Novel growth characteristics and high rates of nitrate reduction of an Escherichia coli strain, LCB2048, that expresses only a periplasmic nitrate reductase

Escherichia coli strain LCB2048 is a double mutant defective in the synthes is of the two membrane-associated nitrate reductases A and Z. This strain c an grow anaerobically on a non-fermentable carbon source, glycerol, in the presence of nitrate even in media supplemented with high concentrations of tungstate. This growth was totally dependent upon a highly active, periplas mic nitrate reductase (Nap). Due to the presence of a previously unreported narL mutation, synthesis of the periplasmic nitrate reductase by this stra in was induced during anaerobic growth by nitrate. We have also demonstrate d that methyl viologen is an ineffective electron donor to Nap: its use lea ds to an underestimation of the contribution of Nap activity to the rate of nitrate reduction in vivo. (C) 2000 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.