作者: Wang, Yujing; Cao, Xinyi; Zeng, Jin; 等

Shallow lakes often exhibit a macrophyte-dominated (MD) clear state or a phytoplankton-dominated (PD) turbid state, each of which has profound impacts on biological communities, including bacterioplankton community composition (BCC). However, the response of microbial functional gene structure (FGS) to regime shift has not been thoroughly elucidated to date. In this study, we used a functional gene array (GeoChip 5.0) in combination with high-throughput sequencing of the bacterial 16S rRNA gene to investigate the FGS and BCC between the two regimes in Lake Taihu, a large shallow freshwater lake in China. A simultaneous change in the BCC and FGS was observed between the two different regimes. We observed higher numbers of bacterial operational taxonomic units and functional genes detected by the GeoChip 5.0 in the MD samples than in the PD samples. By performing network analyses, we observed stronger microbe-microbe interactions but weaker functional gene interactions involved in nutrient metabolism in the MD community than in the PD community. We speculate that at higher concentrations of phosphorus, the domination of Microcystis bloom may weaken the interactions among microbial species by releasing more labile dissolved organic carbon, but enhance the selection and interactions of functional genes involved in carbon cycling in the PD community. In contrast, the lower levels of phosphorus may enhance microbe-microbe interactions but weaken the interactions between the primary nutrients and particular genes. Overall, this study demonstrated contrasting patterns in the BCC and FGS between the MD and PD communities in a large shallow freshwater lake.