Bacterial and archaeal communities in the deep-sea sediments of inactive hydrothermal vents in the Southwest India Ridge.

Kesen Ma,Xiaojian Zhou,Manyu Kang,Yinjie Shuai,Jian Xu,Zhihui Yang,Likui Zhang,Jiajun Xu

doi:10.1038/srep25982

Abstract

Active deep-sea hydrothermal vents harbor abundant thermophilic and hyperthermophilic microorganisms. However, microbial communities in inactive hydrothermal vents have not been well documented. Here, we investigated bacterial and archaeal communities in the two deep-sea sediments (named as TVG4 and TVG11) collected from inactive hydrothermal vents in the Southwest India Ridge using the high-throughput sequencing technology of Illumina MiSeq2500 platform. Based on the V4 region of 16S rRNA gene, sequence analysis showed that bacterial communities in the two samples were dominated by Proteobacteria, followed by Bacteroidetes, Actinobacteria and Firmicutes. Furthermore, archaeal communities in the two samples were dominated by Thaumarchaeota and Euryarchaeota. Comparative analysis showed that (i) TVG4 displayed the higher bacterial richness and lower archaeal richness than TVG11; (ii) the two samples had more divergence in archaeal communities than bacterial communities. Bacteria and archaea that are potentially associated with nitrogen, sulfur metal and methane cycling were detected in the two samples. Overall, we first provided a comparative picture of bacterial and archaeal communities and revealed their potentially ecological roles in the deep-sea environments of inactive hydrothermal vents in the Southwest Indian Ridge, augmenting microbial communities in inactive hydrothermal vents.

Highlights

MiSeq sequencing platform PE250 or PE300 is capable of reading long DNA fragments and is widely used for microbial 16S rDNA sequencing[23], allowing us to detect rare microorganisms with low relative abundance (
The phylum Proteobacteria was dominant in the taxonomic groups of the two samples in this study
Alpha-proteobacteria, Gamma-proteobacteria, and Sphingobacteriia, were the three main classes, which are similar to the reports on the deep-sea sediments from Iheya North and Iheya Ridge[19] and metal-rich vent deposits from Pacific Ocean hydrothermal fields[25,26]

Summary

Introduction

Ridge were revealed[16]. microbial communities in semi-consolidated carbonate sediments (51.009oE, 37.6081oS) of the Southwest Indian Ridge were investigated by traditional 16S rDNA clone library analysis[9]; extensive microbial diversity and abundance in inactive hydrothermal vents in the Southwest Indian Ridge have not been well understood. The primary goal of this study was to reveal microbial communities of two deep-sea sediments located at different regions in inactive hydrothermal vents in the Southwest Indian Ridge. For this purpose, the V4 region of 16S rRNA gene were sequenced via an Illumina MiSeq 2500 platform, which is a high-throughput sequencing technology that has been frequently used to investigate microbial community structure in various environments[17,18,19,20,21]. To the best of our knowledge, this is the first report on bacterial and archaeal communities of the deep-sea sediments in inactive hydrothermal vents in the Southwest Indian Ridge by Illumina high-throughput sequencing

Objectives

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Results

Conclusion