Introduction:
The annual increase in polymer production leads to the accumulation of waste from synthetic polymers, especially microplastics, which are hazardous to the environment. The transition to fully degradable polymer materials, including polyhydroxyalkanoates (PHA), will help solve this problem. Poly(3-hydroxybutyrate) is a polymer from the PHA group, which is included in the global cycle and is transformed by microbial enzymes into carbon dioxide and water. In the environment, the degradation of PHA products is highly variable and depends on climate, hydrothermal conditions, and microbial activity, which poses the challenge of studying the rates of PHA biodegradation in different geographic regions.

Methods:
Thin films of the biopolymer poly(3-hydroxybutyrate) were placed in two experimental sites with significantly different soil and climatic conditions: 1) India (Kottayam, 9°39′ N, 76°32′ E), tropical climate, red ferallite soils; 2) Siberia (Krasnoyarsk, 56°08′ N, 92°52′ E), sharply continental climate, chernozem soils. After exposure, the mass loss of the films and the physicochemical properties of the polymer samples were studied. Strains of P(3HB) degrading microorganisms were isolated and identified.

Results:
During the biodegradation process, a decrease in molecular weight and an increase in the degree of crystallinity of P(3HB) samples were detected in the soils of both geographic regions. In the tropical soil, the mass loss of films occurred 2 times slower than in chernozem, which is due to a decrease in the humidity and microbial activity of red soil. The community of microorganisms – primary degraders of P(3HB), isolated from red soil, differed from the set of degrader species isolated from chernozem.

Conclusion:
The metabolic potential of microorganisms involved in the biodegradation of fully degradable polymers such as PHA may be limited by climatic parameters, requiring the creation of favorable conditions for the disposal of biopolymer waste.