Abstract
The germination of Bacillus megaterium spores both in nutrient broth and in a germinant (L-alanine plus inosine in phosphate buffer) was inhibited by alkyl p-hydroxybenzoates at lower concentrations than those required for inhibiting the outgrowth of germinated spores. The inhibition occurred even when the drugs were added to the spore suspensions where germination had already begun. The degree of inhibition was proportional to the logarithm of alkyl p-hydroxybenzoate concentration present in the germination medium. The concentrations required to completely inhibit germination were 4.5 mM for methyl, 1.6 mM for ethyl, 0.52 mM for propyl, 0.80 mM for isopropyl, 0.22 mM for butyl and 0.22 mM for isobutyl p-hydroxybenzoate. respectively. Free p-hydroxybenzoic acid had no inhibitory activity. There was a linear relationship between the logarithm of germination inhibiting concentration and the number of carbon atoms in the alkyl chain. The inhibition of spore germination by alkyl p-hydroxybenzoates was reversible, since removal of the drugs from spore environment allowed germination to proceed. The possible mechanism of the inhibitory effect of alkyl p-hydroxybenzoates on spore germination is discussed.
