Ampicillin resistance in Neisseria denitrificans: studies on ampicillin-sensitive enzymes

The beta-lactam sensitivities of enzymes involved in peptidoglycan synthesis were examined in two strains of Neisseria denitrificans having widely disparate degrees of ampicillin sensitivity. One strain of n. denitrificans was 400 times more resistant to ampicillin than the other; the former is known to have altered penicillin-binding proteins. No differences in the levels of sensitivities of total peptidoglycan synthesis as measured by the incorporation of glutamate into peptidoglycan, or of D-alanine carboxypeptidase, were observed between the two strains. However, the rate of glutamate incorporation into peptidoglycan by logarithmic growth phase cells was somewhat less for the ampicillin-resistant cells than for the parent cells.