Poly(3-hydroxybutyrate) synthesis genes in Azotobacter sp strain FA8

Genes responsible for the synthesis of poly(3-hydroxybutyrate) (PHB) in Azo tobacter sp. FAS were cloned and analyzed. A PHB polymerase gene (phbC) was found downstream from genes coding for beta -ketothiolase (phbA) and aceto acetyl-coenzyme A reductase (phbB). A PHB synthase mutant was obtained by g ene inactivation and used for genetic studies. The phbC gene from this stra in was introduced into Ralstonia eutropha PHB-4 (phbC-negative mutant), and the recombinant accumulated PHB when either glucose or octanoate was used as a source of carbon, indicating that this PHB synthase cannot incorporate medium-chain-length hydroxyalkanoates into PHB.