Abstract: Previous study in lab showed that Chitosan-g-DMAE-BC, a derivative of a natural product chitosan, has antimicrobial activity. However, the mechanism was not investigated. Here it show a rapid adsorption of E. coli. on the surface of Chitosan-g-DMAE-BC with quantitative suspensiontest. Further experiments using TTC test proved that E. coli absorbed onto Chitosan-g-DMAE-BC were killed. The test of integrity of bacterial membrane demonstrated that DNA and RNA existed in the solution. It was concluded that Chit...