Have you ever noticed the special "earthy smell" after the first rain of a long summer? Of course, rain itself doesn't have smell. This special odor, also referred to as petrichor, actually comes from a bacteria called as actinomycete in soil.

Actinomycetes are thread-like filaments bacteria that usually grow in warm and damp soil. It has many other habitats including water environments or animal bodies; however, soil is their main habitat. After a long period of dry weather, the activities of actinomycetes in soil slow down. Just before the rain, as the soils become damp, actinomycetes start to awake and create a byproduct called geosmin which contributes to the "earthy smell."

Actinomycetes play an important role in soils by improving the soil nutrients and promoting the growth of plants. They can decompose dead animals and plants, then re-make nutrients for plants growth. Moreover, they can also work together to control the growth of harmful soil bacteria to keep a sustainable soil environment.

Micro-earth

People often find it hard to understand the presence and role of microbes in their environment and daily lives. They are hard to see, but are everywhere. In this series, CGTN focuses on one of the smallest organisms in nature, and explores how these powerful organisms can either save us or destroy us.

(All photos via VCG)

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