PRODUCTION OF POLY-BETA-HYDROXYBUTYRATE BY ALCALIGENES-EUTROPHUS TRANSFORMANTS HARBORING CLONED PHBCAB GENES

Three transformants of Alcaligenes eutrophus harbouring the recombinan t plasmids containing phbCAB, phbAB, and phbC genes, were cultivated t o investigate the effect of cloned genes on cell growth and poly-beta- hydroxybutyrate accumulation. Both in the nutrient-rich and minimal me dia, the increased PHB accumulation in the transformants was observed compared to the parent strain, and this was the result of the increase d enzyme activities in the transformants. Low carbon concentration and high CM molar ratio favored higher PHB accumulations in the transform ants. The transformant harbouring the phbC gene showed the highest PHB accumulation, which indicated that PHB synthase was the most critical enzyme for PHB biosynthesis in the transformant.