Metabolic activity of cryogenic soils in the subarctic zone of Siberia towards "green" bioplastics. (January 2021) - Prudnikova, Svetlana V.
Abstract: The present study investigates, for the first time, the structure of the microbial community of cryogenic soils in the subarctic region of Siberia and the ability of the soil microbial community to metabolize degradable microbial bioplastic – poly-3-hydroxybutyrate [P(3HB)]. When the soil thawed, with the soil temperature between 5-7 and 9–11 °C, the total biomass of microorganisms at a 10-20-cm depth was 226–234 mg g −1 soil and CO2 production was 20–46 mg g −1 day −1 . The total abundance of microscopic fungi varied between (7.4 ± 2.3) × 10 3 and (18.3 ± 2.2) × 10 3 CFU/g soil depending on temperature; the abundance of bacteria was several orders of magnitude greater: (1.6 ± 0.1) × 10 6 CFU g −1 soil. The microbial community in the biofilm formed on the surface of P(3HB) films differed from the background soil in concentrations and composition of microorganisms. The activity of microorganisms caused changes in the surface microstructure of polymer films, a decrease in molecular weight, and an increase in the degree of crystallinity of P(3HB), indicating polymer biodegradation due to metabolic activity of microorganisms. The clear-zone technique – plating of isolates on the mineral agar with polymer as sole carbon source – was used to identify P(3HB)-degrading microorganisms inhabiting cryogenic soil in Evenkia. Analysis of nucleotide sequences of rRNA genes was performed to identify the following P(3HB)-degrading species: Bacillus pumilus, Paraburkholderia sp., Pseudomonas sp., Rhodococcus sp., Stenotrophomonas rhizophila, Streptomyces prunicolor, and Variovorax paradoxus bacteria and the Penicillium thomii, P. arenicola, P. lanosum, Aspergillus fumigatus, and A. niger fungi. Graphical abstract: Image 1 Highlights: The metabolic activity of the microbial community of cryogenic soil in Siberia. The biodegradable "green" plastic - microbial poly-3-hydroxybutyrate P(3HB). Isolation and identification of P(3HB)-degrading microorganisms. The biodegradability indicators of P(3HB) films in cryogenic soil.