Gao Minghong, Liu Jiwen, Qiao Yanlu, Zhao Meixun, Zhang Xiao-Hua
College of Marine Life Sciences, Ocean University of China, 5 Yushan Road, Qingdao, 266003, China.
Key Laboratory of Marine Chemistry Theory and Technology, Ministry of Education, Ocean University of China, Qingdao, 266100, China.
Microb Ecol. 2017 Apr;73(3):602-615. doi: 10.1007/s00248-016-0906-6. Epub 2016 Dec 6.
Investigating the environmental influence on the community composition and abundance of denitrifiers in marine sediment ecosystem is essential for understanding of the ecosystem-level controls on the biogeochemical process of denitrification. In the present study, nirK-harboring denitrifying communities in different mud deposit zones of eastern China marginal seas (ECMS) were investigated via clone library analysis. The abundance of three functional genes affiliated with denitrification (narG, nirK, nosZ) was assessed by fluorescent quantitative PCR. The nirK-harboring microbiota were dominated by a few operational taxonomic units (OTUs), which were widely distributed in different sites with each site harboring their unique phylotypes. The mean abundance of nirK was significantly higher than that of narG and nosZ genes, and the abundance of narG was higher than that of nosZ. The inconsistent abundance profile of different functional genes along the process of denitrification might indicate that nitrite reduction occurred independently of denitrification in the mud deposit zones of ECMS, and sedimentary denitrification was accomplished by cooperation of different denitrifying species rather than a single species. Such important information would be missed when targeting only a single denitrifying functional gene. Analysis of correlation between abundance ratios and environmental factors revealed that the response of denitrifiers to environmental factors was not invariable in different mud deposit zones. Our results suggested that a comprehensive analysis of different denitrifying functional genes may gain more information about the dynamics of denitrifying microbiota in marine sediments.
研究环境对海洋沉积物生态系统中反硝化细菌群落组成和丰度的影响，对于理解生态系统水平上对反硝化生物地球化学过程的控制至关重要。在本研究中，通过克隆文库分析，对中国东部边缘海（ECMS）不同泥质沉积区中携带nirK的反硝化群落进行了调查。通过荧光定量PCR评估了与反硝化相关的三个功能基因（narG、nirK、nosZ）的丰度。携带nirK的微生物群由少数几个操作分类单元（OTU）主导，这些OTU广泛分布于不同地点，每个地点都有其独特的系统发育型。nirK的平均丰度显著高于narG和nosZ基因，narG的丰度高于nosZ。不同功能基因在反硝化过程中的丰度分布不一致，这可能表明在ECMS的泥质沉积区，亚硝酸盐还原独立于反硝化过程发生，沉积物反硝化是由不同反硝化物种而非单一物种协同完成的。仅针对单一反硝化功能基因时，这些重要信息将会缺失。丰度比与环境因子之间的相关性分析表明，不同泥质沉积区中反硝化细菌对环境因子的响应并非一成不变。我们的结果表明，对不同反硝化功能基因进行综合分析，可能会获得更多关于海洋沉积物中反硝化微生物群动态的信息。
