Recently, lactic acid bacteria (LAB) have attracted a great deal
of interest because of their potential to serve as oral delivery
vehicles for recombinant protein vaccines. An important limitation
to their use is the typically low level of heterologous expression
obtained in LAB. to address this, a dynamic flux balance analysis
(DFBA) model was used to identify gene targets for increasing specific
expression of Green Fluorescent Protein (GFP), a model heterologous
protein, in Lac to coccus lactis IL1403. Two strains, each targeting
one of the top model-identified genes, were constructed and tested
in vivo. Data show that both strains, by a conservative estimate,
achieved 15% higher GFP per cell than the control strain, a qualitative
confirmation of the model predictions. A genome-scale DFBA model for L.
lactis growing on M17 medium is presented along with the procedure for
screening gene targets and a powerful method for visualizing fluxes in
genome-scale metabolic networks. (C) 2009 Elsevier Inc. All rights reserved.