Wood Degradation and Optimized Laccase Production by Resupinate White-Rot Fungi in Northern Thailand

Pilanee Vaithanomsat, a, * Amornsri Sangnam, b Thitiya Boonpratuang, c Rattaket Choeyklin, a Patcharaporn Promkiam-on, c Sawitri Chuntranuluck, b and Torpong Kreetachat dOne hundred and thirty samples of resupinate white-rot fungi were collected from natural sites in Northern Thailand during the dry season (October-December) as a bioresource for lignin-degrading enzymes (laccase (Lac), lignin peroxidase (LiP), and manganese peroxidase (MnP)).All 130 isolated fungal strains grew well in potato dextrose broth and produced lignin-degrading enzymes at different levels after 7 days of incubation.The selected resupinate fungi, RCK783S, produced maximum Lac at 4,218 U/L, whereas MnP and LiP activities were detected at relatively low levels in all selected fungal strains.The RCK783S was further identified as a new record of Fibrodontia sp. in Thailand.Response surface methodology (RSM) was applied to evaluate the effect of medium composition, i.e., peptone, glycerol, L-asparagine, and CuSO 4 , on Lac production by Fibrodontia sp.RCK783S.The experiments showed optimum concentrations of peptone, glycerol, Lasparagine, and CuSO 4 at 0.625, 15.00, 2.188, and 0.003 g/L, respectively, to produce the highest Lac concentration of 6,086.01U/L, a 1.44-fold increase from that in the original medium.In addition, the degradation of Eucalyptus camaldulensis was investigated during the solid-state cultivation of Fibrodontia sp.RCK783S.The results showed that lignin was degraded, with lignin loss being 18% after 30 days, coinciding with the highest released Lac activity.