Effect of starting xylose concentration on the microaerobic metabolism of Debaryomyces hansenii: the use of carbon material balances.
Xylitol production by Debaryomyces hansenii NRRL Y-7426 was performed on synthetic medium varying the initial xylose concentration between 50 and 300 g/L. The experimental results of these tests were used to investigate the effect of substrate level on xylose consumption by this yeast. Satisfactory values of product yield on substrate (0.74-0.83 g/g) as well as volumetric productivity (0.481-0.694 g/L x h) were obtained over a wide range of xylose levels (90-200 g/L), while a worsening of kinetic parameters took place at higher concentration, likely due to a substrate inhibition phenomenon. The metabolic behavior of D. hansenii was studied, under these conditions, through a carbon material balance to estimate the fractions of xylose consumed by the cell for different activities (xylitol production, biomass growth, and respiration) during the lag, exponential, and stationary phases.
Converti
Attilio
A
Department of Chemical and Process Engineering G.B. Bonino, University of Genoa, Italy. converti@unige.it
Perego
Patrizia
P
Sordi
Andrea
A
Torre
Paolo
P
D018533:Biomass; D002244:Carbon / Q000032:analysis / Q000378:metabolism; D002245:Carbon Dioxide / Q000032:analysis; D002851:Chromatography, High Pressure Liquid; D004579:Electron Transport / Q000502:physiology; D005285:Fermentation / Q000502:physiology; D007700:Kinetics; D004718:Saccharomycetales / Q000254:growth & development / Q000378:metabolism*; D013379:Substrate Specificity; D014993:Xylitol / Q000096:biosynthesis*; D014994:Xylose / Q000378:metabolism* / Q000494:pharmacology
D002245:Carbon Dioxide; D002244:Carbon; D014994:Xylose; D014993:Xylitol