Chemicals from fertilisers and pesticides are highly toxic to human beings and animals alike, and have been polluting our environment. To reduce the environmental degradation caused by chemicals, microbes can be used both as fertilisers and pesticides and can be called biofertilisers and biopesticides, respectively.

Microbes are used as biofertilisers to enrich the soil nutrients, e.g., Rhizobium, Azotobacter, Azospirillum, etc., which can fix atmospheric nitrogen in the soil. Bacillus thuringiensis bacteria act as biopesticides to control the growth of insect pests.

Trichoderma, fungal species, is effective bicontrol agent of several plant pathogens. Baculovirus used as biological control agents in genus Nucleopolyhedrovirus are excellent for species-specific, narrow spectrum insecticidal applications.

A broad spectrum antibiotic is one which can inhibit the growth of both Gram positive and Gram negative bacteria

e.g.,Tetracyclines, phenicols, fluoroquinolones, third-generation and fourth-generation antibiotivcs is cephalosporins.

Viruses parasitising bacteria are called bacteriophages. These viruses do not actually eat bacteria. They infect and replicate within the bacteria.

The bacterium Streptococcus that produces streptokinase is used as a 'clot buster'.

This enzyme has a fibrinolytic action that breaks down the clots formed in the blood vessels of patients who have undergone myocardial infarction. This prevents heart attack in these patients that can otherwise occur because of occlusion by the clots.

Biofertilisers are organisms that enrich the nutrient quality of the soil. The main source of biofertilizers are bacteria, fungi and cyanobacteria.

e.g.,

(i) Azospirillum, Rhizobium and Azotobacter can fix atmospheric nitrogen in the soil.

(ii) Blue-green algae like Anabaena, Nostoc, Occilatoria add organic matter to the soil and responsible for increase its fertility.