Species diversity of culturable halophilic microorganisms isolated from Dingyuan salt mine, Anhui

Abstract:

[Background] Halophilic microorganisms living in hypersaline environment, and conceiving unique physiological and metabolic characteristics, are one type of important microbial resources from extreme environment. [Objective] To uncover species diversity of cultivable halophilic microorganisms in athalassohaline salt mines in China, and to accumulate strains of halophilic microorganisms, this research was conducted. [Methods] Culture-dependent approach was applied to analyze the halophilic microorganisms from salt core samples of Dingyuan salt mine, Anhui province, China. Classification of the culturable halophilic microorganisms was performed based on 16S rRNA gene sequencing and sequence similarity search. On this basis, some representative strains were subjected to colony morphology, salt tolerance and enzyme activity assay. [Results] In total, 264 strains were obtained via culture-dependent approach, of which 150 strains were classified as halophilic archaea, accounting for 56.8%, and 114 strains were affiliated to halophilic bacteria, accounting for 43.2%. Results of 16S rRNA gene sequence similarity search showed that those strains belonged to six haloarchaeal genera, i.e. Halorubrum, Halopenitus, Haloterrigena, Natrinema, Natronoarchaeum and Natronomonas, and five bacterial genera, i.e. Pseudomonas, Aliifodidinibius, Halobacillus, Halomonas and Halospina. Through the enzyme activity assay, one strain producing extracellular protease, one strain conceiving esterase activity and two strains presenting amylase activity, two strains hydrolyzing the gelatin, were found among these selected species. Furthermore, species diversity index of the halophilic archaea was higher than that of halophilic bacteria. [Conclusion] This study reported the species diversity of the culturable halophilic microorganisms isolated from the Dingyuan athalassohaline salt mine (Anhui, China). This study gives us a better understanding of the microbial resources in athalassohaline salt mines, and accumulates rich microbial resources for further application.