SYNERGISTIC OLIGODYNAMIC EFFECT OF MYCOGENIC BIMETALLIC NANOPARTICLES WITH DAPTOMYCIN FOR CONTROLLING PATHOGENS

Bimetallic nanoparticles have several useful opto-electronic and catalytic properties that are different from those of monometallic nanoparticles. The development of non-toxic and eco-friendly protocols for the synthesis of bimetallic nanoparticles is a still less explored area. In the present study, bimetallic silver-gold nanoparticles were synthesized using Trichoderma reesei (NCIM 992). An effective approach for co-reduction of metal salts was adopted wherein the fungal biomass was grown under non-limiting conditions, followed by the addition of metal salts. The bio fabricated bimetallic nanoparticles were characterized using UV-Vis Spectroscopy, ICP-MS, SEM equipped with an EDS, FTIR and XRD. The fungal biomass color changed from colorless to dark purple within 2 days of incubation period. UV-Visible spectrum of the intracellularly produced bimetallic nanoparticles showed characteristic peak between 420 nm and 540 nm. ICP-MS of the residual salt concentration depicted the percentage of bioconversion of metal salts to metal nanoparticles. SEM-EDS studies confirmed the presence of intracellular silver-gold bimetallic nanoparticles. FT-IR analysis revealed the existence of peaks in the amide regions, a characteristic of chemical functional groups that are responsible for the reduction of metal ions and nanoparticles stabilization. XRD results determined that the nanoparticles ranged between 25 – 40 nm in size and were crystalline in nature with the face centered cubic symmetry. The synergistic oligodynamic effect of bimetallic nanoparticles along with Daptomycin showed enhanced antimicrobial activity against methicillin-resistant Staphylococcus and Micrococcus sp.