| Abstract: | The systemic morpholine fungicide tridemorph, which is known to exert its antifungal action through inhibition of ergosterol biosynthesis, can also inhibit the growth of organisms which are incapable of sterol biosynthesis. It was found to inhibit strongly glucose and lactate dehydrogenase activities in cultures of four Gram( +) bacteria, Rhodococcus sp. AK 1, Bacillus cereus Frankland & Frankland, Bacillus subtilis (Ehrenberg) Cohn, Nocardia asteroides and a Gram(?) bacterium, Rhizobium leguminosarum. Growth of these bacteria was inhibited by tridemorph at concentrations between 7 and 60 mg litre?1. In contrast, similar dehydrogenase activities in other Gram(?) organisms, Escherichia coli Cast. & Chalm. and Azotobacter vinelandii, which showed no growth inhibition at 200 mg litre ?1 tridemorph, were either not inhibited or inhibited only slightly. Similarly, succinate dehydrogenase activity in Rhodococcus sp. AK 1 was more strongly inhibited by tridemorph than that in E. coli. In cell-free extracts of Rhodococcus sp. AK1 and E. coli, lactate dehydrogenase activity was also inhibited by tridemorph to a much greater extent in the sensitive strain (63%) than in the resistant ones (8%). |
