Diversity and functional enzymes, antimicrobial activity screening of culturable halophilic bacteria from Aiding Lake

Abstract:

[Objective] To explore secondary metabolites and new bioactive substances, the diversity, functional enzyme activity and antimicrobial activity of halophilic bacteria from Aiding Lake were studied. [Methods] A total of 20 sugars and sugar derivatives were selected as the sole carbon source of medium, and 298 halophilic bacteria were isolated from 5 samples of Aiding Lake. Based on the morphological characteristics, 62 representative strains were selected for 16S rRNA gene sequencing and phylogenetic analysis. Twenty-two halophilic bacteria were chosen from different species to screen functional enzyme activity and antimicrobial activity. Activity for 3 functional enzyme were tested by noculating single colony method. Antimicrobial activity for 12 pathogenic bacteria and fungus were tested by plate confront method. [Results] There were 221, 54, 23 halophilic bacteria isolated from 5%, 10%, 15% salt concentration respectively. They were distributed in 9 families, 18 genera. Actinobacteria were distributed in 4 genera, and bacteria were distributed in 14 genera. Nocardiopsis and Pontibacillus were dominant groups of culturable halophilic bacteria from Aiding Lake, comprising 17.7% and 16.1% respectively. The 16S rRNA gene sequence similarity of 15 halophilic bacteria were lower than 98.5%, which may present potential novel species. Among the 22 representative strains, 68.2%, 22.7%, 72.7% of them showed positive result for protease activity, amylase activity and asterase activity respectively. And 45.5% of the tested strains showed at least one kind of microbial activity against 12 pathogenic bacteria and fungus. Especially, one Nocardiopsis strain exhibited extensive antagonism against 9 pathogenic bacteria and fungus. [Conclusion] The halophilic bacteria of Aiding Lake in Xinjiang has abundant diversity and good biological activity, which provides the basis for further study on secondary metabolites.

Key words:Aiding Lake, Halophilic bacteria, Diversity, Functional enzymes, Antimicrobial activity