Abstract
In connection with the observed growth trend in the production of plastic products, the issue of replacing petrochemical-based plastic with biodegradable polymers of microbial origin is urgent. The most common biopolymers of microbial origin are polyhydroxyalkanoates. When screening natural strains of soil bacteria for their ability to synthesize polyhydroxybutyrate (PHB), the strain Pseudomonas flavescens D5 was selected as the most productive, providing biomass and polyester yields of 9.15±0.37 g/l and 1.61±0.06 g/l , respectively. A comparative analysis of the ability of the selected strain to accumulate PHB on nutrient media of various compositions was carried out: MSM, glucose-peptone, synthetic, modified MSM, acetate, minimal, lysine-acetate, Taran's medium and MSM with urea. The maximum amount of PHB was observed in MSM medium. The most favorable sources of carbon and nitrogen for increasing the yield of PHB are glucose at a concentration of 5% and ammonium nitrate. Adaptation of the Ps strain was carried out. flavescens D5 to a by-product of food production - glycerin. It has been shown that fermentation of the PHB producer strain on a medium using glycerol for 5 cultivation cycles increases the product yield by 1.3 times, while simultaneously reducing the cost of the carbon source. Key words: microbial polymers, carbon sources, nitrogen sources, optimization of nutrient medium, polyhydroxyalkanoate.