Abstract：
Marine organic matter fuels the growth of microbial communities, shaping the composition of bacteria that specialize in its breakdown. However, responses of free-living (FL) and particle-associated (PA) bacterial communities to the changing pools of dissolved organic matter (DOM) and particulate organic matter (POM) remained unclear. This study investigates the composition of size-fractionated bacterial communities, DOM and POM in coastal waters over a 22-day period that includes a diatom bloom. Co-occurrence analysis showed that the FL bacterial communities were significantly less stable than PA communities. During the diatom bloom, we observed a significant increase in DOM molecules, particularly those derived from amino acids and peptides. In contrast, the relative intensities of major POM molecule classes remained stable despite the algal bloom\'s influence. Our study revealed a strong negative correlation between bacterial alpha-diversity and the amount of molecules in the organic matter pool. Similarly, bacterial community beta-diversity was found to be related to the composition of organic matter pool. However, the composition of organic matter was more strongly related to the composition of FL bacterial communities compared to PA communities. This suggests that FL bacteria exhibit greater variations in temporal dynamics and higher sensitivity to the specific structure of organic matter molecules.
摘要：
海洋有机物促进微生物群落的生长，塑造专门分解细菌的成分。然而,自由生活（FL）和颗粒相关（PA）细菌群落对不断变化的溶解有机物（DOM）和颗粒有机物（POM）池的反应尚不清楚。这项研究调查了按大小划分的细菌群落的组成，在22天的时间内，包括硅藻开花在内的沿海水域中的DOM和POM。共现分析表明，FL细菌群落的稳定性明显低于PA群落。在硅藻开花期间，我们观察到DOM分子的显著增加，特别是那些来源于氨基酸和肽的。相比之下,尽管有藻类水华的影响，但主要POM分子类别的相对强度保持稳定。我们的研究表明，细菌α多样性与有机物池中的分子总量之间存在很强的负相关。同样，发现细菌群落β-多样性与有机质池的组成有关。然而,与PA群落相比，有机质的组成与FL细菌群落的组成密切相关。这表明FL细菌在时间动力学上表现出更大的变化，并且对有机物分子的特定结构具有更高的敏感性。
