We often think bacteria are bad. The truth is that there are many different types of bacteria in this world. Some bacteria are harmful to humans but some bacteria in our bodies help us to live. Have you ever considered the possibility that bacteria can also be “factory workers”? Engineers and scientists are working on using bacteria to produce certain chemicals and materials. An example is to use bacteria to produce fuel for us. In engineering, we often want to optimise the process, so we may want to make the bacteria to produce as much fuel as possible in a given time. However, there are often constraints in nature. The truth is that fuel is toxic to bacteria, so we need to find a way for the bacteria to make a lot of fuel but at the same time keep them alive! This biofuel production process is the theme of this assignment.