Recherche et isolement de bactéries du genre Bacillus de différents écosystèmes particuliers algériens

Abstract

With the discovery of numerous caves on planet Mars and the exploration of different types of caves on Earth, the interest and use of cave microorganisms has increased significantly during the last years. Hence, the purpose of this study is to present the first novel data on the presence of culturable, spore-forming bacteria in 10 different caves in Algeria, at depths down to 450 m. Two hundred fifty spore-forming isolates were obtained and their probiotic potential was tested with different methods (pathogenicity, growth at 37°C, survival in gastric juice and simulated intestinal fluid, antibiotic sensitivity, presence of digestive enzymes such as -galactosidase and gliadinase and cell surface properties). 13 of these tested strains (affiliated either to Bacillus or Paenibacillus, according to 16S rRNA analyses by FISH and gene sequencing) showed a rich spectrum of enzymatic and probiotic potential. These strains and their enzymes may therefore serve as useful candidates for future research in food processing and in reducing the effect of digestive disorders. These findings also suggest that novel strains with biotechnological potential can be discovered in pristine, subsurface ecosystems. Phylogenetic evaluation revealed that all selected isolates are affiliated to different Bacilli taxa within Firmicutes: B.gobiensis, B.subtilis, B.tequilensis, B.zhangzhouensis, B.pumilus, B.megaterium, B.simplex and B.pabuli.