Multiplication Expression and Integration of the DNA Insert in Host Genome - Once the clone containing the desired DNA insert is identified, it is multiplied in E. coli to obtain sufficient number of copies to be used in one or more of the following ways.

(1) It can be used for a structural analysis of the insert, e.g., DNA sequencing, chromosome walking, etc.

(2) It may be introduced into a bacterium like B. subtilis for production of the protein encoded by the DNA insert since this host secretes proteins into the medium which allows easy purification.