High laccase producing mutants ofPleurotus florida.

Pleurotus florida produced high amounts of laccase (4.60 U/ml) in malt extract broth after 12 days' growth under stationary conditions. The production of laccase was semi-constitutive. Hyperlaccase mutants ofP. florida were obtained through mutagenesis of mycelial protoplasts usingN-methyl-N'-nitro-N-nitrosoguanidine (50 μg/ml) for 2 min. Three hyperlaccase mutants were selected showing growth and enzyme production responses similar to the parent.