%0 Journal Article %A Jack, G. W. %A Richmond, M. H. %T A Comparative Study of Eight Distinct β-Lactamases Synthesized by Gram-negative Bacteria %D 1970 %J Microbiology, %V 61 %N 1 %P 43-61 %@ 1465-2080 %R https://doi.org/10.1099/00221287-61-1-43 %I Microbiology Society, %X SUMMARY: The enzymic properties of 46 strains of β - lactamase-producing enteric bacteria were examined. Eight distinct types of β - lactamase were detected among these strains when substrate profile, sensitivity to p-chloromercuri- benzoate (pCMB) and to cloxacillin inhibition, reaction with antiserum and charge properties are used as parameters of enzyme type. The types of enzyme detected ranged from molecules with a predominantly cephalo- sporinase profile to those where penicillins were hydrolysed much more rapidly than cephalosporins. The majority of isolates synthesized an enzyme that was almost equally active against penicillins and cephalosporins. To date only three of the eight types of enzyme have been shown to be transferable by conjugation. %U https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-61-1-43