海南热带雨林土壤细菌组成与多样性分析

【目的】明确海南热带雨林土壤细菌的组成与多样性、时空分布规律及对土壤理化性质的响应和功能结构，为海南地区热带雨林的管理和保护提供理论依据。【方法】对海南五大热带雨林吊罗山、五指山、鹦哥岭、霸王岭和尖峰岭的土壤进行采样，每个样地采集13份样本，分旱、雨两季，共130份样本；通过高通量测序技术，分析土壤样本微生物中的细菌组成与多样性随空间位置和季节的变化，应用PICRUSt2功能预测分析土壤细菌功能。【结果】OTU分类统计显示，旱季的细菌OTU数目为10958，雨季的细菌OTU数目为11533，两个季节间差异不显著（P>0.05）。在细菌门水平，热带雨林旱季和雨季土壤细菌的优势菌群为变形菌门（Proteobacteria）、酸杆菌门（Acidobacteria）、放线菌门（Actinobacteria）、浮霉菌门（Planctomycetes）和疣微菌门（Verrucomicrobia）；两个季节间的拟杆菌门（Bacteroidetes）、放线菌门和蓝藻菌门（Cyanobacteria）丰度差异极显著性（（P<0.01，下同）。在细菌纲水平，热带雨林旱季和雨季土壤细菌的优势菌纲为放线菌纲（Actinobacteria）、酸杆菌纲（Acidobacteria）、α-变形菌纲（Alphaproteobacteria）、浮霉菌纲（Planctomycetacia）和斯巴托菌纲（Spartobacteria）；两个季节间的浮霉菌纲、鞘脂杆菌纲（Sphingobacteriia）、纤线杆菌纲（Ktedonobacteria）和放线菌纲丰度差异极显著。冗余分析（RDA）表明pH和全钾对土壤中细菌的贡献度较高，解释率分别为5.03%和4.28%。ANOSIM和Adonis分析显示不同季节细菌多样性差异不明显，不同地点细菌多样性差异明显。KEGG通路显示吊罗山样本中的细菌功能丰度较其他4个样点少。【结论】海南热带雨林土壤细菌在不同地理位置（取样点）的多样性差异明显，季节变换对土壤细菌的组成影响不明显，pH和全钾是土壤中细菌旱、雨季多样性的重要环境因子。

Study on soil bacterial composition and diversity of tropical rainforest in Hainan Island

【Objective】To clarify the soil bacterial composition,diversity,spatio-temporal distribution,response to soil physical and chemical properties and functional structures in tropical rainforests of Hainan Island,so as to provide a theoretical basis for the management and protection of the tropical rainforests in Hainan.【Method】Soil samples were collected from Diaoluoshan,Wuzhishan,Yinggeling,Bawangling and Jianfengling tropical rainforest reserves in Hainan. Thirteen samples were collected from each reserve in both the dry and wet seasons,producing a total of 130 samples. The composition and diversity of bacteria in soil microorganisms were analyzed with a high-throughput sequencing technique and the function of soil bacteria was predicted and analyzed by PICRUSt2 software.【Result】Operational taxonomic unit (OTU)classification statistics show that the number of bacterial OTU in the dry season is 10958 and that in rainy season this increases to 11533. There was no significant difference between the two seasons(P>0.05). At the level of bacteria phylum,the dominant flora of soil bacteria in tropical rain forest in dry season and rainy season were Proteobacteria,Acidobacteria,Actinobacteria,Planctomycetes and Verrucomicrobia. The abundance of Bacteroidetes,Actinobacteria and Cyanobacteria in two seasons showed significant differences(P<0.01,the same below). At the level of bacterial class,the dominant classes in the dry and rainy seasons were Actinomycetia,Acidobacteriia,Alphaproteobacteria,Planctomycetia and Spartobacteria. There were significant differences among the classes Planctomyceteria,Sphingobacteriia,Ktedonobacteria and Actinomycetia. Redundancy analysis(RDA)showed that pH and total potassium(TK)affected the soil bacterial composition substantially,with explanation rates of 5.03% and 4.28% respectively. ANOSIM and Adonis analysis showed that there was no significant difference in bacterial diversity in the different seasons,but significant difference in bacterial diversity in different places. KEGG pathway showed that the bacterial functional abundance in the Diaoluoshan samples was less than that from the other four reserves.【Conclusion】The diversity of soil bacteria in Hainan tropical rainforests is significantly different in different geographical locations(sampling sites),whereas the seasonal change does not affect the composition of soil bacteria significantly. Soil pH and total potassium(TK)content have important effects on the soil bacterial diversity in the dry and rainy seasons.