Limnological Characterization and First Data on the Occurrence of Toxigenic Cyanobacteria and Cyanotoxins in the Plankton of Some Lakes in the Permafrost Zone (Yakutia, Russia)

• Published in: Contemporary problems of ecology 2023-04, Vol.16 (2), p.89-102
• Main Authors: Gabyshev, V. A., Sidelev, S. I., Chernova, E. N., Gabysheva, O. I., Voronov, I. V., Zhakovskaya, Z. A.
• Format: Article
• Language: English
• Subjects: Anthropogenic factors; Biomass; Biomedical and Life Sciences; Biosynthesis; Chlorophyll; Cyanobacteria; Ecology; Environmental DNA; Geographical distribution; Isoforms; Lakes; Life Sciences; Light microscopy; Liquid chromatography; Mass spectrometry; Mass spectroscopy; Microcystins; Microcystis; Neurotoxicity; Nodularins; Optical microscopy; Organic loading; Organic matter; Organic phosphorus; Permafrost; Phytoplankton; Plankton; Polymerase chain reaction; Saxitoxin; Toxins; Water analysis
• ISSN: 1995-4255; 1995-4263
• DOI: 10.1134/S1995425523020087

The first data on the distribution of cyanobacterial toxins have been obtained and a molecular genetic determination of cyanotoxin producers in the plankton of some lakes in the permafrost zone in Yakutia have been performed for the first time. Most of the lakes are characterized by high concentrations of nitrogen, phosphorus, and chlorophyll a and by an increased content of organic matter, which could be associated with a high anthropogenic load. Water blooms were visually observed in three of the six studied lakes during the summer period. The abundance and biomass of cyanobacteria in the lakes varied within 13.7–676.3 million cells/L and 0.6–4.8 mg/L, respectively. Eight species of potentially toxigenic cyanobacteria were found in phytoplankton using light microscopy. Regions of the mcyE gene involved in the biosynthesis of microcystin were amplified using the polymerase chain reaction method in environmental DNA isolated from planktonic samples. Cyanobacteria capable of producing neurotoxic anatoxin-a, saxitoxins, and hepatotoxic nodularins were absent in the lakes during the study period. The use of genus-specific primers to the mcyE gene enables us to find that the main producers of microcystins were represented by species of the genus Microcystis in most of the lakes and by species of Dolichospermum only in one of the lakes. Up to eight structural variants of microcystins, in general, arginine-containing isoforms MC-LR, MC-RR, MC-YR, MC-LY, MC-HIlR, [Asp 3 ]MC-LR, [Asp 3 ]MC-RR, and [Asp 3 ]MC-YR, were identified in lake plankton using liquid chromatography–mass spectrometry. The maximal concentration of microcystins in plankton (intracellular fraction 803 ng/L) was recorded in a sample from Ytyk-Kyuyol Lake. The calculated content of microcystins per unit biomass of producing cyanobacteria (toxin quota) was low (0.005–0.069 µg/mg). In order to assess the potential hazard of toxigenic species of cyanobacteria to human health, the distribution of cyanotoxins and their producers should be further studied in water bodies of the region.