ARS | Publication request: Microbial based pretreatment of corn stover by white rot fungus

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: June 16, 2012
Publication Date: June 19, 2012
Citation: Saha, B.C., Cotta, M.A. 2012. Microbial based pretreatment of corn stover by white rot fungus [abstract]. American Society for Microbiology General Meeting. Poster No. 350.

Technical Abstract: Pretreatment, as the first step towards conversion of lignocellulosic feedstocks to ethanol, makes up one-third of the total production costs and remains one of the main barriers to commercial success. Typically, harsh methods are used to pretreat lignocellulosic biomass prior to its breakdown to sugars by enzymes, which also result in fermentation inhibitor formation. An alternative to harsh chemicals is microbial pretreatment employing fungi and their enzymes to break down or remove lignin from the holocellulose (cellulose and hemicellulose) surface. Twenty six white rot fungal cultures including Bjerkandera adjusta, Ceriporiopsis subvermispora, Cyathus stercoreus, Flamulina velutipes, Irpex lacteus, Phanerochaete chrysosporium, Phlebia brevispora, Polyporus compactus, Pycnoporus sanguineus and Rigidoporus crocatus were screened by growing them under solid state cultivation at 70% moisture level at 28 oC for 30 days using corn stover as feedstock for powerful ability to remove lignin from it with minimum loss of cellulose and hemicellulose. The lignin degrading enzymes (lignin peroxidase, manganese peroxidase and laccase) were assayed. In addition, we monitored the activities of cellulase and hemicellulase enzymes. The enzymatic hydrolysis of pretreated corn stover was performed at pH 5.0 and 45oC for 72 h using commercial cellulase, ß-glucosidase and hemicellulase enzyme preparations. There was significant enhancement of breakdown of corn stover to sugars by enzymes after the fungal pretreatment. The enhancement ability differed from culture to culture. A few fungal cultures were found to be good sources of lignocellulose degrading enzymes. Microbial pretreatment was mild and did not generate any typical fermentation inhibitors. Results of our screening, enzymatic saccharification and profile of various enzyme activities for each culture will be presented. Three strains produced ethanol from glucose. This research demonstrates that microbial pretreatment with a lignin degrading fungus has potential to be used for lignocellulosic biomass pretreatment.