Fig. 2. Observation of the plasma-ion-bombarded whole pUC19-DNA transformed E. coli (DH5α). (a) The bacterial blue and white colonies observed under natural light. (b) The
restreaked bacterial white colony (left) compared with blue colony (right, control). (c) For comparison, the bacterial colonies transferred with plasmid DNA pGFP (3344 base
pairs) bombarded by N-ion beam at energy 2.5 keV and fluence 3×1013 ions/cm2. As the pGFP contained green-fluorescent-protein (GFP) gene marker, the color of non-mutant
bacteria was in green under UV. Obviously, the number of white colonies relative to the colored colonies is seen much more than that in (a). Note: the mutation expressions of
the bacteria transferred with DNA pUC19 and pGFP were observed under different lights and so the colors shown in the photos are seen differently. In black-white photo
modes, the white colonies or mutants in (a) are those in lighter color, while in (c) are those in darker color.