南海北部表层沉积物中原核微生物多样性

Prokaryote diversity in the surface sediment of northern South China Sea

【目的】为研究南海北部沉积物原核微生物的多样性和群落结构。【方法】从南海北部XSCS13站位表层沉积物中扩增古菌和细菌的16S rDNA并构建文库,随机挑出阳性克隆子进行测序,选出所有的OTU构建系统进化树,进行系统发育学分析。【结果】多数克隆子来自于未培养原核微生物,沉积物中的古菌分属3大门类:泉古菌(Crenarchaeota)、奇古菌(Thaumarchaeota)和广古菌(Euryarchaeota),其中泉古菌(Crenarchaeota)为主要门类,占71%;广古菌(Euryarchaeota)最少,只有3个克隆子。泉古菌(Crenarchaeota)又以MGⅠ为主要类群,占61%。细菌多样性明显高于古菌,共9个门类:变形杆菌(Proteobacteria)(32.6%)、疣微菌(Verrucomicrobia)(3.0%)、拟杆菌门(Bacteroidete)(5.2%)、酸杆菌(Acidobacteria)(4.4%)、绿弯菌(Chloroflexi)(6.0%)、厚壁菌(Firmicute)(3.7%)、浮霉菌(Planctomycete)(5.2%)、芽单胞菌(Gemmatimonadete)(11.1%)、放线细菌(Actinobacteria)(4.4%)。变形杆菌为优势类群(包括α-Proteobacteria、γ-Proteobacteria和δ-Proteobacteria 3个亚群),其中γ-Proteobacteria是Proteobacteria中的优势种群,占54.5%。另外所有原核微生物总共有超过50%的克隆子与硫酸盐的还原以及甲烷的形成相关。【结论】结果表明南海北部XSCS13站位表层沉积物中原核微生物的多样性非常丰富,其中蕴含大量未知的微生物资源;另外古菌和细菌群落结构表明该位点可能处于富含甲烷的冷泉活动区。

[ Objective ] In order to investigate the composition and diversity of prokaryotes in marine surface sediment from site XSCS13 at northern South China Sea. [ Method] We extracted environment total DNA directly from the sediment and amplified 16S rRNA genes from the total DNA, thereby constructing 16S rRNA clone libraries of both archaea and bacteria. Then we selected positive clones randomly from the library and identified them by the method of restriction fragment length polymorphism （RFLP）. After that, the unique RFLP pattern corresponded sequences were sequenced, BLAST and then constructed into a phylogenetic tree. [ Results] Most of the clones were sequences from uncultured microbes. For the Archaea part： the community was mainly comprised of 3 phyla： Crenarchaeota, Thaumarchaeota and Euryarchaeota, among which Crenarchaeota was the dominant class with the percentage of 71% , while Euryarchaeota took the least with only 3 clones. The main group of Crenarchaeota was Marine Group I , taking 61% of all. For the bacteria part, all together 9 phyla were included： 32.6% of Proteobacteria, 3% of Verrucomicrobia, 5.2% of Bacteroidete, 4.44% of Acidobacteria, 6% of Chloroflexi, 3.7% of Firmicute, 5.2% of Planctomycete, 11.1% of Gemmatimonadete and 4.44% of Actinobacteria. Unlike archaea, there＇s no overwhelming preponderant phylum in bacterium, each phylum was relatively distributed in. balanced proportions. Proteobacteria had 3 classes involved：α-Proteobacteri, r- Proteobacteria and δ-Proteobacteria, and r-Proteobacteria stood out with 54.5% of proportion. In addition, over half of all the clones were related to reduction reaction of sulfate and generation of methane. [ Conclusion ] The research indicated that prokaryote diversity in marine surface sediment from site XSCS13 at northern South China Sea was quite plentiful, and a great mass of abundant microbial resources still remained unknown. Furthermore, the community structure of archaea and bacteria showed that the sampling site may be in a cold spring area with abundant methane.