Study On Inhibition Mechanism Of10-HDA To E.Coli

10-HDA （10-Hydroxy-2-decenoic acid） is the main active material in royal jelly,belong to the unsaturated fatty acid, it appeart in white or light yellow needle crystal atroom temperature, and, slightly soluble in acetone, easily soluble in methanol, ethanol,ethyl ether, etc. but not soluble in water.10-HDA has a variety of physical activity, itcan not only increase the body’s immune function, have a certain cure function in lowimmunity of prevention, but also have significant effect in antitumor, anticancer,radioresistance, antibacterial, anti-inflammation. Besides,10-HDA also can inhibit fatsynthesis and reduce blood fat.First of all, in this paper, we studied the antibacterial activity of10-HDA bydetecting the diameter of the inhibition zone of4kinds bacteria and2kinds yeast incommon laboratory. And we determine the minimum inhibit concentration （MIC） of10-HDA through the2times dilution method. The results show,10-HDA haveobviously effect against gram-negative bacteria but have no inhibition on yeast;Different strains, the10-HDA MIC is different and the MIC to E.coli was0.25mg/mL.we use E.coli as model strains to study the the antibacterial mechanism of, Because ofthe10-HDA have the most obvious inhibition effect to E. coli.Second, we using atomic force microscope to observe the form of E.coli that10-HDA treated, compare to the control group we found that10-HDA destroy theintegrity of E.coli cells. Through analyzing the change of growth curve, cell wall, andcell membrane, inorganic ions, protein and respiratory chain dehydrogenase aboutE.coli after10-HDA treated. According to the results we concluded the mechanism of10-HDA inhibit E.coli is that:10-HDA will dissociate [HOCH₂（CH₂）₈COO-] and [H+]partly,[HOCH₂（CH₂）₈COO-] as competition adsorption the positive ions of E colisurface, lead to fat polysaccharide exposure, after the10-HDA go into the intercellularsubstance, it can react with the phospholipid molecules of outer membrane andlipopolysaccharide, result in increasing the permeability of cell wall. In addition,10-HDA involved in the formation of the cell membrane phosphatide, cause the cellmembrane liquidity increases, membrane protein shift, breathing chain damaged, thechannel protein damaged, reduce the membrane potential was reduced, ATP synthesisreduced, permeability increased, inorganic ions and small molecules infiltrates. At thesame time,10-HDA into cytoplasm and disrupt the intracellular anion balance, increase the osmotic pressure inside the cell, at last the cell dead.