Laccase and Mn-Peroxidase Production by Coriolus hirsutus Strain 075 in a Jar Fermentor.

Abstract

The white-rot fungus Coriolus hirsutus strain 075 excretes considerable amounts of laccase and Mn-peroxidase into culture broth over a brief production time. The effects of agitation speed, temperature, aeration and inoculum amount on laccase production using a 10-l fermentor were studied. The optimum fermentation conditions were a 15% inoculum, an aeration rate of 0.88 vvm, an agitation speed of 160 rpm, and a temperature of 28°C. By optimizing the fermentation conditions, the laccase activity reached 80±3 U/ml in 3 d and the purified enzyme output was 30 mg/l. The laccase and Mn-peroxidase were purified by means of isoelectrofocusing and ion-exchange chromatography. The pIs of the laccase isoenzymes were 4.2 and 4.5. Mn-peroxidase had only one isoenzyme with a pI of 3.2. The optimum pH was 4.5 for laccase with syringaldazine as the substrate and 5.0–5.3 for Mn-peroxidase with Mn+2 and H2O2 as the substrates. The laccase and Mn-peroxidase retained 50% of their activities at 50°C after 55 h and 12 h of incubation time, respectively.