深海生物学研究室知识库

在三亚天涯海角潮间带沉积物中发现了一定量的海洋趋磁细菌,最大丰度可达100个/cm~3。透射电子显微镜(TEM)观察发现该区域趋磁细菌绝大多数为趋磁球菌。磁小体形状单一,皆为棱柱形;磁小体排列方式多样,以链状排列为主,包括单链、双链,也有少数成簇排列。高分辨率透射电子显微镜(HRTEM)与X-射线能谱仪(EDXS)结果表明,磁小体成分为Fe_3O_4。趋磁细菌的铁含量平均为2.05%(0.70%~7.53%)。通过16S rRNA基因文库的构建与测序,在78个阳性克隆中得到了16个趋磁细菌序列,分属9个OTU。系统发育分析结果表明,其中8个OTU属于α-变形菌纲, 1个OTU属于γ-变形菌纲。在全部9个OTU中,有8个OTU与已知趋磁细菌序列的相似性低于97%,有5个OTU与已知趋磁细菌序列的相似性低于93%,说明该区域存在可观的趋磁细菌资源。

A quantity of magnetotactic bacteria (MTB) were found in the intertidal zone of Tianyahaijiao, Sanya, China, where the maximum abundance can reach up to 100 ind./cm~3. Transmission electron microscopy (TEM) revealed that most of the MTB were magnetotactic cocci, containing magnetosomes, which were prismatic mineral crystals, mostly organized in chain(s) (one or two chains), while some were in cluster. High-resolution Transmission Electron Microscopy (HRTEM) and Energy Dispersive X-ray Spectroscopy (EDXA) showed that the magnetosomes contained magnetite. It was estimated that the percentage of Fe found in the MTB was 0.70%~7.53% (average 2.05%). Phylogenetic analyses, based on 16S rRNA gene sequences, revealed that 16 sequences of MTB belonged to 9 operational taxonomic units (OTUs) and were affiliated to the class Alphaproteobacteria, except that one OTU was affiliated to the class Gammaproteobacteria. Eight OTUs shared < 97% 16S rRNA gene sequence similarity with the nearest known sequences, in which 5 OTUs shared lower than 93% similarity. These results indicate that the MTB resources in Tianyahaijiao were considerable.