However, genes encoding GRs are widely distributed among Bacillus and Clostridium species [5, 19], implicating an essential role in triggering of spore germination in most spore-forming bacteria.

Interestingly, the nutrient specificity of the receptors and the interaction between them varies between and even within species, as has been shown for B. cereus-group members [20–22]. GRs are generally encoded by polycistronic operons that are expressed late in sporulation under the regulation of the forespore-specific transcription factor, sigma G (σG) [23, 24]. These genes constitute a family (gerA family) of homologous Selleckchem Wortmannin genes that probably have evolved from the same ancestor [4, 19]. Three putative gerA family operons, gerA (A, B, C), gerK (A, C, B) and ynd (D,E 3 E 2 , F 1, E 1 ) and the single gerAC homologue yndF2 have been identified within the B. licheniformis type strain ATCC14580/DSM13 Apoptosis inhibitor genome [25–27]. Of these, only the gerA operon has been functionally characterized so far [28]. gerA was found to be essential for germination in

presence of L-alanine. A similar role has been described for gerA in B. subtilis[18]. L-alanine is probably the most universal single nutrient germinant among spore formers [19]. The Bacillus GRs which have been described so far are usually composed of three subunits termed A, B and C. The A and B subunits are predicted to contain 5–6 (A) and 10–11 (B) membrane-spanning domains, respectively [5, 29], while the C subunit is thought to be a membrane-anchored lipoprotein [30]. The tertiary structure of B. subtilis GerBC was determined a few years ago [31]. The B-subunit, whose amino acid sequence shows homology to proteins of the APC (amino acid-polyamine-organocation) superfamily, is proposed to be Celecoxib the most likely site of ligand binding, as mutations within

this subunit alter ligand specificity [4, 32]. However, since mutations in any of the three cistrons are shown to disturb receptor function, the exact site of nutrient binding is still unknown [5]. The genetic relationship of 53 strains of the food-spoilage agent B. licheniformis, a close relative of B. subtilis, was recently described by a novel MLST scheme [33]. One of these strains, NVH1032, was isolated after surviving an “SGC-CBP30 mouse induced germination”-regime (Tyndallization), applied by the food industry to eliminate spore contamination. Preliminary results in our lab suggested that NVH1032 and other B. licheniformis strains germinate considerably slower than the type strain when exposed to L-alanine. Such slow-germinating strains pose a challenge to food manufacturers that want to implement “induced germination” as a strategy to reduce/eliminate spores during processing. In this study, 46 of the 53 genotyped strains were screened for efficiency of L-alanine-induced germination, and the correlation between the genotype and the induced germination was determined.