In this study we wanted to examine how the adhesion of Legionella pneumophila subsp. pneumophila ATCC 33152 bacterial cells is affected by the properties of various types of materials, such as roughness, hydrophobicity and charge, and how the bacteria are affected by different temperature conditions, shear forces and the presence of disinfectants dichloroisocyanuric acid and water softeners sodium polyphosphate. In the first part of the study we determined the adhesion of bacterial cells on borosilicate glass coupons of different roughness, while in the second part adhesion on the surface of materials that are most commonly used for plumbing and ventilation sistems in buildings. The materials differed in composition, roughness and contact angle. The adhesion of the bacteria to different surfaces was determined by the spectrophotometric measurement of the optical density of crystal violet dye released from the stained bacterial cells adhering to the test surface. In the first part of the study, it was established that the roughness of the material affects the adhesion of bacterial cells, as adhesion was higher on rougher glass coupons. The results of the study of bacterial adhesion to materials most commonly used in plumbing showed that adhesion not only depended on the roughness of the material but also on its other properties, as adhesion was not the lowest on the smoothest material. The test bacteria adhered the most firmly to galvanised pipes and the least firmly to polypropylene pipes. Bacteria adhesion was also affected by the incubation temperature, because adhesion was the highest at a temperature of 36 ° C and the lowest at a temperature of 15 ° C. The results show that incubation temperature of 15 ° C is bacteriostatic and temperature of 55 ° C is bactericidal.
|
