Production of laccase by immobilized cells of Agaricus sp.: induction effect of xylan and lignin derivatives.

Laccase was produced in the supernatant of culture of a local isolate of Agaricus sp. obtained from decaying Ficus religiosa wood. The enzyme was produced at a constitutive level when growing the fungus in a nitrogen-limited medium supplemented with either glycerol, glucose, fructose, mannitol, arabinose, maltose, saccharose, cellulose, or cellobiose. A two- to sixfold increase in enzyme specific activity was observed when growing the strain in the presence of straw, xylan, xylose, lignosulfonate, veratryl alcohol, and ferulic and veratric acid. Experiments are consistent with the existence of an induction control on laccase and the absence of a form of carbon catabolite repression mediated by noninducing carbon sources. Immobilization of the Agaricus sp. on several supports, including polyurethane foam, textile strips, and straw, resulted in an increase of enzyme production as compared to cultivation in liquid medium.