Su Ying, Yang Yuanzhi, Zhu Xiao-Yu, Zhang Xiao-Hua, Yu Min
College of Marine Life Sciences, Institute of Evolution & Marine Biodiversity, Ocean University of China, Qingdao, China.
Laboratory for Marine Ecology and Environmental Science, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China.
Front Microbiol. 2021 Jan 15;11:602010. doi: 10.3389/fmicb.2020.602010. eCollection 2020.
Quorum sensing (QS) is a density-dependent communicating mechanism that allows bacteria to regulate a wide range of biogeochemical important processes and could be inhibited by quorum quenching (QQ). Increasing researches have demonstrated that QS can affect the degradation of particulate organic matter (POM) in the photic zone. However, knowledge of the diversity and variation of microbial QS and QQ systems in sinking POM is scarce. Here, POM samples were collected from surface seawater (SW), bottom seawater (BW), and surficial sediment (SS) in the Yellow Sea of China. 16S rRNA gene amplicon and metagenome sequencing were performed to analyze the community structure of particle-associated microorganisms and distribution of QS genes [acylated homoserine lactone (AHL) synthesizing gene and AHL sensing gene ] and QQ genes (genes encoding for AHL lactonase and acylase) in POM. Shifting community structures were observed at different sampling depths, with an increase of microbial abundance and diversity from SW to BW. Along with the variation of microbial communities, the abundances of and decreased slightly but were restored or even exceeded when POM arrived at SS. Comparatively, abundances of AHL lactonase and acylase remained constant during the transportation process from SW to BW but increased dramatically in SS. Correlation tests indicated that abundances of and were positively correlated with temperature, while those of AHL acylase were positively correlated with depth, SiO , PO , and NO , but negatively correlated with temperature and pH. According to phylogenetic analyses, the retrieved QS and QQ genes are more diverse and distinctive than ever experimentally identified. Besides, the vertical transmission of QS and QQ genes along with POM sinking was observed, which could be one of the key factors leading to the prevalence of QS and QQ genes in marine ecosystems. Overall, our results increase the current knowledge of QS and QQ metabolic pathways in marine environment and shed light on the intertwined interspecies relationships to better investigate their dynamics and ecological roles in POM cycling.
群体感应（QS）是一种密度依赖性通讯机制，它使细菌能够调节广泛的对生物地球化学具有重要意义的过程，并且可能会被群体淬灭（QQ）所抑制。越来越多的研究表明，QS会影响光合层中颗粒有机物（POM）的降解。然而，对于下沉POM中微生物QS和QQ系统的多样性及变化情况，我们了解甚少。在此，我们从中国黄海的表层海水（SW）、底层海水（BW）和表层沉积物（SS）中采集了POM样本。通过16S rRNA基因扩增子和宏基因组测序，分析了与颗粒相关的微生物群落结构以及POM中群体感应基因[酰化高丝氨酸内酯（AHL）合成基因和AHL感应基因]和群体淬灭基因（编码AHL内酯酶和酰基转移酶的基因）的分布情况。在不同采样深度观察到群落结构发生了变化，从SW到BW微生物丰度和多样性增加。随着微生物群落的变化，AHL合成基因和AHL感应基因的丰度略有下降，但当POM到达SS时又恢复甚至超过之前的水平。相比之下，AHL内酯酶和酰基转移酶的丰度在从SW到BW的运输过程中保持恒定，但在SS中显著增加。相关性测试表明，AHL合成基因和AHL感应基因的丰度与温度呈正相关，而AHL酰基转移酶的丰度与深度、SiO₃²⁻、PO₄³⁻和NO₃⁻呈正相关，但与温度和pH呈负相关。根据系统发育分析，所检索到的群体感应和群体淬灭基因比以往通过实验鉴定的更加多样和独特。此外，还观察到群体感应和群体淬灭基因随着POM下沉的垂直传递，这可能是导致这些基因在海洋生态系统中普遍存在的关键因素之一。总体而言，我们的研究结果增加了当前对海洋环境中群体感应和群体淬灭代谢途径的了解，并揭示了相互交织的种间关系，以便更好地研究它们在POM循环中的动态变化和生态作用。
