杜仲水提液对嗜酸乳杆菌生长及发酵产物的影响

制备5 种不同质量浓度的杜仲水提液添加到MRS培养基中对嗜酸乳杆菌（Lactobacillus acidophilus）CICC6005进行培养，旨在探究不同质量浓度的杜仲水提液对L. acidophilus CICC6005增殖情况及对发酵过程中胞外和胞内蛋白含量变化的影响，并对其蛋白组分进行分析。发酵所得胞外和胞内蛋白分别用三氯乙酸-丙酮沉淀法和试剂盒法获得，采用Sephadex G-100凝胶层析分离技术对胞外和胞内蛋白分离纯化，用二喹啉甲酸法和十二烷基硫酸钠-聚丙烯酰胺凝胶电泳分别测得各组分蛋白的含量及分子质量。结果显示：当培养基中添加的杜仲水提液质量浓度为0.125 0 g/mL时，对菌体增殖有明显的促进作用，菌体生物量最大（4.38×108 CFU/mL），同时在此质量浓度时菌体胞外和胞内蛋白含量也达到最大值；胞外和胞内蛋白经过Sephadex G-100凝胶层析分离后均得到2 个明显的蛋白峰，胞外蛋白两组分分子质量分别为67、31 ku，胞内蛋白两组分分子质量分别为57、17 ku。综上，添加适宜质量浓度的杜仲水提液对L. acidophilus CICC6005的增殖起到了一定的促进作用，并对其发酵产物组成产生了一定的影响。

Effect of Eucommia ulmoides Oliv. Bark Aqueous Extract on the Growth and Fermentation Products of Lactobacillus acidophilus

This paper is concerned with the effect of different concentrations of Eucommia ulmoides Oliv. bark aqueous extract on the proliferation of Lactobacillus acidophilus CICC6005 and the changes in extracellular and intracellular protein contents during fermentation. For this purpose, Lactobacillus acidophilus CICC6005 was cultured in MRS medium added with five different concentrations of Eucommia ulmoides Oliv. bark aqueous extract. The extracellular and intracellular proteins were obtained with trichloroacetic acid-acetone precipitation and a commercial kit, respectively, and purified by Sephadex G-100 gel filtration chromatography. All separated fractions were quantified by the bicinchoninic acid (BCA) method and their molecular weights were measured by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDSPAGE). Results showed that addition of 0.125 0 g/mL Eucommia ulmoides Oliv. bark aqueous extract significantly promoted bacterial growth, giving the maximum biomass of 4.38 × 108 CFU/mL and maximum extracellular and intracellular protein contents. The extracellular proteins were separated into two apparent peaks with molecular weights of 67 and 31 ku, and the intracellular proteins were also separated into two apparent peaks with molecular weights of 57 and 17 ku. In conclusion, the appropriate concentration of Eucommia ulmoides Oliv. bark aqueous extract played a role in promoting the growth of L. acidophilus CICC6005 and also affected its fermentation products.