Comparative study of the synthesis of polyhydroxyalkanoates by cyanobacteria Spirulina platensis and green microalga Chlorella vulgaris

Abstract

The article presents the results of the study of the growth and synthesis of degradable polyhydroxyalkanoates (PHA) of cyanobacteria Spirulina platensis (Nordst) Geitl. and green microalga Chlorella vulgaris (Beijer), in the cultures of which the production of “green” plastics was studied, including in relation to the dynamics of the fatty acid composition of lipids associated with the formation of PHA. The reorganization of constructive metabolism during the development of both cultures and the dynamics of accumulation of lipids and PHA in cells against the background of a decrease in protein were studied. On a modified BG-11 medium, with a decrease in the NaNO3 concentration to 0.5 g/L and the addition of sodium acetate (3/0 g/L), the yields of polymers for C. vulgaris and S. platensis reached 20.0 and 16.2 %, respectively. The composition and properties of the polymer, which is a homopolymer of 3-hydroxybutyric acid (P(3HB)), were studied using GC, FTIR spectroscopy, HPLC, and DTA. The average molecular weight of P(3HB) samples was determined to be 416–467 kDa; crystallinity was 54–56 % with a gap between the melting point and thermal degradation temperature of 109–114 °C.