Original Article

The ISME Journal (2016) 10, 1064–1080; doi:10.1038/ismej.2015.199; published online 3 November 2015

Legionella species diversity and dynamics from surface reservoir to tap water: from cold adaptation to thermophily

René Lesnik1, Ingrid Brettar1 and Manfred G Höfle1

1Department of Vaccinology and Applied Microbiology, Helmholtz Centre for Infection Research, Braunschweig, Germany

Correspondence: M Höfle, Department of Vaccinology and Applied Microbiology, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, Braunschweig 38124, Germany. E-mail: manfred.hoefle@helmholtz-hzi.de

Received 5 May 2015; Revised 12 August 2015; Accepted 22 September 2015
Advance online publication 3 November 2015

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Abstract

Water samples of the Drinking Water Supply System (DWSS) of the city of Braunschweig were analysed for its Legionella species composition using genus-specific PCR amplicons and single-strand conformation polymorphism (SSCP) fingerprint analyses based on 16S rRNA genes. These analyses comprised the whole supply chain including raw water, treatment process and large-scale storage, and a seasonal study of finished drinking water sampled monthly from cold and hot tap water. Treatment of raw water had a major impact on Legionella species by reducing their diversity and abundances. The Legionella species composition of the tap water was highly distinct from that of both source waters. In cold water, 8–14 different phylotypes of Legionella (PTLs) were observed per sample with relative abundances ranging from >1% to 53%. In hot water, L. pneumophila was present during all seasons at high relative abundances (8–40%) accompanied by 5–14 other PTLs of which 6 PTLs were in common with cold water. This thermophilic Legionella community, including L. pneumophila, was able to grow in the hot water above 50°C. Such thermophilic Legionella populations are of general relevance for drinking water management and public health, but also for the ecology and evolution of the genus Legionella.