Abstract

The aim of this study was investigating the effects of hertogeneous catalytic ozonation process with copper (HCO) as a new designed disinfectant for inhibition of virulence factors in L. pneumophila in hospital water. The hospital water was selected as a natural contaminant source for L. pneumophila. The samples were exposed with ozone with MIC= 0.5 mu g/mL for single ozonation (SO) in 20 min, and HCO for 15 min. HCO led to complete removal of bacteria after 10 min. The mRNA of the exposed and unexposed samples with SO and HCO was extracted by GmbH Jena bioscience (Germany). Then, the cDNA of the samples was synthesized and the change of expression levels of the selected genes was evaluated. The effects of modified disinfectant against gene expression inhibition t2ss and t4ss were studied by the RTPCR. Both SO and HCO led to completely L.P. removal, in which the second system was fast. Gene expression of t2ss and t4ss decreased after exposure to the disinfectant but did not change the expression level of housekeeping gene mip. Also, HCO reduced gene expression more than SO. The removal efficiency of L.P in HCO was higher than SO. There was an interaction effect between the two types of ozonation processes, and the exposure time colonies to removal (p=.001). The MIC results for both SO at 20 min and HCO with copper at 15 min were 0.5 mu g/mL. HCO successfully can inhibit the expression of virulence genes of L. pneumophila. Therefore, this system can be used for hospital water disinfection and control of L. pneumophil concerns in health care systems.