Growth on nitrate as electron acceptor and the sole N source. A) Growth on 0.1% glucose and 15 mM nitrate. Ammonia (0.25 g/L) was either added or omitted from the medium. B) Production of nitrite. The medium contained 0.1% lactate and 20 mM nitrate, ammonia was omitted. C) Experimental vs. predicted growth rate ratios with and without added ammonia. D) Experimental vs. predicted ratio of nitrate converted to nitrite.