Abstract
Microorganisms form complex and dynamic communities that play a key role in the biogeochemical cycles of lakes. A high level of urbanization is currently a serious threat to bacterial communities and the ecosystem of freshwater bodies. To assess the contribution of anthropogenic load to variations in the structure of winter microbial communities in lakes, microorganisms of four water bodies of Chelyabinsk region were studied for the first time. We used cultural, chromatography-mass spectrometric, and modern methods of statistical data processing (particularly, multivariate exploratory analysis and canonical analysis of correspondences). The research showed that the composition of winter microbial communities in lakes Chebarkul’, Smolino, Pervoye, and Shershenevskoye Reservoir did not differ significantly between the main phyla of microorganisms. The dominant microorganisms were found to be of the Firmicutes phylum and Actinobacteria phylum. The structure of bacterial communities had special features depending on the characteristics of the water body and the sampling depths. Thus, in the lakes Smolino, Pervoye, and Shershenevskoye Reservoir, an important role was played by associations between microorganisms – indicators of fecal contamination: coliform bacteria and Enterococcus. On the contrary, in Chebarkul’ Lake, members of the genus Bacillus, which are natural bioremediators, formed stable winter associations. However, the differences between water bodies and sampling depths reflected 28.1% and 9.8% of the variability of the winter microbial communities, respectively. The largest contribution (about 60%) to the variability of the structure was made by intra-water processes, which determined the high heterogeneity of samples from different water areas. We assume that an important role in this variability was played by the high anthropogenic impact in a large industrial metropolis. In our opinion, this line of research is very promising for addressing key environmental issues.
Highlights
Communities of microorganisms are fundamental components of the aquatic environment
The following are the conditions for chromatographic separation: Using a combination of the classical cultural method and the GCMSMM method, 42 operational taxonomic units (OTU) were identified in the winter communities of microorganisms in four lakes of Chelyabinsk region
They belonged to four bacterial phyla (Bacteroidetes, Firmicutes Actinobacteria, and Proteobacteria) and fungi kingdom
Summary
Communities of microorganisms are fundamental components of the aquatic environment They are extremely diverse and play a key role in managing global energy flows and biogeochemical cycles (Ren et al, 2017; Qu et al, 2018; Yadav et al, 2018). Taxonomic and functional changes in microbial communities in lake water can lead to disturbances in ecosystem processes (David et al, 2021; Xie et al, 2021). Anthropogenic transformation of lakes leads to the introduction of non-typical bacteria (including fecal) into the water systems and can change the natural composition of the microbial community of freshwater (Numberger et al, 2019; Cao et al, 2020; Yang et al, 2020). Communities of natural microorganisms are able to limit the growth of pathogens sporadically polluting water bodies. In lakes that are subjected to a strong anthropogenic load, new communities are appearing that are favourable for the survival and spread of pathogens (Falk et al, 2019; Mathai et al, 2019; Beattie et al, 2020)
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