Diversity, seasonal succession and host specificity of bacteria associated with cyanobacterial aggregates in a freshwater lake

Cyanobacterial blooms are threatening our global freshwater ecosystem due to eutrophication and global warming. The heterotrophic Bacteria Associated with Cyanobacterial Aggregates (BACA) are known to provide adaptative support to cyanobacterial species which outcompete the microorganisms during the period of bloom formation. In this study, diversity, seasonal succession, spatial, and host specificity of BACA were explored by analyzing their diversity in time-series samples from a eutrophic freshwater lake, Lake Taihu. Diversity analysis using high-throughput sequencing of the samples investigated here revealed that four Microcystis species including Microcystis aeruginosa, Microcystis wesenbergii, Microcystis panniformis, and Microcystis flos-aquae tend to exhibit host specificity. However, no obvious differences between the BACA of floating and sinking samples were observed in this study. Water temperature was found as a key factor driving the succession of BACA in Taihu Lake. BACA was not only observed, exhibiting long term seasonal succession but intra-seasonal succession in response to steep environmental changes was also observed. This study provides detailed insights into the diversity, seasonal succession, spatial and host specificity of BACA in Lake Taihu. (C) 2021 Elsevier B.V. All rights reserved.