Explanation

Escherichia coli and Agrobacterium tumefaciens are microbes found to be very useful in genetic engineering. E. coli is motile, Gram negative, rod shaped bacterium which is a normal inhabitant of human colon. It is most extensively used in bacterial genetics and molecular biology. Agrobacterium tumefaciens is a soil bacterium. It has $T_{i}$ plasmid (Tumour inducing plasmid) and it can be used for the transfer of a desired gene in dicot plants.