How Bacteria Eat

Bacteria do not have a mouth. They make proteins called enzymes inside the cell and these travel thru the cell wall into the surrounding medium. These enzymes chop the food into tiny subunits that then come into the bacteria cell by osmosis or active transport. Active transport is the process by which the cell grabs a molecule of glucose or other food and pulls it in thru the cell wall. Many specialized proteins and other molecules made by the bacterium are involved in this active transport process.

The process by which the enzyme chops the food into subunits is also very complex and specific and usually requires one molecule of water for each split. If water is consumed, the chopping process is called hydrolysis (splitting by water). The enzyme that is able to hydrolyze lactose (milk sugar) will not fit into a protein molecule the right way to be able to hydrolyze a protein. Further, lactase (an enzyme able to hydrolyze lactose) will not be able to fit into a starch molecule to split it. Thus, if a bacterium is going to eat many kinds of foods, it must have many kinds of hydrolyses because each enzyme does very specific jobs. Some bacteria have many kinds of enzymes and can eat many kinds of foods. Other bacteria have few enzymes and are able to digest very few kinds of food. Bacteria which do not have the correct enzymes can still live off a given food by growing where other bacteria have ready broken the food down into simpler compounds or elements. Thus, in processing waste, we might use a "mixed culture" to work as a consortium able to digest the waste foods at the various stages of decomposition.