Evaluation of some halogen biocides using a microbial biofilm system

• Published in: Water research (Oxford) 2005-10, Vol.39 (17), p.4126-4132
• Main Authors: Tachikawa, Mariko, Tezuka, Masakatsu, Morita, Masahiro, Isogai, Katsuhisa, Okada, Shoji
• Format: Article
• Language: English
• Subjects: Anti-Bacterial Agents - pharmacology; antimicrobial agents; Applied sciences; biofilm; Biofilm images by CLSM; Biofilms; Biological and medical sciences; Biotechnology; Bromamines; Bromochloramine; Chloramines; disinfection; Disinfection efficacy; Environment and pollution; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; Halogen biocides; halogens; Halogens - pharmacology; HOCL; Industrial applications and implications. Economical aspects; Klebsiella pneumoniae; Klebsiella pneumoniae - drug effects; Other industrial wastes. Sewage sludge; Pollution; Pseudomonas aeruginosa; Pseudomonas fluorescens; Pseudomonas fluorescens - drug effects; Spectrophotometry, Ultraviolet; Wastes; water treatment; Water treatment and pollution
• ISSN: 0043-1354; 1879-2448
• DOI: 10.1016/j.watres.2005.07.039

A simple method for the formation of microbial biofilms of three species, Pseudomonas fluorescens, Pseudomonas aeruginosa, and Klebsiella pneumoniae, on a small glass slide was established, and its suitability for evaluation of disinfectant efficacy was examined. The biofilms formed were observed in situ by confocal laser scanning microscopy (CLSM). Using the biofilms established, biocidal efficacy of several halogen biocides, such as hypochlorite (HOCl), bromochlorodimethylhydantoin (Br, Cl-DMH), ammonia monochloramine (NH 2Cl), a stabilized hypobromite biocide named STABREX ®, and a mixed solution of NH 4Br and HOCl, was evaluated. The formation of NHBrCl in the mixed solution was indicated by UV spectra analysis. Biofilm cells were more resistant to these biocides than planktonic cells and the extent of resistance varied with the biocide tested. Among the biocides tested, the biocidal potency of HOCl was the most susceptible to the change brought about by biofilm formation. By CLSM observation, differences in biofilm conformation were revealed between the microbial species. The efficacy of the biocide tested varied with the structure of biofilms formed. The assay method developed in the present study would be useful for further investigation on biofilm disinfection.