Endogenous, spontaneous formation of beta-lactamase in Staphylococcus aureus

In a beta-lactamase-inducible strain of Staphylococcus aureus, the enzyme appears spontaneously in the absence of added inducer during lag and early log phases of growth and then declines rapidly to low levels. The endogenous inducer responsible for appearance of the enzyme has been isolated and purified and characterized as a peptidoglycan, containing muramic acid, glucosamine, glutamic acid, alanine, lysine, and glycine. The inducing compound could be isolated from the cells only during the lag and early log phases and from no other later periods. The data obtained are consistent with the thesis advanced earlier from this laboratory that beta-lactamase serves a cellular function in the producing cell more important and beyond its capability of hydrolyzing certain penicillins to the antibiotically inactive penicilloic acids.