Figure 5
The ability of ∆nnaR, ∆glnR, ∆nnaR–attB::phspnnaR, ∆glnR-attB::phspnnaR M. smegmatis strains to reduce nitrate to nitrite and nitrite to ammonium. (A) M. smegmatis cells were grown on nitrogen-limiting Sauton’s medium containing 10 mM sodium nitrate as sole nitrogen source. Accumulation of nitrite at the indicated time points was assessed by measuring the nitrite concentration using the Griess Reagent System Kit. Three biologically independent experiments were performed, and a representative graph is shown. (B) The presence of ammonium ions in the same set of samples was assessed at the indicated time points using the ammonium test (Merck). The samples were tested according to the manufacturer’s protocol, while the reactions were downscaled accordingly. The presence of green colour, resulting from the formation of indophenol blue derivative, indicates the presence of ammonium ions in the culture’s medium. Representative samples are shown.
