State Key Laboratory for Marine Environmental Science, Institute of Marine Microbes and Ecospheres, College of Ocean and Earth Sciences, Xiamen University, Xiang'an Campus, Xiang'an South Road, Xiamen 361102, China; Fujian Key Laboratory of Marine Carbon Sequestration, Xiamen University, Xiang'an Campus, Xiang'an South Road, Xiamen 361102, China.
Institute of Marine and Environmental Technology, University of Maryland Center for Environmental Science, 701 East Pratt Street, Baltimore, MD 21202, United States.
Environ Int. 2021 Sep;154:106558. doi: 10.1016/j.envint.2021.106558. Epub 2021 Apr 23.
Dissolved organic matter (DOM) changes in quantity and quality over time and space, especially in highly dynamic coastal estuaries. Bacterioplankton usually display seasonal and spatial variations in abundance and composition in the coastal regions, and influence the DOM pool via assimilation, transformation and release of organic molecules. The change in DOM can also affect the composition of bacterial community. However, little is known on the correspondence between DOM molecules and bacterial composition, particularly through a systematic field survey. In this study, the spatiotemporal signatures of microbial communities and DOM composition in the subtropical coastal estuary of Xiamen are investigated over one and half years. The co-occurrence analysis between bacteria and DOM suggested microorganisms likely transformed the DOM from a relatively high (>400 Da) to a low (<400 Da) molecular weight, corresponding to an apparent increase in overall aromaticity. This might be the reason why microbial transformation renders "dark" organic matter visible in mass spectrometry due to more efficient ionization of microbial metabolites, as well as photodegradation processes. K- and r-strategists exhibited different correlations with two-size categories of DOM molecules owing to their different lifestyles and responses to environmental nutrient conditions. A comparison of the environmental variables and DOM composition with the microbial communities showed that the environmental/DOM variations played a more important role in shaping the microbial communities than vice versa. This study sheds light on the interactions between microbial populations and DOM molecules at the spatiotemporal scale, improving our understanding of microbial roles in marine biogeochemical cycles.
溶解有机质（DOM）在时间和空间上不断变化，尤其是在高度动态的沿海河口。浮游细菌在沿海地区的丰度和组成通常表现出季节性和空间变化，并通过同化、转化和释放有机分子来影响 DOM 库。DOM 的变化也会影响细菌群落的组成。然而，对于 DOM 分子与细菌组成之间的对应关系，特别是通过系统的野外调查，人们知之甚少。本研究在一年半的时间里，调查了亚热带厦门沿海河口的微生物群落和 DOM 组成的时空特征。细菌和 DOM 之间的共现分析表明，微生物可能将 DOM 从相对较高（>400 Da）的分子量转化为较低（<400 Da）的分子量，这对应于整体芳香度的明显增加。这可能是由于微生物代谢物的更有效离子化以及光降解过程，微生物转化使“暗”有机质在质谱中可见的原因。K-策略者和 r-策略者与两种大小类别的 DOM 分子表现出不同的相关性，这是由于它们不同的生活方式和对环境营养条件的反应。将环境变量和 DOM 组成与微生物群落进行比较表明，环境/DOM 变化在塑造微生物群落方面比反之更为重要。本研究揭示了微生物种群和 DOM 分子在时空尺度上的相互作用，提高了我们对微生物在海洋生物地球化学循环中作用的理解。
