Sun Feifei, Zhang Xiaoli, Zhang Qianqian, Liu Fanghua, Zhang Jianping, Gong Jun
College of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang, China Laboratory of Microbial Ecology and Matter Cycles, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China Sericultural Research Institute, Chinese Academy of Agricultural Sciences, Zhenjiang, China.
Laboratory of Microbial Ecology and Matter Cycles, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China Laboratory of Coastal Biology and Utilization, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai, China.
Appl Environ Microbiol. 2015 Oct;81(19):6901-14. doi: 10.1128/AEM.01382-15. Epub 2015 Jul 24.
Seagrass colonization changes the chemistry and biogeochemical cycles mediated by microbes in coastal sediments. In this study, we molecularly characterized the diazotrophic assemblages and entire bacterial community in surface sediments of a Zostera marina-colonized coastal lagoon in northern China. Higher nitrogenase gene (nifH) copy numbers were detected in the sediments from the vegetated region than in the sediments from the unvegetated region nearby. The nifH phylotypes detected were mostly affiliated with the Geobacteraceae, Desulfobulbus, Desulfocapsa, and Pseudomonas. Redundancy analysis based on terminal restriction fragment length polymorphism analysis showed that the distribution of nifH genotypes was mostly shaped by the ratio of total organic carbon to total organic nitrogen, the concentration of cadmium in the sediments, and the pH of the overlying water. High-throughput sequencing and phylogenetic analyses of bacterial 16S rRNA genes also indicated the presence of Geobacteraceae and Desulfobulbaceae phylotypes in these samples. A comparison of these results with those of previous studies suggests the prevalence and predominance of iron(III)-reducing Geobacteraceae and sulfate-reducing Desulfobulbaceae diazotrophs in coastal sedimentary environments. Although the entire bacterial community structure was not significantly different between these two niches, Desulfococcus (Deltaproteobacteria) and Anaerolineae (Chloroflexi) presented with much higher proportions in the vegetated sediments, and Flavobacteriaceae (Bacteroidetes) occurred more frequently in the bare sediments. These data suggest that the high bioavailability of organic matter (indicated by relatively lower carbon-to-nitrogen ratios) and the less-reducing anaerobic condition in vegetated sediments may favor Desulfococcus and Anaerolineae lineages, which are potentially important populations in benthic carbon and sulfur cycling in the highly productive seagrass ecosystem.
海草定殖改变了由微生物介导的沿海沉积物中的化学性质和生物地球化学循环。在本研究中，我们对中国北方一个被大叶藻定殖的沿海泻湖表层沉积物中的固氮菌组合和整个细菌群落进行了分子特征分析。在植被覆盖区域的沉积物中检测到的固氮酶基因（nifH）拷贝数高于附近无植被区域的沉积物。检测到的nifH系统型大多隶属于地杆菌科、脱硫球茎菌属、脱硫荚膜菌属和假单胞菌属。基于末端限制性片段长度多态性分析的冗余分析表明，nifH基因型的分布主要受总有机碳与总有机氮的比例、沉积物中镉的浓度以及上覆水的pH值影响。细菌16S rRNA基因的高通量测序和系统发育分析也表明这些样品中存在地杆菌科和脱硫球菌科系统型。将这些结果与先前研究的结果进行比较表明，在沿海沉积环境中，铁（III）还原地杆菌科和硫酸盐还原脱硫球菌科固氮菌普遍存在且占主导地位。尽管这两个生态位之间的整个细菌群落结构没有显著差异，但脱硫球菌属（δ-变形菌纲）和厌氧绳菌科（绿弯菌门）在植被覆盖的沉积物中所占比例更高，而黄杆菌科（拟杆菌门）在裸露沉积物中出现的频率更高。这些数据表明，植被覆盖沉积物中较高的有机质生物可利用性（以相对较低的碳氮比表示）和还原程度较低的厌氧条件可能有利于脱硫球菌属和厌氧绳菌科谱系，它们可能是高产海草生态系统中底栖碳和硫循环的重要种群。
