Improved production of poly(4-hydroxybutyrate) by Comamonas acidovorans and its freeze-fracture morphology.
Production of poly(4-hydroxybutyrate) [P(4HB)] by Comamonas acidovorans JCM10181 was studied by introducing additional copies of its PHA synthase gene and the beta-ketothiolase gene. A multi-copy-number broad-host-range plasmid vector, pJRD215, was modified to contain the strong hybrid trc promoter in order to express these genes in the wild-type C. acidovorans. Increased copy-number of genes resulted in significant increase in the activities of corresponding enzymes, which could further be increased by inducing with isopropyl-beta-D-thiogalactopyranoside (IPTG), indicating that the expression is under the transcriptional control of the trc promoter. P(4HB) biosynthesis in the recombinant C. acidovorans increased 2-fold to constitute more than 60 wt% of the dry cell weight. No significant decrease in the number-average molecular weights of P(4HB) in the recombinant strain was observed when compared with that of the wild-type. Freeze-fracture electron microscopy of intracellular P(4HB) granules revealed almost similar fracture morphology to the well-known mushroom-type deformation shown by polyhydroxyalkanoates with medium-chain-length monomers.
Department of Biological and Environmental Sciences, Saitama University, Urawa, Japan.
K
K
Sudesh
T
T
Fukui
K
K
Taguchi
T
T
Iwata
Y
Y
Doi
D000102:Acetyl-CoA C-Acyltransferase / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D000217:Acyltransferases / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular / Q000379:methods; D004790:Enzyme Induction / Q000187:drug effects; D005614:Freeze Fracturing; D016946:Gram-Negative Aerobic Rods and Cocci / Q000201:enzymology* / Q000235:genetics* / Q000648:ultrastructure; D007544:Isopropyl Thiogalactoside / Q000494:pharmacology; D007700:Kinetics; D008854:Microscopy, Electron; D010957:Plasmids; D011091:Polyesters / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000378:metabolism
D011091:Polyesters; D011994:Recombinant Proteins; C107955:poly(4-hydroxybutanoate); D007544:Isopropyl Thiogalactoside; D000217:Acyltransferases; C077225:poly(3-hydroxyalkanoic acid) synthase; D000102:Acetyl-CoA C-Acyltransferase