Metabolic engineering of Alcaligenes eutrophus through the transformation of cloned phbCAB genes for the investigation of the regulatory mechanism of polyhydroxyalkanoate biosynthesis

• Published in: Enzyme and microbial technology Vol. 26; no. 2; pp. 201 - 208
• Main Authors: Jung, Young-Mi, Park, Jin-Seo, Lee, Yong-Hyun
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Inc 01.02.2000; Elsevier Science
• Subjects: Acetoacetyl-CoA reductase; Alcaligenes eutrophus; Biological and medical sciences; Biosynthesis; Biotechnology; Enzyme kinetics; Fundamental and applied biological sciences. Psychology; Genes; Genetic engineering; Genetic technics; Granular structure; Metabolic engineering; Metabolism; Methods. Procedures. Technologies; Microorganisms; Modification of gene expression level; P(3HB-3HV) biosynthesis; PHB synthase; phbCAB gene; phbCAB genes; poly(3-hydroxybutyrate-co-3-hydroxyvaleric acid); poly-^b-hydroxybutyric acid; poly-b-hydroxybutyric acid-co-b-hydroxyvaleric acid; Polymerization; Rate constants; Regulation mechanism of PHB; β-Ketothiolase; Alcaligenes eutrophus; β-Ketothiolase; Regulation mechanism of PHB; P(3HB-3HV) biosynthesis; Metabolic engineering; PHB synthase; phbCAB genes; Acetoacetyl-CoA reductase; Granular structure; Recombinant microorganism; Valerate(hydroxy) copolymer; Biodegradability; Ester polymer; Butyrate(hydroxy) copolymer; Butyrate(hydroxy)polymer; Biosynthesis; Gene expression; Ralstonia eutropha; Regulation(control); Gene; Microorganism culture; Bacteria; Biomaterial; Genetic engineering
• ISSN: 0141-0229; 1879-0909
• DOI: 10.1016/S0141-0229(99)00156-8

The regulatory mechanisms of the biosynthesis of in vivo poly-β-hydroxybutyrate [PHB] and poly(3-hydroxybutyrate-3-hydroxyvalerate) [P(3HB-3HV)] of Alcaligenes eutrophus were investigated by using various transformants with enzyme activities that were modified through the transformation of cloned phbCAB genes. The biosynthesis rates of PHB and P(3HB-3HV) were controlled by β-ketothiolase and acetoacetyl-CoA reductase, and especially by β-ketothiolase condensing acetyl-CoA or propionyl-CoA. The contents of PHB and P(3HB-3HV) were controlled by PHB synthase, polymerizing 3-hydroxybutyrate to PHB or 3-hydroxybutyrate and 3-hydroxyvalerate to P(3HB-3HV). The molar fraction of 3-hydroxyvalerate in P(3HB-3HV) was also closely connected with PHB synthase. This may be due to the accelerated polymerization between 3-HB from glycolysis pathway and 3-HV converted from propionate supplied as precursor. Enforced β-ketothiolase and acetoacetyl-CoA reductase to PHB synthase tended to enlarge the size of the PHB and P(3HB-3HV) granules, however, higher activity ratio of PHB synthase to β-ketothiolase and acetoacetyl-CoA reductase than parent strain tended to induce the number of granules.