Properties of Spontaneous Mutant of KO-1297.

The J1074 strain remains one of the most popular platforms for the discovery of new natural compounds due to the expression of biosynthetic gene clusters (BGCs) from the microorganisms of the class. Different methods were tested to provide a maximal expression of heterologous BGCs in this strain. However, there is still no description of the properties of spontaneous J1074 mutants in the gene encoding a ribosomal protein S12. The interest in such mutations in actinobacteria is due to the fact that they provide a considerable increase in the antibiotic activity. In this work, we describe the isolation and characterization of the KO-1297 strain, which contains a spontaneous missense mutation in the gene leading to a Lys88Glu substitution in the protein S12. As compared with the initial strain, this mutant exhibits an increased resistance to streptomycin and higher antibiotic productivity. The KO-1297 strain and genetically engineered mutant K88E are not identical in their ability to produce antibiotics. KO-1297 also exhibits a certain level of instability of mutation. The genomes of KO-1297 and its revertant contain the mutations that can cause phenotypic differences between these strains (as well as between them and SAM2 and K88E strains).