Functionalization with bio-molecules derived from oyster mushroom (Pleurotus florida) diminished the antibacterial potential of the mycogenic metal oxide nanoparticles (nps)

Mushrooms are mostly decomposers and possess the ability to digest food extracellularly by secreting specific enzymes. These enzymes and other bio-molecules present in the mycelium extracts of the P. florida have been used to produce zinc, copper and iron NPs extracellularly using metal salts as precursors. This work includes synthesis of metal oxide NPs by use of different concentrations (0.1to 0.9 mM) of three metal salts viz., zinc, copper and iron which were formed by incubating the salts with mycelium extracts of P. florida up to 96 hours under shaking conditions at 25±2°C in BOD incubator. The synthesis of the NPs was identified by performing the UV-Vis spectroscopy analysis at regular intervals to observe the time-dependent NPs synthesis. The visual color change in the reaction mixture was recorded and development of white, green and brown colors in zinc, copper andiron salt precursor containing sols respectively was recorded. The shape and formation of NPs was identified through TEM analysis. Incubation of the ferric chloride salt precursor with mycelial extract produced cubic shaped NPs. The antibacterial activity studies of the developed NPs using different concentrations (0.1 to 0.9 mM) along with the antibiotic standards (penicillin and gentamycin at the rate of 200 and 20 mg L-1 respectively) were performed against both gram positive and gram-negative bacteria. The results revealed formation of no inhibition zone by the biogenic NPs as compared to inhibition zones formed by the standard antibiotics (maximum 17 mm for E . coli in gentamycin).