CYANOBACTERIAL BLOOMS- INSIGHTS FROM MICROBIAL ECOLOGY AND METAGENOMIC ANALYSIS

FAINSTEIN, LOLA; POSSE, ALBA; ALVAREZ DALINGER, FLORENCIA SOLEDAD; MACCHIAROLI, NATALIA; KAMENETZKY, LAURA; LOZANO, VERÓNICA LAURA; GASULLA, JAVIER; FIGUEROLA, EVA

Congreso; Congreso de la Sociedad Argentina de microbiología; 2023

Sociedad Argentina de Microbiología General

Cyanobacterial blooms (CB) constitute a problem on a global scale, affecting the water quality and producing associated economic losses. Their frequency has increased in the last few years, along with concerns about their impact on public and environmental health. High nutrient load provided by agricultural, industrial, and domestic pollution coupled with climate change are the most obvious factors related to its occurrence. Cyanobacteria are photosynthetic organisms naturally present in surface water, where they fulfill a fundamental role. However, eutrophication and global warming can disturb the ecosystem balance promoting the blooms. The massive and sudden growth affects the whole community of micro and macroorganisms. There are also harmful cyanobacterial blooms, characterized by the production of a wide variety of toxic metabolites (cyanotoxins), which could be dangerous for human and animal life. Several genera are capable of cyanotoxin production, i.e. Dolichospermum (formerly Anabaena), Anabaenopsis, Cylindrospermopsis, Lyngbya, Microcystis, Nostoc, Oscillatoria (Planktothrix), and Synechococcus, among others. However, not all the blooms are toxin-producers, making the design of warning systems and risk analysis more complicated. Abiotic factors conditioning CB have been widely studied, but biotic factors, like biotic interactions, ecosystem diversity, and stability have received less attention. Despite the fact that both diversity and interspecific interactions are considered to be determining factors of ecosystem stability.We propose to apply a metagenomic approach for the construction of co-occurrence networks for a set of freshwater bodies affected by CB across the country. The structure of these networks will give us insights about biotic interactions, and relationships with physicochemical factors, stability, and CB frequency. With the cooperation of researchers or managers of 12 water bodies, we collected, to date, 30 water samples and their metadata. The samples were filtered and processed to obtain high-quality DNA suitable to be sequenced. Additionally, we have performed long read (ONT) sequencing of the metagenome of samples from a Salta reservoir afflicted by a CB, in order to identify toxin synthetic clusters. Promethion sequencing yielded 8.0 M of reads, accounting for 6.6 Gbases with an average Qscore of 19. From the metagenome, it was possible to detect genes closely related to Microcystis aeruginosa PCC 7806 polyketide synthetase (mycD), demonstrating the ability to find, through this strategy, cyanotoxin synthetic clusters occurring in the environment. The information obtained contributes to raising awareness of the need to monitor the presence of cyanotoxins that are not currently being analyzed, but are a potential source of environmental risk