Solid-state fermentation for enhanced production of laccase using indigenously isolated Ganoderma sp.

Laccase production by solid-state fermentation (SSF) using an indigenously isolated white rot basidiomycete Ganoderma sp. was studied. Among the various agricultural wastes tested, wheat bran was found to be the best substrate for laccase production. Solid-state fermentation parameters such as optimum substrate, initial moisture content, and inoculum size were optimized using the one-factor-at-a-time method. A maximum laccase yield of 2,400 U/g dry substrate (U/gds) was obtained using wheat bran as substrate with 70% initial moisture content at 25 degrees C and the seven agar plugs as the inoculum. Further enhancement in laccase production was achieved by supplementing the solid-state medium with additional carbon and nitrogen source such as starch and yeast extract. This medium was optimized by response surface methodology, and a fourfold increase in laccase activity (10,050 U/g dry substrate) was achieved. Thus, the indigenous isolate seems to be a potential laccase producer using SSF. The process also promises economic utilization and value addition of agro-residues.

Synthetic dye decolorization by white rot fungus, Ganoderma sp. WR-1.

Decolorization of recalcitrant dyes by an indigenous strain of white rot fungus isolated from bark of dead tree, WR-1 identified as Ganoderma sp. was investigated. The fermentation medium was optimized using a combination of one factor at a time and orthogonal array method. Maximum decolorization (96%) of 100 ppm amaranth was achieved in 8 h with optimized medium containing 2% starch and 0.125% yeast extract. Rate of dye decolorization by the indigenous isolate Ganoderma sp. WR-1 was very high compared to the most widely used strains of Trametes versicolor and Phanerochaete chrysosporium. The broad-spectrum decolorization efficiency of the isolate was assessed using chemically different dyes. The isolate was further evaluated for the decolorization of industrial effluent. Complete decolorization was achieved in 12 days.