Abstract

To report the effects of pulsed ultraviolet (PUV) radiation, we have developed a reliable biological monitoring system based on two approaches. Firstly, a conventional method was used to measure the number of colonies by the estimation of viable and cultivable bacteria before, and after each exposure to PUV radiation. The second method was a DNA-dosimeter system based on polymerase chain reaction (PCR) 16S ribosomal DNA (rDNA) and on terminal restriction fragment length polymorphism (T-RFLP) analysis. PCR was performed using 27F and 905R primers to replicate a fragment of the rDNA gene. The comparison of inactivation kinetic results obtained by a classic account of viable and cultivable bacteria (UV dose/ response) and the analysis of DNA-dosimeter determined by PCR amplification and peak-profiles T-RFLP; shows a correlation between the reduction of the colony-forming ability of Pseudomonas aeruginosa and the progressive decrease of 16S rDNA PCR products and of relative peak area of a specific terminal restriction fragment (T-RF).

Key words: Pulsed UV light, Pseudomonas aeruginosa, viable but non-culturable (VBNC) bacteria, 16S rDNA, terminal restriction fragment length polymorphism (T-RFLP).