Abstract: Our objective is to study the effects of acetic acid from fermentationon the growth of the recombinant Escherichia coli BL21（DE3）/pET15b-TreS as well as the expression of the recombinant trehalose synthase gene, and the action mechanism was also discussed. Firstly, we studied the effect of acetic acidon the growth of recombinant Escherichia coli by experiments with adding acetic acid（sodium acetate）, and observed the morphological changes of recombinant bacteria by using environmental scanning electron microscope. Then, the effects of acetic acid（sodium acetate）on the permeability and the integrity of cell membrane were studied through the determination of electrical conductivityof the brothand the changes of OD_{260 of the supernatant. The activity of β-galactosidase in the supernatant was measured to determine the effect of sodium acetate on intracellular membrane, and then the influence of acetic acidon the conformation of membrane protein by using fluorescence analysis were detected. Finally, the effect of sodium acetate on the expression of the recombinant trehalose synthase gene by SDS-PAGE was studied. Results showed that the acetic acid（sodium acetate）could have certain inhibition effects on the recombinant bacteria growth, and caused cell surface to be depressed and shrinkage. The permeability and integrity of cellmembranes were affected by the acetic acid（sodium acetate）, leading some substances in cells to leak out. And experiments also revealed that the acetic acid could make effects on the conformation of the membrane proteinin the cell membrane,which caused a certain degree of damages to the membrane structure. SDS-PAGE analysis suggested that the sodium acetate had impacts on the expression of the recombinant trehalose synthase gene. The acetic acid（sodium acetate）was confirmed to affect the cell growth and the expression of the recombinant trehalose synthase gene, and the cell membrane was a target of its function.}

Key words: acetic acid, Recombinant Escherichia coli, antimicrobial mechanism, cell membrane, trehalose synthase