Fed-batch approach to production of 2,3-butanediol by Klebsiella pneumoniae grown on high substrate concentrations

Abstract

The bioconversion of sugars present in wood hemicellulose to 2,3-butanediol by Klebsiella pneumoniae grown on high sugar concentrations was investigated. When K. pneumoniae was grown under finite air conditions in the presence of added acetic acid, 50 g of D-glucose and D-xylose per liter could be converted to 25 and 27 g of butanediol per liter, respectively. The efficiency of bioconversion decreased with increasing sugar substrate concentrations (up to 200 g/liter). Butanediol production at low sugar substrate concentrations was less efficient when the organism was grown under aerobic conditions; however, final butanediol values were higher for cultures grown on an initial sugar concentration of 150 g/liter, particularly when the inoculum was first acclimatized to high sugar levels. When a double fed-batch approach (daily additions of sugars together with yeast extract) was used under aerobic conditions, up to 88 and 113 g of combined butanediol and acetyl methyl carbinol per liter could be obtained from the utilization of 190 g of D-xylose and 226 g of D-glucose per liter, respectively.