Effect of pectin on epsilon-polylysine purification: Study on preparation, physicochemical property, and bioactivity of pectin-epsilon-polylysine complex

Abstract Epsilon-polylysine (e-PL) is a typical antibacterial peptide with a wide spectrum and high safety. Pectin could form electrostatic complex with e-PL and affects the antibacterial performance. However, the potential application of pectin on e-PL purification has not been discussed. In this study, a novel process for preparation antibacterial complex pectin-e-PL was carried out by adding pectin to the e-PL fermentation broth and further processing. The results showed that e-PL could be completely collected when the mass ratio of pectin to e-PL was 8. After further removing pectin by ethanol precipitation, pectin-e-PL complex was obtained. The content of e-PL in pectin-e-PL complex was 30.59% ± 1.21%, and the recovery rate of e-PL was 62.63% ± 0.63%. In addition, the physicochemical properties of pectin-e-PL complex were discussed. The Zeta-potential analysis suggested that the intrinsic pK of pectin-e-PL complex was 7.74. Furthermore, the cytotoxicity test showed that for Raw264.7 cells pectin-e-PL was a more compatible and safer product than e-PL alone. At last, the minimal inhibitory concentration (MIC) of pectin-e-PL for B. subtilis, and E. coli were 0.25 mg/mL and 0.1 mg/mL respectively, which presented the same activity as high purity e-PL. Therefore, the separation of e-PL from fermentation broth by pectin is a novel promising technological process, and the obtained pectin-e-PL complex is an outstanding product with high stability and antibacterial performance.