Enhancement of cell growth and glycolic acid production by overexpression of membrane-bound alcohol dehydrogenase in Gluconobacter oxydans DSM 2003.
Membrane-bound alcohol dehydrogenase (mADH) was overexpressed in Gluconobacter oxydans DSM 2003, and the effects on cell growth and glycolic acid production were investigated. The transcription levels of two terminal ubiquinol oxidases (bo3and bd) in the respiratory chain of the engineered strain G. oxydans-adhABS were up-regulated by 13.4- and 3.8-fold, respectively, which effectively enhanced the oxygen uptake rate, resulting in higher resistance to acid. The cell biomass of G. oxydans-adhABS could increase by 26%-33% when cultivated in a 7L bioreactor. The activities of other major membrane-bound dehydrogenases were also increased to some extent, particularly membrane-bound aldehyde dehydrogenase (mALDH), which is involved in the catalytic oxidation of aldehydes to the corresponding acids and was 1.26-fold higher. Relying on the advantages of the above, G. oxydans-adhABS could produce 73.3gl-1glycolic acid after 45h of bioconversion with resting cells, with a molar yield 93.5% and a space-time yield of 1.63gl-1h-1. Glycolic acid production could be further improved by fed-batch fermentation. After 45h of culture, 113.8gl-1glycolic acid was accumulated, with a molar yield of 92.9% and a space-time yield of 2.53gl-1h-1, which is the highest reported glycolic acid yield to date.
State Key Laboratory of Bioreactor Engineering, New World Institute of Biotechnology, East China University of Science and Technology, Shanghai 200237, China.
Huan
H
Zhang
State Key Laboratory of Bioreactor Engineering, New World Institute of Biotechnology, East China University of Science and Technology, Shanghai 200237, China.
Lulu
L
Shi
State Key Laboratory of Bioreactor Engineering, New World Institute of Biotechnology, East China University of Science and Technology, Shanghai 200237, China.
Xinlei
X
Mao
State Key Laboratory of Bioreactor Engineering, New World Institute of Biotechnology, East China University of Science and Technology, Shanghai 200237, China. Electronic address: jplin@ecust.edu.cn.
Jinping
J
Lin
State Key Laboratory of Bioreactor Engineering, New World Institute of Biotechnology, East China University of Science and Technology, Shanghai 200237, China.
Dongzhi
D
Wei
D000426:Alcohol Dehydrogenase / Q000096:biosynthesis* / Q000378:metabolism; D000444:Aldehyde Dehydrogenase / Q000378:metabolism; D061249:Batch Cell Culture Techniques; D018533:Biomass; D019149:Bioreactors; D004789:Enzyme Activation; D005285:Fermentation; D020600:Gluconobacter oxydans / Q000201:enzymology / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D006016:Glycolates / Q000378:metabolism*; D008566:Membranes / Q000201:enzymology*; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000096:biosynthesis / Q000378:metabolism
D006016:Glycolates; C031149:glycolic acid; D010088:Oxidoreductases; D000426:Alcohol Dehydrogenase; C432586:ubiquinol oxidase; D000444:Aldehyde Dehydrogenase
Alcohol dehydrogenase; Gluconobacter oxydans; Glycolic acid; Respiratory chain