Glycolytic flux is increased and acetate production is reduced in Escherichia coli by the expression of heterologous NADH oxidase (NOX) from Streptococcus pneumoniae coupled with the deletion of the arcA gene, which encodes the ArcA regulatory protein. In this study, we examined the overproduction of a model recombinant protein in strains of E. coli expressing NOX with or without an arcA mutation. The presence of NOX or the absence of ArcA reduced acetate by about 50% and increased beta-galactosidase production by 10-20%. The presence of NOX in the arcA strain eliminated acetate production entirely in batch fermentations and resulted in a 120% increase in beta-galactosidase production. (c) 2006 Wiley Periodicals, Inc.