NEW TECHNIQUE FOR RECOVERY OF PHB FROM RECOMBINANT Escherichia coli BASED ON EXPRESSION OF LYTIC GENES OF PHAGE λ WITH S AMBER MUTATION

The lytic genes of phage λ with S amber mutation( S - RRz ) were introduced into the recombinant E. coli VG1(pTU14) producing poly- β -hydroxybutyrate(PHB)to attain controllable lysis of cells. The results of EDTA/Tris(pH8.0)buffer treatment showed that S -RRz were successfully expressed in VG1(pTU14),and cell lysis was realized due to the action of EDTA on cytoplasm membrane.Here the function of EDTA was similar to that of S gene product.When PHB content was 85%—90%,membrane permeability would be increased by the abundantly accumulated in-cell PHB granules,and then the autolysis of recombinant cells occurred. After studies on different projects for direct separation of PHB from fermentation broth,a new technique, in which temperature treatment was introduced to simulate the function of S gene product,was presented,and the autolysis of cells was then easily realized based on the successful expression of S - RRz .By this simple technique,the final purity of PHB product could be up to 95%.