海南高隆湾红树林及其近岸海域沉积物的弗兰克氏菌(Frankia)多样性分布及其与环境因子的关系

弗兰克氏菌(Frankia)因其独特高效的固氮效率而备受关注，然而目前的研究还局限于陆地生境。基于nifH基因采用高通量测序对高隆湾红树林及其近岸海域沉积物的Frankia多样性进行分析，共获得261条属于Frankia的nifH序列，共11个OTUs,序列主要分布在红树林区样品，其中以角果木和红海榄为优势树种的红树林样品中序列较多，在潮间带样品中也有少量分布，海草区样品未检测到，序列在不同生境中的分布存在较大差异。OTU818在10个站位都有分布，说明OTU818代表的Frankia类群分布比较广泛，且为红树林沉积物的优势类群。系统进化分析表明Frankia与NCBI数据库中的Frankia基因序列在系统发育树上形成不同分支。通过Network分析Frankia与其他细菌类群的共发生关系，发现Frankia与来自Verrucomicrobia、Proteobacteria、Firmicutes、Cyanobacteria的多种固氮细菌类群存在紧密联系，表明Frankia在稳定红树林固氮细菌群落结构中起着重要作用。利用典范对应分析(canonical correspondence an...

Diversity Distribution of Frankia in Sediments of Mangrove and Its Offshore Sea Area in Gaolong Bay Hainan Island and Its Relationship with Environmental Factors

Frankia attracted much attention because of its unique and efficient nitrogen-fixation efficiency. However, the current research on Frankia is limited to terrestrial habitats. In this study, diversity of Frankia in the sediments of Gaolong Bay Mangrove and its offshore sea area was analyzed by high-throughput sequencing of nifH gene. A total of 261 nifH sequences belonged to Frankia were obtained, 11 OTUs in all. The sequences were mainly detected in sediment samples of mangrove with Ceriops tagal and Rhizophora stylosa as dominant species, a small amount were also distributed in intertidal zone samples, no sequence was detected in samples from sediment of seaweed area, however, there were comparative differences of those in diverse habitats. OTU818 was distributed in all 10 station positions, suggested that OTU818 represented the distribution of Frankia groups were comparatively wide, also were the dominant group in mangrove sediment. Phylogenetic evolution analysis showed that Frankia in this study formed different branches with Frankia gene sequences from NCBI database on the phylogenetic tree. It was found that through Network analysis that symbiosis of Frankia with other bacteria, Frankia had close relationship with multiple nitrogen-fixing bacterial groups from Verrucomicrobia, Proteobacteria, Firmicutes, and cyanobacteria, indicating that Frankia played an important role in stabilizing the community structure of nitrogen fixing bacteria in mangrove sediment. The effects of environmental factors on the diversity distribution of Frankia were analyzed by canonical correspondence analysis (CCA), indicated that salinity, As and Al were the significant environmental factors affecting the diversity of Frankia. These results provided a new understanding of the ecological distribution of Frankia and its relationship with environmental factors, also provided preliminary data support for subsequent development and utilization of Frankia with more dominance in nitrogen fixation capability.