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. Perhaps someday you can figure out ways to study the mechanisms of active transport. 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. Thus, if a bacterium is going to eat many kinds of foods, it must have many kinds of hydrolases because enzymes do 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. This is similar to a gull eating bits of sealion meat left by a shark that killed the sealion. This website has some very interesting experiments like this for the home fermentation of special foods. We have just learned that bacteria differ in the foods they are able to digest and that is one of the ways we can tell them apart.