title: Pretreatment of lignocellulosic material with fungi capable of higher lignin degradation and lower carbohydrate degradation improves substrate acid hydrolysis and the eventual conversion to ethanol.
abstract: Phanerochaete chrysosporium, Pycnoporus cinnabarinus,and fungal isolates RCK-1 and RCK-3 were tested for their lignin degradation abilities when grown on wheat straw (WS) and Prosopis juliflora (PJ) under solid-state cultivation conditions. Fungal isolate RCK-1 degraded more lignin in WS (12.26% and 22.64%) and PJ (19.30% and 21.97%) and less holocellulose in WS (6.27% and 9.39%) and PJ (3.01% and 4.58%) after 10 and 20 days, respectively, than other fungi tested. Phanerochaete chrysosporium caused higher substrate mass loss and degraded more of holocellulosic content (WS: 55.67%; PJ: 48.89%) than lignin (WS: 18.89%; PJ: 20.20%) after 20 days. The fungal pretreatment of WS and PJ with a high-lignin-degrading and low-holocellulose-degrading fungus (fungal isolate RCK-1) for 10 days resulted in (i) reduction in acid load for hydrolysis of structural polysaccharides (from 3.5% to 2.5% in WS and from 4.5% to 2.5% in PJ), (ii) an increase in the release of fermentable sugars (from 30.27 to 40.82 g L(-1) in WS and from 18.18 to 26.00 g L(-1) in PJ), and (iii) a reduction in fermentation inhibitors (total phenolics) in acid hydrolysate of WS (from 1.31 to 0.63 g L(-1)) and PJ (from 2.05 to 0.80 g L(-1)). Ethanol yield and volumetric productivity from RCK-1-treated WS (0.48 g g(-1) and 0.54 g L(-1) h(-1), respectively) and PJ (0.46 g g(-1) and 0.33 g L(-1) h(-1), respectively) were higher than untreated WS (0.36 g g(-1) and 0.30 g L(-1) h(-1), respectively) and untreated PJ (0.42 g g(-1) and 0.21 g L(-1) h(-1), respectively).
authors.affiliation: Lignocellulose Biotechnology Laboratory, Department of Microbiology, University of Delhi South Campus, New Delhi-110021, India.
authors.forename: Sarika
authors.initials: S
authors.lastname: Kuhar
authors.forename: Lavanya M
authors.initials: LM
authors.lastname: Nair
authors.forename: Ramesh Chander
authors.initials: RC
authors.lastname: Kuhad
mesh_terms: D001487:Basidiomycota / Q000145:classification / Q000378:metabolism*; D001709:Biotechnology / Q000379:methods; D050260:Carbohydrate Metabolism; D002482:Cellulose / Q000378:metabolism*; D000431:Ethanol / Q000378:metabolism*; D005285:Fermentation; D006868:Hydrolysis; D008031:Lignin / Q000378:metabolism*; D010843:Pichia / Q000254:growth & development / Q000378:metabolism; D029862:Prosopis / Q000737:chemistry / Q000378:metabolism / Q000382:microbiology*; D014908:Triticum / Q000737:chemistry / Q000378:metabolism / Q000382:microbiology*
chemical_list: D000431:Ethanol; D002482:Cellulose; D008031:Lignin