Background: The rapid spread of antibiotic resistance has increased research interest in the discovery of natural products, mainly from actinomycetes, which have been the primary source of antimicrobial compounds. This study aimed to isolate, characterize, and optimize the production of some of the bioactive compounds from bioactive soil actinomycetes. Results: One promising soil actinomycete, which was molecularly identified as Streptomyces sp. and designated as Streptomyces sp. MS. 10, showed broad-spectrum antimicrobial activity, including activity against methicillin-resistant Staphylococcus aureus. Thus, it was selected for isolation of its major bioactive compounds. Polymerase chain reaction amplification of the genes responsible for antibiotic biosynthesis showed the presence of genes encoding type I and type II polyketide synthase. Liquid chromatography-mass spectrometry analysis found that the major antimicrobial compounds produced by Streptomyces sp. MS. 10 were weakly ionized bioactive secondary metabolites. A large-scale fermentation experiment of Streptomyces sp. MS. 10 using pre-optimized culture conditions followed by bioassay-guided chromatographic separation of its secondary metabolites resulted in the isolation of putative bioactive compounds that were identified as fatty acids using proton nuclear magnetic resonance spectroscopy. Conclusions: Egyptian soil is still a good source for exploring bioactive actinomycetes. Additionally, this study highlighted the importance of combining both physicochemical and genotypic characterization with spectroscopic analysis of the major natural products when isolating bioactive metabolites.

Background: Polycyclic aromatic hydrocarbons (PAHs) such as anthracene are one of the most toxic contaminants to our environment. Microbial biodegradation of these xenobiotics is a cost-effective technological solution. The present study aimed to recover some bacterial isolates from Beni-Suef Governorate in Egypt with high capabilities of anthracene biodegradation. The selected isolates were molecularly characterized by 16S rRNA gene sequencing, the degree of anthracene biodegradation was monitored using optical density (OD) and high-performance liquid chromatography (HPLC), PCR amplification of some selected genes encoding biodegradation of PAHs was monitored, and gas chromatography–mass spectrometry (GC–MS) analysis was applied for detecting the resulted metabolites. Result: Three bacterial isolates were studied, the 16s rRNA sequences of the isolates showed homology of the first isolate to Brevibacillus sp. (94.58 %), the second isolates showed homology to Pseudomonas sp. (94.53%) and the third isolate showed homology to Methylocystis sp. (99.61 %), all isolates showed the ability to degrade anthracene. PCR amplification of some selected genes encoding biodegradation of PAHs revealed the presence of many biodegrading genes in the selected strains. Gas chromatography-mass spectrometry (GC–MS) analysis of the metabolites resulted from anthracene biodegradation in the present study suggested that more than one biodegradation pathway was followed by the selected isolates. Conclusions: The selected strains could represent a potential bioremediation tool in solving the PAHs problem in the Egyptian environment with a clean and cost-effective technique. Graphical