Factors affecting the production of the rare sugar l-xylulose from xylitol using resting cells were investigated. An E. coli BPT228 strain that recombinantly expresses a gene for xylitol dehydrogenase was used in the experiments. The ratio of xylitol to l-xylulose was three times lower in the cytoplasm than in the medium. The effects of pH, temperature, shaking speed, and initial xylitol concentration on l-xylulose production were investigated in shaking flasks using statistical experimental design methods. The highest production rates were found at high shaking speed and at high temperature (over 44°C). The optimal pH for both productivity and conversion was between 7.5 and 8.0, and the optimal xylitol concentration was in the range 250–350 g l−1. A specific productivity of 1.09 ± 0.10 g g−1 h−1 was achieved in a bioreactor. The response surface model based on the data from the shake flask experiments predicted the operation of the process in a bioreactor with reasonable accuracy.
|Number of pages||8|
|Journal||Journal of industrial microbiology and biotechnology|
|Publication status||Published - 2009|
|MoE publication type||A1 Journal article-refereed|
- rare sugars
- resting cells
- xylitol dehydrogenase