Abstract
Myomycin, an antibiotic reported by French et al. in 1973, was tested for the biological effect on 7 species of plant pathogenic bacteria. The bacterial growth was perfectly inhibited at concentrations of 25 to 100μg/ml by agar dilution method. In turbidimetric method, perfect inhibitory concentration for the growth of those bacteria widely ranged from 2 to 100μg/ml. In agar diffusion method, inhibitory zones of those bacteria caused by myomycin were small even at a concentration of 100μg/ml. On the other hand, in vivo assay, myomycin remarkably protected Chinese cabbage against soft rot caused by Erwinia carotovora at 45μg/ml, and cucumber against angular leaf spot caused by Pseudomonas lachrymans at 75μg/ml, while the antibiotic did not suppress efficiently bacterial leaf blight of rice caused by Xanthomonas oryzae at 75μg/ml. Although the protective effect against angular leaf spot caused by a streptomycin-resistant strain of P. lachrymans was slightly less than in the case of sensitive strain, its protective value was higher than those of streptomycin and a copper compound.
