Low pH D-xylonate production with Pichia kudriavzevii

D-Xylonic acid is one of the top 30 most desirable chemicals to be derived from biomass sugars identified by the US Department of Energy, being applicable as a non-food substitute for D-gluconic acid and as a platform chemical. We engineered the non-conventional yeast Pichia kudriavzevii VU C-79090T to express a D-xylose dehydrogenase coding gene from Caulobacter crescentus. With this single modification the recombinant P. kudriavzevii strain produced up to 171 g L-1 of D-xylonate from 171 g L-1 D-xylose at a rate of 1.4 g L-1 h(-1) and yield of 1.0 g [g substrate consumed](-1), which was comparable with D-xylonate production by Gluconobacter oxydans or Pseudomonas sp. The productivity of the strain was also remarkable at low pH, producing 146 g L-1 D-xylonate at 1.2 g L-1 h(-1) at pH 3.0. This is the best low pH production reported for D-xylonate. These results encourage further development towards industrial scale production. (C) 2013 Elsevier Ltd. All rights reserved.