Abstract: 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.

Key words: Eucommia ulmoides Oliv. bark, Lactobacillus acidophilus CICC6005, proliferation, extracellular proteins, intracellular proteins