title: Metabolic engineering of Acinetobacter baylyi ADP1 for improved growth on gluconate and glucose.
abstract: A high growth rate in bacterial cultures is usually achieved by optimizing growth conditions, but metabolism of the bacterium limits the maximal growth rate attainable on the carbon source used. This limitation can be circumvented by engineering the metabolism of the bacterium. Acinetobacter baylyi has become a model organism for studies of bacterial metabolism and metabolic engineering due to its wide substrate spectrum and easy-to-engineer genome. It produces naturally storage lipids, such as wax esters, and has a unique gluconate catabolism as it lacks a gene for pyruvate kinase. We engineered the central metabolism of A. baylyi ADP1 more favorable for gluconate catabolism by expressing the pyruvate kinase gene (pykF) of Escherichia coli. This modification increased growth rate when cultivated on gluconate or glucose as a sole carbon source in a batch cultivation. The engineered cells reached stationary phase on these carbon sources approximately twice as fast as control cells carrying an empty plasmid and produced similar amount of biomass. Furthermore, when grown on either gluconate or glucose, pykF expression did not lead to significant accumulation of overflow metabolites and consumption of the substrate remained unaltered. Increased growth rate on glucose was not accompanied with decreased wax ester production, and the pykF-expressing cells accumulated significantly more of these storage lipids with respect to cultivation time.
authors.affiliation: Department of Chemistry and Bioengineering, Tampere University of Technology, Tampere, Finland matti.kannisto@tut.fi.
authors.forename: Matti
authors.initials: M
authors.lastname: Kannisto
authors.affiliation: Department of Chemistry and Bioengineering, Tampere University of Technology, Tampere, Finland.
authors.forename: Tommi
authors.initials: T
authors.lastname: Aho
authors.affiliation: Department of Chemistry and Bioengineering, Tampere University of Technology, Tampere, Finland.
authors.forename: Matti
authors.initials: M
authors.lastname: Karp
authors.affiliation: Department of Chemistry and Bioengineering, Tampere University of Technology, Tampere, Finland.
authors.forename: Ville
authors.initials: V
authors.lastname: Santala
mesh_terms: D000150:Acinetobacter / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics; D029968:Escherichia coli Proteins / Q000235:genetics* / Q000378:metabolism; D015870:Gene Expression; D005942:Gluconates / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism*; D060847:Metabolic Engineering; D011770:Pyruvate Kinase / Q000235:genetics* / Q000378:metabolism
chemical_list: D029968:Escherichia coli Proteins; D005942:Gluconates; D011770:Pyruvate Kinase; D005947:Glucose; C030691:gluconic acid