Microbes found to be very useful in genetic engineering are:
(a) Escherichia coli and Agrobacterium tumefaciens
(b) Vibrio cholerae and a tailed bacteriophage
(c) Diplococcus sp. and Pseudomonas sp.
(d) Crown gall bacterium and Caenorhabditis elegans
(a) Escherichia coli and Agrobacterium tumefaciens are the microbes found to be very useful in genetic engineering. E.coli is a 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 Ti plasmid (Tumour inducing plasmid) and it can be used for the transfer of a desired gene in dicot plants.