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Biosynthesis of miglitol intermediate 6-(N-hydroxyethyl)-amino-6-deoxy-α-L-sorbofuranose by an improved D-sorbitol dehydrogenase from Gluconobacter oxydans

Ke, Xia, Wang, Ning-Ning, Yu, Pan-Hong, Lu, Yang-Hui, Hu, Zhong-Ce, Zheng, Yu-Guo
3 Biotech 2018 v.8 no.5 pp. 231
Gluconobacter oxydans, L-iditol dehydrogenase, biosynthesis, biotransformation, breeding, catalytic activity, colorimetry, fermentation, mutagenesis, mutants, screening, sorbitol, ultraviolet radiation
Adaptable exploitation of the catalytic potential of membrane-bound D-sorbitol dehydrogenase (mSLDH) from Gluconobacter oxydans is desperately needed in the industrial-scale production of miglitol. In the present study, a carbonyl group-dependent colorimetric quantification method was developed for the assay of miglitol key intermediate 6-(N-hydroxyethyl)-amino-6-deoxy-α-L-sorbofuranose (6NSL), and a high-throughput screening process of positive mutants was processed. Combined with several rounds of ultraviolet irradiation mutagenesis and screening procedure, a positive mutant strain G. oxydans ZJB16009 was obtained with significant increase in mSLDH catalytic activity by 1.5-fold, which exhibited an extremely accelerated uptake rate of D-sorbitol, and the fermentation time was significantly shortened from 22 to 11 h. In a 5-L biotransformation system, 60 g/L substrate N-2-hydroxyethyl glucamine (NHEG) was catalyzed by the resting cells of the mutant strain within 36 h and accumulated 53.6 g/L 6NSL, showing a 33.6% increase in the product yield. Therefore, it was indicated that the established high-throughput screening method could provide a highly efficient platform for the breading of G. oxydans strain for the industrial biosynthesis of miglitol intermediate 6NSL.