title: Enzymatic hydrolysis and ethanol production using xyloglucanase and Debaromyces hansenii from tamarind kernel powder: galactoxyloglucan predominant hemicellulose.
abstract: The hydrolysis and ethanol production from tamarind kernel powder (TKP), a rich source of galactoxyloglucan (GXG) was investigated for the first time using xyloglucanase and thermotolerant Debaromyces hansenii. The acid hydrolysis of TKP with 2N H(2)SO(4) at 120 degrees C for 30 min yielded an overall saccharification of 94% based on the total available carbohydrate content and further fermentation at 40 degrees C with thermotolerant D hansenii produced an ethanol yield of 0.35 g/g. A maximum hydrolysis of 55 and 78% for GXG was obtained in 48 h at 50 degrees C using Thermomonospora xyloglucanase (TXy) and accellerase1000, respectively. The synergistic effect of beta-galactosidase and xyloglucanase was demonstrated by the exogenous addition of beta-galactosidase to TXy which improved the overall hydrolysis of GXG by 30%. The rate of hydrolysis of GXG with TXy and accellerase was increased by 15-20% in the presence of chemical surfactants (tween 80 and toluene) or protein additive (BSA). The fermentation of enzymatic hydrolysates of GXG by TXy and accellerase with free cells at 40 degrees C produced an ethanol yield of 0.39 and 0.41 g/g whereas with immobilized cells produced 0.45 and 0.43 g/g, respectively, with a theoretical conversion efficiencies of 78-88%. The immobilized yeast cells were reused six times at 40 degrees C with 100% fermentation efficiency.
authors.affiliation: Division of Biochemical Sciences, National Chemical Laboratory, Pashan, Pune, Maharashtra, India.
authors.forename: Vishnu
authors.initials: V
authors.lastname: Menon
authors.forename: Gyan
authors.initials: G
authors.lastname: Prakash
authors.forename: Mala
authors.initials: M
authors.lastname: Rao
mesh_terms: D055165:Debaryomyces / Q000378:metabolism*; D000431:Ethanol / Q000138:chemical synthesis / Q000378:metabolism*; D005936:Glucans / Q000378:metabolism*; D006026:Glycoside Hydrolases / Q000737:chemistry*; D006868:Hydrolysis; D010936:Plant Extracts / Q000737:chemistry; D011134:Polysaccharides / Q000737:chemistry*; D011208:Powders; D029861:Tamarindus / Q000737:chemistry*; D001616:beta-Galactosidase / Q000737:chemistry*
chemical_list: D005936:Glucans; D010936:Plant Extracts; D011134:Polysaccharides; D011208:Powders; D000431:Ethanol; C007916:hemicellulose; D006026:Glycoside Hydrolases; C072818:xyloglucan endo(1-4)-beta-D-glucanase; D001616:beta-Galactosidase