Construction and selection of the novel recombinant Escherichia coli strain for poly(beta-hydroxybutyrate) production

Heterogeneous cloning of Vitreoscilla hemoglobin gene (vgb), lytic genes of phage lambda with S amber mutation (S(-)RRz) and PHB biosynthetic genes (phbCAB) in the same host strain E. coli JM105 was carried out for production of poly(beta-hydroxybutyrate) (PHB). A superior novel strain, VG1 (pTU14), was constructed and selected, which contained the vgb gene in the chromosomal DNA and the plasmid pTU14 containing S(-)RRz and phbCAB genes. When cultured in 100 ml of LBG medium in a 300-ml flask, all of the exogenous genes in VG1 (pTU14) were expressed. The cell concentration of VG1 (pTU14) grown by batch culture in a flask reached 10.2 gl(-1); PHB concentration, PHB content and PHB yield, which is the ratio of the PHB accumulation to the glucose consumption, were 8.54 gl(-1), 84% and 0.43 gg(-1), respectively. When cultured by batch-feeding of glucose in a 300-ml shaking flask, the cell concentration and PHB content reached 26 gl(-1) and over 96%, respectively.