Catalyzes the conversion of L-ornithine to N(5)-hydroxyornithine, the first step in the biosynthesis of all hydroxamate-containing siderophores, such as deferriferrichrysin. L-ornithine + NADPH + O2 = H2O + N(5)-hydroxy-L-ornithine + NADP(+) L-ornithine + NADH + O2 = H2O + N(5)-hydroxy-L-ornithine + NAD(+) Binds 1 FAD per subunit. Siderophore biosynthesis. Homotetramer. Induced under iron-limiting conditions. Belongs to the lysine N(6)-hydroxylase/L-ornithine N(5)-oxygenase family.