Culture-dependent diversity of bacteria from Laohugou glacier, Qilian Mts., China and their resistance against metals.

In the current study, psychrophilic, endolithic, and epilithic bacterial strains were isolated and characterized from the nonpolar Laohugou glacier (LHG) no. 12, the largest valley glacier in the western Qilian Mts. located on the northeastern edge of the Tibetan Plateau. Five different types of samples, rocks, soil, glacial water, ice/snow, and cryoconite, were collected. A total of 48 bacterial strains were isolated by using the R2A bacterial cultural medium. The findings revealed that the Gram-positive bacteria 41 (85.4%) dominated the Gram-negative bacteria 7 (14.6%) in this extremely harsh environment. Molecular characterization based on 16S ribosomal RNA gene sequencing exhibited that the obtained isolates belong to four phyla, among which the diversity of Firmicutes (58.33%) was higher followed by Actinobacteria (23.0%), Proteobacteria (14.6%), and least diversity was reported in Euryarchaeota (4.2%). The bacterial communities were most dominant in soil samples followed by cryoconite sample and least dominant in the ice and snow samples. Moreover, the obtained bacterial isolates were found resistant to high concentrations of heavy metals (Cr ³⁺ , Cd ²⁺ , Hg ²⁺ , and Ar ³⁺ ) and sodium chloride, and, therefore, exhibited polyextremophilic characteristics. LHG no. 12 is rich in bacterial and archaeal diversities and provides a potentially curious site for further in-depth exploration of microbial diversity and their biotechnological applications.
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