FIG. 4.

Nitrate reduction and nitrite formation by L. plantarum WCFS1 in the presence of mannitol. The bars indicate the average values ± standard deviations. Wild-type cells were grown overnight in anaerobic batch cultures in MRS broth from which acetate, citrate, and glucose were omitted (modified MRS broth). This medium was further supplemented with heme, menaquinone, nitrate, and various concentrations of mannitol (man) (in mM). Nitrate reduction is not repressed at high mannitol concentrations.