Microbes living in the soil provide plants with natural protection from pests and diseases. They also are essential for converting nitrogen and other nutrients into forms that plants can use to grow. Microorganisms can derive energy from carbohydrates, alcohols, and amino acids. Most microorganisms will metabolize simple sugars such as glucose. Others can metabolize more complex carbohydrates, such as starch or cellulose, or glycogen found in muscle foods. Some microorganisms can use fats as an energy source. Microorganisms can derive energy from carbohydrates, alcohols, and amino acids. Most microorganisms will metabolize simple sugars such as glucose. Others can metabolize more complex carbohydrates, such as starch or cellulose, or glycogen found in muscle foods. Some microorganisms can use fats as an energy source.

The most significant effect of the microbes on earth is their ability to recycle the primary elements that make up all living systems, especially carbon, oxygen, and nitrogen. Primary production involves photosynthetic organisms which take up CO2 from the atmosphere and convert it to organic material. Microorganisms have several vital roles in ecosystems: decomposition, oxygen production, evolution, and symbiotic relationships. Decomposition is where dead animal or plant matter is broken down into more basic molecules. Microbes living in the soil provide plants with natural protection from pests and diseases. They also are essential for converting nitrogen and other nutrients into forms that plants can use to grow. Microorganisms can derive energy from carbohydrates, alcohols, and amino acids. Most microorganisms will metabolize simple sugars such as glucose. Others can metabolize more complex carbohydrates, such as starch or cellulose, or glycogen found in muscle foods. Some microorganisms can use fats as an energy source. Microorganisms are the backbone of all ecosystems, but even more so in the zones where photosynthesis is unable to take place because of the absence of light. In such zones, chemosynthetic microbes provide energy and carbon to the other organisms.Within food plant cropping systems, microorganisms provide vital functions and ecosystem services, such as biological pest and disease control, promotion of plant growth and crop quality, and biodegradation of organic matter and pollutants.