Scientists can identify pathogenic genes through genetic engineering. This involves adding human-made DNA into a bacterial cell. However, the problem is that bacteria have evolved complex defense systems to protect against foreign intruders — especially foreign DNA. Current genetic engineering approaches often disguise the human-made DNA as bacterial DNA to thwart these defenses, but the process requires highly specific modifications and is expensive and time-consuming.

In a paper published recently in the Proceedings of the National Academy of Sciences journal, Dr. Christopher Johnston and his colleagues at the Forsyth Institute describe a new technique to genetically engineer bacteria by making human-made DNA invisible to a bacterium’s defenses. In theory, the method can be applied to almost any type of bacteria.

Johnston is a researcher in the Vaccine and Infectious Disease Division at the Fred Hutchinson Cancer Research Center and lead author of the paper. He said that when a bacterial cell detects it has been penetrated by foreign DNA, it quickly destroys the trespasser. Bacteria live under constant threat of attack by a virus, so they have developed incredibly effective defenses against those threats.