Production of 2-butanol from crude glycerol by a genetically-engineered Klebsiella pneumoniae strain

Klebsiella pneumoniae was engineered to produce 2-butanol from crude glycerol as a sole carbon source by expressing acetolactate synthase (ilvIH), keto-acid reducto-isomerase (ilvC) and dihydroxyacid dehydratase (ilvD) from K. pneumoniae, and aketoisovalerate decarboxylase (kivd) and alcohol dehydrogenase (adhA) from Lactococcus lactis. Engineered K. pneumoniae, DldhA/pBR-iBO (ilvIH–ilvC– ilvD–kivd–adhA), produced 2-butanol (160 mg/L) from crude glycerol. To increase the yield of 2-butanol, we eliminated the 2,3-butanediol pathway from the recombinant strain by inactivating a-acetolactate decarboxylase (adc). This further engineering step improved the yield of 2-butanol from 160 to 320 mg/L. This represents the first successful attempt to produce 2-butanol from crude glycerol.