Physiological Properties of a Mutant of Pachysolen tannophilus Deficient in NADPH-Dependent d-Xylose Reductase

Schneider, H.; Lee, H.; Barbosa, M.d.F.; Kubicek, C.P.; James, A.P.

Applied and Environmental Microbiology 55(11): 2877-2881


ISSN/ISBN: 0099-2240
PMID: 16348050
Accession: 049924393

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A d-xylose reductase mutant of Pachysolen tannophilus was isolated on the basis of its poor growth on d-xylose but normal growth on xylitol and d-glucose. Fractionation of cell extracts indicated that the mutant was deficient in d-xylose reductase activity that used NADPH exclusively as a cofactor, but not in activity that used both NADH and NADPH. Mutant cultures grown on d-xylose as the sole carbon source exhibited some properties that would be desired in improved strains. Growth rate, growth yield, and d-xylose consumption rate of the mutant were less sensitive than those of the wild type to changes in aeration rate. d-Xylose was utilized more efficiently in that less of a by-product, xylitol, was produced. In addition, under low aeration conditions, more ethanol was produced. A disadvantage was a relatively slow rate of d-xylose utilization.