Furthermore, in order to measure the ability of engineered bacteria to kill iron bacteria and the work time our bacteria needed to collapse the iron system, we developed another model which is used to descrip the production of the cecropin AD and the sterilizing ability of the cecropin. This model includes three parts: the iron sensor, the inverter system, the sterilizing system. The sensor model tells the concentrate of Fe2+ when our bacteria start working. The inverter system shows the cecropin productin and the sterilize system demonstrates the sterilization effect. The model makes the function with above all parts.