The present invention provides modified bacterial cells and methods for using them. A modified bacterial cell can exhibit increased NADH oxidase activity, decreased ArcA activity, or the combination thereof. The methods include culturing a modified bacterial cell in aerobic conditions. The modified bacterial cell can produce less acetate during the culturing than the unmodified bacterial cell under comparable conditions. In some aspects, the modified bacterial cell produces a recombinant polypeptide, and the bacterial cell may produce more recombinant polypeptide than the unmodified bacterial cell under comparable conditions.
 The present invention was made with government support under Grant No. DE-FG36-01ID14007, awarded by the U.S. Department of Energy, and Grant No. QSB 0222636, awarded by the National Science Foundation. The Government has certain rights in this invention.