Bacteria are single-celled organisms that live out their lives at a microscopic scale. We can find bacteria everywhere we look for them, including inside of our own bodies. Bacteria are incredibly diverse and come in many shapes and sizes. They also vary widely in how they live and grow. Some bacteria grow very quickly and others grow slowly. We wanted to measure the growth of many different types of bacteria in the environment. Unfortunately, some species of bacteria are very difficult to grow in the laboratory. To get around this, we designed a method to predict how fast a type of bacteria can grow, just from its DNA. This way, if we have the DNA of a bacterial species, we can measure its growth even if we cannot get it to grow in our laboratory.