In this study, Illumina MiSeq sequencing of the 16 S rRNA gene was used to describe the bacterial communities in the South China Sea (SCS) during the southwest monsoon period. We targeted different regions in the SCS and showed that bacterial community was driven by the effects of the river, upwelling, and mesoscale eddy through changing the environmental factors (salinity, temperature, and nutrients). Distinct bacterial communities were observed among different chemical conditions, especially between the estuary and the open sea. The abundance of Burkholderiales, Frankiales, Flavobacteriales, and Rhodobacterales dominated the estuary and its adjacent waters. Bacteria in cyclonic eddy were dominated by Methylophilales and Pseudomonadales, whereas Prochlorococcus, SAR11 clade, and Oceanospirillales had relatively high abundance in the anticyclonic eddy. Overall, the abundance of specific phylotypes significantly varied among samples with different chemical conditions. Chemical conditions probably act as a driver that shapes and controls the diversity of bacteria in the SCS. This study suggests that the interaction between microbial and environmental conditions needs to be further considered to fully understand the diversity and function of marine microbes.

在这项研究中，16 S rRNA 基因的 Illumina MiSeq 测序被用于描述西南季风期间南海 (SCS) 的细菌群落。我们针对南海的不同区域，表明细菌群落是由河流、上升流和中尺度涡流的影响通过改变环境因素（盐度、温度和营养物质）驱动的。在不同的化学条件下观察到不同的细菌群落，特别是在河口和公海之间。Burkholderiales、Frankiales、Flavobacteriales 和 Rhodobacterales 的丰富支配了河口及其邻近水域。气旋涡流中的细菌以嗜甲基菌和假单胞菌为主，而原绿球藻则以、SAR11 进化枝和海洋螺旋藻在反气旋涡流中的丰度相对较高。总体而言，特定系统发育型的丰度在具有不同化学条件的样品之间存在显着差异。化学条件可能是塑造和控制 SCS 中细菌多样性的驱动因素。这项研究表明，需要进一步考虑微生物与环境条件之间的相互作用，以充分了解海洋微生物的多样性和功能。