Data_Sheet_2_Environmental and Microbial Interactions Shape Methane-Oxidizing Bacterial Communities in a Stratified Lake.zip

In stratified lakes, methane-oxidizing bacteria (MOB) are strongly mitigating methane fluxes to the atmosphere by consuming methane entering the water column from the sediments. MOB communities in lakes are diverse and vertically structured, but their spatio-temporal dynamics along the water column as well as physico-chemical parameters and interactions with other bacterial species that drive the community assembly have so far not been explored in depth. Here, we present a detailed investigation of the MOB and bacterial community composition and a large set of physico-chemical parameters in a shallow, seasonally stratified, and sub-alpine lake. Four highly resolved vertical profiles were sampled in three different years and during various stages of development of the stratified water column. Non-randomly assembled MOB communities were detected in all compartments. We could identify methane and oxygen gradients and physico-chemical parameters like pH, light, available copper and iron, and total dissolved nitrogen as important drivers of the MOB community structure. In addition, MOB were well-integrated into a bacterial-environmental network. Partial redundancy analysis of the relevance network of physico-chemical variables and bacteria explained up to 84% of the MOB abundances. Spatio-temporal MOB community changes were 51% congruent with shifts in the total bacterial community and 22% of variance in MOB abundances could be explained exclusively by the bacterial community composition. Our results show that microbial interactions may play an important role in structuring the MOB community along the depth gradient of stratified lakes.

在分层湖泊中，甲烷氧化细菌（methane-oxidizing bacteria, MOB）可通过消耗沉积物释放入水体水柱的甲烷，显著减缓甲烷向大气的排放通量。湖泊中的MOB群落具有多样性且垂直分层，但目前学界尚未对其沿水体水柱的时空动态、相关理化参数，以及驱动该群落组装的与其他细菌类群的互作关系展开深入探究。本研究针对一座浅湖、季节性分层亚高山湖中的甲烷氧化细菌与细菌群落组成，以及多组理化参数开展了详尽调查。研究在三个不同年份、分层水体发育的不同阶段，采集了4组高分辨率垂直剖面样本。在所有水体深度分区中均检测到非随机组装的MOB群落。研究鉴定出甲烷、氧浓度梯度，以及pH、光照、有效铜与铁、总溶解氮等理化参数为调控MOB群落结构的重要驱动因子。此外，MOB深度融入细菌-环境互作网络。对理化变量与细菌的关联网络开展偏冗余分析（partial redundancy analysis）后，可解释最高达84%的MOB丰度变异。时空尺度下的MOB群落变化与总细菌群落的演替一致性达51%，而22%的MOB丰度变异可仅由细菌群落组成单独解释。本研究结果表明，微生物互作可能在分层湖泊沿深度梯度构建MOB群落的过程中发挥关键作用。