Strategies on Improving the trans4-Hydroxyproline Production from the Engineering Strain E. coli

Abstract:

To enhance the yield of trans-4-Hydroxyproline from the engineering strain E. coli JM109ΔargB/pUC19-BH，optimization of fermentation medium and culture condition was carried out with a single-factor and orthogonal design experiment. Further，a recombinant E. coli JM109ΔargB/pUC19-BHV，containing the vitrescilla hemoglobin gene VHB was constructed to be desirable for high-density fermentation. Results showed that the fermentation medium was optimized as follows：maltose 10 g/L，glycerol 5 g/L，trypsin 22 g/L，K₂HPO₄ 4 g/L，FeSO₄：VC 5 mmol/L，MgSO₄ 1.7 g/L，NaCl 3 g/L and CaCl2 0.005 g/L. The optimal fermentation conditions were as below：inoculum size 4%（v/v），initial pH 8.5 and culture temperature 30 ℃. At 24 h of the fermentation，the yield of P4H reached 1 602 mg/L，which was about 1.4 times of that before the optimization. In a 7 L fermenter，the recombinant E. coli JM109ΔargB/pUC19-BHV yielded 18.3 g/L of P4H，13.2% higher than that of the parental strain，indicating that the introduction of VHB gene was beneficial for the high-density production of trans-4-Hydroxyproline.