Cyanobacteria in Waterbodies of the Biggest Anthropogenic Agglomeration: Combined DNA Metabarcoding, Microscopy, and Culture Analysis

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This study describes the results of integrative analysis of cyanobacterial communities in waterbodies of Moscow, Russia. 16S rRNA V3–V4 metabarcoding and light microscopy are implemented to investigate the diversity, abundance, and distribution of cyanobacteria, including the representatives of potentially toxigenic taxa—Anabaena, Aphanizomenon, Dolichospermum, Microcystis, and Planktothrix. High convergence is observed between microscopy and metabarcoding data for dominant genera, including Microcystis and Planktothrix. Sequence verification reveals total (100%) similarity between previously isolated toxigenic strains (e.g., Microcystis aeruginosa CBMC403m and CBMC523m) and corresponding highly abundant ASVs. In addition, current study ascertains the efficiency of metabarcoding for detection of rare cyanobacterial taxa missed by microscopy. We hereby acknowledge the limitations of V3–V4 16S rRNA-based metabarcoding approach for region species-level resolution and distinguishing potentially toxigenic taxa of cyanobacteria. At the same time, our findings validate metabarcoding as a rapid and reliable tool for monitoring of CyanoHABs in urban water ecosystems.