Effects of polyoxin D on germination, morphological development and biosynthesis of the cell wall of Trichoderma...

When polyoxin D is added to a spore suspension of Trichoderma viride at a concentration from 50-100 mug/ml, it inhibits from 40-60% of germination. This percentage increases if dimethylsulfoxide (DMSO) is added. Mycelium growing in the presence of polyoxin D becomes irregular and loses its rigidity, showing several bulges along the hypha. Under the electron microscope the features of the cell wall and cytoplasmic content are apparently normal. Nevertheless, after incubation with different lytic systems or with (14C) glucose, it can be seen that polyoxin D partially inhibits the biosynthesis of beta-(1-3) glucan and the biosynthesis of chitin to a greater extent attaining inhibition of 83% at 100 mug/ml of the antibiotic concentration. Rgenerating protoplasts are less affected by polyoxin D. They do regenerate slower but the percentage of regeneration is more than 80%. Aberrant tubes synthesized by these protoplasts are not affected, they manifest their usual morphology and lack of chitin is confirmed in their composition.