Lignocellulose-degrading enzymes produced by the ascomycete Coniochaeta ligniaria and related species: Application for a lignocellulosic substrate treatment

Lignocellulose-degrading microorganisms are of interest for biomass upgrading. In a previous work, we isolated the ascomycete Coniochaeta ligniaria NRRL 30616 that metabolized phenolics and furans in lignocellulosic acid hydrolysates. This fungal isolate was investigated in the present work for the ability to produce lignocellulose-degrading enzymes during batch cultivation using different substrates as carbon source. This microorganism produced cellulase, xylanase and two lignin peroxidases (manganese peroxidase, MnP and lignin peroxidase, LiP), but laccase activity was not detected. The same enzyme activities were also found in 23 related fungal strains, and C. ligniaria NRRL 30616 showed the highest levels for some of the enzymes. Treatment of pepper plant residues (PPR) with this fungus was monitored during 20 days in solid and semisolid-state cultures. It was found that all enzymes initially detected were produced under these conditions at the early culture stages (5 days) and lignocellulose polymers were consequently degraded. Losses of about 75%, 50% and 40% were obtained for hemicellulose, cellulose and lignin, respectively, in semisolid cultures after 20 days. The lignocellulolytic activity of C. ligniaria detected in this study may be exploited for lignocellulosic biomass treatment.