Due to its hazardous nature and anti-environmental effect the use of chemical fertilisers and chemical insecticides are very illegitimate. The development of biofertilisers and bioinsecticides has enabled us to reduce the use of chemical fertilisers and chemical insecticides. Microbes are very important biological agents as biofertilisers and biopesticides.

Microbes as biofertilisers

1. Free-living nitrogen-fixing bacteria – Azotobactcr, Clostridium.
2. Free-living nitrogen-fixing cyanobacteria – Anabaena, Nostoc.
3. Symbiotic nitrogen-fixing bacteria – Rhizobium
4. Symbiotic nitrogen-fixing cyanobacteria – Azolla – Anabaena
5. Mycorrhiza – symbiotic association between fungi and roots of a higher plant.

Microbes as bio-pesticides:

Biopesticides are that biological agents that are used to control weeds, insects, and pathogens. The microorganisms used as biopesticides are viruses, bacteria, protozoa, fungi, and mites. Some of the biopesticides are being used at a commercial scale. Most important example is the soil bacterium Bacillus thuringiensis (Bt). Spores of this bacterium produce the insecticidal Cry protein. This bacterium was the first biopesticide to be used on a commercial scale in the world. Through the use of genetic engineering, the scientists have introduced the B. thuringiensis toxin gene into plants. Such plants are resistant to attack by insect pests.