Optimization of Polyhydroxybutyrate Production by Alcaligenes eutrophus and Its Application

Abstract

The suitable carbon source for the growth of Alcaligenes eutrophus and polyhydroxybutyrate production was molasses. The highest cell growth (4.16 g/L) and polyhydroxybutyrate (2.35 g/L, 56.49% of dry cell weight) was obtained from molasses after 108 h of cultivation. Afterwards, the effect of fermentation condition was studied. Batch fermentation yielded the highest cell growth and polyhydroxybutyrate (54.69% of dry cell weight). While only 38.43% of polyhydroxybutyrate was obtained under fed-batch fermentation. The isolated polymer was characterized for chemical composition by Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy and Gas Chromatography. The obtained polymer was similar to polyhydroxybutyrate in comparing with commercial polyhydroxybutyrate. Isolated polyhydroxybutyrate was utilized as substrate for hydroxybutyrate methyl ester. Interestingly, the chemical composition of hydroxybutyrate methyl ester was similar to biodiesel.