Increase of xylitol yield by feeding xylose and glucose in Candida tropicalis.
Candida tropicalis, a strain isolated from the sludge of a factory manufacturing xylose, produced a high xylitol concentration of 131 g/l from 150 g/l xylose at 45 h in a flask. Above 150 g/l xylose, however, volumetric xylitol production rates decreased because of a lag period in cell growth. In fed-batch culture, the volumetric production rate and xylitol yield from xylose varied substantially with the controlled xylose concentration and were maximum at a controlled xylose concentration of 60 g/l. To increase the xylitol yield from xylose, feeding experiments using different ratios of xylose and glucose were carried out in a fermentor. The maximum xylitol yield from 300 g/l xylose was 91% at a glucose/xylose feeding ratio of 15%, while the maximum volumetric production rate of xylitol was 3.98 g l-1 h-1 at a glucose/xylose feeding ratio of 20%. Xylitol production was found to decrease markedly as its concentration rose above 250 g/l. In order to accumulate xylitol to 250 g/l, 270 g/l xylose was added in total, at a glucose/xylose feeding ratio of 15%. Under these conditions, a final xylitol production of 251 g/l, which corresponded to a yield of 93%, was obtained from 270 g/l xylose in 55 h.
Oh
D K
DK
Department of Food Science and Technology, Woosuk University, Chonbuk, Korea.
Kim
S Y
SY
D002175:Candida / Q000254:growth & development / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D005285:Fermentation; D005947:Glucose / Q000008:administration & dosage / Q000378:metabolism; D013997:Time Factors; D014993:Xylitol / Q000378:metabolism*; D014994:Xylose / Q000008:administration & dosage / Q000378:metabolism*
D014994:Xylose; D005947:Glucose; D014993:Xylitol