Fermentation optimization and metabolomic analysis of ε-polylysine production in Streptomyces albulus

Abstract

ε-Polylysine (ε-PL) is a natural preservative with broad-spectrum antibacterial activity and has been widely used as a green food additive. However, the low yield and high cost of wild-type strains have restricted its industrial development. In this study, the production of ε-PL by Streptomyces albulus CICC11022 under different medium components and fermentation conditions was compared. The yield of ε-PL was increased from 0.70 g/L to 2.89 g/L, a 3.1-fold increase. Metabolomics analysis indicated that nitrogen source, as a key factor in increasing yield, mainly exerted its effect by enhancing the synthesis of L-lysine, the precursor of ε-PL, via the alpha aminoadipic acid (AAA) pathway. Based on this result, exogenous addition of L-lysine increased the concentration of ε-PL to 4.13 g/L. This is the relatively high yield of ε-PL produced by shake-flask fermentation at present, and provides a reference for improving the industrial production of ε-PL.