The harmonious existence among the various microbial inhabitants of the gut is critical for good health. However, inflammation from injury or inflammatory bowel disease can disrupt this balance and lead to the outgrowth of particular bacteria. The outgrowth of members of the Enterobacteriaceae family, which includes Escherichia coli, is often observed. Because E. coli are facultative rather than obligate anaerobes, Winter et al. postulated that they may be able to use by-products of reactive oxygen and nitrogen species, which are produced during inflammation, for anaerobic respiration, thereby edging out other fermenting bacteria. Indeed, in two mouse models of colitis and in a model of intestinal injury, various E. coli strains were able to use host-derived nitrate as an energy source and outcompete mutant strains unable to do this.
S. E. Winter, M. G. Winter, M. N. Xavier, P. Thiennimitr, V. Poon, A. M. Keestra, R. C. Laughlin, G. Gomez, J. Wu, S. D. Lawhon, I. E. Popova, S. J. Parikh, L. G. Adams, R. M. Tsolis, V. J. Stewart, A. J. Bäumler, Host-derived nitrate boosts growth of E. coli in the inflamed gut. Science 339, 708–711 (2013). [Abstract] [Full Text]