Microbial Diversity In The Hypersaline Dabuxun Lake In Qaidam Basin, China

The study on microbial diversity in saline environments is of great significancedue to the following two reasons. First, some of the earliest microbial life on Earthmight have been halophilic because of high salt and organic compound concentrationsin evaporitic environments, and thus research on microbial survivability andadaptation in saline environments bears relevance to our understanding of the earlyevolution of life and the biosphere on Earth. Second, some microorganisms in the(hyper)saline environments have potential biotechnological applications.The microbial diversity in the water and sediment of hypersaline Dabuxun Lakewas investigated by using culture-dependent and-independent techniques includingcultivation, quantitative polymerase chain reaction (qPCR), and16S rRNA gene454pyrosequencing.(1) The qPCR results showed that in the water of Dabuxun Lake the bacterial andarchaeal16S rRNA gene abundances were3.27×107and4.35×104copies mL-1,respectively.(2) The454pyrosequencing-based phylogenetic results showed that the majorbacterial phyla were Actinobacteria, Bacteroidetes, Proteobacteria, andVerrucomicrobia, accounting for53.0%,25.8%,14.1%and1.6%of the total sequencereads, respectively. The dominant archaeal reads belonged to Halobacteriaceae,accounting for5.5%in total reads.(3) The cultivation-based phylogenetic analysis showed that bacterial isolateswere classified into Pseudomonas and Bacillus, and archaeal isolates were affiliatedwith three haloarchaeal genera: Haloarcula, Halorubrum, and Halorhabdus.Strain CUG00001T, a novel nano-sized, red-pigmented, aerobic, extremelyhalophilic archaeon with a coccus morphology was isolated from the surface sedimentof hypersaline Dabuxun Lake on the northern Qinghai-Tibetan Plateau, China. The16S rRNA gene analysis revealed that strain CUG00001Twas a member of theHalorhabdus. CUG00001Twas most similar (95.9%) to Halorhabdus utahensis DSM 12940T. Based on phylogenetic, physiological and biochemical characterization, strainCUG00001Tis a novel species of Halorhabdus within the family Halobacteriaceae,for which the name Halorhabdus dabuxunensis sp. nov. was proposed. The GenBankaccession number for the16S rRNA gene sequence of strain CUG00001TisKC831442.Our results gave a thorough understanding of the microbial composition in thehypersaline Dabuxun Lake, providing a solid base for further exporation of microbialresource.