基于高通量测序方法分析荣成月湖潮间带趋磁细菌多样性

Diversity of magnetotactic bacteria in intertidal sediments of Lake Yuehu, Rongcheng

摘要:荣成月湖是一个典型天然潟湖,潮间带沉积物中存在多种形态趋磁细菌。通过Roche454高通量测序平台,对沉积物样品(B_S)和磁收样品(B_M)进行16SrRNA基因高通量测序,认识荣成潮间带沉积物的细菌群落结构,并了解趋磁细菌多样性及系统进化地位。研究结果表明沉积物样品中主要的细菌类群为δ-变形菌纲,占总细菌数的26.4%,其次是γ-变形菌纲和α-变形菌纲;而磁收样品中细菌多样性和种类明显降低,以α-变形菌纲占绝对优势,相对比例达72.6%。在磁收样品和沉积物样品分别发现了1612条和186条reads与趋磁细菌相关,分别占细菌总数的5.76%和0.85%,磁收样品中趋磁细菌数是沉积物样品的6.8倍。对两个样品中获得的趋磁细菌序列进行系统进化分析,发现这些序列多数属于变形菌门的α-变形菌纲,以趋磁球菌占绝对优势,少数属于δ-变形菌纲,与多细胞趋磁原核生物亲缘关系最近。海洋趋磁螺菌属仅在B_M样品中检出,趋磁弧菌属在B_M样品优势度高于B_S样品,而多细胞趋磁原核生物和趋磁螺菌属在B_S样品中优势度更高。通过分析样品间的差异OTUs,认为荣成潮间带沉积物中可能存在大量未知的趋磁细菌新类群。研究结果为下一步培养和开发趋磁细菌这一功能菌群,发现趋磁细菌新类群及趋磁细菌生态功能提供了基础资料。

Lake Yuehu is a typical natural lagoon, and several types of magnetotactic bacteria have been found in the intertidal sediments. To extend the knowledge about the bacterial community structure and the diversity of magnetotactic bacteria in the intertidal sediments, we conducted a systematic analysis of the population composition of 16 S rDNA amplicons of sediment samples (B_S) and magnetic samples (B_M) using the Roche 454 high-throughput sequencing platform. The major bacterial group in the sediment was found to be δ-Proteobacteria, accounting for 26.4% of the total bacteria, followed by Chlorophyceae,γ-Proteobacteria, and α-Proteobacteria, whereas there was an obvious reduction in the diversity and species richness in the magnetic samples, in which α-Proteobacteria predominated with a relative proportion of 72.6%. In the magnetic samples and the sediment samples, 1 612 and 186 reads were found to be related to magnetotactic bacteria, accounting for 5.76% and 0.85% of the total bacterial reads, respectively. The number of magnetotactic bacteria in the magnetic samples was 6.8 times that of magnetotactic bacteria in the sediment samples. Phylogenetic analysis of the magnetotactic bacterial sequences revealed that the majority of them belonged to α-Proteobacteria, with Magnetococcus being dominant, and a few sequences belonged to the multicellular magnetotactic prokaryotes of δ-Proteobacteria. Magnetospirillum sp. was detected only in B_M samples, and Magnetovibrio sp. in B_M samples was found in a higher proportion than that in B_S samples. Meanwhile, multicellular magnetotactic prokaryotes and Magnetospira sp. were more predominant in B_S samples. By analyzing the different Operational taxonomic units (OTUs) between the two samples, it is believed that there may be a large number of unknown new groups of magnetotactic bacteria in the intertidal sediments. These analysis results will provide the basic information necessary for the next step of cultivating and developing the functional species among the magnetotactic bacteria and discovering the novel groups and the ecological functions of magnetotactic bacteria.