Bacterial diversity of disused thermal vents in Tibetan Yangbajing Region

Abstract:

[Objective] To study the bacterial diversity in sediment and water from two disused thermal vents in Yangbajing, Tibet, China. [Methods] We constructed 16S rRNA gene libraries of the total DNA from three samples. Sediment sample A and water sample A were from thermal vent A. Sediment sample B was from thermal vent B. Positive clones from the libraries were analyzed randomly by amplified ribosomal DNA restriction analysis. Positive clones’ sequences of every Operational Taxonomic Units from libraries were determined, and sequence data were submitted to GenBank and contrasted to those known sequences. Phylogenetic trees were built up by using MEGA4.0 program. [Results] Most of bacteria communities of the two thermal vents were typical thermophilc inhabitants, the predominant proteobacteria communities were found in thermal vent A and thermal vent B (ratios in sediment A, water sample A and sediment B were 41.08%, 38.00% and 42.57%) One of the sub-predominant bacteria communities, Deinococcus-Thermus, was found in thermal vent A and thermal vent B (ratios in sediment A, water sample A and sediment B were 10.71%, 20.00% and 21.30%). Moreover, one of the sub-predominant bacteria communities, Acidobacteria that was rarely found in hot springs or thermal vents, was present both in sediments of thermal vent A and B (16.07%, 19.15%). The third sub-predominant community in sediment of thermal vent A was Eubacterium sp. (14.28%), belonging to phylum Firmicutes whereas no Acidobacteria was found in water sample A. Instead, Hydrogenobacter, belonging to phylum Aquificae, was another sub-predominant community (16.00%) in water sample A. In addition, Chloroflexi, Cyanobacteria and CFB group (Cytophaga-Flexibacter-Bacteroides) were detected in both thermal vents. [Conclusion] Compared with and contrasted to the references, we found that bacteria communities in Yangbajing thermal field were similar to that in some hot springs and thermal vents around the world but slightly abnormal. Some bacteria communities in thermal vent A and thermal vent B were not very popular, such as Vibrio sp., Bacteriovorax sp., Holophaga/Acidobacterium, Verrucomicrobium.