Question

Bacteria are used extensively in Biotechnology/Genetic Engineering. Describe two different techniques or tools used in biotechnology/genetic engineering that involve bacteria (i.e. whole cells, genetic information, protein products, etc.) Be sure to explain how bacteria are involved in the technique you described.

Answer 1

The use of bacteria is one of the most common techniques in Biotechnology /Genetic Engineering for genetic manipulation or modification. Two such different techniques involving bacteria are the following:

1. T-DNA tagging: This technique is used to identify a gene sequence by tagging it by a known sequence such that of a transfer DNA also called T-DNA.

T-DNA is a segment of DNA found in the tumor inducing plasmid called Ti plasmid which is present in the soil bacteria Agrobacterium tumefaciens. The bacteria is known to induce tumor like outgrowths in the plants that are infected by it. This is due to the Ti plasmid which carries tumor inducing genes. This process of tumor formation by the bacteria in plants occurs in nature. Hence using the specific properties of Agrobacterium, the Ti plasmid as well as it's DNA segment fraction called T- DNA are now used in genetic engineering. T-DNA tagging also causes insertional mutation in the gene, hence, making it easy to recognise the mutated gene when compared with the wild gene.

2. Bt Gentically Modified crops: Bt stands for Bacillus thuringiensis. It is a bacteria found in soil and produces an endotoxin called as cry protein encoded by cry genes. The endotoxin when ingested by insects, kills them, thus works as an insecticidal agent. This property of Bt has been utilized in genetic engineering by making crops insect resistant by inserting the cry genes responsible for the resistance from the Bt bacteria to the plant. Thus the plant becomes a genetically modified (GM) crop and is capable of producing the cry protein or the endotoxin itself. Examples of such GM crops are Bt maize, Bt brinjal, and Bt cotton.