Fernandes Genevieve L, Shenoy Belle Damodara, Damare Samir R
Biological Oceanography Division, CSIR-National Institute of Oceanography, Dona Paula, India.
Department of Microbiology, Goa University, Taleigao, India.
Front Microbiol. 2020 Jan 21;10:3153. doi: 10.3389/fmicb.2019.03153. eCollection 2019.
The Indian Ocean harbors oxygen minimum zones (OMZs) in the Arabian Sea and Bay of Bengal, with dissolved oxygen < 20 μM, located at the mid-depths of the water column. Till date, high-throughput sequence-data on depth-wise distribution of prokaryotic communities have rarely been reported from these OMZs. The present study aimed to characterize the prokaryotic diversity inhabiting Arabian Sea Time Series (ASTS) and India's Idea 2 (II2) in the Arabian Sea, and Bay of Bengal Time Series (BoBTS) in the Bay of Bengal OMZs based on amplicon sequencing of 16S rRNA gene regions, along six sampled depths in the water column. High prokaryotic richness was observed in the Arabian Sea and Bay of Bengal samples. Operational taxonomic units (OTUs) in the range of 1249-3298 were identified, wherein, less prokaryotic diversity was observed at surface and within oxygen minimum depths. At phylum level, most OTUs were affiliated to Bacteroidetes, Chloroflexi, Cyanobacteria, Marinimicrobia, Planctomycetes, and Proteobacteria. Prokaryotic community differed between ASTS, II2 and BoBTS locations along varying physicochemical conditions. Predictive functional profiling of the bacterial communities suggested the involvement of abundant microbes in nitrogen and sulfur metabolism pathways. Bacterial isolates belonging to genera from the clades, δ-Proteobacteria and γ-Proteobacteria, described previously for their participation in biogeochemical cycling of N-and-S in the OMZs were reported from deoxygenated waters of both the basins. Bacteria involved in anammox such as Scalindua were found to be relatively high at ASTS and II2 locations in the Arabian Sea. Further studies are required to ascertain the role of abundant bacteria along the dynamic oceanographic processes in the OMZs.
印度洋在阿拉伯海和孟加拉湾拥有氧含量极低区域（OMZs），溶解氧低于20μM，位于水柱的中深度。迄今为止，关于这些氧含量极低区域原核生物群落深度分布的高通量序列数据鲜有报道。本研究旨在基于16S rRNA基因区域的扩增子测序，沿着水柱中的六个采样深度，对阿拉伯海时间序列（ASTS）、阿拉伯海的印度理念2（II2）以及孟加拉湾氧含量极低区域的孟加拉湾时间序列（BoBTS）中栖息的原核生物多样性进行表征。在阿拉伯海和孟加拉湾的样本中观察到了较高的原核生物丰富度。鉴定出了1249 - 3298范围内的操作分类单元（OTUs），其中在表层和氧含量最低深度内观察到的原核生物多样性较低。在门水平上，大多数OTUs隶属于拟杆菌门、绿弯菌门、蓝细菌门、海洋微生物门、浮霉菌门和变形菌门。原核生物群落在不同理化条件下的ASTS、II2和BoBTS位置之间存在差异。细菌群落的预测功能分析表明，大量微生物参与了氮和硫代谢途径。从两个盆地的缺氧水域中报道了属于先前描述的参与氧含量极低区域氮和硫生物地球化学循环的δ - 变形菌和γ - 变形菌分支的属的细菌分离株。在阿拉伯海的ASTS和II2位置发现参与厌氧氨氧化的细菌如厌氧氨氧化菌相对较多。需要进一步研究以确定大量细菌在氧含量极低区域动态海洋学过程中的作用。
