Phylogeny and characterization of bacterial strains producing cold-active amylase from sediments of the bottom layer of the Glacier No.1 in the Tianshan Mountains

The purpose of this research was to isolate cold- adapted bacterial strains producing amylase from permafrost sediments of the bottom layer of the Glacier No.1 in the Tianshan Mountains, China.By using the screening media containing starch, eight cold-adapted and amylase-producing bacterial isolates were recovered from sediments of the bottom layer of the Glacier No.1 in the Tianshan Mountains, China.Based on their phenotypes, biochemical test, and partial 16S rRNA gene sequence, the isolates X2 and M12-1 were identified as Paenibacillus polymyxa while the isolate L10- 1 affiliated with the genus Hymenobacter.Three isolates producing amylase showed the optimal growth temperature ranging from 20℃ to 25℃, indicating that they were psychrotrophic.Of three cold- adapted bacterial isolates, the high level of extracellular amylase activity was observed from isolate L10-1 at optimal growth temperatures ranging from 20℃ to 24℃ in plate assay.The optimal activity pH and temperature of the isolate L10-1 amylase were 35℃ and 6.0, respectively, and the activity decreased dramatically at temperatures above 40℃.The isolate L10-1 amylase had a maximum activity of 86.8U/mL under the optimal reaction Conditions.The results enrich our knowledge on the phylogenetic and physiological diversity of cold-adapted strains producing amylase in cold environments.