Index >> Soil Microorganisms >> Algae

Algae

Soil algae are ubiquitous in nature wherever moisture and sunlight are available. They are visible to the unaided eye in the form of green scum on the surface of soils. Numerically they are not as many as fungi, bacteria or actinomycetes.

Morphologically, they may be unicellular or filamentous and belong to the families Chlorophyceae (green algae) and Cyanophyceae (blue-green algae). Other forms like diatoms also occur under certain environmental conditions.

The blue-green algae contain a pigment known as phycocyanin in addition to chlorophyll which imparts a special blue-green colour to these organisms.

The dominant blue-green algae in Indian soils belong to the genera: Chroococcus, Aphanocapsa, Lyngbya, Oscillatoria, Phonnidium, Microcoleus, Cylindrospemum, Anabaena, Nostoc, Scytonema and Fischerella.

Some of the blue-green algae possess specialized cells known as heterocysts which are implicated in nitrogen fixation. The waterlogged rice soil provides an ideal environment for the growth of certain blue-green algae and the role of such algae in nitrogen fixation is discussed elsewhere in this book.