ABSTRACT
The chapter presents the results of the synthesis of various types of polyhydroxyalkanoates (PHA) by wild-type strains of hydrogen-oxidizing bacteria. Technologies of synthesis of PHA with different chemical compositions (a homopolymer of 3-hydroxybutyrate; co-, ter-, and quaterpolymers containing 3- and 4-hydroxybutyrate, 3-hydroxyvalerate, and 3-hydroxyhexanoate; copolymers containing 3-hydroxybutyrate and diethylene glycol or 3-hydroxy-4-methylvalerate) have been developed. The structure and physicochemical properties of polymers synthesized have been studied. Technologies of PHA synthesis on various substrates (mixtures of electrolytic hydrogen with CO2 and O2; syngas obtained by conversion of natural gas and gasification of brown coal and hydrolysis lignin; sugars; organic and fatty acids; vegetable oils and glycerol) have been implemented. The process of PHA synthesis was scaled-up under pilot production conditions. PHA production has reached 500 kg per year.
The conditions for polymer processing into special products from different phase states by various methods (solvent evaporation, electrospinning, pressing from powders and melts, 3D printing) have been studied. Polymer monofilaments, nonwoven materials, microparticles, 3D compact and porous prints, and tubes have been produced and characterized. Biological compatibility of the products has been studied in vitro, in cell cultures, and in vivo. The promise of their application in drug delivery systems, restoring damaged skin, reconstructive osteogenesis, and stenting blood vessels, bile ducts, and ureters has been shown.
In vivo biodegradation of various types of PHA implanted subcutaneously, intramuscularly, and into internal organs has been studied. Biodegradation of PHA in soil and natural aquatic ecosystems of various types in the northern, middle, and tropical latitudes has been studied. A new PHA application has been initiated and developed: the use of PHA as a matrix in slow-release formulations of herbicides and fungicides for crop protection in order to reduce the accumulation and uncontrolled spread of pesticides in the biosphere.
