ACTION OF THE FUNGICIDE TRIDEMORPH ON THE GLUCOSE, LACTATE AND SUCCINATE-DEHYDROGENASE ACTIVITIES OF SOME TRIDEMORPH-SENSITIVE AND TRIDEMORPH-ESISTANT BACTERIA

The systemic morpholine fungicide tridemorph, which is known to exert its antifungal action through inhibition of ergosterol biosynthesis, c an also inhibit the growth of organisms which are incapable of sterol biosynthesis. It was found to inhibit strongly glucose and lactate deh ydrogenase activities in cultures of four Gram(+) bacteria, Rhodococcu s sp. AK 1, Bacillus cereus Frankland and Frankland, Bacillus subtilis (Ehrenberg) Cohn, Nocardia asteroides and a Gram(-) bacterium, Rhizob ium leguminosarum. Growth of these bacteria was inhibited by tridemorp h at concentrations between 7 and 60 mg litre-1. In contrast, similar dehydrogenase activities in other Gram(-) organisms, Escherichia coli Cast. and Chalm. and Azotobacter vinelandii, which showed no growth in hibition at 200 mg litre(-1) tridemorph, were either not inhibited or inhibited only slightly. Similarly, succinate dehydrogenase activity i n 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. c oli, lactate dehydrogenase activity was also inhibited by tridemorph t o a much greater extent in the sensitive strain (63%) than in the resi stant ones (8%).