Abstract
Cells of Staphylococcus aureus MF-31 which have been heat-injured at 52 C have an altered metabolic activity. Analyses of whole-cell preparations by means of the Thunberg technique and Warburg manometry showed decreased dehydrogenase activity and oxygen uptake on a variety of substrates. In cell-free extracts prepared from injured cells, it was demonstrated that the specific activity of fructose diphosphate aldolase, lactate dehydrogenase, and butanediol dehydrogenase was less than that of extracts prepared from normal unheated cells. Recovery of the heat-injured cells in a suitable medium supported a return of the dehydrogenase activity and oxygen uptake, but the activity of the enzymes in cell-free extracts prepared from such partially recovered cells did not fully return to the level of normal (unheated) preparations. Addition of chloramphenicol or actinomycin D to the recovery medium, singly or in combination, retarded the return of the normal metabolic activity. Radiorespirometric experiments indicated that the percentage participation of the Embden-Meyerhoff Parnas and hexose monophosphate pathways remained the same for normal and heat-injured cells. The sublethal heat treatment decreased the catabolic capabilities of S. aureus and the production of selected end products associated with the metabolism of glucose.