ABSTRACT
To obtain a number of extracellular penicillinase,the gene(penp)encoding penicillinse of Bacillus cereus ATCC10987 was cloned into expression vector in Bacillus subtilis,transformed into Bacillus subtilis DB104 deficient in two proteases.When recombinant bacteria was cultured in LB medium for 24 hours,the result of SDS-PAGE showed that the molecular weight of the protein was 28kDa and the penicillinase activity reached 339U/ml.By screening seven different fermentation media,the result showed that 4# medium is favorable to producing penicillinase by the recombinant cells than the others,with the yield of the enzyme being 1580U/ml.When the recombinant cells was cultured in 7 liter fermentor for 24h,the penicillinase activity reached 1255.8U/ml.