GC-MS identification of a lacthydrazide-class siderophore produced by Streptomyces sp. VITGV100: its antimicrobial activity and molecular docking

Abstract

The bacterial genus Streptomyces comprises well-known producers of bioactive compounds, mainly antibiotics. Specifically, the strain Streptomyces sp. VITGV100 shows promise as a potent antimicrobial source. This study investigates the activation of cryptic biosynthetic genes within this strain through chemical elicitation to amplify the production of secondary metabolites. To achieve this, Streptomyces sp. VITGV100 was cultured in nutrient broth supplemented with 0.5% dimethyl sulfoxide (DMSO) to elicit metabolic changes over 7, 14, and 21 days. The resulting crude extracts were screened for antimicrobial activity against four human pathogens: Escherichia coli (Microbial Type Culture Collection and Gene Bank [MTCC] 1687), Pseudomonas aeruginosa (MTCC 3541), Bacillus subtilis (MTCC 2756), and Staphylococcus aureus (MTCC 737). Bioactive fractions were characterized by gas chromatography-mass spectrometry (GC-MS). Finally, identified compounds, namely lacthydrazide, were docked against target proteins: E. coli Z-ring-associated protein (5IMJ), P. aeruginosa OXA10 (4WZ5), S. aureus TyrRS (1JIJ), and B. subtilis DLTA (3E7X). The 7-day crude extract exhibited the strongest antimicrobial activity, yielding a maximum inhibition zone of 31 mm against E. coli at 100 µg/ml and a minimum zone of 9 mm against B. subtilis at 25 µg/ml. GC-MS analysis revealed 45 distinct peaks in the included extracts versus 30 in controls, identifying lacthydrazide as a primary compound. Molecular docking confirmed the strong binding affinity of lacthydrazide to the target proteins, supporting its antimicrobial potential. Streptomyces sp. VITGV100, elicited with 0.5% DMSO, effectively activated cryptic genes to synthesize potent antibacterial compounds. These findings position this strain as a valuable resource for discovering novel antimicrobials.