Biodegradation of chlorolignin and lignin-like compounds contained in E1-pulp bleaching effluent by fungal treatment.

Abstract

The ligninolytic system from the fungi Trametes villosa and Panus crinitus can efficiently degrade all fractions of different molecular mass contained in E1-bleaching effluent, but with different degradation rates. The lower-molecular-mass (MM) materials were better characterized when the elution in the size-exclusion high-performance liquid chromatography were monitored at 210 than at 280 nm, which indicates that these compounds may be ring cleavage byproducts from depolymerized chlorolignin. The biodegradation of E1 effluent by both fungi was a multistage process, involving an initial chemical modification of the higher-MM compounds and concomitant oxidation of the lower-MM materials. A subsequent depolymerization of chemically modified polymeric lignin-like compounds also took place. Each stage may require one or several different enzymes. The results suggested that laccase was involved in the initial stage.