title: Structural changes and enzymatic response of Napier grass (Pennisetum purpureum) stem induced by alkaline pretreatment.
abstract: Napier grass is a promising energy crop in the tropical region. Feasible alkaline pretreatment technologies, including NaOH, Ca(OH)2, NH3, and alkaline H2O2 (aH2O2), were used to delignify lignocellulose with the aim of improving glucose recovery from Napier grass stem cellulose via enzymatic saccharification. The influences of the pretreatments on structural alterations were examined using SEM, FTIR, XRD, and TGA, and the relationships between these changes and the enzymatic digestibility of cellulose were addressed. The extensive removal of lignin (84%) in NaOH-pretreated fibre agreed well with the high glucan conversion rate (94%) by enzymatic hydrolysis, while the conversion rates for fibre pretreated with Ca(OH)2, NH3, and aH2O2 approached 60%, 51%, and 42%, respectively. The substantial solubilisation of lignin created porosity, allowing increased cellulose accessibility to cellulases in NaOH-pretreated fibre. In contrast, high lignin content, lignin redeposition on the surface, and residual internal lignin and hemicellulose impeded enzymatic performance in Ca(OH)2-, NH3-, and aH2O2-pretreated fibres, respectively.
authors.affiliation: Division of Biochemical Technology, School of Bioresources and Technology, King Mongkut's University of Technology Thonburi, Bangkuntien, Bangkok 10150, Thailand. Electronic address: paripok.phi@kmutt.ac.th.
authors.forename: Paripok
authors.initials: P
authors.lastname: Phitsuwan
authors.affiliation: Graduated School of Bioresources, Mie University, 1577 Kurimamachiya-cho, Tsu 514-8507, Japan.
authors.forename: Kazuo
authors.initials: K
authors.lastname: Sakka
authors.affiliation: Division of Biochemical Technology, School of Bioresources and Technology, King Mongkut's University of Technology Thonburi, Bangkuntien, Bangkok 10150, Thailand.
authors.forename: Khanok
authors.initials: K
authors.lastname: Ratanakhanokchai
mesh_terms: D000468:Alkalies / Q000737:chemistry*; D064751:Ammonium Compounds / Q000737:chemistry; D002126:Calcium Hydroxide / Q000737:chemistry; D044602:Cellulases / Q000737:chemistry; D002482:Cellulose / Q000737:chemistry; D006861:Hydrogen Peroxide / Q000737:chemistry; D006868:Hydrolysis; D008031:Lignin / Q000737:chemistry; D031782:Pennisetum / Q000737:chemistry* / Q000648:ultrastructure; D018547:Plant Stems / Q000737:chemistry / Q000648:ultrastructure; D011134:Polysaccharides / Q000737:chemistry; D059205:Renewable Energy; D012972:Sodium Hydroxide / Q000737:chemistry
chemical_list: D000468:Alkalies; D064751:Ammonium Compounds; D011134:Polysaccharides; C036909:lignocellulose; D012972:Sodium Hydroxide; C007916:hemicellulose; D002482:Cellulose; D008031:Lignin; D006861:Hydrogen Peroxide; D044602:Cellulases; D002126:Calcium Hydroxide
keywords: Alkaline pretreatment; Cellulase; Cellulose accessibility; Lignin; Napier grass