e first set included irradiation times of 0, 10, 30 and 60 seconds
at 30cm from the plate. This kill curve actually appears to be an ideal exponential decay curve except that we were
not satisfied with one main area. The curve only contained 4 points and the actual shape of the curve was
determined in large by the time point at 10 seconds of exposure. Looking back at this set, it may have prove
beneficial to repeat this set of conditions with several more time points. The second set of conditions involved
exposure times of 0, 5, 10, and 15 seconds at 60cm away from the plate. This provided a better curve because it was
more reliable due to several points falling closely together, giving more confidence to the curve. Furthermore, this
set gave a 10 5 -fold killing compared to 10 4 -fold killing in the first set which is much closer to the ideal kill of 10 6
(Dr. Ramey, personal communication). In the end, the second set was chosen as the kill parameters for a majority of
the project.
Photoreactivation after UV irradiation. Photoreactivation was briefly looked at in this experiment by exposing
UV irradiated plates to natural sunlight. The strains DH5α(pUC19) and INVα(pUC19) were usually irradiated for
10 seconds and then placed at the windowsill for an hour to two hours. The results obtained from these quick tests
were varied, during some runs there was about 100-fold reactivation by sunlight while on other runs, the
photoreactivation was only 5-fold. But in general, all plates