title: Enhanced enzymatic hydrolysis of mild alkali pre-treated rice straw at high-solid loadings using in-house cellulases in a bench scale system.
abstract: In the present study, scale-up systems for cellulase production and enzymatic hydrolysis of pre-treated rice straw at high-solid loadings were designed, fabricated and tested in the laboratory. Cellulase production was carried out using tray fermentation at 45 °C by Aspergillus terreus in a temperature-controlled humidity chamber. Enzymatic hydrolysis studies were performed in a horizontal rotary drum reactor at 50 °C with 25 % (w/v) solid loading and 9 FPU g(-1) substrate enzyme load using in-house as well commercial cellulases. Highly concentrated fermentable sugars up to 20 % were obtained at 40 h with an increased saccharification efficiency of 76 % compared to laboratory findings (69.2 %). These findings demonstrate that we developed a simple and less energy intensive bench scale system for efficient high-solid saccharification. External supplementation of commercial β-glucosidase and hemicellulase ensured better hydrolysis and further increased the saccharification efficiency by 14.5 and 20 %, respectively. An attempt was also made to recover cellulolytic enzymes using ultrafiltration module and nearly 79-84 % of the cellulases and more than 90 % of the sugars were recovered from the saccharification mixture.
authors.affiliation: Sardar Patel Renewable Energy Research Institute, P. Box No. 2, Vallabh Vidyanagar, 388 120, Gujarat, India. madhuri68@gmail.com.
authors.forename: Madhuri
authors.initials: M
authors.lastname: Narra
authors.affiliation: Sardar Patel Renewable Energy Research Institute, P. Box No. 2, Vallabh Vidyanagar, 388 120, Gujarat, India.
authors.forename: Velmurugan
authors.initials: V
authors.lastname: Balasubramanian
authors.affiliation: Sardar Patel Renewable Energy Research Institute, P. Box No. 2, Vallabh Vidyanagar, 388 120, Gujarat, India.
authors.forename: Jisha P
authors.initials: JP
authors.lastname: James
mesh_terms: D000468:Alkalies / Q000378:metabolism*; D002480:Cellulase / Q000378:metabolism*; D004795:Enzyme Stability; D006868:Hydrolysis; D012275:Oryza / Q000378:metabolism*
chemical_list: D000468:Alkalies; D002480:Cellulase
keywords: Concentrated fermentable sugars; High-solid saccharification; In-house cellulases; Mild alkali pretreatment