Metabolic flux analysis of Escherichia coli expressing the Bacillus subtilis acetolactate synthase in batch and continuous cultures.
Metabolically engineered Escherichia coli expressing the B. subtilis acetolactate synthase has shown to be capable of reducing acetate accumulation. This reduction subsequently led to a significant enhancement in recombinant protein production. The main focus of this study is to systematically examine the effect of ALS in the metabolic patterns of E. coli in batch and continuous culture. The specific acetate production rate of a strain carrying the B. subtilis als gene is 75% lower than that of the control strain (host carrying the control plasmid pACYC184) in batch cultures. The ALS strain is further demonstrated to be capable of maintaining a reduced specific acetate production rate in continuous cultures at dilution rates ranging from 0.1 to 0.4 h-1. In addition, this ALS strain is shown to have a higher ATP yield and lower maintenance coefficient. The metabolic flux analysis of carbon flux distribution of the central metabolic pathways and at the pyruvate branch point reveals that this strain has the ability to channel excess pyruvate to the much less toxic compound, acetoin.
Aristidou
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Department of Bioengineering and Chemical Engineering, Institute of Biosciences and Bioengineering, Rice University, P.O. Box 1892, Houston, Texas 77251-1892, USA.
San
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Bennett
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D000095:Acetolactate Synthase / Q000235:genetics / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism; D000693:Anaerobiosis; D001412:Bacillus subtilis / Q000201:enzymology*; D001709:Biotechnology / Q000379:methods; D002455:Cell Division; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D005285:Fermentation; D008954:Models, Biological; D009243:NAD / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism
D011994:Recombinant Proteins; D009243:NAD; D000255:Adenosine Triphosphate; D000095:Acetolactate Synthase