Selective isolation and diversity of cold-adapted lipase-producing strains from permafrost soil at the terminus of a glacier in the Tianshan Mountains Selective isolation and diversity of cold-adapted lipase-producing strains from permafrost soil at the

Abstract:

Abstract:［Objective］The diversity of culturable lipase-producing bacterial strains from permafrost soils at the terminus of a glacier in the Tianshan Mountains was investigated. Isolation and molecular phylogenetic analysis were performed to expand our knowledge on diversity of psychrotrophic and psychrophilic bacteria. In addition, efforts were made focusing on screening for cold active lipases.［Methods］Lipase-producing bacterial strains were detected on tween 80 and olive oil plates, respectively. Identity and genetic diversity of strains isolated were determined by spatial 16S rRNA gene sequences and rep-PCR fingerprint. The physiological tests were carried out to determine the phonotypic differences between strains showing high similarity of 16S rRNA gene sequences.［Results］Of the total 17 bacterial stains exhibiting cold-adapted lipase activity, we found that only 8 stains were able to hydrolyze olive oil. Based on 16S rRNA gene sequences, the lipase-producing bacterial isolates fell in five phylogenetic groups: subclasses ?, ? and ? of Proteobacteria, Actinobacteria, and the Cytophaga-Flexibacter-Bacteroides (CFB) phylum. Nearly 59% of the isolates were affiliated with the genus Pseudomonas.［Conclusion］The results enrich our knowledge on the psychrotrophic bacterial diversity and biogeographic distribution of cold active lipases-producing bacteria in cold environments.

Key words:Keywords: alpine permafrost; Tianshan Mountains; Cold active lipase; 16S rDNA; diversity