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

Abstract

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 dihydroxy-acid dehydratase (ilvD) from K. pneumoniae, and α-ketoisovalerate decarboxylase (kivd) and alcohol dehydrogenase (adhA) from Lactococcus lactis. Engineered K. pneumonia, {increment}ldhA/pBR-iBO (ilvIH-ilvC-ilvD-kivd-adhA), produced 2-butanol (160 mg l-1) from crude glycerol. To increase the yield of 2-butanol, we eliminated the 2,3-butanediol pathway from the recombinant strain by inactivating α-acetolactate decarboxylase (adc). This further engineering step improved the yield of 2-butanol from 160 to 320 mg l-1. This represents the first successful attempt to produce 2-butanol from crude glycerol.