Persistence of Klebsiella pneumoniae on Simulated Biofilm in a Model Drinking Water System

• Published in: Environmental science & technology Vol. 40; no. 16; pp. 4996 - 5002
• Main Authors: Szabo, Jeffrey G, Rice, Eugene W, Bishop, Paul L
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 15.08.2006
• Subjects: Applied sciences; Bacteria; Biofilms; Buildings. Public works; Cell adhesion & migration; Chlorine - analysis; Corrosion; Drinking water; Drinking water and swimming-pool water. Desalination; Electrodes; Environmental Monitoring - methods; Exact sciences and technology; Iron; Klebsiella pneumoniae; Klebsiella pneumoniae - metabolism; Oxygen - chemistry; Pollution; Sewerage. Sewer construction; Static Electricity; Temperature; Time Factors; Water Microbiology; Water Purification; Water Supply; Water treatment and pollution; Drinking water; Drinking water pipe; Iron; Microbial biomass; Modeling; Corrosion product; Water supply system network; Bioreactor; Water quality; Biofilm; Bacteria; Oligotrophy; Klebsiella pneumoniae; Enterobacteriaceae
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es060857h

Persistence of Klebsiella pneumoniae on corroded iron surfaces in drinking water was studied using biofilm annular reactors operated under oligotrophic conditions. Reactors were inoculated with K. pneumoniae, and persistence was monitored in the bulk and biofilm phases. Initial cell concentration of 106 MPN/mL in the bulk water phase resulted in significantly longer adhesion than initial concentrations 1 and 2 orders of magnitude lower. K. pneumoniae cultured in low nutrient growth medium persisted longer in dechlorinated tap water than those cultured in full strength medium. Cell surface charge was more negative under low nutrient conditions, and this influenced electrostatic attraction between the cells and the oxidized iron surface. Cells grown in full strength media persisted longer in water with both low (<0.2 mg/L) and high (>0.5 mg/L) free chlorine residuals. Growth media injected with the cells dechlorinated the water allowing adhesion without inactivation. Microelectrode measurements showed a 40−70% drop in free chlorine from the bulk to the coupon surface, which decreased disinfectant potency against adhered cells. Growth and injection conditions clearly influenced cell adhesion and persistence, but permanent colonization of the corroded iron surface by K. pneumoniae was not observed.