Biosynthesis of poly(3-hydroxybutyrate-co-3-hydroxyalkanoates) by recombinant bacteria expressing the PHA synthase gene phaC1 from Pseudomonas sp. 61-3.
Pseudomonas sp. 61-3 accumulated a blend of poly(3-hydroxybutyrate) [P(3HB)] homopolymer and a random copolymer consisting of 3-hydroxyalkanoate (3HA) units of 4-12 carbon atoms. The genes encoding beta-ketothiolase (PhbA(Re)) and NADPH-dependent acetoacetyl-CoA reductase (PhbB(Re)) from Ralstonia eutropha were expressed under the control of promoters for Pseudomonas sp. 61-3 pha locus or R. eutropha phb operon together with phaC1(Ps) gene (PHA synthase 1 gene) from Pseudomonas sp. 61-3 in PHA-negative mutants P. putida GPp104 and R. eutropha PHB(-4) to produce copolyesters [P(3HB-co-3HA)] consisting of 3HB and medium-chain-length 3HA units of 6-12 carbon atoms. The introduction of the three genes into GPp104 strain conferred the ability to synthesize P(3HB-co-3HA) with relatively high 3HB compositions (up to 49 mol%) from gluconate and alkanoates, although 3HB units were not incorporated at all or at a very low fraction (3 mol%) into copolyesters by the strain carrying phaC1Ps gene only. In addition, recombinant strains of R. eutropha PHB(-4) produced P(3HB-co-3HA) with higher 3HB fractions from alkanoates and plant oils than those from recombinant GPp104 strains. One of the recombinant strains, R. eutropha PHB(-4)/ pJKSc46-pha, in which all the genes introduced were expressed under the control of the native promoter for Pseudomonas sp. 61-3 pha locus, accumulated P(3HB-co-3HA) copolyester with a very high 3HB fraction (85 mol%) from palm oil. The nuclear magnetic resonance analyses showed that the copolyesters obtained here were random copolymers of 3HB and 3HA units.
Matsusaki
H
H
Polymer Chemistry Laboratory and the RIKEN Group of Japan Science and Technology Corporation, RIKEN Institute, Saitama, Japan.
Abe
H
H
Taguchi
K
K
Fukui
T
T
Doi
Y
Y
D000217:Acyltransferases / Q000235:genetics* / Q000378:metabolism*; D020118:Cupriavidus necator / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D006885:Hydroxybutyrates / Q000378:metabolism*; D011091:Polyesters / Q000378:metabolism*; D016958:Pseudomonas putida / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism
D006885:Hydroxybutyrates; D011091:Polyesters; D011994:Recombinant Proteins; D000217:Acyltransferases; C077225:poly(3-hydroxyalkanoic acid) synthase