Enhancing ε-poly-L-lysine production in Streptomyces albulus through tea polyphenols addition.

ε-Poly-L-lysine(ε-PL), a natural and efficient antiseptic, is extensively utilized in food, pharmaceutical, and cosmetic industries. In this study, the effect of tea polyphenols (TP) on ε-PL production in Streptomyces albulus was investigated. Under optimized conditions, TP supplementation (1.41 g/L) increased the ε-PL titer by 15.76% to 2.13 g/L in shake flasks. Additionally, the cell viability and respiratory intensity were improved. At 48 h, the activities of SOD and CAT in the TP group were increased by 95.03% and 99.41%, respectively. Moreover, transcriptomic analysis indicated that 175 significantly upregulated genes and 40 downregulated genes were identified. Among them, the upregulated genes of SDH, MDH, CS led to enhanced TCA cycle and oxidative phosphorylation, boosting the energy and precursor supply for ε-PL production. Conversely, the downregulation of Race and FabH genes in competitive pathways improved metabolic flux toward ε-PL biosynthesis. Finally, the ε-PL production in fed-batch fermentation achieved 43.4 g/L with a yield of 5.32 g/(L·d) in a 5-L bioreactor. In summary, this study presents an effective strategy for enhancing ε-PL production through tea polyphenol supplementation.