Exploitation of a waste from the brewing industry for laccase production by two Trametes species

Abstract

Firstly, the potential of barley bran, a common waste from the brewing industry, as a support-substrate for laccase production by the well-known laccase producer Trametes versicolor under solid-state conditions was assessed. The effect of the initial ammonium concentration on laccase activity was also studied. Operating with barley bran at an initial ammonium concentration of 0.2 g/l, laccase activities were enhanced by 13-fold in relation to inert support cultures. Secondly, laccase production by T. versicolor and the newly isolated Trametes hirsuta grown on barley bran was improved by supplementing the cultures with 2,5-xylidine and copper sulphate. Thus, laccase from T. hirsuta cultures supplemented with both 1 mM copper sulphate and 2 mM xylidine was enhanced 5-fold. Finally, the in vitro decolourisation of several synthetic dyes by the extracellular liquid produced by T. hirsuta cultures was carried out. Decolourisation was more effective at pH 4 than 5. High decolourisation percentages in short incubation times were achieved for Bromophenol Blue, Indigo Carmine and Methyl Orange, whereas Poly R-478 presented much more resistance to degradation.