[Rifampicin use for potency stabilization in Rif(r) mutants of Streptomyces recifensis subsp. lyticus, an organism producing lytic enzymes].

Rif(r) mutants 1P-92 and 2P-15 were isolated as a result of selection of Streptomyces recifensis subsp. lyticus, an organism producing lytic enzymes. The effect of rifampicin on the biosynthetic potency of the mutants was studied. When added to the medium for cultivation of Rif(r) mutants 1P-92 and 2P-15 in the optimal concentrations (7.5 and 10.0 mcg/ml respectively), the antibiotic showed stabilizing effect on their potency in successive subcultures and recovered the initial potency of the old laboratory strains. Preliminary cultivation of strain 2P-15 after its storage for 6 years at a temperature of -20 degrees C made it possible to increase the efficiency of the initial potency recovery in the analytical selection.