OBTAINING food And energy
From the bacteria that live in the soil to those that live in the pores of your skin, all Bacteria need certain things to survive. Bacteria must have a source of food and a way of breaking down the food to release its energy.
Some Bacteria are autotrophs and make their own food. Autotrophic bacteria make food in one of two ways. Some capture and use the sun's energy as plants do. Others, such as bacteria that live deep in mud, do not use the sun's energy. Instead, these bacteria use the energy from chemical substances in their environment to make their food. Some bacteria are heterotrophes and cannot make their own food. Instead, heterotrophic bacteria must consume other organisms or the food other organisms make. Heterotrophic bacteria can consume a variety of foods- from milk and meat to the decaying leafes on a forest floor. The process of breaking down food to obtain energy is called respiration. Most bacteria need oxygen for this process while some bacteria do not. Still other Bacteria are killed if they are even exposed to oxygen.