Bioethanol production from hemicellulose rich Populus nigra involving recombinant hemicellulases from Clostridium thermocellum

Bioethanol was produced from poplar leafy biomass rich in hemicelluloses content involving recombinant Clostridium thermocellum hemicellulases and pentose sugar utilizing Candida shehatae. FT-IR analysis revealed effective AFEX pretreatment of poplar leaves. Repetitive batch strategy yielded similar to 1.5-fold rise in cell biomass and specific activity of both, acetylxylanesterase (Axe) and GH43 hemicellulase. TLC and HPAEC exhibited xylose and arabinose release from hydrolyzed biomass. SSF trial with 1% (w v (1)) pretreated poplar and mixed enzymes showed similar to 1.5-fold higher ethanol titre as compared with SHF. The shake flask SSF with 5% (w v (1)) pretreated poplar furnished 4.56 and 5.43 g L (1) ethanol with Axe and mixed enzymes, respectively. Whereas, bioreactor scale-up exhibited similar to 1.25-fold increase in ethanol titres (5.68, 6.75 g L (1)) as compared with shake flask with an yield of 0.295 (g g (1)) and 0.351 (g g (1)), respectively with Axe and mixed enzymes. (C) 2014 Elsevier Ltd. All rights reserved.