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Carbon Material and Bioenergetic Balances of Xylitol Production from Corncobs by Debaryomyces hansenii
Author(s) -
Rivas Beatriz,
Torre Paolo,
Manuel Domínguez José,
Perego Patrizia,
Converti Attilio,
Carlos Parajó Juan
Publication year - 2003
Publication title -
biotechnology progress
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.572
H-Index - 129
eISSN - 1520-6033
pISSN - 8756-7938
DOI - 10.1021/bp025794v
Subject(s) - xylitol , debaryomyces hansenii , chemistry , xylose , arabitol , fermentation , food science , pichia stipitis , yeast , biomass (ecology) , hydrolysis , biochemistry , biology , agronomy
The effect of oxygenation on xylitol production by the yeast Debaryomyces hansenii has been investigated in this work using the liquors from corncob hydrolysis as the fermentation medium. The concentrations of consumed substrates (glucose, xylose, arabinose, acetate and oxygen) and formed products (xylitol, arabitol, ethanol, biomass and carbon dioxide) have been used, together with those previously obtained varying the hydrolysis technique, the level of adaptation of the microorganism, the sterilization procedure and the initial substrate and biomass concentrations, in carbon material balances to evaluate the percentages of xylose consumed by the yeast for the reduction to xylitol, alcohol fermentation, respiration and cell growth. The highest xylitol concentration (71 g/L) and volumetric productivity (1.5 g/L·h) were obtained semiaerobically using detoxified hydrolyzate produced by autohydrolysis‐posthydrolysis, at starting levels of xylose ( S 0 ) and biomass ( X 0 ) of about 100 g/L and 12 g DM /L, respectively. No less than 80% xylose was addressed to xylitol production under these conditions. The experimental data collected in this work at variable oxygen levels allowed estimating a P / O ratio of 1.16 mol ATP /mol O . The overall ATP requirements for biomass production and maintenance demonstrated to remarkably increase with X 0 and for S 0 ≥ 130 g/L and to reach minimum values (1.9–2.1 mol ATP /C‐mol DM ) just under semiaerobic conditions favoring xylitol accumulation.