Study on Heterologous Expression of Penicillinase Gene and the Penicillinase Degrading Residual Penicillin in Milk
青霉素酶基因异源表达及该酶分解牛奶中残留青霉素的研究

To obtain a number of penicillinases and degrade penicillin in milk by using the penicillinases, the gene encoding penicillinase was amplified by PCR from Bacillus cereus ATCC10987, cloned into pET28a(+), transformed into E. coli BL21; analysis of SDS-PAGE and penicillinase activity of the recombinant protein were done under induction of IPTG and the result showed that the maximum penicillinase activity reached 480 U/mL; the purity of penicillinase purified by Ni2+ Purification System was more than 90%; the immobilized penicillinases were obtained by sodium periodate method and the residual quantity of penicillin in milk(containing 0.5 U penicillin G/mL) was less than 4 ppb after degraded by the immobilized penicillinase.