| Presently, more and more attention has been concentrated on the study of the starch and their derivates. As one of the most abundant nature resource, starch has particular advantages, such as biological compatibility, degradable ability, and also it can be modified by several methods, so it is used in extensive field. However, because starch is an excellent nourishing material which is conductive to bacteria breeding, it can be contaminated or infected by microorganisms such as bacteria if it is exposed to the atmosphere. This character limits application of the starch-based material use in medical field, hygienic and food packaging. To solve this problem, this paper introduces a kind method to prepare the antibacterial starch by modifying the starch with amino acid.Firstly, starch grafted acrylamide copolymer (St-g-PAM) was prepared by using cerium nitrate amine as initiator. The effect of reaction condition on the grafted ratio was investigated. The optimism reaction condition is: 1g starch, 20ml water, 0.4ml initiator and 1.8g acrylamide(AM) reacted at 50℃for 4 hours, the ratio of graft of St-g-PAM is 101.4%.And then, St-g-PAM was modified with four kind amino acids. The structure of the amino acid modified St-g-PAM was characterized by the IR spectrum. The reaction condition on the transform ratio of amino acid was investigated. The optimism reaction condition is: 0.4g St-g-PAM, dissolved in 10ml water, and added 0.4g Glycin, reacted at 70℃with pH 11 for 10 hours. The transform ratio of amino acid is 24.2%.At last, the antimicrobial activity of the modified copolymer was studied by using lawn count method. The result indicated that the copolymer modified with amide acid had antimicrobial activity to the Escherichia coli and Staphylococcus. The St-g-PAM-g-Cys got the best antimicrobial activity to Escherichia coli, the rate of antimicrobial is 60.4%; and the St-g-PAM-g-His got the best antimicrobial activity to Staphylococcus, the rate of antimicrobial is 62.0%.
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