The Agrobacterium tumefaciens is a plant pathogen which carries the tumor-inducing plasmid. The pBR322 is an artificial plasmid and a cloning vector of the bacterium E. coli. The bacterium Thermus aquaticus is a kind of bacteria that can tolerate extremes of temperature and therefore falls in the category of thermophilic bacteria. Ligase is a DNA binding that connects the two strands of DNA by forming a phosphodiester bond.