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Title: Investigating the Role of Extensin Proteins in Poplar Biomass Recalcitrance

The biological conversion of cellulosic biomass to biofuel is hindered by cell wall recalcitrance, which can limit the ability of cellulases to access and break down cellulose. The purpose of this study was to investigate whether hydroxyproline-rich cell wall proteins (extensins) are present in poplar stem biomass, and whether these proteins may contribute to recalcitrance. Three classical extensin genes were identified in Populus trichocarpa through bioinformatic analysis of poplar genome sequences, with the following proposed names: PtEXTENSIN1 (Potri.001G019700); PtEXTENSIN2 (Potri.001G020100); PtEXTENSIN3 (Potri.018G050100). Tissue print immunoblots localized the extensin proteins in poplar stems to regions near the vascular cambium. Different thermochemical pretreatments reduced but did not eliminate hydroxyproline (Hyp, a proxy for extensins) from the biomass. Protease treatment of liquid hot water-pretreated poplar biomass reduced Hyp content by a further 16% and increased subsequent glucose yield by 20%. These data suggest that extensins may contribute to recalcitrance in pretreated poplar biomass, and that incorporating protease treatment into pretreatment protocols could result in a small but significant increase in the yield of fermentable glucose.
Authors:
 [1] ;  [2] ;  [3]
  1. Colorado State Univ., Fort Collins, CO (United States); USDA Agricultural Research Service, Fort Collins, CO (United States)
  2. National Renewable Energy Lab. (NREL), Golden, CO (United States)
  3. Colorado State Univ., Fort Collins, CO (United States)
Publication Date:
OSTI Identifier:
1254919
Report Number(s):
NREL/JA-2700-66526
Journal ID: ISSN 1930-2126
Grant/Contract Number:
AC36-08GO28308
Type:
Accepted Manuscript
Journal Name:
BioResources
Additional Journal Information:
Journal Volume: 11; Journal Issue: 2; Related Information: BioResources; Journal ID: ISSN 1930-2126
Publisher:
NC State University
Research Org:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Bioenergy Technologies Office (EE-3B)
Country of Publication:
United States
Language:
English
Subject:
09 BIOMASS FUELS; 59 BASIC BIOLOGICAL SCIENCES; extensin; hydroxyproline-rich glycoprotein; cellulosic biofuel; biomass recalcitrance; acid fungal protease; poplar; pretreatment