Actinobacteria, or actinomycetes, are a group of bacteria that are very common in soil.

Actinobacteria are the chief agents of decomposition in the relatively dry and alkaline soil of grasslands.

In 1900s Martinus Beijerinck, a Dutch botanist and microbiologist, was the first to point out how essential actinomycetes are to soil health.

In the 1920s, soil microbiologists discovered that when soil samples are grown in a laboratory, between 30 and 40 percent of the colonies that develop are actinomycetes.

Some actinomycetes decompose cellulose, which is one of the most abundant materials in the plant remains, while others act on the substances that result from this decomposition.

In 1940, Selman Waksman, an American microbiologist and biochemist discovered that some actinobacteria produce actinomycin, which is an antibiotic. His work led to the discovery of other natural antibiotics, such as streptomycin. He received the 1952 Nobel Prize in Medicine for his work.


Fungi live in many different soils, but they are especially important as agents of decay in woodland soils. They seem to tolerate the acid conditions of woodland soils better than bacteria.

If you turn over a few inches of woodland soil, you will probably expose an irregular network of thin grey or white filaments. These filaments are branching fungal cells known as hyphae.

Soil fungi decompose cellulose, as well as pectins - substances found in plant cell walls - and chitins, which are found in insect exoskeletons.


Although we often think of algae as water organisms, many species of algae live in soil.

Algae may form surface crusts in desert soils and so help reduce soil erosion.

In rice paddy soils, algae increase crop yields by adding nitrogen and oxygen to the soil.


Common soil animals include earthworms, nematodes (roundworms), small insects, millipedes, centipedes and mites.