Structural features of natural Nostoc commune biofilms growing in the same technogenic ecotope for 20 years were analyzed. These biofilms are multicomponent communities, including phototrophic and saprotrophic microorganisms of various taxonomic groups. The structure of such biofilms is characterized by an extremely high population density, reaching −109 cells/1 g of dry mass. Nostoc commune is the dominant edifier of such terrestrial consortia. It has the ability to long-term coexistence with representatives of other phototrophic and heterotrophic microorganisms, both prokaryotic and eukaryotic. However, the species and quantitative composition of these biofilms changes affected by natural and technogenic factors. Nevertheless, the biofilm mesh-filament structure resembling pseudo-fabric retains. Probably, a natural in-soil pool of microorganisms is the basis for the N. commune biofilms forming. Spherical colonies of pure N. commune culture are the initial ones that subsequently combine other soil microbes. The N. commune has high affinity for its partners in biofilm. We confirmed in while determining the species, quantitative and structural features of biofilms collected in 2005 and 2025. Biofilms living and growing in a technogenic ecotope are resistant to possible contamination due to the multifunctional abilities of the partners, such as photosynthesis of cyanobacteria and algae, nitrogen-fixing ability of heterocyst-forming cyanobacteria and heterotrophic nitrogen fixers, destructive activity of ammonificators, micromycetes and actinomycetes. The above may be updated by the biofilm mechanical stability associated with the development of filamentous cyanobacteria, micromycetes (the total length of which can reach 1 km/g), and active mucus secretion, primarily by N. commune itself and other representatives. The data obtained indicate that N. commune biofilms function for a long period as a holistic “city of microbes”, and all its inhabitants adapt in coordinated manner to changing environment. Understanding this unique phenomenon of self-regulation opens up prospects for solving theoretical and applied problems in microbiology and ecology.
Keywords: Nostoc commune, natural biofilms, phototrophic and heterotrophic microorganisms, biofilm species and quantitative composition
Article published in number 1 for 2026 DOI: 10.25750/1995-4301-2026-1-209-216
ISSN 1995-4301
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