Genomic and phenotypic comparison of Bacillus fumarioli isolates from geothermal Antarctic soil and gelatine.

Bacillus fumarioli was originally isolated from geothermal soils in continental and maritime Antarctica, and recently, it has been shown to be a frequent contaminant of gelatine extracts obtained from European and American production plants. These habitats are geographically widely separated, share similar temperature and pH conditions, but have substantially different organic loads. Because of the prevalence in gelatine extracts and the dissimilarity of this habitat to geothermal soil, a comparative study was performed to assess the diversity among B. fumarioli strains and reveal possible intraspecies differences that might correspond to their niches of origin. Genomic (rep-PCR, 16S rDNA sequencing, DNA-DNA hybridisations) and phenotypic techniques (analysis of fatty acid content, total cellular proteins, metabolic and morphological traits) illustrate the very close relationship between isolates from the two niches. An abundant protein band was demonstrated for gelatine isolates only. This band was shown to result from a protein with high similarity to a stress response protein. Furthermore, subtractive hybridisation revealed genomic differences between Antarctic and gelatine isolates that may indicate adaptive evolution to a specific environment.