Increased laccase production by Trametes hirsuta grown on ground orange peelings

The present work focuses on the obtaining of high laccase activity levels by optimising several variables affecting laccase production under solid-state conditions. Thus, the effect of the addition of laccase-inducing compounds (syringaldazine, copper sulphate) and the amount of support utilised on laccase activity was studied. The highest activities (31,786 U/L) were obtained operating at the following conditions: 2.5 g ground orange peelings and 5 mM copper sulphate. The process was also scaled to 250 mL fixed-bed and 1.8 L tray reactors. The former produced maximal activities of about 3000 U/L, whereas the latter exhibited much higher values of around 12,000 U/L. To our knowledge, these activities are higher than those reported to date at bioreactor scale operating with a wild organism.