Study On Vitreoscilla Hemoglobin Gene And Phage λ Lysis Genes In Recombinant Escherichia Coli Strain Producing Polyhydroxyalkanoates

The strain containing the high-copy plasmid with the VHb gene had low production of poly-p-hydroxybutyrate. The strain HV integrated the VHb gene into the chromosome of E.coliHMS174 was constructed. The VHb expression in the strain HV was investigated by CO-binding assay. In flask culture, the strain HV had almost cell densities compared with E.coliHMS174 in the early phase of the growth. However, in the late phase of the growth, the strain HV grew a little faster than E.coliHMS174.HV(pTZ101) was constructed by the plasmid containing the phb operon and the parDE gene tansformed into the strain HV. In flask culture for 40 hours, the final OD600 and the poly-p-hydroxybutyrate concentration of HV(pTZlOl) were more than E.coliHMS174( pTZ104) not containing the VHb gene. In feed-bach culture for 30 hours in 5L automatic fermentor, the final OD600 and the poly-p-hydroxybutyrate concentration of HV(pTZlOl) were 50 and 47.3%, respectively. The final OD600 and the poly-p-hydroxybutyrate concentration of HMS174(pTZ101) were 172 and 64.2%, respectively.The promoter and structure genes of X phage lysis genes were amplified by PCR,respectively. The plasmid MVPS was constructed for integrating the VHb gene and the lysis genes into the chromosome of E.coliHMS174 by ligating the lysis genes to mini-Tn5. However, the experiment did not success.