中印度洋与南海西部表层海水细菌多样性

Diversity of culturable and in situ bacteria in surface seawater from the central Indian Ocean and the western South China Sea

细菌在海洋生物地球化学循环中发挥着重要作用。为更好地了解海洋细菌的特征及其在海洋环境中的潜在作用,本文利用纯培养与16S rRNA基因高通量测序技术对中印度洋与南海西部海域表层海水细菌多样性进行研究。纯培养结果表明,自中印度洋与南海西部表层海水中共分离275株可培养海洋细菌,隶属于4门49属75种。变形菌门是绝对优势类群(占总株数的68.7%),其次是放线菌门(21.5%)、拟杆菌门(9.1%)和厚壁菌门(0.7%)。在属水平,微杆菌属(Microbacterium)与弧菌属(Vibrio)是主要的优势属,共占总株数的30.0%。在3种分离培养基中,自1/10×2216E培养基中分离细菌的数目与种类最多(89株,30属);分离菌株中的细菌菌株有7、9与3个属分别仅在2216E、1/10×2216E及葡萄糖甘露糖(glucose-mannose, GM)培养基中生长。此外,共分离培养出50株细菌(26种)可能代表潜在新分类单元。高通量测序结果显示,中印度洋和南海西部表层海水中共有23个门531个属。优势门类为变形菌门(72.2%)和拟杆菌门(15.3%),优势属为嗜冷杆菌属(Psychrobacter,24.4%)、盐单胞菌属(Halomonas, 16.3%)和亚硫酸杆菌属(Sulfitobacter, 13.9%)。此外,中印度洋表层海水细菌Shannon-Wiener指数与Pielou均匀度指数显著高于南海西部(P <0.05),且细菌群落结构显著不同(P <0.05)。综合纯培养与原位细菌数据得出,中印度洋与南海西部海洋细菌具有丰富的多样性,具有进一步开发研究的价值。

Aims: Bacteria play an important role in driving biogeochemical cycling in the open ocean. Therefore, it is of great significance to investigate the characteristics of marine bacteria and their potential role in the marine environment.Methods: In this study, surface seawater was collected from 8 sites in the central Indian Ocean and the western South China Sea. Three different media were utilized for strains isolation and identification, and the 16 S r RNA gene high-throughput sequencing method was used to analyze the microbial classification and community composition of each study site.Results: A total of 275 strains, belonging to 4 phyla, 49 genera and 75 species, were isolated and identified.Proteobacteria were the most dominant, accounting for 68.7% of the total isolates, followed by Actinobacteria(21.5%),Bacteroidetes(9.1%) and Firmicutes(0.7%). At the genus level, Microbacterium and Vibrio were the dominant genera,accounting for 30.0% of the total number of isolates. Bacterial abundance and species(89 isolates, 30 genera) in the 1/10 × 2216 E medium were the highest among the three kinds of media. Seven, nine and three genera were only found in 2216 E, 1/10 × 2216 E and glucose-mannose(GM) medium, respectively. Fifty strains(26 species) were identified as potential novel taxa. The sequencing analysis revealed that 23 phyla and 531 genera were found in the surface seawater. Dominant phyla were Proteobacteria(72.2%) and Bacteroidetes(15.3%), dominant genera were Psychrobacter(24.4%), Halomonas(16.3%), and Sulfitobacter(13.9%). In addition, the Shannon-Wiener index and Pielou’s evenness index were significantly higher in the Indian Ocean than the South China Sea(P < 0.05), and bacterial community structure was significantly different between those two regions(P < 0.05). Conclusion: The results indicated that marine bacteria from the surface seawater of central Indian Ocean and western South China Sea were rich in diversity, and help the most value for further development and research.