Two microbes found to be very useful in genetic engineering are:

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. Related Theory Using Agrobacterium vectors, nematode specific genes are introduced into host plants. The introduction of DNA produces both sense and antisense RNA in host cells. These two RNAs being complementary form a double stranded RNA (dsRNA) that initiates the RNAs and silence the specific $m R N A$ of the nematode. As a result of this, the parasite cannot survive in the transgenic host expressing specific interfering $R N A$.