Fig. 2

Effects of l-lysine concentration (a), ratio of α-ketoglutarate acid/lysine (b), concentrations of Fe(II) c and Vc (d), pH (e), and temperature f on hydroxylysine synthesis. Washed cells were resuspended in 20 mL of 50 mM PBS at varying pH values (4.0, 5.0, 6.0, 7.0, 8.0, and 9.0). The hydroxylysine synthesis reaction contained l-lysine (30, 60, 150, and 250 g/L), α-ketoglutaric acid (molar ratio, 0.5:1, 1:1, 1.5:1, 2:1, and 3:1), Vc (0, 5, 10, 20, and 30 mM), FeSO₄ (1, 5, 10, 20, and 30 mM), and 5 g dry cell weight (DCW)/L and was incubated at different temperatures (18, 25, 30, 37, and 50 °C) with shaking at 200 rpm for different lengths of time (0, 12, 24, 48, and 72 h)