Occurrence of sessile Pseudomonas oryzihabitans from a karstified chalk aquifer

Pseudomonas oryzihabitans is an uncommon pathogen that may cause opportunistic infections. Although it has been previously isolated from the environment, the source of human infection has not been well documented. In this study, we describe the presence of P. oryzihabitans adhering on suspended particulate matters recovered from karst groundwaters. The isolated pathogen was capable of forming biofilms on silicon supports and clay beads. Adherent P. oryzihabitans cells displayed a high resistance to chlorine as compared with the same organisms cultured in the planktonic mode. These results demonstrate that aquifer biofilms are potential environmental sources for water-born P. oryzihabitans infections and that bacterial attachment might affect drinking water purification.