Involved in the biodegradation of nitroaromatic compounds (PubMed:8368838). Catalyzes the two-electron reduction of nitrobenzene (NB) to produce a nitrosobenzene (NOB) intermediate, which is immediately reduced to hydroxylaminobenzene (HAB) by a second two-electron transfer (PubMed:7601851). Also active on menadione and nitrofurazone (PubMed:7601851). Replacing NADPH with NADH results in a 4-fold decrease in the reaction rate (PubMed:8368838). H2O + N-phenylhydroxylamine + 2 NADP(+) = 2 H(+) + 2 NADPH + nitrobenzene Binds 2 FMN per subunit. Inhibited by dicumarol, p-hydroxymercuribenzoate and salicyl hydroxamate. Optimum pH is 8. Stable at 40 degrees Celsius and below, but it loses activity rapidly at temperatures above 45 degrees Celsius. Xenobiotic degradation; nitrobenzene degradation. Monomer. By nitrobenzene. Belongs to the nitroreductase family.