title: Bioethanol production involving recombinant C. thermocellum hydrolytic hemicellulase and fermentative microbes.
abstract: The enhancement of the biomass productivity of Escherichia coli cells harbouring the truncated 903 bp gene designated as glycoside hydrolase family 43 (GH43) from Clostridium thermocellum showing hemicellulase activity along with its further use in simultaneous saccharification and fermentation (SSF) process is described. (Phosphoric acid) H(3)PO(4)-acetone treatment and ammonia fibre expansion (AFEX) were the pretreatment strategies employed on the leafy biomass of mango, poplar, neem and asoka among various substrates owing to their high hemicellulose content. GH43 showed optimal activity at a temperature of 50 °C, pH 5.4 with stability over a pH range of 5.0-6.2. A 4-fold escalation in growth of the recombinant E. coli cells was observed when grown using repeated batch strategy in LB medium supplemented with glucose as co-substrate. Candida shehatae utilizing pentose sugars was employed for bioethanol production. AFEX pretreatment proved to be better over acid-acetone technique. The maximum ethanol concentration (1.44 g/L) was achieved for AFEX pretreated mango (1%, w/v) followed by poplar with an ethanol titre (1.32 g/L) in shake flask experiments. A 1.5-fold increase in ethanol titre (2.11 g/L) was achieved with mango (1%, w/v) in a SSF process using a table top 2-L bioreactor with 1 L working volume.
authors.affiliation: Department of Biotechnology, Indian Institute of Technology Guwahati, Guwahati 781039, Assam, India.
authors.forename: Saprativ P
authors.initials: SP
authors.lastname: Das
authors.forename: Rajeev
authors.initials: R
authors.lastname: Ravindran
authors.forename: Shadab
authors.initials: S
authors.lastname: Ahmed
authors.forename: Debasish
authors.initials: D
authors.lastname: Das
authors.forename: Dinesh
authors.initials: D
authors.lastname: Goyal
authors.forename: Carlos M G A
authors.initials: CM
authors.lastname: Fontes
authors.forename: Arun
authors.initials: A
authors.lastname: Goyal
mesh_terms: D001483:Base Sequence; D019149:Bioreactors; D002175:Candida / Q000378:metabolism; D003001:Cloning, Molecular; D048013:Acetivibrio thermocellus / Q000201:enzymology / Q000378:metabolism*; D017931:DNA Primers; D004591:Electrophoresis, Polyacrylamide Gel; D000431:Ethanol / Q000378:metabolism*; D005285:Fermentation; D006026:Glycoside Hydrolases / Q000235:genetics / Q000378:metabolism*; D006868:Hydrolysis; D016133:Polymerase Chain Reaction; D011994:Recombinant Proteins / Q000378:metabolism
chemical_list: D017931:DNA Primers; D011994:Recombinant Proteins; D000431:Ethanol; D006026:Glycoside Hydrolases; C023305:hemicellulase