The growth and synthesis of exotic and insufficiently studied sulfur-containing polyhydroxyalkanoates was studied in a culture of the wild-strain C. necator B-10646 on fructose with the addition of three different precursors (3-mercaptopropionic acid, 3,3'-dithiodipropionic and 3,3'-thiodipropionic acids). By varying the concentration and number of doses of the precursor introduced into the bacterial culture, it was possible to find conditions that ensure the formation of 3MP monomers from the precursor and their incorporation into the C-chain of poly-3-hydroxybutyrate. The results made it possible to synthesize a set of copolymers with different contents of 3-hydroxybutyrate (3HB) monomers (from 60.10 to 97.96 mol.%) and inclusions of 3-mercaptopropionate (3MP) monomers (from 2.04 to 39.9 mol.%). Quantities made it possible to purify the samples to a homogeneous state suitable for detecting the true chemical composition. Using high-performance liquid chromatography, differential thermal analysis and differential scanning calorimetry, as well as X-ray diffraction analysis, studies have been carried out for the first time that have revealed a relationship between the composition of P(3HB-co-3MP) copolymers and the ratio of different types of monomers in them. It is shown how inclusions of new types of monomers (3MPs) into PHA affect the molecular weight and temperature characteristics of the synthesized copolymers and the degree of crystallinity. An important result of the influence of new monomers on the properties of PHA was obtained, which consists in the alignment of the amorphous and ordered phases and a significant decrease in the degree of crystallinity (below 50%) of the synthesized copolymer samples into a polymer C-chain. A decrease in the degree of crystallinity of PHA samples has a positive effect on their properties and crystallization kinetics, which facilitates processing into specialized products, improving technological properties.

Conflicts of Interest:
The authors declare that they have no conflict of interest in the publication of this article. The authors have no conflicts of interest to report in this work. Abstract was not submitted elsewhere and published here firstly.

Funding:
The study was funded by State Assignment of the Ministry of Science and Higher Education of the Russian Federation (Project No. 0287-2021-0025).