Reinforcing sorbitol bio-oxidative conversion with Gluconobacter oxydans whole-cell catalysis by acetate-assistance

Abstract

Acetate (Ac-) is a critical factor for the biochemical regulation of G. oxydans which has widely applied in food industry. Herein, a basic scheme to determine the effect of Ac- concentrations on G. oxydans was established. Low concentrations of Ac- were beneficial in improving the whole-cell catalysis for sorbose bioconversion from 39.23 g/L to 53.79 g/L. From the enzyme activity test results showed that low Ac- concentration promoted enzyme activity by about 7% and increased the relative transcription level of membrane-bound sorbitol dehydrogenase (mSLD) by 2–3 times. The contradiction between the enhancement of relative transcription level and the inhibition of cell-growth and bio-conversion efficiency by high Ac- concentration was elucidated through the carbohydrate metabolism and adenosine triphosphate (ATP) assays. Finally, the bioprocess regulation of G. oxydans was determined through multi-dimensional comprehensive explorations. This study provides an increased understanding of G. oxydans and lays a solid theoretical foundation for its use as a food industrial bio-catalyst, especially to lignocellulosic hydrolysates.