Chlorination of Pseudomonas aeruginosa in potable water

The present study examined the effects of chlorine (NaOCl) disinfection on Pseudomonas aeruginosa in potable water. The adhesion of the bacteria on glass surfaces and the growth of the adherent cells were measured after treatment with chlorine (0, 0.25, 0.5, 0.75, and 1 mg/L). Adhesion was assessed by optical microscopy, and cultivability of the adherent cells was estimated by counting the bacteria on solid medium after being recovered from the support surface. Regardless of the concentration applied, P. aeruginosa did not lose the ability to adhere or grow after adhesion. However, the two factors were influenced by the chlorine treatments. The results showed that the adhesive capacity and cultivability of adherent cells were linked. The maximum inhibition of adherence and cultivability was observed in the 0.25 and 0.5 mg/L treatments. At 0.75 and 1 mg/L, the adhesive capability and post-adhesive cultivability were slightly increased. The results suggest that residual concentrations of sodium hypochlorite fixed by standards (less than 1 mg/L) may be ineffective against P. aeruginosa, and thus could have an impact on consumers.