The impact of monochloramine on the diversity and dynamics of Legionella pneumophila subpopulations in a nuclear power plant cooling circuit

• Published in: FEMS microbiology ecology 2013-08, Vol.85 (2), p.302-312
• Main Authors: Jakubek, Delphine, Brun, Matthieu Le, Leblon, Gerard, DuBow, Michael, Binet, Marie
• Format: Article
• Language: English
• Subjects: Animal, plant and microbial ecology; Bacteriology; Biochemistry, Molecular Biology; Biodiversity; Biological and medical sciences; Chemical treatment; Chloramines - pharmacology; Community structure; Disinfectants - pharmacology; disinfection; dynamics; Ecology; Fundamental and applied biological sciences. Psychology; Growth conditions; IRS‐PCR; Legionella pneumophila; Legionella pneumophila - classification; Legionella pneumophila - drug effects; Legionella pneumophila - isolation & purification; Life Sciences; Microbial ecology; Microbiology; Microbiology and Parasitology; Miscellaneous; monochloramine; Nuclear Power Plants; Subpopulations; Various environments (extraatmospheric space, air, water); water cooling circuit
• ISSN: 0168-6496; 1574-6941
• DOI: 10.1111/1574-6941.12121

Abstract Members of the pathogenic Legionella genus encounter suitable growth conditions in nuclear power plant cooling circuits. To limit its proliferation and ensure that levels remain below regulatory thresholds, chemical treatment with monochloramine can be used in continuous or sequential conditions. The aim of this study was to determine the impact of monochloramine on L. pneumophila subpopulations in the cooling circuits of a nuclear power plant. The chosen procedure involved monitoring the diversity and dynamics of L. pneumophila subpopulations every month over the course of a year in a nuclear power plant cooling circuit, which was treated for 2 months during the period under study. This study confirmed the effectiveness of monochloramine to limit L. pneumophila concentrations in cooling circuits. The culturable L. pneumophila community was strongly affected by the injection of monochloramine. Several subpopulations persisted during treatment at low concentrations (below the detection limit of standard methods), suggesting that the susceptibility of L. pneumophila is strain dependent. Although the composition of the subpopulations was not similar, the resilience of the community structure was observed. Indeed, the community eventually returned to its initial structure and presented a similar pattern of richness, diversity and uniformity to that seen before treatment.