[Action of novobiocin on the capacity of Nocardia fructiferi var. ristomycini for ristomycin biosynthesis]. / Deistvie novobiotsina na sposobnost' Nocardia fructiferi var. ristomycini k biosintezu ristomitsina.

The effect of novobiocin in concentrations of 0.05 and 0.2--0.3 microgram/ml on morphological variation of N. fructifer and its capacity for ristomycin production was studied. It was found that the number of colonies with the maximum activity increased under the effect of novobiocin used in a concentration of 0.05 microgram/ml. An increase in the level of novobiocin in the medium up to 0.2--0.3. microgram/ml markedly increased the number of the colonies with low antibiotic productivity.

[Action of antibiotics on the growth and metabolic processes of streptomycetes and Nocardia]. / Izuchenie deistviia antibiotikov na rost i protsessy metabolizma u streptomitsetov i nokardii.

New experimental data on the effect of novobiocin, ristomycin and nystatin on growth and metabolism of Streptomycetes and Nocardia are presented. The study of the organisms producing other antibiotics showed that they were tens, hundreds and even thousands times more sensitive to the tested biologically active compounds than the organisms producing these compounds. The protein synthesis and antibiotic biosynthesis proved to be most sensitive out of the processes studied. The findings showed that during their evolution the antibiotic-producing organisms have developed definite protective mechanisms which enable them to resist relatively high concentrations of their own metabolites (antibiotics). This ensures them in their struggle for existence.