防腐型乳化剂葡聚赖氨酸的研究

利用白色链霉菌(Streptomyces albus)发酵、分离纯化得到聚赖氨酸(PL)，其与葡聚糖(Dextran)在Maillard 反应中通过共价结合生成一种防腐型乳化剂--葡聚赖氨酸(DPL)。通过测定420nm 波长下吸光度和SDS 聚丙烯酰胺电泳(SDS-PAGE)分析，检测聚赖氨酸与葡聚糖的共价结合过程。乳化活性和最小抑菌浓度(MIC)测定结果表明，DPL 不但具有比传统乳化剂优良的乳化能力，而且还保留了聚赖氨酸大部分的抑菌活性，并且其乳化活性在pH 值为7 时最高，在NaCl 浓度为1.75mol/L 时依然没有下降。

Antibacterial Activity and Emulsifying Activity of Polylysine and Dextran Conjugate by Maillard Reaction

A Maillard reaction was carried out between 1 g of polylysine (PL) produced through fermentation of Streptomyces albus and 9 g of dextran with 40 kD molecular weight. The covalent attachment of PL to dextran was confirmed by SDS-PAGE and the absorbance measurement of Maillard reaction system at 420 nm wavelength was conducted to determine the conjugation progress between the above two materials. Subsequently, the antibacterial activity and emulsifying activity of PL-dextran conjugate were investigated. The results indicated that the PL-dextran conjugate not only had higher emulsifying activity than that of 0.9% dextran or 0.1% PL, but retained the antibacterial activity of PL. Its emulsifying activity reached the maximum at pH 7.0, and did not decrease in the presence of 1.75 mol/L of NaCl.