Optimization of Medium Constituents for ε-Poly-L-Lysine Fermentation with Response Surface Methodology

摘要

ε-Poly-L-lysine (ε-PL) is a novel food biopreservative with broad antimicrobial activity. In the present study, single-factor experiments were applied to screen optimal carbon and nitrogen sources that affect the yield of a e-PL-producing strain, Streptotnyces violaceusniger, which was obtained in our laboratory recently. Box-Behnken design and response surface methodology (RSM) were adopted to derive a statistical model for optimizing the composition of the fermentation medium. The results showed that the main factors that affect e-PL production were glucose, carbon source; peptone, organic nitrogen source; and (NH_4)_2SO_4, inorganic nitrogen source. The optimum fermentation medium for e-PL production of 5. violaceusniger consisted of (g/L) glucose, 62.49; peptone, 5.71; (NH_4)_2SO_4, 11.19; MgSO_4, 0.5; FeSO_4, 0.03; ZnSO_4, 0.04; KH_2PO_4, 1.36; and Na_2HPO_4.12H_2O, 3.58. When cultured in the optimum medium, the ε-PL production was an average of 0.349 ± 0.025 mg/mL, which was 1.75 times higher than the initial medium.