title: Production of 2,3-butanediol by a low-acid producing Klebsiella oxytoca NBRF4.
abstract: 2,3-Butanediol (2,3-BDO) is a value-added chemical with great potential for the industrial production of synthetic rubber, plastic and solvent. For microbial production of 2,3-BDO, in this study, Klebsiella oxytoca NBRF4 was constructed by chemical mutation and screening against NaBr, NaBrO(3) and fluoroacetate. Among metabolic enzymes involved in the production of lactate, acetate and 2,3-BDO, K. oxytoca NBRF4 possessed 1.2 times lower specific activities of lactate dehydrogenase and phosphotransacetylase, and 22% higher specific acetoin reductase activity than the K. oxytoca ATCC43863 control strain. A series of batch fermentations in a defined medium and application of a statistical tool of response surface method led to the determination of optimal culture conditions: 10% dissolved oxygen level, pH 4.3 and 38°C. The actual results of batch fermentation at the optimal conditions using 44 g/L glucose were coincident with the predetermined values: 14.4 g/L 2,3-BDO concentration, 0.32 g/g yield. To increase 2,3-BDO titer, fed-batch fermentation of K. oxytoca NBRF4 was performed by an intermittent feeding of 800 g/L glucose to control its concentration around 5-20 g/L in the culture broth. Finally, 34.2g/L 2,3-BDO concentration and 0.35 g/g yield were obtained without organic acid production in 70 hours of the fed-batch culture, which were 2.4 and 1.2 times higher than those of the batch fermentation using 44 g/L glucose.
authors.affiliation: Department of Advanced Fermentation Fusion Science and Technology, Kookmin University, Seoul 136-702, Republic of Korea.
authors.forename: Sung-Hyuk
authors.initials: SH
authors.lastname: Han
authors.forename: Jung-Eun
authors.initials: JE
authors.lastname: Lee
authors.forename: Kyungmoon
authors.initials: K
authors.lastname: Park
authors.forename: Yong-Cheol
authors.initials: YC
authors.lastname: Park
mesh_terms: D000143:Acids / Q000378:metabolism*; D061249:Batch Cell Culture Techniques; D019149:Bioreactors / Q000382:microbiology; D001709:Biotechnology / Q000379:methods*; D002072:Butylene Glycols / Q000378:metabolism*; D049109:Cell Proliferation; D005285:Fermentation; D005947:Glucose / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D041121:Klebsiella oxytoca / Q000166:cytology / Q000201:enzymology / Q000378:metabolism*; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D053858:Metabolic Networks and Pathways; D009154:Mutation / Q000235:genetics; D010100:Oxygen / Q000378:metabolism; D010709:Phosphate Acetyltransferase / Q000378:metabolism; D013696:Temperature
chemical_list: D000143:Acids; D002072:Butylene Glycols; C026978:2,3-butylene glycol; D007770:L-Lactate Dehydrogenase; D010709:Phosphate Acetyltransferase; D005947:Glucose; D010100:Oxygen