scholarly journals Microbial Nitrogen Metabolism in Chloraminated Drinking Water Reservoirs

mSphere ◽  
2020 ◽  
Vol 5 (2) ◽  
Author(s):  
Sarah C. Potgieter ◽  
Zihan Dai ◽  
Stephanus N. Venter ◽  
Makhosazana Sigudu ◽  
Ameet J. Pinto
Keyword(s):  
Nitric Oxide ◽  
Drinking Water ◽  
Nitrogen Metabolism ◽  
Distribution Systems ◽  
Water Systems ◽  
Nitrite Reduction ◽  
Water Utilities ◽  
Water Reservoirs ◽  
Nitrite Oxidizing Bacteria ◽  
Drinking Water Systems

ABSTRACT Ammonia availability due to chloramination can promote the growth of nitrifying organisms, which can deplete chloramine residuals and result in operational problems for drinking water utilities. In this study, we used a metagenomic approach to determine the identity and functional potential of microorganisms involved in nitrogen biotransformation within chloraminated drinking water reservoirs. Spatial changes in the nitrogen species included an increase in nitrate concentrations accompanied by a decrease in ammonium concentrations with increasing distance from the site of chloramination. This nitrifying activity was likely driven by canonical ammonia-oxidizing bacteria (i.e., Nitrosomonas) and nitrite-oxidizing bacteria (i.e., Nitrospira) as well as by complete-ammonia-oxidizing (i.e., comammox) Nitrospira-like bacteria. Functional annotation was used to evaluate genes associated with nitrogen metabolism, and the community gene catalogue contained mostly genes involved in nitrification, nitrate and nitrite reduction, and nitric oxide reduction. Furthermore, we assembled 47 high-quality metagenome-assembled genomes (MAGs) representing a highly diverse assemblage of bacteria. Of these, five MAGs showed high coverage across all samples, which included two Nitrosomonas, Nitrospira, Sphingomonas, and Rhizobiales-like MAGs. Systematic genome-level analyses of these MAGs in relation to nitrogen metabolism suggest that under ammonia-limited conditions, nitrate may be also reduced back to ammonia for assimilation. Alternatively, nitrate may be reduced to nitric oxide and may potentially play a role in regulating biofilm formation. Overall, this study provides insight into the microbial communities and their nitrogen metabolism and, together with the water chemistry data, improves our understanding of nitrogen biotransformation in chloraminated drinking water distribution systems. IMPORTANCE Chloramines are often used as a secondary disinfectant when free chlorine residuals are difficult to maintain. However, chloramination is often associated with the undesirable effect of nitrification, which results in operational problems for many drinking water utilities. The introduction of ammonia during chloramination provides a potential source of nitrogen either through the addition of excess ammonia or through chloramine decay. This promotes the growth of nitrifying microorganisms and provides a nitrogen source (i.e., nitrate) for the growth for other organisms. While the roles of canonical ammonia-oxidizing and nitrite-oxidizing bacteria in chloraminated drinking water systems have been extensively investigated, those studies have largely adopted a targeted gene-centered approach. Further, little is known about the potential long-term cooccurrence of complete-ammonia-oxidizing (i.e., comammox) bacteria and the potential metabolic synergies of nitrifying organisms with their heterotrophic counterparts that are capable of denitrification and nitrogen assimilation. This study leveraged data obtained for genome-resolved metagenomics over a time series to show that while nitrifying bacteria are dominant and likely to play a major role in nitrification, their cooccurrence with heterotrophic organisms suggests that nitric oxide production and nitrate reduction to ammonia may also occur in chloraminated drinking water systems.

scholarly journals Microbial Nitrogen Metabolism in Chloraminated Drinking Water Reservoirs

2019 ◽  
Author(s):  
Sarah C Potgieter ◽  
Zihan Dai ◽  
Stefanus N Venter ◽  
Makhosazana Sigudu ◽  
Ameet J Pinto
Keyword(s):  
Nitric Oxide ◽  
Drinking Water ◽  
Nitrogen Metabolism ◽  
Distribution Systems ◽  
Water Distribution ◽  
Water Utilities ◽  
Quality Data ◽  
Water Reservoirs ◽  
Microbial Nitrogen ◽  
Drinking Water Distribution

