Submitted to: Enzyme and Microbial Technology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/14/2006
Publication Date: 2/1/2007
Citation: Lopez, M.J., Vargas-Garcia, M., Suarez-Estrella, F., Nichols, N.N., Dien, B.S., Moreno, J. 2007. Lignocellulose-degrading enzymes produced by the ascomycete Coniochaeta ligniaria and related species: application for a lignocellulosic substrate treatment. Enzyme and Microbial Technology. 40:794-800. Interpretive Summary: Coniochaeta ligniaria is a fungus that can degrade compounds (phenolics and furans) that are toxic to many other microbes. In this work, this type of fungus was shown to also have a second valuable trait: the ability to break down plant cell walls. A group of 24 related strains was tested for production of enzymes that degrade the plant cell wall polymers cellulose, hemicellulose, and lignin. These strains constitute a new source of enzymes (cellulases, xylanases, and lignin peroxidases) for degrading cell walls. Some of these enzymes efficiently attack and degrade agricultural biomass and could be used to release sugars that could then be fermented to renewable fuels or chemicals.
Technical Abstract: Lignocellulose-degrading microorganisms are of interest for biomass upgrading. In 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 help to develop methods for lignocellulosic biomass upgrading.