Diversity of arsenic-oxidizing prokaryotes containing arxA gene in Yunnan-Tibet hot springs and the influencing factors

Abstract:

[Objective] To study the diversity of microorganisms in sediments of hot springs in Yunnan and Tibet, the existence of arxA in them, and the influencing factors. [Methods] Illumina MiSeq and statistical analysis were employed for geochemical analysis and microbial diversity analysis of the 22 samples in 3 geothermal areas in Yunnan and Tibet and the relationship between the microorganisms and environmental factors was elucidated. [Results] The dominant phyla in the sediments were Chloroflexi (abundance: 21.27%), Deinococcus-Thermus (abundance: 17.25%), Aquificae (abundance: 13.39%), Proteobacteria (abundance: 9.27%), Acetothermia (abundance: 8.3%), Bacteroidetes (abundance: 4.96%), and Crenarchaeota (abundance: 4.57%). arxA gene-harboring phyla were Proteobacteria (abundance: 64.87%), Bipolaricaulota (abundance: 9.55%), Deinococcus-Thermus (abundance: 6.42%), and Crenarchaeota (abundance: 4.05%). The dominant populations were different among the geothermal areas, which was mainly caused by the temperature, pH, arsenic content, total dissolved solids (TDS), and altitude, as manifested by the significant correlation (P<0.001) between the microorganisms and the environmental factors verified by Mantel test. [Conclusion] arxA gene-harboring microorganisms in the sediments of hot springs were dominated by Proteobacteria and were affected by environmental factors and geographical isolation. They exhibited geographical distribution pattern, as indicated by unique dominant microbial groups in different geothermal areas. In contrast, the arxA gene-containing microbial groups showed no correlation with pH, but were mainly influenced by altitude, arsenic content, TDS, and spatial variables. This suggests the unique physiological characteristics of them among the whole microbial communities.

Key words:Yunnan and Tibet;hot springs;arsenic oxidation;arxA gene