Abstract: In order to evaluate the inhibitory effect of Galla chinensis isolates on Streptococcus agalactiae and to utilize gallnut more effectively in practice,Galla chinensis was separated by using high-speed counter current chromatography (HSCCC),for which the optimal separation solvent system was confirmed to be ethyl acetate,ethanol and water ( with a volume ratio of 5:1:5) .The in vitro antibacterial effects of the crude extract and the separate components on the Streptococcus lactis TN3L was detected by microcalorimetry,and the half inhibitory concentration of the ingredients of the Chinese gall group on Streptococcus lactis was calculated to evaluate.The study shows that the Chinese gall can separate 5 components (W₁,W₂,W₃,W₄,W₅) .The W₁ fraction had no inhibitory effect on S.agalactiae TN3L.The IC50 of W₂-W₅ fractions were found to be 2.229 4 mg/mL,0.257 0 mg/ mL,0.668 7 mg/mL,and 0.175 0 mg/mL.The inhibitory effect of component W₅ and W₃ was obvious.W₅ and W₃ were deduced the main antibacterial fractions of G.chinensis on S.agalactiae TN3L.

Key words: Galla chinensis, HSCCC, Streptococcus agalactiae TN3L, microcalorimetry, half inhibitiory concentration