Diversity and cyclical seasonal transitions in the bacterial community in a large and deep perialpine lake

High-Throughput Sequencing (HTS) was used to analyze the seasonal variations in the bacterioplankton community composition (BCC) in the euphotic layer of Lake Garda, a large and deep lake south of the Alps. BCC was analysed throughout two annual cycles by monthly samplings using the amplification and sequencing of the V3-V4 hypervariable region of the 16S rRNA gene by the MiSeq Illumina platform. The dominant bacterioplankton phyla were among the more frequent reported in freshwater ecosystems, including the Proteobacteria, Cyanobacteria, Bacteroidetes, Verrucomicrobia, Actinobacteria and Planctomycetes. The development of the BCC showed a cyclical temporal pattern. Besides environmental drivers, the recurring temporal developoment was possibly controlled by the remarkable annual cyclical development of the bacterioplankton hosting cyanobacteria and eukaryotic phytoplankton that characterizes large temperate lakes.