AbstractNitrification is a common concern in chloraminated drinking water distribution systems. The addition of ammonia promotes the growth of nitrifying organisms, causing the depletion of chloramine residuals and resulting in operational problems for many drinking water utilities. Therefore, a comprehensive understanding of the microbially mediated processes behind nitrogen metabolism together with chemical water quality data, may allow water utilities to better address the undesirable effects caused by nitrification. In this study, a metagenomic approach was applied to characterise the microbial nitrogen metabolism within chloraminated drinking water reservoirs. Samples from two geographically separated but connected chloraminated reservoirs within the same drinking water distribution system (DWDS) were collected within a 2-year sampling campaign. Spatial changes in the nitrogen compounds (ammonium (NH4+), nitrites (NO2−) and nitrates (NO3−)) across the DWDS were observed, where nitrate concentrations increased as the distance from the site of chloramination increased. The observed dominance ofNitrosomonasandNitrospira-like bacteria, together with the changes in the concentration of nitrogen species, suggests that these bacteria play a significant role in contributing to varying stages of nitrification in both reservoirs. Functionally annotated protein sequences were mined for the genes associated with nitrogen metabolism and the community gene catalogue contained mostly genes involved in nitrification, nitrate and nitrite reduction and nitric oxide reduction. Furthermore, based on the construction of Metagenome Assembled Genomes (MAGs), a highly diverse assemblage of bacteria (i.e., predominatelyAlpha- andBetaproteobacteriain this study) was observed among the draft genomes. Specifically, 5 MAGs showed high coverage across all samples including twoNitrosomonas, Nitrospira, Sphingomonasand aRhizobiales-like MAGs. The role of these MAGs in nitrogen metabolism revealed that the fate nitrate may be linked to changes in ammonia concentrations, that is, when ammonia concentrations are low, nitrate may be assimilated back to ammonia for growth. Alternatively, nitrate may be reduced to nitric oxide and potentially used in the regulation of biofilm formation. Therefore, this study provides insight into the genetic network behind microbially mediated nitrogen metabolism and together with the water chemistry data improves our understanding nitrification in chloraminated DWDSs.

scholarly journals The Water Safety Plan Approach: Application to Small Drinking-Water Systems—Case Studies in Salento (South Italy)

2021 ◽  
Vol 18 (8) ◽  
pp. 4360
Author(s):  
Francesca Serio ◽  
Lucia Martella ◽  
Giovanni Imbriani ◽  
Adele Idolo ◽  
Francesco Bagordo ◽  
...  
Keyword(s):  
Drinking Water ◽  
Case Studies ◽  
Distribution Systems ◽  
Water Systems ◽  
Water Safety ◽  
Quality Of Water ◽  
Safety Plan ◽  
Water Safety Plan ◽  
Drinking Water Systems

Background: The quality of water for human consumption is an objective of fundamental importance for the defense of public health. Since the management of networks involves many problems of control and efficiency of distribution, the Water Safety Plan (WSP) was introduced to address these growing problems. Methods: WSP was applied to three companies in which the water resource assumes central importance: five water kiosks, a third-range vegetable processing company, and a residence and care institution. In drafting the plan, the terms and procedures designed and tested for the management of urban distribution systems were applied to safeguard the resource over time. Results: The case studies demonstrated the reliability of the application of the model even to small drinking-water systems, even though it involved a greater effort in analyzing the incoming water, the local intended use, and the possibilities for managing the containment of the dangers to which it is exposed. This approach demonstrates concrete effectiveness in identifying and mitigating the dangers of altering the quality of water. Conclusions: Thanks to the WSP applied to small drinking-water systems, we can move from management that is focused mainly on verifying the conformity of the finished product to the creation of a global risk assessment and management system that covers the entire water supply chain.

scholarly journals Use of Newly Designed Primers for Quantification of Complete Ammonia-Oxidizing (Comammox) Bacterial Clades and Strict Nitrite Oxidizers in the Genus Nitrospira

2020 ◽  
Vol 86 (20) ◽  
Author(s):  
Ran Jiang ◽  
Jian-Gong Wang ◽  
Ting Zhu ◽  
Bin Zou ◽  
Dan-Qi Wang ◽  
...  
Keyword(s):  
Drinking Water ◽  
Water Samples ◽  
Water Systems ◽  
Ammonia Oxidizers ◽  
Specific Primer ◽  
High Coverage ◽  
Nitrite Oxidizing Bacteria ◽  
Nitrite Oxidoreductase ◽  
Primer Sets ◽  
Drinking Water Systems

