engleski

Influence of assembly processes on the diversity of microbial communities and dissolved organic compounds in lake ecosystems

Lakes are active components of the global carbon cycle and host a range of processes that degrade and modify organic carbon compounds. Degrading DOM molecules and synthesizing new compounds, microbes of the aquatic ecosystems vigorously and continuously influence the chemodiversity of the available organics, subsequently impacting and the diversity of microbial communities. To unravel the underlying biotic and abiotic assembly mechanisms that control the structure and patterns of microbial communities and DOM in lakes, we combined high-throughput sequencing (18S and 16S rRNA genes) and ultra-high resolution mass spectrometry together with a null model approach. The present study includes spatiotemporal signatures of DOM and the microbial community in six lakes contrasting continental and Mediterranean climate during the productive season. The studied lakes were characterized by different environmental conditions and nutrient sources in a relatively small geographical area. Our results showed that microbial communities along with DOM correlated with nitrate concentration in the continental region, while there was a higher correlation with water temperature and sulfates in the Mediterranean region. We found that the differences between climatic regions were mainly reflected in the diversity of DOM at the molecular formula-level and microeukaryota community. Furthermore, using null model approach, these differences in DOM composition were not persisted, whereas deterministic processes dominated remarkably in each lake. In contrast, microbial community assembly processes were highly variable despite trophic status or climatic region. Taken together, our research provides novel insight into understanding DOM-microbial associations and influence on the carbon cycle under the influence of global change.

freshwater lakes ; DOM ; microbial communties

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