Composition of Microbial Fouling on the Surface of Plastics and Steel Exposed in a Pond at a Solid Waste Landfill

— The work was aimed at investigation of the composition of microbial communities formed on the surface of samples of polyethylene terephthalate (PET), polystyrene (PS) and steel (ST) materials that were exposed in a small pond located at the territory of a solid waste landfill. The taxonomic composition of bacteria and fungi was determined by high-throughput sequencing of the V4 region of the 16S rRNA gene and of the ITS ribosomal operon, respectively. Bioinformatic analysis revealed predominance of bacteria of the phyla Pseudomonadota ( Proteobacteria ), Actinomycetota, Bacteroidota , and Bacillota in the biofilms formed on all samples. The observed quantitative changes in the composition of the dominant bacterial taxa were associated mainly with the exposure time, rather than the material of the samples. The iVikodak program was used to predict the functional characteristics of bacteria in the biofilms. The studied bacterial communities were shown to be potentially able to cause the degradation of polymer materials and xenobiotics and corrosion of steel. The fungal communities were dominated by saprotrophic representatives of the phyla Ascomycota and Basidiomycota . The effect of the conditions of the aquatic environment on the overall composition of the fungal community during exposure turned out to be less significant than that observed for bacteria; similar to the effect of the sample material, it could be traced for certain fungal genera. Among the dominant fungi, species potentially capable of biodegradation of polymers and corrosion of metals were identified. Microscopy confirmed the local degradation of the initial samples of materials as a result of exposure to the aquatic environment. Pure bacterial cultures of the genera Bacillus and Brevundimonas were isolated, which degraded alkanes, fatty acids, and phenols.