Biodegradation of lignin in oil palm fronds by white rot fungi

Oil palm fronds are by-product from the harvesting of oil palms fresh fruits. Nowadays, oil palm fronds are used as roughage source for ruminants. However, its effective use is limited by poor nutrient compositions, mainly due to its high lignin and also low protein levels. White rot fungi which degrade cellulose, hemi-cellulose and lignin are widely used to increase the digestibility of agro-residues. In this research, sixty three isolates of white-rot fungi were isolated in Thailand, were screened for their ligninolytic enzymes production by agar plate screening method. The result showed that forty five isolates could produce laccase, manganese peroxidase, and/or lignin peroxides. Twenty seven isolates that exhibited high ligninolytic enzymes activity were selected to study the lignin degradation in oil palm fronds by solid-state fermentation. It was found that only seven isolates: OP04, OP06, OP13, OP16, OP47, OP53 and OP61 could reduce lignin in oil palm fronds from 30/s to 15-18% within 30 days at 30 degrees C and OP06 showed the highest laccase and manganese peroxidase activities of 0.896 +/- 0.02 and 0.799 +/- 0.07 U/g of dry weight, respectively.