Terrestrial phototrophic biofilms on artificial substrates: diversity of cyanobacteria and microalgae in a small urban town (Pushchino, Russia)

Abstract

We aimed to study the taxonomic diversity of cyanobacteria and eukaryotic microalgae that form phototrophic biofilms on artificial substrates in a small town. During the study, 19 strains of phototrophic microorganisms were isolated and characterized from various building materials of urban buildings and structures (concrete, cement-sand mortar, plaster, metal, and wood). Combined molecular phylogenetic and morphological analyses permitted the characterization of 5 cyanobacterial and 14 microalgal strains, among which the genera Klebsormidium and Chloroidium predominated. Substrate specificity of the phototrophs was confirmed: the highest taxonomic richness was associated with porous and moisture‑retaining materials (concrete), as well as with metal surfaces. Of particular interest were two strains, Leptolyngbya sp. VKM Al‑382 and Cymatolege sp. VKM Al‑383, which are candidates for species new to science. For the first time, a member of the genus Cymatolege, previously known exclusively as an associated symbiont of marine sponges, was detected in a terrestrial biotope on an anthropogenic substrate, substantially expanding our knowledge of the ecological plasticity of this group. All obtained cultures were deposited in the microbial collection, thereby providing a foundation for further fundamental and applied research in the fields of biocorrosion and the development of bioprotection methods for building materials.