Antimicrobial Activity of Microorganisms Isolated from the Soil of the Tropical Desert of the Sinai Peninsula

Background . The spread of pathogenic antibiotic-resistant microorganisms often leads to the inefficiency of antimicrobial therapy. One of the solutions to this problem is the search for new active natural antibiotics. The aim of the study. The search for producers that show antibiotic activity in relation to resistant test microorganisms, including those from the ESKAPE group, in the natural environment. The object of the study was bacteria isolated from a poorly studied environment — the soil of the tropical desert, namely the soil of the Sinai Peninsula. Methods. Soil suspensions were sown on universal sterling agar environment No. 2 Gause, suitable for the growth of many bacteria and fungi. The isolated microorganisms were identified by morphological characteristics and by the analysis of ribosomal RNA genes. Deep cultivation was carried out in nutrient media of various compositions under aeration conditions. Test strains of gram-positive and gram-negative bacteria, as well as fungi, were used to evaluate antimicrobial activity. Results. 38 cultures of microorganisms were isolated: 9 strains of fungi, 5 strains of streptomycetes, 2 strains of Bacillus subtilis , and 22 strains of representatives of other taxonomic groups of bacteria. 5 strains of streptomycetes and 2 strains of B. subtilis exhibit antibiotic activity, in particular against resistant pathogens of the ESKAPE group, namely methicillin-resistant Staphylococcus aureus (MRSA), Pseudomonas aeruginosa , Escherichia coli , as well as Mycobacterium smegmatis — a preliminary test in the search for anti-tuberculosis drugs. Conclusion. The search for antibiotic producers from the isolated desert soil was productive, due to the fact that a quarter of the isolated bacterial strains exhibited antimicrobial activity, even against multidrug-resistant test strains. Bio-synthesis conditions have been developed for subsequent isolation and chemical study. The most promising strains are Streptomyces rochei INA 01452 and INA 01509, as well as Streptomyces sp. INA 01523.