β-Lactamase activity of Escherichia intermedia

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Abstract
Escherichia intermedia produced a [beta]-lactamase that hydrolyzed several penicillin and cephalo-sporin C derivatives. Culture conditions affecting production of the enzyme were studied. The enzyme was non-inducible and cell-bound. Growth temperature, medium and physiological age had a marked effect on production of the enzyme. Properties of the enzyme were studied with intact cells and with a cell-free preparation. Although the [beta]-lactam-ase of E. intermedia was different in some respects to that produced by gram-positive organisms, it was found to have properties similar to the B-lactamases of gram-negative organisms. 6-Aminopenicillanic acid was cleaved by the enzyme, but 7-aminocephalosporanic acid was resistant to cleavage. The rate of hydrolysis by intact cells and the purified preparation was influenced by the type of N-acyl sidechain of 7-aminocephalosoporaftic acid and 6-aminopenicillanic acid. The desace-toxy derivatives of cephalosporinC and cephalothin were hydrolyzed less rapidly than the parent compounds. The specific activity of the intact cells on cephalonium and methicillin was substantially less than that of the purified preparation.