Saccharothrix sp TD-093 from the Thar Desert, India: Metabolite Fingerprinting of Antimicrobial Compounds and in silico Analysis

During a screening program for actinomycetes from underexplored and arid Thar Desert (India), TD-093 was isolated. The isolate was characterized based on 16S rDNA sequencing. Aqueous and organic solvent extracts of culture supernatant were investigated for antimicrobial activity. Bioactive fractions, after column chromatography separation, were subjected to GC-MS analysis. Based on 16S rDNA sequence result, isolate TD-093 showed nearest match to Saccharothrix (96%) and is a potential new species. Aqueous and organic solvent extracts showed antimicrobial activity against Staphylococcus epidermidis, Micrococcus luteus, Pseudomonas fluorescens, and Escherichia coli as well as clinical isolates (Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli, and Acinetobacter baumannii). GC-MS metabolite fingerprinting resulted in 32 compounds belonging to fatty acid, hydrocarbon, alcohol, aldehyde, amide, ester, ketone, disulfide, and nitrile chemical groups. Combination analyses of the compounds based on retention time, similarity index, mass ion spectra, and retention indices-observed and calculated, showed that many of the compounds could be presumed to be novel. Further, four compounds showed retention indices that have not been documented in databases. In silico analysis (using software Prediction of Activity of Spectra for Substances) of compounds predicted by GC-MS data showed that 21 compounds had potential antibacterial activity.