Current knowledge on isobutanol production with Escherichia coli, Bacillus subtilis and Corynebacterium glutamicum.
Due to steadily rising crude oil prices great efforts have been made to develop designer bugs for the fermentative production of higher alcohols, such as 2-methyl-1-butanol, 3-methyl-1-butanol and 2-Methyl-1-propanol (isobutanol), which all possess quality characteristics comparable to traditional oil based fuels. The common metabolic engineering approach uses the last two steps of the Ehrlich pathway, catalyzed by 2-ketoacid decarboxylase and an alcohol dehydrogenase converting the branched chain 2-ketoacids of L-isoleucine, L-leucine, and L-valine into the respective alcohols. This strategy was successfully used to engineer well suited and industrially employed bacteria, such as Escherichia coli, Bacillus subtilis and Corynebacterium glutamicum for the production of higher alcohols. Among these alcohols, isobutanol is currently the most promising one regarding final titer and yield. This article summarizes the current knowledge and achievements on isobutanol production with E. coli, B. subtilis and C. glutamicum regarding the metabolic engineering approaches and process conditions.
Institute of Biochemical Engineering, University of Stuttgart, Stuttgart, Germany. blombach@ibvt.uni-stuttgart.de
Bastian
B
Blombach
Bernhard J
BJ
Eikmanns
D000426:Alcohol Dehydrogenase / Q000378:metabolism; D001412:Bacillus subtilis / Q000235:genetics* / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D000440:Butanols / Q000378:metabolism*; D002262:Carboxy-Lyases / Q000378:metabolism; D048230:Corynebacterium glutamicum / Q000235:genetics* / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D007218:Industrial Microbiology / Q000379:methods*; D007651:Keto Acids; D060847:Metabolic Engineering / Q000379:methods*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism
D001426:Bacterial Proteins; D000440:Butanols; D007651:Keto Acids; D011994:Recombinant Proteins; C040507:isobutyl alcohol; D000426:Alcohol Dehydrogenase; D002262:Carboxy-Lyases