Laccase production by Pycnoporus cinnabarinus grown on sugar-cane bagasse: Influence of ethanol vapors as inducer

Abstract : The influence of gaseous ethanol addition as inducer of laccase produced by Pycnoporus cinnabarinus ss3 in a biofilter packed with sugarcane bagasse was investigated. Gaseous-ethanol concentration up to 13.3 g m -3 allowed an important increment of laccase activity. Maximum of laccase production of 90 U g -1 dry support, which was 45 times higher than that without ethanol, was obtained for a concentration of about 7 gethanol m -3 (ethanol concentration in the liquid phase of 31 g L- 1). At this concentration, the maximum laccase activity was reached after 14 days, and then remained steady for 15 days. For other gaseous-ethanol concentrations, enzyme activity reached a maximum after 6–9 days, and then decreased. In spite of the inhibitory effect of ethanol on P. cinnabarinus ss3 growth, it provides an opportunity to improve the production of laccases. It is noteworthy that to obtain highest laccase production, ethanol vapours have to be added at the beginning of the experiment at a low air flow-rate of 40 mL min -1. A gradient of laccase activity down along the column was observed and correlated with gaseous-ethanol concentrations.