In particular,

the ability to biodegrade various types of dyes by white-rot fungi has proven to be effective, with their elimination being mediated through oxidoreduction reactions catalyzed by the lignin degrading enzymes they produce, click here such as lignin peroxidase, manganese peroxidase and laccase [10]. Most studies, dealing with ligninolytic enzyme production by white-rot fungi, have been carried out using the liquid culture conditions, in spite of the fact that these organisms grow in nature in solid-state conditions. Recent reviews on solid-state fermentation (SSF) point out the enormous potential of this culture technique for the development of different bioprocesses [11]. A lot of reports have emerged in the last few years describing the preparation and characterization of gold nanoparticles (GNPs), due to the extraordinary physicochemical characteristics and wide usages in different fields. Although preparation of nano-gold by physical procedures Talazoparib (such as laser ablation) provides GNPs with narrow range of particle size, it needs expensive equipment and has low yield [12]. Hazardous effects of organic solvents, reducing agents and toxic reagents applied for

chemical synthesis of GNPs on the environment, has encouraged the development of eco-friendly methods for preparation of gold Orotidine 5′-phosphate decarboxylase nanoparticles [13]. The aim of the present work is to optimize the production of laccase by Pleurotus

ostreatus under SSF and to evaluate the industrial applications of laccase in the decolorization of several dyes and in the synthesis of GNPs. Seven locally isolated fungal strains (Gliocladuim virens, Sclerotiam rolfsii, Penicilluim chrysogenum, Pleurotus ostreatus, Gliocladuim deliquescence, Rhizoctania solani and Penicilluim citrinum) were used in the study obtained from the culture collection in the Pharmaceutical Microbiology Laboratory Drug Radiation Research Department (NCRRT, Egypt). All strains were microscopically identified and kept on potato dextrose agar (PDA) at 4 °C and periodically sub-cultured to maintain viability. All strains were tested for production of laccase enzyme. Fermentation was done in 250 ml Erlenmeyer flasks, where 8 ml of distilled water were added to 5 gm carbon source (66% moisture content) [14]. The chosen concentrations of inducers were then added (according to the experiment design) and autoclaved at 121 °C for 20 min. The fungus was added to the medium as a 2 ml spore suspension (∼8 × 106 spores/ml) and incubated at 29 °C statically in complete darkness. After seven days, the whole contents of the flask were soaked in 100 ml, 1 mM citrate phosphate buffer (pH 5) for 2 h and put in a shaker at 200 rpm (LAB-Line R Orbit Environ, U.S.