Diversity dynamics of aerobic anoxygenic phototrophic bacteria in a freshwater lake

Aerobic anoxygenic photoheterotrophic (AAP) bacteria substantially contribute to microbial activity and food webs in freshwater lakes. Their importance for the carbon fluxes in surface layer depends on their relative abundance in the total prokaryotic numbers and community composition. However, information on temporal changes in AAP bacteria community composition in freshwater lakes are scarce, and limited to surface layer. This study is the first one to investigate AAP diversity in epi- and hypolimnion of a temperate, freshwater lake. We found very high dynamics of photoheterotrophic members within little known phyla such as Gemmatimonadota and Chlorofloxota. What is more, we documented a high degree of novelty even in the best studied phylum of Proteobacteria. Finally, we identified environmental factors explaining the observed diversity dynamics.