CHARACTERISTICS OF CELL-GROWTH AND POLY-BETA-HYDROXYBUTYRATE BIOSYNTHESIS OF ALCALIGENES-EUTROPHUS TRANSFORMANTS HARBORING CLONED PHBCAB GENES

Alcaligenes eutrophus transformants harboring rite cloned phbCAB, phbA B, and phbC genes were cultivated under various culture conditions to determine the optimal cultivation condition for an effective accumulat ion of poly-beta-hydroxybutyrate. The transformants showed significant ly increased total cell growth and PHB accumulation due to the increas ed activities of enzymes of PHB biosynthesis. In the batch cultivation , the transformant can synthesize PHB more favorably at the high C/N, molar ratio and low carbon concentration compared to the parent strain , The fedbatch cultivation was confirmed to be a more effective method for maximizing the effect of cloned genes to PHB biosynthesis compare d to the batch cultivation. The plasmid stability was maintained at ar ound 85% after 36 h and elongated morphological changes of transforman t at the early growth stage was observed The gene amplification throug h the transformation of cloned PHB biosynthesis genes in A. eutrophus seems to be an excellent method for strain improvement to achieve an e ffective accumulation of PHB. (C) 1997 Elsevier Science Inc.