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Occurrence and genetic diversity of uncultured Legionella spp. in drinking water treated at temperatures below 15 degrees C.

ABSTRACT: Representatives of the genus Legionella were detected by use of a real-time PCR method in all water samples collected directly after treatment from 16 surface water (SW) supplies prior to postdisinfection and from 81 groundwater (GW) supplies. Legionella concentrations ranged from 1.1 x 10(3) to 7.8 x 10(5) cells liter(-1) and were significantly higher in SW treated with multiple barriers at 4 degrees C than in GW treated at 9 to 12 degrees C with aeration and filtration but without chemical disinfection. No Legionellae (<50 CFU liter(-1)) were detected in treated water by the culture method. Legionella was also observed in untreated SW and in untreated aerobic and anaerobic GW. Filtration processes in SW and GW treatment had little effect or increased the Legionella concentration, but ozonation in SW treatment caused about 1-log-unit reduction. A phylogenetic analysis of 16S rRNA gene sequences of 202 clones, obtained from a selection of samples, showed a high similarity (>91%) with Legionella sequences in the GenBank database. A total of 40 (33%) of the 16S rRNA gene sequences obtained from treated water were identified as described Legionella species and types, including L. bozemanii, L. worsleiensis, Legionella-like amoebal pathogen types, L. quateirensis, L. waltersii, and L. pneumophila. 16S rRNA gene sequences with a similarity of below 97% from described species were positioned all over the phylogenetic tree of Legionella. Hence, a large diversity of yet-uncultured Legionellae are common members of the microbial communities in SW and GW treated at water temperatures of below 15 degrees C.

SUBMITTER: Wullings BA

PROVIDER: S-EPMC1352175 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Concentration and diversity of uncultured Legionella spp. in two unchlorinated drinking water supplies with different concentrations of natural organic matter.

Project description:Two unchlorinated drinking water supplies were investigated to assess the potential of water treatment and distribution systems to support the growth of Legionella spp. The treatment plant for supply A distributed treated groundwater with a low concentration (<0.5 ppm of C) of natural organic matter (NOM), and the treatment plant for supply B distributed treated groundwater with a high NOM concentration (8 ppm of C). In both supplies, the water temperature ranged from about 10°C after treatment to 18°C during distribution. The concentrations of Legionella spp. in distributed water, analyzed with quantitative PCR (Q-PCR), averaged 2.9 (± 1.9) × 10(2) cells liter(-1) in supply A and 2.5 (± 1.6) × 10(3) cells liter(-1) in supply B. No Legionella was observed with the culture method. A total of 346 clones (96 operational taxonomical units [OTUs] with ≥97% sequence similarity) were retrieved from water and biofilms of supply A and 251 (43 OTUs) from supply B. The estimation of the average value of total species richness (Chao1) in supply A (153) was clearly higher than that for supply B (58). In each supply, about 77% of the sequences showed <97% similarity to described species. Sequences related to L. pneumophila were only incidentally observed. The Legionella populations of the two supplies are divided into two distinct clusters based on distances in the phylogenetic tree as fractions of the branch length. Thus, a large variety of mostly yet-undescribed Legionella spp. proliferates in unchlorinated water supplies at temperatures below 18°C. The lowest concentration and greatest diversity were observed in the supply with the low NOM concentration.

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Legionella spp. All Ears? The Broad Occurrence of Quorum Sensing Elements outside Legionella pneumophila.

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| S-EPMC3194851 | biostudies-literature

Occurrence of <i>Legionella</i> spp. in Man-Made Water Sources: Isolates Distribution and Phylogenetic Characterization in the Emilia-Romagna Region.

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2016-12-12 | E-MTAB-4808 | biostudies-arrayexpress

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