Isolation and identification of Bacillus-like species from glacier soil samples collected from Hailuogou in Sichuan Province

Abstract:

[Background] Bacillus-like bacteria can form endospores with strong resistance and thus, can survive in a variety of extreme environments. Their multiple metabolic products make them have important research value in many fields. Because glacier has the low temperature and oligotrophic unique environment, Bacillus-like bacteria in this environment would be specific, which could be expected to enrich the Bacillus-like resources and discover new functional genes. [Objective] The aim of this study is to understand the diversity of the Bacillus-like resources in the Hailuogou glacier, Sichuan Province, providing a foundation for mining new Bacillus-like resources. [Methods] Bacillus-like strains were isolated by the culture-dependent method and identified using 16S rRNA gene sequence. Subsequently, physiological-biochemical characteristics of the typical strains selected were determined and further performed cluster analysis by the group-average method with the Euclidean distance model. [Results] In total, 44 strains were obtained and 36 strains belonged to Bacillus-like bacteria. The 16S rRNA gene phylogenetic analysis showed that they could be assigned to 19 species within 4 genera including Bacillus (11 species 24 strains), Paenibacillus (2 species 3 strains), Brevibacillus (4 species 5 strains) and Lysinibacillus (2 species 4 strains). Thus, the genus Bacillus was dominant. The physiological-biochemical characteristics showed that: i) only 3 strains could survive at 4 °C, 7 strains could grow at 50 °C, whereas most strains could grow well at 30 °C; ii) 74% of the Bacillus-like strains had alkali resistance; and iii) 37% of them could grow without NaCl. According to the physiological and biochemical results, those strains could be divided into 3 groups by cluster analysis using the group average method and Euclidean distance models. The first group could hydrolyze esculin and utilize glucose. The second groups could not hydrolyze esculin and utilize glucose, and the third group could only utilize glucose. [Conclusion] Hailuogou glacier soil is rich in the Bacillus-like resources, providing a basis for the mining of them.