西藏热泉沉积物的硫氧化细菌多样性及其影响因素

Distribution and diversity of sulfur-oxidizing bacteria in the surface sediments of Tibetan hot springs

摘要:

[目的]探究西藏热泉沉积物中硫氧化细菌群落多样性及其环境影响因素。[方法]选取西藏5个地热区的25个热泉样点，现场测量各采样点的水体理化参数，并采集热泉水和沉积物样品。通过功能基因（硫代硫酸盐水解酶编码基因：soxB）克隆文库分析方法，研究沉积物样品中硫氧化细菌群落的组成和多样性，并统计分析其与环境参数之间的相关性。[结果]克隆文库分析结果显示，西藏热泉沉积物样品中的硫氧化细菌主要分属于α-Proteobacteria、β-Proteobacteria和γ-Proteobacteria纲。研究样品中的硫氧化菌群落香农指数与溶解有机碳的浓度（R=0.489，P<0.05）呈显著正相关。另外，统计发现西藏各热泉之间的硫氧化菌群落组成差异较大，其优势硫氧化细菌种群差异明显，大多数样点的优势硫氧化细菌种群为β-Proteobacteria，少量样点以α-Proteobacteria和γ-Proteobacteria为主。Mantel检验结果显示，西藏热泉样品中的硫氧化细菌群落组成与温度、硫化物、电导率、海拔、总溶解固体和pH显著（P<0.05）相关。[结论]西藏热泉沉积物中的硫氧化细菌群落广泛分布，且主要以变形菌门为主。地理隔离和理化差异导致了热泉沉积物样品间的硫氧化菌群落组成差异。

Abstract:

[Objective] To study the distribution and diversity of sulfur-oxidizing bacteria (SOB) in the surface sediments of Tibetan hot springs. [Methods] We collected 25 hot spring sediments from 5 Tibetan geothermal areas. In the field or laboratory, we measured the physicochemical parameters of water or sediment samples. We constructed soxB gene-based clone libraries and performed phylogenetic analysis to analyze the SOB community diversity. We conducted statistical analysis to assess the influencing factors on the SOB community. [Results] Phylogenetic analysis showed that the SOB mainly consisted of α-Proteobacteria, β-Proteobacteria and γ-Proteobacteria in the Tibetan hot spring sediments. The former were dominant classes. The dominant SOB classes differ among the sampled hot springs in our research:β-Proteobacteria were dominant in most of the studied samples, whereas only a few of them were dominated by α-Proteobacteria or γ-Proteobacteria. Mantel test showed that the SOB community composition of the studied samples significantly (P<0.05) correlated with altitude, conductivity, pH, sulfide, total dissolved solids and temperature. [Conclusion] In Tibetan hot spring sediments, α-Proteobacteria and β-Proteobacteria were the main SOB communities, but γ-Proteobacteria was rare. The SOB community structures differed significantly among the studied hot springs, which is mainly caused by their different physical and chemical properties.