Dataset Information

Water Quality, Toxicity and Diversity of Planktonic and Benthic Cyanobacteria in Pristine Ancient Lake Khubsugul (Hovsgol), Mongolia.

ABSTRACT: For the first time, microcystin-producing cyanobacteria have been detected in Khubsugul, which is ancient, pristine and one of the world's largest lakes. The microcystin synthetase genes belonged to the genera Nostoc, Microcystis and possibly Snowella spp. No microcystins were found in the water of the lake. Using the HPLC-HRMS/TOF, five microcystin congeners were identified in biofilms from stony substrates sampled in the coastal zone. The concentration of microcystins in biofilms was low: 41.95 µg g^-1 d. wt. by ELISA and 55.8 µg g^-1 d. wt. using HPLC. The taxonomic composition of planktonic and benthic cyanobacterial communities was determined by means of microscopy and high-throughput sequencing of 16S rDNA amplicons. Nostocales cyanobacteria dominated benthos of Lake Khubsugul and Synechococcales-plankton. The abundance of cyanobacteria was low both in plankton and benthos; there was no mass development of cyanobacteria. Hydrochemical and microbiological analyses showed that the water in the lake was clean; the number of faecal microorganisms was significantly below the acceptable guideline values. Hydrochemical and hydrophysical parameters, and the concentration of chlorophyll a, were low and within the range of values recorded in the 1970s to 1990s, and corresponded to the oligotrophic state of the lake. There were no signs of anthropogenic eutrophication of the lake and no conditions for the cyanobacterial blooms.

SUBMITTER: Belykh OI

PROVIDER: S-EPMC10053237 | biostudies-literature | 2023 Mar

REPOSITORIES: biostudies-literature

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Publications

Water Quality, Toxicity and Diversity of Planktonic and Benthic Cyanobacteria in Pristine Ancient Lake Khubsugul (Hövsgöl), Mongolia.

Belykh Olga I OI Sorokovikova Ekaterina G EG Tomberg Irina V IV Fedorova Galina A GA Kuzmin Anton V AV Krasnopeev Andrey Yu AY Suslova Maria Yu MY Potapov Sergey A SA Belykh Tatiana I TI Norovsuren Jadambaa J Galachyants Agnia D AD Tikhonova Irina V IV

Toxins 20230310 3

For the first time, microcystin-producing cyanobacteria have been detected in Khubsugul, which is ancient, pristine and one of the world's largest lakes. The microcystin synthetase genes belonged to the genera Nostoc, Microcystis and possibly Snowella spp. No microcystins were found in the water of the lake. Using the HPLC-HRMS/TOF, five microcystin congeners were identified in biofilms from stony substrates sampled in the coastal zone. The concentration of microcystins in b ...[more]

PMID: 36977104

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Project description:Carbon dioxide fixation is carried out primarily through the Calvin-Benson-Bassham reductive pentose phosphate cycle, in which ribulose-1, 5-bisphosphate carboxylase/oxygenase (RubisCO) is the key enzyme. The primary structure of the large subunit of form I RubisCO is well conserved; however, four distinct types, A, B, C, and D, may be distinguished, with types A and B and types C and D more closely related to one another. To better understand the environmental regulation of RubisCO in Lake Erie phytoplanktonic microorganisms, we have isolated total RNA and DNA from four Lake Erie sampling sites. Probes prepared from RubisCO large-subunit genes (rbcL) of the freshwater cyanobacterium Synechococcus sp. strain PCC6301 (representative of type IB) and the diatom Cylindrotheca sp. strain N1 (representative of type ID) were hybridized to the isolated RNA and DNA. To quantitate rbcL gene expression for each sample, the amount of gene expression per gene dose (i.e., the amount of mRNA divided by the amount of target DNA) was determined. With a limited number of sampling sites, it appeared that type ID (diatom) rbcL gene expression per gene dose decreased as the sampling sites shifted toward open water. By contrast, a similar trend was not observed for cyanobacterial (type IB) rbcL gene expression per gene dose. Complementary DNA specific for rbcL was synthesized from Lake Erie RNA samples and used as a template for PCR amplification of portions of various rbcL genes. Thus far, a total of 21 clones of rbcL genes derived from mRNA have been obtained and completely sequenced from the Ballast Island site. For surface water samples, deduced amino acid sequences of five of six clones appeared to be representative of green algae. In contrast, six of nine sequenced rbcL clones from 10-m-deep samples were of chromophytic and rhodophytic lineages. At 5 m deep, the active CO2-fixing planktonic organisms represented a diverse group, including organisms related to Chlorella ellipsoidea, Cylindrotheca sp. strain N1, and Olisthodiscus luteus. Although many more samplings at diverse sites must be accomplished, the discovery of distinctly different sequences of rbcL mRNA at different water depths suggests that there is a stratification of active CO2-fixing organisms in western Lake Erie.

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Dataset Information

Water Quality, Toxicity and Diversity of Planktonic and Benthic Cyanobacteria in Pristine Ancient Lake Khubsugul (Hovsgol), Mongolia.

Publications

Water Quality, Toxicity and Diversity of Planktonic and Benthic Cyanobacteria in Pristine Ancient Lake Khubsugul (Hövsgöl), Mongolia.

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