earticle

영어

2,3-Butanediol (2,3-BDO) is a four-carbon chemical intermediate with industrial potentials for the production of synthetic rubber, plastic, antifreezing agent and octane enhancer. Traditional and chemical synthesis of 2,3-BDO has faced the drawback of the petroleum deficiency and environmental pollution that allows the development of microbial production of 2,3-BDO from renewable biomass. A potential microorganism for 2,3-BDO production, Klebsiella oxytoca is a gram negative bacteria grown in both aerobic and anaerobic conditions. In anaerobic or micro-aerobic condition, K. oxytoca generally produces 2,3-BDO from glucose as a carbon source because the 2,3-BDO synthetic enzymes play a role of the oxidation of NADH arising from glucose conversion to pyruvate. Since K. oxytoca has insufficient power of NAD oxidation by the 2,3-BDO synthetic enzymes, some organic acids are produced from pyruvate. To increase 2,3-BDO yield from glucose, organic acid production should be reduced. In this study, chemical mutation and evolutionary engineering were employed to obtain mutant strains of K. oxytoca containing the reduced ability of organic acid production. K. oxytoca mutant library was cultured in a medium containing both sodium bromide and sodium bromate, of which compound, bromine can kill high acid-producing strain and hence K. oxytoca mutants with reduced acid-forming ability were screened. Batch fermentation was carried out to validate the effect of organic acid production on 2,3-BDO production.