title: Two-stage fermentation for 2-Ketogluconic acid production by Klebsiella pneumoniae.
abstract: 2-Ketogluconic acid production by Klebsiella pneumoniae is a pH-dependent process, strictly proceeding under acidic conditions. Unfortunately, cell growth is inhibited by acidic conditions, resulting in low productivity of 2-ketogluconic acid. To overcome this deficiency, a two-stage fermentation strategy was exploited in the current study. During the first stage, the culture was maintained at neutral pH, favoring cell growth. During the second stage, the culture pH was switched to acidic conditions favoring 2-ketogluconic acid accumulation. Culture parameters, including switching time, dissolved oxygen levels, pH, and temperature were optimized for the fed-batch fermentation. Characteristics of glucose dehydrogenase and gluconate dehydrogenase were revealed in vitro, and the optimal pHs of the two enzymes coincided with the optimum culture pH. Under optimum conditions, a total of 186 g/l 2- ketogluconic acid was produced at 26 h, and the conversion ratio was 0.98 mol/mol. This fermentation strategy has successfully overcome the mismatch between optimum parameters required for cell growth and 2-ketogluconic acid accumulation, and this result has the highest productivity and conversion ratio of 2-ketogluconic and produced by microorganism.
authors.affiliation: Department of Biological Engineering, College of Environmental and Chemical Engineering, Yanshan University, Qinhuangdao, 066004, P. R. China, Laboratory of Biorefinery, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Pudong, Shanghai, 201210, P. R. China.
authors.forename: Yuehong
authors.initials: Y
authors.lastname: Sun
authors.forename: Dong
authors.initials: D
authors.lastname: Wei
authors.forename: Jiping
authors.initials: J
authors.lastname: Shi
authors.forename: Ljiljana
authors.initials: L
authors.lastname: Mojović
authors.forename: Zengsheng
authors.initials: Z
authors.lastname: Han
authors.forename: Jian
authors.initials: J
authors.lastname: Hao
mesh_terms: D061249:Batch Cell Culture Techniques / Q000379:methods*; D003470:Culture Media / Q000737:chemistry / Q000378:metabolism; D005285:Fermentation; D005942:Gluconates / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007711:Klebsiella pneumoniae / Q000254:growth & development / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism; D013696:Temperature
chemical_list: D003470:Culture Media; D005942:Gluconates; C008229:2-ketogluconate; D010100:Oxygen