Why Are Bacteria Good Organisms For Transformation?

Bacteria are essential components of the eco system. They break down complex substances in waste and increase the fertility of soil. They decompose corpses, paper, vegetable waste etc. Composting is nothing else but using bacteria and other micro organisms to break down waste into aerated fertile soil. Bacteria is beneficial because as it breaks down or transforms one substance to another the material it leaves behind is either directly beneficial to us humans and the environment. These nutrients are then later consumed by plants or other micro organisms. Take yogurt or yeast for example, both are examples of bacteria benefiting man directly.
The uses bacteria can be put to are just opening up to man. Imagine bacteria that eat up the oil from an oil spill, or one that cures other diseases etc.