Recently,more and more studies focus on the application of antimicrobial peptides to control bacterial diseases.For the first time,we report the using of plant bioreactor to develop functional feed additives in China.During our previous work,the penaeidin 3-2 gene from the shrimp Fenneropenaeus chinensis was transformed into rice Aichi ashahi. Tilapia feed which contained different levels of the transgenic or non-transgenic rice bran were tested for the effect of antimicrobial peptide expressed by rice plant on feed spoilage and disease control.The results of total bacteria and mold count showed that penaeidin 3-2 expressed in rice could effectively restrain growth of microorganisms in feed and bran.Another experiment was conducted to study the effect of different levels of transgenic rice bran(10%,20%,30%,respectively)on survival rate of tilapia infected by Aeromonas hydrophila.The results showed that survival rates of tilapia fed transgenic rice bran were significantly higher than those fed non-transgenic rice bran.In-depth study of the mechanism of enteritis control by transgenic bran was conducted by studying the gut microbial community and intestinal structure.The results showed that transgenic rice bran restrained growth of Escherichia coli, but enhanced lactic acid bacteria proliferation.And the intestinal structure of those fish fed transgenic bran was more intact than the control.So it is indicated that the disease control effect could be in connection with the change of gut microbial community and protective effect of intestinal structure.But it is noteworthy that the excessive addition of transgenic rice bran(30%)could cause epithelial cells degeneration.