Modification and Evolution of <Emphasis Type="Italic">Gluconobacter oxydans</Emphasis> for Enhanced Growth and Biotransformation Capabilities at Low Glucose Concentration |
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Authors: | Kun Zhu Leifang Lu Liujing Wei Dongzhi Wei Tadayuki Imanaka Qiang Hua |
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Institution: | (1) State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, 200237, China; |
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Abstract: | Gluconobacter oxydans is widely used in several biotechnological applications, where sorbitol or mannitol is commonly used as carbon source at
high concentration. In this study, a membrane-bound glucose dehydrogenase-deficient strain (GDHK) was constructed to eliminate
growth problems on glucose caused by direct oxidation of glucose in the medium. To achieve improved growth properties for
the GDHK strain on glucose, a laboratory adaptive evolution experiment was performed with glucose as the sole carbon source.
Results indicated evident, albeit modest, improvements in cell growth after a 50-day (about 430 generations) experimental
evolution on glucose. The maximum specific growth rate and biomass yield of the resulting GDHE50 strain were increased around
1.35- to 1.4-fold compared with those of the GDHK strain. Meanwhile, two types of biotransformation reactions using resting
cells of G. oxydans were investigated. Significant elevations in biotransformation performance of the GHDE50 strain were observed in comparison
with that of the wild-type strain. In addition, resting cells of the GDHE50 strain grown on a relatively low concentration
of glucose (10 g/l) could catalyze the biotransformation of glycerol to dihydroxyacetone and ethylene glycol to glycolic acid
as efficient as the wild-type G. oxydans cultured on higher concentration of sorbitol or other carbon sources. These results suggest very favorable prospects of using
glucose to lower production cost in many important industrial biocatalysis and biotransformation processes. |
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