The eastern Arabian Sea has a unique and permanent oxygen minimum zone (OMZ) extending along the western continental margin of India. The Arabian Sea OMZ is a site of intense denitrification, contributing to 20% of the global oceanic denitrification, playing a significant role in the nitrogen cycle. This study reveals the members of the culturable marine bacterial communities thriving and functioning in the sediment underlying the Arabian Sea OMZ, through 16S rDNA phylogenetic analysis and elucidating their nitrate reduction potential. Phylogenetic analyses revealed that these cultured bacteria distributed into five phyla, viz. Firmicutes (45.7%) Gammaproteobacteria (36.84%), Actinobacteria (8.7%), Bacteroidetes (5.26%), and Alphaproteobacteria (3.5%). The presence of denitrification genes such as narG, nirS, and nosZ in the cultured bacteria (39%) explains their importance in this process. Present study on the diversity and distribution of bacterial communities in the OMZ surface sediment and their probable role in the nitrogen cycle will provide insight into the microbial biogeochemical processes occurring in this region.

中文翻译：

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来自阿拉伯海最低氧区的沉积物中可培养海洋细菌的系统发生多样性及其在硝酸盐还原中的作用

阿拉伯海东部沿印度西部大陆边缘有一个独特的永久性氧气最低限度区（OMZ）。阿拉伯海OMZ是强烈反硝化的场所，占全球海洋反硝化的20％，在氮循环中起着重要作用。这项研究通过16S rDNA系统发育分析并阐明了其硝酸盐还原的潜力，揭示了可培养的海洋细菌群落成员在阿拉伯海OMZ底层沉积物中的旺盛功能。系统发育分析表明，这些培养的​​细菌分布成五个门，即。硬毛菌（45.7％）γ变形杆菌（36.84％），放线菌（8.7％），拟杆菌（5.26％）和丙酸杆菌（3.5％）。培养细菌中反硝化基因（如nar G，nirS和nosZ）的存在（39％）说明了它们在此过程中的重要性。目前对OMZ表层沉积物中细菌群落的多样性和分布及其在氮循环中可能作用的研究，将提供对该区域发生的微生物生物地球化学过程的深入了解。