INACTIVATION OF ENZYMES WITHIN SPORES OF BACILLUS-MEGATERIUM ATCC-19213 BY HYDROPEROXIDES

The organic hydroperoxides t-butyl hydroperoxide, cumene hydroperoxide , and peracetic acid were found to act similarly to hydrogen peroxide in causing inactivation of enzymes within intact spores of Bacillus me gaterium ATCC 19213 concomitant with mortality. Spores treated with le thal levels of the agents were germinated and permeabilized for enzyme assays. The hierarchy of sensitivities among enolase, glucose-6-phosp hate dehydrogenase (G6Pdh), and pyruvate kinase to inactivation varied somewhat with the specific hydroperoxide used, possibly because of di fferences in the types of radicals generated. However, each agent inac tivated each of the enzymes, albeit at different rates. Comparative as sessments of enzyme inactivation by lethal levels of H2O2 or by moist heat showed that some enzymes, such as G6Pdh, are highly sensitive to inactivation, while others, such as ATPases, are much more resistant. The enzymes G6Pdh and aldolase were highly sensitive to hydroperoxide inactivation and also to moist heat, while pyruvate kinase was much mo re sensitive to hydroperoxides than to moist heat. Our overall interpr etation of the findings is that hydroperoxides and moist heat can prod uce cumulative damage to sensitive enzymes within spores, which progre ssively diminishes the capacities of the cells to undergo the outgrowt h required for return to vegetative life.