INFLUENCE OF PLUMBING MATERIALS ON BIOFILM FORMATION AND GROWTH OF LEGIONELLA-PNEUMOPHILA IN POTABLE WATER-SYSTEMS

A two-stage chemostat model of a plumbing system was developed, with t ap water as the sole nutrient source. The model system was populated w ith a naturally occurring inoculum derived from an outbreak of Legionn aires' disease and containing Legionella pneumophila along with associ ated bacteria and protozoa. The model system was used to develop biofi lms on the surfaces of a range of eight plumbing materials under contr olled, reproducible conditions. The materials varied in their abilitie s to support biofilm development and the growth of L. pneumophila. Ela stomeric surfaces had the most abundant biofilms supporting the highes t numbers of L. pneumophila CFU; this was attributed to the leaching o f nutrients for bacterial growth from the materials. No direct relatio nship existed between total biofouling and the numbers of L. pneumophi la CFU.