Inhibition of in vitro enzymatic DNA amplification reaction by ultra-violet light irradiation.

Ultra-violet light irradiation of containers and components used in in vitro DNA amplification reactions catalyse by Taq DNA polymerase is a simple and effective method to reduce carry-over contamination and can reduce false-positive results. However, we found that prolonged exposure of water in polypropylene microcentrifuge tubes to u.v. light can result in reduction of amplification efficiency by at least two orders of magnitude when these water specimens are used in amplification reaction mixtures. Although the mechanism that causes this inhibition of DNA amplification is unclear now, the results seem to suggest that u.v. irradiation for routine anti-contamination purposes should be used with caution.