Antibacterial Activity Of Soy Isoflavones And The Antibacterial Mechanism Of The Initial Discussion

In this paper, the optimal extraction conditions of soybean isoflavone from defatted soybean meal are searched and the antimicrobial action and antimicrobial mechanism of soybean isoflavone are studied.The optimal extraction conditions from defatted soybean meal are confirmed as follows :60% ethanol, temperature is 70℃, ratio of solvent to material is 18:1, extracting time was 2 hours, twice.The contents of soybean isoflavone is reached 0.45% under the condition. The extraction rate of soybean isoflavone by ultrasonic wave for 30min was higher than that by heating - circumfluence for once , 120min about 46 % and was equal to the rate of heating-circumfluence for twice , 240min.The effect of soybean isoflavone on anti-microoganism is studied.It is found that soybean isoflavone possess anti-bacteria and anti-fungi activity. It shows obvious inhibition for Staphyloccus aureus, Micrococcus luteus, Bacillus cereus, Bacillus pumilus, Bacillus subtilis, Listeria monocytogens, Candida albicans, Absidia spit, Aspergillus oryzae. But it has no inhibition for Escherichia coli and Yeast The component of anti-microorganism in soybean isoflavone is Aglycons.In the paper,the antimicrobial mechanism of soybean isoflavone is studied.The soybean isoflavone could inhibit cell division at logarithmic phase. The result of scanning eliectron microscope reveals that the cell become considerable roughening and blebbing.The result of transmission electron microscope demonstrated that the membrane is separated from cell wall and the cytoplasm shrank with condensed plasma, vesicle and wild periplasmic space . The result of respiratory inhibition experiment reveals that soybean isoflavone mainly inhibit TCA route of the bacteria .Therefore,it is supposed that the soybean isoflavone could destroy the integrality of cell wall and membrane ,prevent the respiration and metabolism of the bacteria.