新疆天山北坡不同盐湖微生物菌群结构及其影响因子

Abstract

新疆分布的众多湖泊由于干旱气候成盐作用强烈，近半数已演化到盐湖发展阶段，不同盐湖中也因此蕴含着丰富的耐盐及嗜盐微生物资源。为更好的掌握新疆盐湖微生物资源分布规律及对环境因子变化的响应规律，利用高通量测序技术对新疆天山北坡5个不同演化阶段盐湖湖底沉积物中细菌、古菌多样性和菌群结构及其主要驱动因子进行研究，探讨盐湖演化过程中原核微生物群落结构变化规律。分别采集5个盐湖湖底沉积物样本，进行理化因子测试与细菌和古菌16S rRNA扩增子测序分析，比较不同盐湖理化性质和原核微生物菌群差异，并对原核微生物丰度与环境因子进行关联分析。实验结果表明：5个盐湖湖底沉积物总盐和Na⁺含量顺序为：巴里坤湖 > 伊吾湖 > 艾比湖 > 盐湖 > 柴窝堡湖，除艾比湖外其他四个盐湖沉积物均呈碱性。Alpha多样性结果显示5个盐湖细菌richness、chao1、ACE和shannon丰富度指数均大于古菌相应丰富度指数，不同盐湖细菌丰富度指数差异较大，古菌丰富度指数差异相对较小。从5个盐湖湖底沉积物中共检测获得细菌58门、68纲、138目、253科和560属，古菌4门、8纲、12目、21科和60属，细菌以变形菌门为主，古菌以广古菌门为主。不同盐湖细菌和古菌优势属种类均不相同，巴里坤湖主要是一些嗜盐和耐盐细菌属，而伊吾湖主要是嗜盐和耐盐古菌属，PCoA分析结果也表明不同盐湖微生物在OTUs水平有其独特菌群结构类型。RDA和Bioenv分析结果表明，盐湖湖底沉积物中微生物菌群群落结构主要受Na⁺和总盐（TS）浓度的影响，对细菌菌群结构影响较大，而古菌菌群结构可能受多种理化因子共同调节。此外，盐湖特殊卤水成分会对微生物群落结构产生重大影响。;There are many lakes in Xinjiang, but nearly half of the lakes have evolved to the stage of salt lake development because of the strong salt formation effect in arid climate. The different salt lakes contain rich resources of halophilic and halotolerant microorganisms. In order to better acquire the distribution of microbial resources and the response to environmental factors of salt lakes in Xinjiang, the bacterial and archaeal diversities of five salt lakes bottom sediment at different evolutionary stages of Xinjiang Tianshan north slope. The main driving factors were studied using the high-throughput sequencing technique in this paper to reveal the pattern of microbial community structure change during the salt lake evolution process. The sediment samples from the bottom of five salt lakes were collected, the sediment properties were tested, and the bacterial and archaeal 16S rRNA gene were sequenced. In the five salt lakes, the differences of sediment properties and microbial community structure were compared and the correlation of microbial richness and environmental factors sediment was analyzed. The results showed that the order of total salt and Na⁺ content in the bottom sediments of the five salt lakes was Barkol lake > Yiwu lake > Ebinur lake > Yanhu lake > Chaiwobao lake. The sediments of other four salt lakes are alkaline except Ebinur lake. Alpha diversity displayed that the bacterial richness, chao1, ACE and Shannon richness indexes of the five salt lakes were all higher than the corresponding richness indexes of archaea. The diversity of bacterial richness indexes was greater than that of archaeal richness indexes in these lakes. Through the annotation with sliva database, the bacterial and archaeal communities containing 58 phyla, 68 classes, 138 orders, 253 families, 560 genera and 4 phyla, 8 classes, 12 orders, 21 families, 60 genera, respectively, were found in the bottom sediments of the five salt lakes, in which Proteobacteria was the main phylum of bacteria and Euryarchaeota was the main phylum of archaea. The dominant genus of bacteria and archaea in different salt lakes are different, for example, Barkol lake was mainly some halophilic and halotolerant bacterial genus and Yiwu lake was mainly some halophilic and halotolerant archaeal genus. The PCoA analysis results also demonstrated that the different salt lakes had their unique microbial community structure at the operational taxonomic units (OTUs) level. The results of RDA and Bioenv analysis showed that the microbial community structure in the sediments of the salt lake bottom was mainly affected by the Na⁺ and total salt concentration, while the archaeal community might be regulated by many physical and chemical factors. Moreover, the special brine components of the salt lake would have a significant impact on the microbial community structure.