Write notes on:

Useful bacteria:

1) Bacteria are microorganisms with free chromosomes having cell membrane, cell wall and cytoplasm.

2) Some bacteria are useful to humans, plants, animals.

3) Few well known useful bacteria are:

Rhizobium bacteria found in nodules on the roots of leguminous plants are useful as nitrogen fixing agents,

They function by transforming nitrogen in air to nitrogen compound; this nitrogen enters the soil making it fertile.

Azetobacter bacteria, an independent bacteria fixes nitrogen in air.

Soil contains several bacteria which decompose dead plants and animals and produce humus to increasing the fertility.