ABSTRACT Complete ammonia-oxidizing (comammox) bacteria play key roles in environmental nitrogen cycling and all belong to the genus Nitrospira, which was originally believed to include only strict nitrite-oxidizing bacteria (sNOB). Thus, differential estimation of sNOB abundance from that of comammox Nitrospira has become problematic, since both contain nitrite oxidoreductase genes that serve as common targets for sNOB detection. Herein, we developed novel comammox Nitrospira clade A- and B-specific primer sets targeting the α-subunit of the ammonia monooxygenase gene (amoA) and a sNOB-specific primer set targeting the cyanase gene (cynS) for quantitative PCR (qPCR). The high coverage and specificity of these primers were checked by use of metagenome and metatranscriptome data sets. Efficient and specific amplification with these primers was demonstrated using various environmental samples. Using the newly designed primers, we successfully estimated the abundances of comammox Nitrospira and sNOB in samples from two chloramination-treated drinking water systems and found that, in most samples, comammox Nitrospira clade A was the dominant type of Nitrospira and also served as the primary ammonia oxidizer. Compared with other ammonia oxidizers, comammox Nitrospira had a higher abundance in process water samples in these two drinking water systems. We also demonstrated that sNOB can be readily misrepresented by an earlier method, calculated by subtracting the comammox Nitrospira abundance from the total Nitrospira abundance, especially when the comammox Nitrospira proportion is relatively high. The new primer sets were successfully applied to comammox Nitrospira and sNOB quantification, which may prove useful in understanding the roles of Nitrospira in nitrification in various ecosystems. IMPORTANCE Nitrospira is a dominant nitrite-oxidizing bacterium in many artificial and natural environments. The discovery of complete ammonia oxidizers in the genus Nitrospira prevents the use of previously identified primers targeting the Nitrospira 16S rRNA gene or nitrite oxidoreductase (nxr) gene for differential determination of strict nitrite-oxidizing bacteria (sNOB) in the genus Nitrospira and among comammox bacteria in this genus. We designed three novel primer sets that enabled quantification of comammox Nitrospira clades A and B and sNOB with high coverage, specificity, and accuracy in various environments. With the designed primer sets, sNOB and comammox Nitrospira were differentially estimated in drinking water systems, and we found that comammox clade A predominated over sNOB and other ammonia oxidizers in process water samples. Accurate quantification of comammox Nitrospira and sNOB by use of the newly designed primers will provide essential information for evaluating the contribution of Nitrospira to nitrification in various ecosystems.

DASH of Water – water distribution system modelling in the age of smart water meters

2020 ◽  
Author(s):  
David Steffelbauer ◽  
Mirjam Blokker ◽  
Arno Knobbe ◽  
Edo Abraham
Keyword(s):  
Drinking Water ◽  
Distribution Systems ◽  
Water Distribution ◽  
Data Science ◽  
Water Systems ◽  
Simulation Software ◽  
Water Utilities ◽  
Smart Meter ◽  
Smart Meters ◽  
Demand Models

<p>Worldwide, water utilities face exceptional challenges as communities are running out of water and new resources are ill-equipped to meet rising water demands. Furthermore, in many cities, years of stringent financial constraints on water utilities, unoptimized operations and the unaffordability for utilities to maintain and replace their aging infrastructure has resulted in dramatically growing leakage levels, especially in places already under high water stress. Even in Europe, as a matter of fact, nearly one quarter of treated water is lost in the distribution systems before reaching the customers. As a result, the aging water infrastructure is challenged to become more efficient.</p><p>Nowadays, an increasing number of water utilities use hydraulic simulation software to design and operate water systems in a more efficient way. However, measurements in water distribution are scarce, which results in inaccurate computer models of real systems. Recently, smart meters have become available as a promising remedy. These smart meters measure water usage of households and transmit information to water utilities in real-time. Now is the time to make water distribution simulation software fit for the future, by exploiting this new Big-data source and start a new era in hydraulic modeling, aiming to increase the operational efficiency of our drinking water systems and save our precious water resources.</p><p>This work proposes an innovative new way of combining hydraulic models, data from smart meters and stochastic demand modelling to develop beyond state-of-the-art methods to simulate water distribution systems. It is shown how data science algorithms (e.g. dynamic time warping, clustering, demand disaggregation, household activity identification, …) can be used to extract high-level information from smart meter data (e.g. daily water use routines, work schedules, socio-economic characteristics). Such information is crucial for simulating water demand accurately. Hence, data science algorithms can be used to automatically parametrize stochastic demand models (e.g. SIMDEUM) based on smart meter data, and improve their accuracy. The improved demand models are coupled with hydraulic simulations, leading to a more realistic way of simulating real water systems. Examples on a wide range of real-world applications show how these novel modelling approaches can be used to increase the operational efficiency of drinking water systems. For instance, more accurate models enable faster detection and localization of leaks in water pipes and, thus, minimize distribution losses. This work is part of the project “DASH of Water”, which aims to develop advanced <strong>da</strong>ta-driven <strong>s</strong>tochastic <strong>h</strong>ydraulic (DASH) models of drinking water distribution systems.</p>

