title: A synergistic effect of pretreatment on cell wall structural changes in barley straw (Hordeum vulgare L.) for efficient bioethanol production.
abstract: BACKGROUND
  Barley straw (Hordeum vulgare L.) is an attractive lignocellulosic material and one of the most abundant renewable resources for fuel ethanol production. Although it has high cellulose and hemicellulose contents, there are several challenges and limitations in the process of converting it to fuel ethanol. High ash, silica and lignin contents in barley straw make it an inferior feedstock for enzymatic hydrolysis. Therefore pretreatment of barley straw could play an important role in inducing structural and compositional changes that increase the efficiency of enzymatic hydrolysis and make the whole process economically viable.
  
  
  RESULTS
  Saccharification was enhanced using various concentrations (0.0, 0.5, 1.0, 2.0 and 3.0% v/v) of a solution of sodium hypochlorite (NaClO) and hydrogen peroxide (H₂O₂) and various reaction times (15, 30 and 45 min) during pretreatment at 121 °C. The highest yield of glucose (447 mg g⁻¹) was achieved by pretreatment with 2.0% NaClO+H₂O₂ solution for 30 min, representing an increase of 65.99% compared with untreated barley straw (152 mg g⁻¹). During fermentation, the highest amount of ethanol (207 mg g⁻¹) was obtained under anaerobic plus 0.4 mmol L⁻¹ benzoic acid conditions, representing an increase of 57.49, 38.16 and 10.14% compared with untreated sample (88 mg g⁻¹), aerobic (128 mg g⁻¹) and anaerobic (186 mg g⁻¹) conditions respectively.
  
  
  CONCLUSIONS
  The results suggest that pretreatment with 2.0% NaClO+H₂O₂ solution disrupted the recalcitrant structure of barley straw and enhanced the glucose yield and subsequent bioethanol production.
authors.affiliation: Department of Environmental Material Science, IALS, Gyeongsang National University, Jinju 660-701, Republic of Korea.
authors.forename: Md Mominul Islam
authors.initials: MM
authors.lastname: Sheikh
authors.forename: Chul-Hwan
authors.initials: CH
authors.lastname: Kim
authors.forename: Hyeong-Hun
authors.initials: HH
authors.lastname: Park
authors.forename: Hye-Gyeong
authors.initials: HG
authors.lastname: Nam
authors.forename: Gyeong Sun
authors.initials: GS
authors.lastname: Lee
authors.forename: Hu Seung
authors.initials: HS
authors.lastname: Jo
authors.forename: Ji-Young
authors.initials: JY
authors.lastname: Lee
authors.forename: Jae Won
authors.initials: JW
authors.lastname: Kim
mesh_terms: D019817:Benzoic Acid / Q000494:pharmacology; D056804:Biofuels / Q000032:analysis*; D002473:Cell Wall / Q000737:chemistry / Q000187:drug effects* / Q000648:ultrastructure; D018556:Crops, Agricultural / Q000737:chemistry / Q000187:drug effects* / Q000378:metabolism / Q000382:microbiology; D004357:Drug Synergism; D000431:Ethanol / Q000032:analysis / Q000737:chemistry / Q000378:metabolism*; D005285:Fermentation; D005947:Glucose / Q000032:analysis / Q000737:chemistry / Q000378:metabolism; D001467:Hordeum / Q000737:chemistry / Q000187:drug effects* / Q000378:metabolism / Q000382:microbiology; D006861:Hydrogen Peroxide / Q000819:agonists / Q000494:pharmacology; D006868:Hydrolysis; D007700:Kinetics; D008031:Lignin / Q000032:analysis / Q000737:chemistry / Q000378:metabolism; D008855:Microscopy, Electron, Scanning; D016877:Oxidants / Q000819:agonists / Q000494:pharmacology; D035261:Plant Components, Aerial / Q000737:chemistry / Q000187:drug effects* / Q000378:metabolism / Q000382:microbiology; D056910:Republic of Korea; D012441:Saccharomyces cerevisiae / Q000254:growth & development / Q000378:metabolism; D012973:Sodium Hypochlorite / Q000819:agonists / Q000494:pharmacology; D013499:Surface Properties
chemical_list: D056804:Biofuels; D016877:Oxidants; C036909:lignocellulose; D000431:Ethanol; D019817:Benzoic Acid; D008031:Lignin; D006861:Hydrogen Peroxide; D012973:Sodium Hypochlorite; D005947:Glucose
keywords: barley straw; fermentation; lignocellulose; pretreatment; saccharification