Streptomyces Ghanaensis sp. VITHM1-mediated Green Synthesis of Gold Nanoparticles and its Cytotoxic Activity

Abstract

Microbial green synthesis of nanoparticles and exploiting them for biological applications has received considerable attention in the recent past. Gold (Au) nanoparticles were synthesised using Streptomyces ghanaensis sp. VITHM1 (MTCC #12465) biomass and evaluated for its cytotoxic activity. Au NPs were synthesised after 56 h of incubation of cell free supernatant with 1 mM HAuCl4 at room temperature. The synthesized NPs were characterized by UV-visible spectrum, X-ray diffraction (XRD), atomic force microscopy, scanning electron microscopy equipped with energy dispersive spectroscopy, transmission electron microscopy, fourier transform infrared spectroscopy, dynamic light scattering (DLS) and zeta potential. The synthesised gold nanoparticles were highly stable, spherical in shape and the average size was 30-50 nm. The secondary metabolites present in the biomass were identified by gas chromatography-mass spectrometry (GC-MS). The mechanism of formation of gold nanoparticles with the two major secondary metabolites present in the extracted biomass was proposed. The 3D structure of the unit cell in the synthesized nanoparticles was determined by XRD data base. The synthesized gold nanoparticles (200 µg/mL) exhibited admirable cytotoxic activity by inducing apoptosis in Hep-2 cells after 48 h of incubation. Gold nanoparticles (250 µg/mL) did not cause any haemolysis on human red blood cells. These results of this study suggest that Streptomyces biomass- mediated gold nanoparticles can be explored for cytotoxic activity