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- Ahlinder, Jon, et al.
(författare)
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Upstream land use with microbial downstream consequences : iron and humic substances link to Legionella spp
- 2024
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Ingår i: Water Research. - : Elsevier. - 0043-1354 .- 1879-2448. ; 256
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Tidskriftsartikel (refereegranskat)abstract
- Intensified land use can disturb water quality, potentially increasing the abundance of bacterial pathogens, threatening public access to clean water. This threat involves both direct contamination of faecal bacteria as well as indirect factors, such as disturbed water chemistry and microbiota, which can lead to contamination. While direct contamination has been well described, the impact of indirect factors is less explored, despite the potential of severe downstream consequences on water supply. To assess direct and indirect downstream effects of buildings, farms, pastures and fields on potential water sources, we studied five Swedish lakes and their inflows. We analysed a total of 160 samples in a gradient of anthropogenic activity spanning four time points, including faecal and water-quality indicators. Through species distribution modelling, Random Forest and network analysis using 16S rRNA amplicon sequencing data, our findings highlight that land use indirectly impacts lakes via inflows. Land use impacted approximately one third of inflow microbiota taxa, in turn impacting ∌20–50 % of lake taxa. Indirect effects via inflows were also suggested by causal links between e.g. water colour and lake bacterial taxa, where this influenced the abundance of several freshwater bacteria, such as Polynucleobacter and Limnohabitans. However, it was not possible to identify direct effects on the lakes based on analysis of physiochemical- or microbial parameters. To avoid potential downstream consequences on water supply, it is thus important to consider possible indirect effects from upstream land use and inflows, even when no direct effects can be observed on lakes. Legionella (a genus containing bacterial pathogens) illustrated potential consequences, since the genus was particularly abundant in inflows and was shown to increase by the presence of pastures, fields, and farms. The approach presented here could be used to assess the suitability of lakes as alternative raw water sources or help to mitigate contaminations in important water catchments. Continued broad investigations of stressors on the microbial network can identify indirect effects, avoid enrichment of pathogens, and help secure water accessibility.
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| 2. |
- Rosenqvist, Tage, et al.
(författare)
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Succession of bacterial biofilm communities following removal of chloramine from a full-scale drinking water distribution system
- 2023
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Ingår i: npj Clean Water. - 2059-7037. ; 2023:6
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Tidskriftsartikel (refereegranskat)abstract
- Monochloramine is used to regulate microbial regrowth in drinking water distribution systems (DWDS) but produces carcinogenic disinfection byproducts and constitutes a source of energy for nitrifying bacteria. This study followed biofilm-dispersed microbial communities of a full-scale DWDS distributing ultrafiltered water over three years, before and after removal of monochloramine. Communities were described using flow cytometry and amplicon sequencing, including full-length 16S rRNA gene sequencing. Removal of monochloramine increased total cell counts by up to 440%. Increased abundance of heterotrophic bacteria was followed by emergence of the predatory bacteria Bdellovibrio, and a community potentially metabolizing small organic compounds replaced the nitrifying core community. No increased abundance of Mycobacterium or Legionella was observed. Co-occurrence analysis identified a network of Nitrosomonas, Nitrospira, Sphingomonas and Hyphomicrobium, suggesting that monochloramine supported this biofilm community. While some species expanded into the changed niche, no immediate biological risk to consumers was indicated within the DWDS.
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