If our intestine harbors microbial flora exactly similar to that found in the rumen of cattle, we would be able to digest the cellulose present in our foods because the microbes present in the rumen (a part of stomach) of cattle, collectively called methanogens, are capable of digesting cellulose as they have cellulase enzyme.

Two microbes that are useful in biotechnology are

(i) Bacillus thuringiensis a gene isolated from this bacterium is introduced in cotton plants to make them able to kill butterfly caterpillars.

(ii) Escherichia coli is a bacterium that is used in many biotechnology procedures. Their plasmid is used as vector to introduce foreign DNA segment in desired organisms.

Escherichia coli strain RY 13 is the source organism for Eco RI.

Bt cotton is a genetically modified plant that has been modified to resist attack by insect pests e.g., cotton ball worm). These are developed by introducing a gene from Bacillus thuringiensis which produces toxin is plants which is lethat to insects.

Blue-green algae add organic matter to the soil and increase its fertility still these are not popular as biofertilisers. This is due to several constraints that limit the application or implementation of the biofertiliser technology. The constraints may be environmental, technological, infrastructural, financial, unawareness, quality, marketing etc.