Halophilic and halotolerant bacterial resources and their response to NaCl stress in Emerald Lake of Mangya

Abstract:

The high salt concentration of Emerald Lake in Mangya, Qinghai Province, makes it an ideal environment for mining halophilic (halotolerant) microorganisms.Objective To mine the halophilic (halotolerant) microbial resources in the Emerald Lake, compare the morphological characteristics of halophilic (halotolerant) bacteria exposed to different concentrations of NaCl, and explore the response of halophilic (halotolerant) microorganisms to NaCl stress.Method Lake water, lake salt, and lakeshore saline soil samples were collected from the nearshore area of the Emerald Lake. The halophilic (halotolerant) bacteria were isolated by eight different media with three salt concentrations (10%, 15%, and 20%). The colony morphology, cell morphology, and internal structures of three strains of halophilic (halotolerant) bacteria exposed to different concentrations of NaCl were observed by optical microscopy, scanning electron microscopy, and transmission electron microscopy, respectively.Results A total of 58 strains of halophilic (halotolerant) bacteria were isolated, including 31 strains of halotolerant bacteria and 27 strains of halophilic bacteria, belonging to 16 genera. Halobacillus (40.7%) and Bacillus (19.3%) were the dominant genera of halophilic bacteria and halotolerant bacteria, respectively. The strains tolerant to Na⁺, Mg²⁺, K⁺, and Ca²⁺ accounted for 84.5%. The cell lengths of Virgibacillus litoralis TRM 83602 and Piscibacillus salipiscarius TRM 83622 exposed to different concentrations of NaCl were significantly different, while that of Brevibacterium epidermidis TRM 83610 did not change significantly.Conclusion The Emerald Lake harbors abundant halophilic (halotolerant) bacteria. NaCl concentrations can affect the growth, reproduction, colony morphology, cell morphology, and internal structures of halophilic (halotolerant) bacteria. This study enriches the understanding about the microbial resources in the Emerald Lake, providing abundant strain resources for further development and utilization of halophilic (halotolerant) microorganisms.