This work aimed to study the genome organization and the metabolic potential of Streptomyces carpaticus strain SCPM-O-B-9993, a promising plant-protecting and plant-stimulating strain isolated from brown semi-desert soils with very high salinity. The strain genome contains a linear chromosome 5,968,715 bp long and has no plasmids. The genome contains 5331 coding sequences among which 2139 (40.1%) are functionally annotated. Biosynthetic gene clusters (BGCs) of secondary metabolites exhibiting antimicrobial properties (ohmyungsamycin, pellasoren, naringenin, and ansamycin) were identified in the genome. The most efficient period of SCPM-O-B-9993 strain cultivation was 72 h: during this period, the culture went from the exponential to the stationary growth phase as well as exhibited excellent phytostimulatory properties and antiviral activity against the cucumber mosaic virus in tomatoes under laboratory conditions. The Streptomyces carpaticus SCPM-OB-9993 strain is a biotechnologically promising producer of secondary metabolites exhibiting antiviral and phytostimulatory properties.

The genetic characteristics and protective potential of the Nocardiopsis tropica strains SCPM-O-B-12605 (RCAM04882) and SCPM-O-B-12606 (RCAM04883), previously identified as N. umidischolae, have been studied. In this study, we aimed to conduct a comparative analysis of the functional genetic pool of N. tropica strains SCPM-O-B-12605 and SCPM-O-B-12606 and evaluate the effectiveness of their culture suspensions in a field experiment on the Azhur F1 tomato variety in terms of phytostimulatory, insectoacaricidal, and antiviral activity. Field trials were conducted in open ground in an arid zone of southern Russia. A high degree of genetic similarity was established among the studied strains: the average nucleotide identity of their genomes was 99.9978%. At the same time, differences in the composition of biosynthetic gene clusters were identified. SCPM-O-B-12605 contains clusters of non‑ribosomal peptide synthesis, type I polyketide synthases, and terpene precursor biosynthesis; SCPM-O-B-12606 contains clusters of class III and IV lantipeptides. The genomes also contain genes associated with resistance to heavy metals, drought, and osmotic stress, including systems for the synthesis and transport of compatible osmolytes. The results indicate the potential of the studied strains for the development of biopreparations aimed at increasing productivity and protecting tomatoes in arid conditions.