Lakes receive large amounts of terrestrially derived dissolved organic matter (tDOM). However, little is known about how aquatic microbial communities interact with tDOM in lakes. Here, by performing microcosm experiments we investigated how microbial community responded to tDOM influx in six Tibetan lakes of different salinities (ranging from 1 to 358 g/l). In response to tDOM addition, microbial biomass increased while dissolved organic carbon (DOC) decreased. The amount of DOC decrease did not show any significant correlation with salinity. However, salinity influenced tDOM transformation, i.e., microbial communities from higher salinity lakes exhibited a stronger ability to utilize tDOM of high carbon numbers than those from lower salinity. Abundant taxa and copiotrophs were actively involved in tDOM transformation, suggesting their vital roles in lacustrine carbon cycle. Network analysis indicated that 66 operational taxonomic units (OTUs, affiliated with Alphaproteobacteria, Actinobacteria, Bacteroidia, Bacilli, Gammaproteobacteria, Halobacteria, Planctomycetacia, Rhodothermia, and Verrucomicrobiae) were associated with degradation of CHO compounds, while four bacterial OTUs (affiliated with Actinobacteria, Alphaproteobacteria, Bacteroidia and Gammaproteobacteria) were highly associated with the degradation of CHOS compounds. Network analysis further revealed that tDOM transformation may be a synergestic process, involving cooperation among multiple species. In summary, our study provides new insights into a microbial role in transforming tDOM in saline lakes and has important implications for understanding the carbon cycle in aquatic environments.

湖泊接受大量陆地衍生的溶解有机物（tDOM）。但是，人们对水生微生物群落如何与湖泊中的tDOM相互作用了解甚少。在这里，通过进行微观实验，我们研究了六个不同盐度（范围为1至358 g / l）的藏族湖泊中微生物群落对tDOM流入的响应。响应添加tDOM，微生物生物量增加，而溶解有机碳（DOC）减少。DOC的减少量与盐度没有显着相关性。但是，盐度影响了tDOM的转化，即高盐度湖泊中的微生物群落比低盐度湖泊具有更高的利用高碳数tDOM的能力。丰富的生物分类和类营养生物积极参与了tDOM的转化，表明它们在湖碳循环中的重要作用。网络分析表明，有66个业务分类单位（OTU，隶属于α-变形菌，放线菌，  Bacteroidia，芽孢杆菌，γ-变形菌， 嗜盐菌，Planctomycetacia，  Rhodothermia和 Verrucomicrobiae）与CHO化合物的降解的相关，而4个OTUs细菌（与附属放线菌，α-变形菌，Bacteroidia和γ-变形菌）与CHOS化合物的降解高度相关。网络分析进一步表明，tDOM转化可能是一个协同过程，涉及多个物种之间的合作。总而言之，我们的研究为盐湖中微生物在转化tDOM中的作用提供了新见解，并且对理解水生环境中的碳循环具有重要意义。