Laccase isolation by foam fractionation—New prospects of an old process

A laccase (E.C. 1.10.3.2) from Trametes spec. was isolated from aqueous media using foam fractionation. The pH value, superficial velocity, foaming period, and temperature were varied to optimise the transport of the active enzyme into the foam phase. Several detergents were added in varying concentrations to form and stabilize the foam, and the cationic detergent cetyltrimethylammonium bromide (CTAB) proved to be the most appropriate. From water as a model system, maximum recovery rates of 94% of laccase activity were achieved at pH 6.0 in 6 min. For separation of the enzyme from protein rich culture media, the operation conditions had to be adjusted. At pH 5.4, 89% of laccase activity was transported into the foam phase after 15 min. The method established was successfully applied to the isolation of an active laccase isoenzyme from submerged cultures of the basidiomycete Pleurotus sapidus.