The microbes simply eat up contaminants such as oil and organic matter (e.g., waste food), convert them and then let off carbon dioxide and water. The process uses naturally occurring bacteria, fungi or plants to degrade substances that are hazardous to human health or the environment.
The microorganisms decompose dead organic wastes of plants and animals converting them into simple substances. These substances are again used by other plants and animals. Thus, microorganisms can be used to degrade the harmful and smelly substances and thereby cleans up the environment.