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Biologically synthesized nanoparticles are gaining importance as they offer several advantages, such as the ease with which they can be scaled up, the cost-effectiveness of the process and the green route of production. In this study, silver (Ag) nanoparticles were biosynthesized using the cellular extract of Penicillium oxalicum GRS-1 and then characterized by ultraviolet visible spectroscopy, X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy. The biosynthesis of nanoparticles was optimized by following the one factor at a time approach, wherein the temperature of 60°C, pH 7.0 and 1.5 mm silver nitrate (AgNO3) concentration were found to be most favorable factors for the production of Ag nanoparticles. Upon statistical optimization, the maximum production of Ag nanoparticles with a concentration of 136 ppm was achieved at pH 7.2, AgNO3 concentration 1.975 mm and 86 h using the crude cellular extract of P. oxalicum GRS-1 having nitrate reductase activity. TEM analysis showed that the Ag nanoparticles were spherical in shape with sizes ranging from 10 to 40 nm. The biosynthesized nanoparticles showed strong antimicrobial activity against the common food-borne, pathogens including Staphylococcus aureus, Escherichia coli and Salmonella typhimurium with respective minimum bactericidal concentrations of 32, 16 and 32 μg/ml.

Microbial sources for phospholipase A1 (PLA1) are economic and industry relevant for degumming of oils and also their product lyso-phospholipids have been widely used as emulsifying agent. Numerous PLAs1 have been reported, but still the few enzymes have got position in the commercial sector. Due to enormous demand of PLA1 in the industrial sector, the present study was carried out to optimize PLA1 production using cheaper agro-industrial waste like defatted rice bran. For this, defatted rice bran was used in solid state fermentation for the production of PLA1.One-factor at a time approach was used to obtain maximum production of 51.5 U/gm which is 2.15 folds more than un-optimized medium. The optimized medium components were (pH 7): defatted rice bran (5gm), glucose (1% w/v), peptone (1% w/v) and olive oil (0.5 % v/v) with moisture content of 1:1.5 and after 48h of incubation at 37°C. This approach will provide the cleaner solution for degumming of oil as compare to the acid degumming and also help to reduce the stress of the environment by utilizing waste. This is the first report where in Bacillus subtilis subsp. inaquosorum was employed for PLA1 production via solid state fermentation. [ABSTRACT FROM AUTHOR]