Phage-resistant Streptomyces abietis and its telomycin bioactive metabolite as a possible alternative to antibiotics.

Multidrug-resistant pathogens are now thought to be the primary global causes of disease and death. Therefore, it is imperative to develop new effective bioactive compounds from microbial sources, such as Streptomyces species. Nevertheless, the pharmaceutical industry suffered financial losses and low-quality end products as a result of Streptomyces bacteriophage contamination. To reduce the likelihood of phage-induced issues in the medical industry, it is crucial to develop a method for finding phage-resistant strains. Hence, we aimed to isolate and characterize Streptomyces spp. and Streptomyces phages from various rhizospheric soil samples in Egypt and to investigate their antibacterial activities. Moreover, we targeted development of a Streptomyces phage-resistant strain to extract its active metabolites and further testing its antibacterial activity. Herein, the antibacterial activities of the isolated 58 Streptomyces isolates showed that 10 (17.2 %) Streptomyces isolates had antibacterial activities against the tested bacteria including Listeria monocytogenes, E. coli O157, Acinetobacter baumannii, methicillin resistant-vancomycin-intermediate Staphylococcus aureus (MRSA-VISA) and Micrococcus luteus. Three lytic bacteriophages (ϕPRSC1, ϕPRSC2, and ϕPRSC4) belonging to the families Siphoviridae and Podoviridae were obtained from the rhizospheric soil samples using the most potent S. abietis isolate as the host strain. The three isolated Streptomyces phages were thermostable, ultraviolet stable, infectious, and had a wide range of hosts against the 10 tested Streptomyces isolates with antibacterial activities. The DNA of the ϕPRSC1 and ϕPRSC4 phages were resistant to digestion by EcoRI and HindIII, but the DNA of ϕPRSC2 was resistant to digestion by EcoRI and sensitive to digestion by HindIII. Of note, we developed a S. abietis strain resistant to the three isolated phages and its antibacterial activities were twice that of the wild strain. Finally, telomycin was recognized as an antibacterial metabolite extracted from phage-resistant S. abietis strain, which was potent against the tested Gram-positive bacteria including L. monocytogenes, MRSA-VISA, and M. luteus. Thus, our findings open new horizons for researching substitute antimicrobial medications for both existing and reemerging illnesses.