ABSTRACT: Bacteria play a central role in the degradation of phytoplankton-derived dissolved organic matter (P-DOM) particularly in algal-blooming aquatic systems; yet our understanding of the interaction between bacteria and P-DOM is still poor. We supplied differential P-DOM that varied in concentration and molecular weight (released from distinct phytoplankton collected from blue-green algal-blooming grass carp Ctenopharyngodon idellus farming ponds) to similar aquatic bacterial communities (isolated from non-blooming grass carp ponds), to explore how P-DOM affects bacterial community dynamics and to identify the most responsive degrading taxa using UV-visible absorption spectroscopy and high-throughput sequencing. Bacterial cultures all had similar degradation effects upon P-DOM, causing decreases in its concentration but increases in its molecular weight and aromaticity. In contrast, bacterial compositional changes varied primarily depending on P-DOM molecular weight, and Bacteroidia taxa were mostly affected, appearing more adapted to metabolize high-molecular-weight P-DOM. Nevertheless, most of the degrading taxa were recurrent and typically members within Gammaproteobacteria and Bacilli, indicating substrate-controlled bacterial responses induced by P-DOM. Network analysis revealed that bacterial communities harbored relatively low-abundant degrading members rather than dominant ones as keystone taxa, which presented simultaneously crucial microbial connections within communities and strong associations with environments and therefore played an over proportional role in maintaining community stability and functioning. Moreover, the keystone taxa may be generalists, and their ecological attributes can be described by oligotrophs that correspond to the K-strategists. Generally, this study implied a pivotal role of Gammaproteobacteria, particularly Pseudomonas, in P-DOM biodegradation, most probably in algal-blooming aquatic environments.

中文翻译：

---

水生细菌群落的组成反应及其网络对淡水池塘中浮游植物衍生的溶解有机物的相互作用

摘要：细菌在降解浮游植物衍生的溶解有机物 (P-DOM) 中起着核心作用，特别是在藻类繁盛的水生系统中；然而我们对细菌和 P-DOM 之间相互作用的了解仍然很差。我们提供了浓度和分子量不同的差异 P-DOM（从蓝绿藻盛开的草鱼Ctenopharyngodon idellus收集的不同浮游植物中释放养殖池塘）到类似的水生细菌群落（从未开花的草鱼池塘中分离出来），以探索 P-DOM 如何影响细菌群落动态，并使用紫外-可见吸收光谱和高通量测序来识别反应最灵敏的降解类群。细菌培养物对 P-DOM 都有类似的降解作用，导致其浓度降低但分子量和芳香性增加。相比之下，细菌组成的变化主要取决于 P-DOM 的分子量，拟杆菌类群主要受到影响，似乎更适合代谢高分子量的 P-DOM。尽管如此，大多数降解类群都是反复出现的，通常是Gammaproteobacteria和Bacilli的成员，表明由 P-DOM 诱导的底物控制的细菌反应。网络分析表明，细菌群落拥有相对低丰度的降解成员，而不是作为关键分类群的优势成员，它同时呈现出群落内重要的微生物联系和与环境的强烈关联，因此在维持群落稳定性和功能方面发挥了过大的作用。此外，基石类群可能是通才，它们的生态属性可以用对应于K -strategists 的寡养生物来描述。一般来说，这项研究暗示了Gammaproteobacteria的关键作用，特别是假单胞菌，在 P-DOM 生物降解中，很可能是在藻类繁盛的水生环境中。