Abstract: 【Objective】An experiment was carried out to study the bacteriostatic action and mechanism of S.flavescens on E.coli. 01c84010. 【Method】Cylinder-plate and liquid doubling dilution, drafted curves, electron microscope, SDS-PAGE and flow cytometry, were ued in the study.【Results】The result showed that the extracts had obvious bacteriostatic action upon Gram-positive and Gram-negative bacteria and the bacteristatic spectrum was wide. Though restraining the expression of functional protein, the cell cycle was effected and the count of bacteria in phase I increased and that in phase R reduced. Finally, the E.coli 01 C84010 went into decline phase straightly instead of the normal logarithmic phase. Observation under electron microscope revealed that the E.coli 01 C84010, which depressed on center had been constricted into shoe-shaped gold ingots. The cytoplasm was concentrated, the cell was plasmolysed, then the cell wall was damaged, the contents were leaked out and the cell was killed. 【Conclusion】It is suggested that the bacteriostatic mechanism is that the matrine inhibited the synthesis of proteins associated with growth and cleavage of bacteria, then blocked their division and development. Furthermore, the drug combined with the protein, made the cytoplasm pyknosis and killed the bacteria finally.

Key words: Sophora, flavescens, Ait, matrine, bacteriostatic action, bacteriostatic mechanism