Bacteria play a crucial role in humans, animals and the environment. These are some of many reasons why bacteria are important: 

• Help break down the food we eat thereby making nutrients available to us
• Play a vital role in defending against infections
• Used in the manufacture of antibiotics and other chemicals
• Facilitate fermentation, an essential step in cheese and yogurt production
• Help in extracting economically viable metals such as gold, copper and palladium from rock ores
• Play vital roles in cleaning up oil spills and in sewage treatment