four types of beta-lactamases consisting of a penicillinase type i ( tem-1 ) , a penicillinase type ii ( oxa-1 ) , a cephalosporinase of citrobacter freundii , and a cephalosporinase of proteus vulgaris were introduced into escherichia coli mc4100 and its omp mutants , mh1160 ( mc4100 ompr1 ) and mh760 ( mc4100 ompr2 ) , by transformation .
C0597979
beta-lactamases
C0728805
cephalosporinase