The collapse and re-establishment of stability regulate the gradual transition of bacterial communities from macrophyte: to phytoplankton-dominated types in a large eutrophic lake.

Eutrophic lakes often exhibit two alternative types: macrophytes-dominated (MD) and phytoplankton-dominated (PD) types. However, the nature of bacterial community types that whether the transition from the MD to PD types occurs in a gradual or abrupt manner remains hotly debated. Further, the theoretical recognition that stability regulates the transition of bacterial community types remains qualitative. To address these issues, we divided the transition of bacterial communities along a trophic gradient into 12 successional stages, ranging from the MD to PD types. Results showed that 12 states were clustered into 3 distinct regimes: MD type, intermediate transitional type, and PD type. Bacterial communities were not different between consecutive stages, suggesting that the transition of alternative types occurs in a continuous gradient. At the same time, the stability of bacterial communities was significantly lower in the intermediate type than in the MD or PD types, highlighting that the collapse and re-establishment of community stability regulate the transition. Further, our results showed that high complexity of taxon interactions and strong stochastic processes disrupt the stability. Ultimately, this study enables us deeper insights into the understanding the alternative types of microbial communities in the view of community stability.