title: Bioconversion of water-hyacinth (Eichhornia crassipes) hemicellulose acid hydrolysate to motor fuel ethanol by xylose-fermenting yeast.
abstract: Water-hyacinth (Eichhornia crassipes) hemicellulose acid hydrolysate has been utilized as a substrate for ethanol production using Pichia stipitis NRRL Y-7124. Hydrolysate fermentability was considerable improved by boiling, and overliming up to pH 10.0 with solid Ca(OH)(2) in combination with sodium sulfite. The percent total sugar utilized and ethanol yield (Y(p/s)) for the untreated hydrolysate were 20.15+/-0.17% and 0.19+/-0.003 g(p) g(s)(-1), respectively, compared with 76.0+/-0.32% and 0.35 g(p) g(s)(-1), respectively for the treated material. The fermentation was very effective at an aeration rate of 0.02 v/v/m, temperature 30+/-0.2 degrees C and pH 6.0+/-0.2. However, the volumetric productivity (Q(p)) was still considerably less than observed in a simulated synthetic hydrolysate medium with a sugar composition similar to the hemicellulose acid hydrolysate. L-Arabinose was not fermented but assimilated. The presence of acetic acid in the hydrolysate decreased the ethanol yield and productivity considerably.
authors.affiliation: Biochemistry Division, Regional Research Laboratory, Jorhat, Assam 785 006, India. jn_nigam@yahoo.co.in
authors.forename: J N
authors.initials: JN
authors.lastname: Nigam
mesh_terms: D018533:Biomass; D000431:Ethanol / Q000032:analysis / Q000138:chemical synthesis* / Q000378:metabolism*; D005285:Fermentation; D005742:Gasoline; D006868:Hydrolysis; D010100:Oxygen / Q000378:metabolism* / Q000494:pharmacology; D010843:Pichia / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*; D010944:Plants / Q000378:metabolism*; D011134:Polysaccharides / Q000378:metabolism*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D005742:Gasoline; D011134:Polysaccharides; D000431:Ethanol; C007916:hemicellulose; D010100:Oxygen