This was the first study on low-energy PIII of extracellular plasmid
DNA and marker gene fragment to investigate the relevant effects on
mutation of the DNA- or fragment-transformed bacteria. Mutation
could indeed be induced by keV-ion bombardment of DNA. In the
ranges of a few keV of the N-ion energy and 0.5–6×1015 ions/cm2
in fluence, the bacterial mutation frequency was linearly proportional
to the deposited ion energy and ion fluence for the DNA-transformed
E. coli and the lacZ-gene-fragment-transformed E. coli. Damage to the
lacZ gene was identified as the dominant mutation source. The DNA
mutation types were dominated by the base substitution and cytosine
had the highest radiation-sensitivity