The same, only different: Do all C. botulinum Groups follow the same germination path?

A recently published IFR paper in Frontiers in Microbiology describes evidence for the role of germination proteins in spore germination in C. botulinum and C. sporogenes.

Dr Jason Brunt

Dr Jason Brunt

Here, Dr Jason Brunt, an IFR scientist working in Professor Mike Peck’s research group within the GHFS Research Programme and the Food Safety Centre, blogs about the research behind this new paper.

Clostridium botulinum is a dangerous pathogen that forms the highly potent botulinum toxin, which when ingested causes botulism, a deadly neuroparalytic disease. The closely related Clostridium sporogenes is a significant cause of waste through food spoilage, is occasionally pathogenic, and is often regarded as the non-toxigenic equivalent of C. botulinum. All Clostridium species form highly heat resistant endospores, enabling these bacteria to survive adverse conditions. Subsequently, spores may germinate, giving rise to vegetative cells that multiply and lead to adverse events such as toxin production or food spoilage.

Although published research has traditionally focussed on the genetics and production of the neurotoxins of C. botulinum, in practice much of the hazard posed to human and animal health is due to the fact that this organism forms very heat-resistant spores which persist in the environment and so are often present in raw food ingredients. Spore germination is the key step in the transition from a dormant spore to an actively growing cell. Currently, our knowledge of the mechanisms by which Gram positive bacterial spores germinate relies almost entirely on studies of Bacillus, C. perfringens and C. difficile, organisms with different genetics and biochemistry.  This paper is the first to address such a large gap in scientific knowledge by focussing specifically on the germination mechanisms of C. botulinum Groups I to IV and the closely related C. sporogenes. We have used a combination of bioinformatics, gene insertional knockouts and phenotypic germination studies to determine germination mechanisms in the C. botulinum/C. sporogenes groups.

This approach, refined by a detailed analysis of the number of and distribution of ger receptor operons and cortex lytic enzymes, has allowed for the first time, the proposal of a working model (See Figure 1 below) for germination in C. botulinum Groups I to IV and C. sporogenes.

Proposed working model for germination in C. botulinum Groups I to IV and C. sporogenes

Proposed working model for germination in C. botulinum Groups I to IV and C. sporogenes

Reference: Brunt J, van Vliet AHM, van den Bos F, Carter AT, Peck MW (2016). Diversity of the Germination Apparatus in Clostridium botulinum Groups I, II, III and IV. Frontiers in Microbiology

Written by Jason Brunt, November 2016

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The programme receives funding from the BBSRC - Biotechnology and Biological Sciences Research Council and involves leading researchers from the Quadram Institute Bioscience, Imperial College, University of East Anglia and St. Mark's Hospital and Academic Institute

Quadram InstituteImperial College LondonUniversity of East AngliaSt. Mark's Hospital and Academic InstituteBBSRC - Biotechnology and Biological Sciences Research Council