Abstract
Green biosynthesis of nanoparticles yielded from the extracellular metabolites of marine derived actinomycetes is covering enormous attention due to their superior applications and broad spectrum of bioactive secondary metabolites. The present study aimed to explore the characterization of novel bioactive Streptomyces sp. Al-Dhabi-89 derived from the Arabian Gulf region of Dammam was authenticated based on their physiological, biochemical characterization and molecular level amplification of the 16S rRNA was guided for the green biosynthesis of silver nanoparticles from the cell free extract. The reducing potential of Streptomyces sp. Al-Dhabi-89 cell surface extracts was explored for the green synthesis of the silver nanoparticles without the supplementation of the external capping substance, were characterized by UV-Vis, XRD, SEM, TEM, EDX, FTIR, and antimicrobial activities were determined by performing broth micro-dilution techniques. Results indicated that UV-Vis absorption spectrum of the bio-reduced nanoparticles documented the major peak at 310 nm confirmed the silver nanoparticles surface plasmon resonance. TEM and SEM characterization authenticated the morphological size ranged from 11 to 21 nm and cubic in their appearances; in addition, FTIR spectrum revealed variation in the band values from 626 cm
to 3432 cm
respectively. While, the EDX study pronounced strong band at 3 keV evidenced the presence of metallic silver. The synthesized nanoparticles showed better antimicrobial activity against the standard Gram-negative bacteria such as Escherichia coli (31.25 μg/ml), Klebsiella pneumoniae (62.5 μg/ml), and Pseudomonas aeruginosa (15.6 μg/ml) respectively. In addition, the prolific MIC values against the drug resistant clinical pathogens namely Acinetobacter baumannii (7.81 μg/ml), multidrug resistant Staphylococcus aureus (7.81 μg/ml) and Proteus mirabilis (15.6 μg/ml) were its advantage. Alternatively, considerable activity towards the wound infecting bacteria Enterococcus faecium (62.5 μg/ml) was its value-added properties. In conclusion, the silver nanoparticles produced from marine Streptomyces sp. Al-Dhabi-89 exhibited potential activity against both standard and clinical drug resistant microbial pathogens.