Antimicrobial Profile of Actinomycin D Analogs Secreted by Egyptian Desert Streptomyces sp. DH7

Abstract

Egyptian deserts are an underexplored ecological niche, especially the Sinai Peninsula. In our recent study, we explored this extreme environment and shed light on the bioactive capabilities of desert Actinobacteria isolated from Sinai. Fifty desert Actinobacteria were isolated from the Sinai desert using mineral salt media, basal media, and starch casein media. The filtrate of Streptomyces sp. DH 7 displayed a high inhibitory effect against multidrug-resistant Staphylococcus aureus (MRSA) strains. The 16S rDNA sequencing confirmed that isolate DH7 belongs to the genus Streptomyces. The NJ phylogenetic tree showed relatedness to the Streptomyces flavofuscus strain NRRL B-2594 and Streptomyces pratensis strain ch24. The minimum inhibitory concentrations against MRSA were 16 and 32 μg/μL. Chemical investigation of the ethyl acetate extract of Streptomyces sp. DH7 led to the isolation and purification of natural products 1–4. Structure elucidation of the purified compounds was performed using detailed spectroscopic analysis including 1 and 2D NMR, and ESI-MS spectrometry. To the best of our knowledge, this is the first report for the isolation of compounds 1–4 from a natural source, while synthetic analogs were previously reported in the literature. Compounds 3–4 were identified as actinomycin D analogues and this is the first report for the production of actinomycin D analogs from the Sinai desert with an inhibitory effect against MRSA. We indorse further study for this analog that can develop enhanced antimicrobial activities. We confirm that the desert ecosystems in Egypt are rich sources of antibiotic-producing Actinobacteria.

Actinomycins produced by endophyte Streptomyces sp. GLL‐9 from navel orange plant exhibit high antimicrobial effect against Xanthomonas citri susp. citri and Penicillium italicum

“…20,21 Streptomycetes belonging to the family Streptomycetaceae, are Gram-positive bacteria, which have a widespread distribution in nature and are found in soils, waters, as well as in plants as endophytes. 22 Actinomycins are a well-known class of chromopeptide isolated from many species of Streptomyces, and have been reported to exhibit anti-MRSA (methicillin-resistant Staphylococcus aureus), 23,24 antitumor, 25 and anti-tuberculosis 26 activities. Actinomycin consists of two macrocyclic pentapeptidolactones attached to an actinocinyl chromophore through amide bonds.…”

Biological control and plant growth promotion properties of Streptomyces albidoflavus St-220 isolated from Salvia miltiorrhiza rhizosphere

“…The strains of Streptomyces genus employ their secondary metabolites as weapons to inhibit phytopathogenic fungi ( Amin et al, 2021 ; Hotta, 2021 ; Mahasneh et al, 2021 ; Terra et al, 2021 ). In this study, genome sequencing revealed that the chromosome of the St. albidoflavus St-220 contained 21 conserved biosynthesis gene clusters (BGCs), of which 10 showed high similarities in structure with known BGCs encoding terpenes, non-ribosomal peptides, polyketides, siderophores, and ectoines, which had been proven to participate in the regulation of antimicrobial activities of Streptomyces strains ( van Bergeijk et al, 2020 ).…”