Production and Physiochemical Characterization of Poly(3-hydroxybutyrate) Bioplastic by Brazilian Bacterium Ralstonia solanacearum under Different Production Media and Saline Stress Conditions

Abstract

The effect of different culture media containing different nitrogen sources (F4, urea; BEI, tryptose and yeast extract; MM, ammonium sulfate), carbon sources (glucose, sucrose), and salinity (0, 5, 50 and 100 g/L of NaCl) on the accumulation and physiochemical properties of poly(3-hydroxybutyrate) from Ralstonia solanacearum was evaluated. The biomass concentration, measured by optical density (OD600nm) and dry cell weight (DCW); total residual sugars; and pH were studied. The best culture condition was MM culture medium containing sucrose, resulting in an OD600nm of 16.8, DCW of 5.7 g/L and accumulation 46.8%, totaling 2.67 g/L of bioplastic. These results are intermediate when compared with other bacteria. The addition of a low concentration of NaCl to the culture medium did not cause any significant differences in relation to the control treatment. However, the addition of high concentrations of salt negatively influenced the biomass and polymer yields; therefore, R. solanacearum RS can be classified as a halotolerant microorganism. Bioplastics with differentiated characteristics were produced.