Effect of two wastes from groundnut processing on laccase production and dye decolourisation ability

The potential of two wastes generated by the groundnut processing industry such as groundnut shells and groundnut seeds for laccase production by the white-rot fungus Trametes hirsuta under solid state conditions was assessed. Groundnut seeds gave the highest laccase activities, showing average values around 600–700 nkat/L, which were around 10-fold higher than those attained in the groundnut shell cultures. In addition, the ability to degrade three structurally different dyes (Nickel (II) phthalocyanine, Lissamine Green B and Acid Black 48) by the extracellular liquid from the above cultures was analysed. Extracellular liquid from groundnut seed cultures was able to decolourise the three dyes tested, whereas the extracellular liquid from groundnut shell cultures only decolurised the dye Acid Black 48, indicating the different composition of the enzymatic complex secreted by each culture. Moreover, it was found that dye decolourisation strongly depended on pH. Thus, at pH 5.0 the dyes were hardly decolourised whereas at pH 3.0 they were decolourised to a certain extent.