Lignin degradation in plants remnants under liquid-phase fermentation conditions

Abstract

Peroxidase, laccase and tyrosinase activities of micromycetes Galactomyces geotrichum, Myrothecium verrucaria, Mortierella verticillata, Sporotrichum pruinosum and Papularia sphaerosperma were investigated, and lignin degradation in rye straw by these fungi after 4, 8, 12, 16, 20 days of cultivation under liquid-phase fermentation conditions was evaluated. The maximum of peroxidase activity (136.25 a.u./ml) was detected in the case of Myrothecium verrucaria after 16 days of cultivation. The highest tyrosinase activity was shown by Galactomyces geotrichum after 20 days (1.25 c.u./ml) and by Myrothecium verrucaria after 12 days (1.06 c.u./ml). The laccase activity of all the micromycetes tested was weak. A higher enzymatic activity was found in Galactomyces geotrichum after 20 days (extinction coefficient 0.136). A more significant lignin degradation (to 8.81%) was performed by Myrothecium verrucaria within 16 days. This corresponded with the highest peroxidase activity. Keywords: phenoloxidases: peroxidase, tyrosinase, laccase, lignin