clinical cases of Campylobacter enteritis. However, despite the increasing evidence that the chicken reservoir is the number one risk factor for disease in humans, no effective strategy exists to reduce Campylobachter prevalence in poultry flocks, which can in part be explained by the incomplete understanding of the epidemiology of C. jejuni in broiler flocks. As a result, the number of human campylobacteriosis cases associated with the chicken vector remains strikingly high.