Biotic factors shape the structure and dynamics of denitrifying communities within cyanobacterial aggregates.

Eutrophication caused by human activities has severely impacted freshwater ecosystems, leading to harmful cyanobacterial blooms that threaten water quality and ecosystem stability. During blooms, denitrification is a key process for nitrogen removal, which can occur both in the sediment and in the waterbody mediated by cyanobacterial aggregate (CA)-associated microorganisms. In this study, the structure, dynamics and assembly mechanisms of CA-associated nirK-, nirS-, and nosZ-encoding denitrifying communities were investigated in the eutrophic Lake Taihu across the bloom season.

Determinants of Total and Active Microbial Communities Associated with Cyanobacterial Aggregates in a Eutrophic Lake.

Cyanobacterial aggregates (CAs) comprised of photosynthetic and phycospheric microorganisms are often the cause of cyanobacterial blooms in eutrophic freshwater lakes. Although phylogenetic diversity in CAs has been extensively studied, much less was understood about the activity status of microorganisms inside CAs and determinants of their activities. In this study, the 16S rRNA gene (rDNA)-based total communities within CAs in Lake Taihu of China were analyzed over a period of 6 months during the bloom season; the 16S rRNA-based active communities during daytime, nighttime, and under anoxic conditions were also profiled.