Whole-cell biotransformation for large scale production of carcinine in Escherichia coli

Carcinine is a natural imidazole-containing peptide derivative. It is widely used in the cosmetics industry as anti-aging supplement with antioxidant, anti-glycation and glycation reversal functions, and it also has a notable pharmacological effect as anti-tumor drug and in protection against retinopathy. However, a technological method for synthesis and production of carcinine has not been established. In this study, a whole-cell transformation system converting β-alanine and histamine to carcinine by the enzymes Ebony and phosphopantetheine transferase (Sfp) has been developed. The results revealed that the catalytic efficiency of the strain containing the fusion protein of Ebony and Sfp (Sfp-glycine-serine-glycine-Ebony, SGE) in Escherichia coli W3110 (WSGE strain) is significantly higher (7.45 mM) than the combinatorial strain of pET28a-ebony and pACYCDuet-sfp in E. coli BL21(DE3) (BSE strain) (2.17 mM). Under the optimal reaction conditions (25 ℃, pH 7.0, 12.5 g/L wet cells, 20 mM β-alanine and 40 mM histamine), the carcinine can be quickly synthesized within 24 h up to a concentration of 22.63 mM. To achieve a continuous and efficient conversion of the precursors, a batch-feeding catalysis was designed. With this system, β-alanine (40 mM) and histamine (40 mM) could be completely transformed to carcinine (40.34 mM) in 36 h with a productivity of 0.204 g/L h reaching a titer of 7.34 g/L. Hence, the batch-feeding whole-cell biocatalysis is a promising technology for the high yield production of carcinine which can promote the industrial production of carcinine.