天山北麓典型水库细菌多样性分析

为了探讨天山北麓中段水库细菌的多样性及其功能，选取蘑菇湖水库（MGW）、奎屯/车排子水库（KCW）、安集海水库（AJW）和八一水库（BYW）为典型水库进行宏基因组学分析。多点采集水库水样，收集水样中的微生物，CTAB法提取总DNA，用细菌16S rDNA通用引物扩增V3-V4区，扩增产物进行高通量测序，使用BLAST、USEARCH、QIIME等软件和在线工具分析水库细菌的多样性，使用PICRUSt软件和KEGG数据库预测细菌功能基因组成。结果表明，水库细菌分属18个门、38个纲和181个属，其中AJW的操作分类单元（Operational taxonomic units，OTUs）数量和多样性指数较高。4个水库菌群组成有一定的共性，在门分类阶元上优势菌为变形菌门（Proteobacteria）和拟杆菌门（Bacteroidetes）；在纲分类阶元上优势菌为黄杆菌纲（Flavobacteriia）；在属分类阶元上优势菌为黄杆菌属（Flavobacterium）。然而各水库菌群组成也存在较大差异，在变形菌门中，γ-变形菌纲（Gammaproteobacteria）的相对丰度在MGW和BYW较高，α-变形菌纲（Alphaproteobacterial）和β-变形菌纲（Betaproteobacteria）分别于AJW和KCW具有较高丰度；芽孢杆菌纲（Bacilli）在AJW和MGW具有较高丰度；相对丰度较高的菌属还包括AJW的动性杆菌属（Planomicrobium）、KCW的马赛菌属（Massilia）、MGW的不动杆菌属（Acinetobacter）和动性杆菌属以及BYW的假单胞菌属（Pseudomonas）和嗜冷杆菌属（Psychrobacter）；另外，AJW特有多种丰度较高的菌纲和菌属，其中微小杆菌属（Exiguobacterium）和CL500-29_marine_group均有利于水质和菌群多样性的维持。PICRUSt功能预测分析表明，4个水库菌群的多种代谢以及遗传信息处理、信号传递和细胞生长相关功能基因丰度较高，并含有环境异生物降解代谢相关基因，其中苯甲酸、氨基苯甲酸酯、氯烷烃和氯烯烃以及萘降解相关基因的相对丰度较高。以上结果提示，天山北麓中段不同水库菌群组成存在差异，其与水源、周边环境和人类活动等因素相关。水库菌群含有芳香族和有机氯等化合物降解相关基因，其可在污染物的降解和生物修复中发挥作用。

Diversity of the bacterial community in reservoirs in the north part of Tianshan Mountain

To examine the diversity and function of the bacterial community in the reservoirs at the middle part of Northern Tianshan Mountain, Moguhu reservoirs (MGW), Kuitun/Chepaizi reservoirs (KCW), Anjihai reservoirs (AJW), and Bayi reservoirs (BYW) were selected as the typical reservoirs for metagenomics analysis. The surface water samples of the reservoirs were collected at multiple points, the bacteria in the water samples were collected by centrifugation. The bacterial DNAs were extracted by CTAB method, the V3-V4 regions were amplified with bacterial 16S rDNA universal primer followed by high-throughput sequencing. The software and online tools including BLAST, USEARCH and QIIME were used to analyze the bacterial diversity, and the functional gene compositions were predicted using PICRUSt software and KEGG database. The results showed that the bacteria from the four reservoirs belonged to 18 phyla, 38 classes and 181 genera, the operational taxonomic units (OTUs) number and diversity index of AJW was higher. There was something in common in the bacterial community compositions of the four reservoirs. The Proteobacteria and Bacteroidetes were the dominant bacteria at the phylum level, Flavobacteria was the dominant bacteria at the class level, and Flavobacterium was the dominant bacteria at the genus level. However, there were great differences in the bacterial community compositions of the four reservoirs. In Proteobacteria, Gammaproteobacteria showed a higher relative abundance in MGW and BYW, and Alphaproteobacterial and Betaproteobacteria showed a higher relative abundance in AJW and KCW, respectively; Bacillus exhibited a higher relative abundance in AJW and MGW; other bacteria with higher abundance included Planomicrobium in AJW, Massilia in KCW, Acinetobacter and Planomicrobium in MGW, and Pseudomonas and Psychrobacter in BYW; in addition, some specific high-abundance classes and genera were found in AJW, among them, both Exiguobacterium and CL500-29_marine_group were conducive to maintaining the water quality and bacterial diversity. PICRUSt function prediction analysis indicated that the genes of the bacterial community in four reservoirs related to metabolism, genetic information processing, environmental information processing and cellular processes showed relatively a high abundance. In addition, some bacterial genes were related to the biodegradation of xenobiotic compounds, and the relative abundances of genes related to degradation of benzoate, aminobenzoate, chloroalkane and chloroalkene, and naphthalene were higher. In summary, the compositions of the bacterial community in different reservoirs were varied, which could be related to the water source, surrounding environment, and human activities. The presence of the genes related to the degradation of aromatic compounds and organochlorine compounds in the reservoirs could play a potential role in pollutant degradation and bioremediation.