scholarly journals Disinfectant residuals in drinking water systems select for mycobacterial populations with intrinsic antimicrobial resistance

2019 ◽  
Author(s):  
Maria Sevillano ◽  
Zihan Dai ◽  
Szymon Calus ◽  
Quyen M Bautista-de los Santos ◽  
A. Murat Eren ◽  
...  
Keyword(s):  
Drinking Water ◽  
Antimicrobial Resistance ◽  
Distribution Systems ◽  
Water Distribution ◽  
Water Cycle ◽  
Water Systems ◽  
Intrinsic Resistance ◽  
Drinking Water Distribution Systems ◽  
The Impact ◽  
Drinking Water Systems

AbstractAntimicrobial resistance (AMR) in drinking water has received less attention than counterparts in the urban water cycle. While culture-based techniques or gene-centric PCR have been used to probe the impact of treatment approaches (e.g., disinfection) on AMR in drinking water, to our knowledge there is no systematic comparison of AMR traits between disinfected and disinfectant residual-free drinking water systems. We use metagenomics to assess the associations between disinfectant residuals and AMR prevalence and its host association in full-scale drinking water distribution systems (DWDSs). The differences in AMR profiles between DWDSs are associated with the presence or absence of disinfectant. Further, AMR genes and mechanisms enriched in disinfected systems are associated with drug classes primarily linked to nontuberculous mycobacteria (NTM). Finally, evaluation of metagenome assembled genomes (MAGs) of NTM indicates that they possess AMR genes conferring intrinsic resistance to key antibiotics, whereas such NTM genomes were not detected in disinfectant residual free DWDSs. Thus, disinfection may not only influence the AMR profiles of the drinking water microbiome but also select for NTM with intrinsic AMR.

scholarly journals A Snapshot of the Global Drinking Water Virome: Diversity and Metabolic Potential Vary with Residual Disinfectant Use

2021 ◽  
Author(s):  
Bridget Emily Hegarty ◽  
Zihan Dai ◽  
Lutgarde Raskin ◽  
Ameet J Pinto ◽  
Krista Wigginton ◽  
...  
Keyword(s):  
Water Quality ◽  
Drinking Water ◽  
Dna Sequences ◽  
Distribution Systems ◽  
Drinking Water Treatment ◽  
Taxonomic Diversity ◽  
Water Systems ◽  
Free Chlorine ◽  
Metabolic Potential ◽  
Drinking Water Systems

Viruses are important drivers of microbial community ecology and evolution, influencing microbial mortality, metabolism, and horizontal gene transfer. However, the effects of viruses remain largely unknown in many environments, including in drinking water systems. Drinking water metagenomic studies have offered a whole community perspective of bacterial impacts on water quality, but have not yet considered the influences of viruses. In this study, we address this gap by mining viral DNA sequences from publicly available drinking water metagenomes from distribution systems in six countries around the world. These datasets provide a snapshot of the taxonomic diversity and metabolic potential of the global drinking water virome, and provide an opportunity to investigate the effects of geography, climate, and drinking water treatment practices on viral diversity. Both environmental conditions and differences in sample processing were found to influence the viral composition. Using free chlorine as the residual disinfectant was associated with clear differences in viral taxonomic diversity and metabolic potential, with significantly fewer viral populations and less even viral community structures than observed in distribution systems without residual disinfectant. Additionally, significantly more viral-encoded genes involved in mitigating oxidative stress were observed in systems that use free chlorine, while significantly more viral genes involved in nitrogen metabolism were observed in systems that do not. Through this study, we have demonstrated that viral communities are diverse across drinking water systems and vary with the use of residual disinfectant. Our findings offer directions for future research to develop a more robust understanding of how virus-bacteria interactions in drinking water distribution systems affect water quality.

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