In-situ tryptophan-like fluorescence: A real-time indicator of faecal contamination in drinking water supplies

Efficient management of drinking water quality is critical for the water supply, so effective monitoring of supply and storage systems is a priority. This project aims to predict the presence of Taste and Odour (T&O) compounds in drinking water reservoirs, using molecular analyses and smart in-situ monitoring systems. The most common T&O compounds, Geosmin and 2-MIB, are secondary metabolites that can be produced in waterbodies by cyanobacteria and actinomycetes and impact drinking water taste and odour. Although there is no evidence of related health risks, they can be perceived by humans at very low concentrations (5-10 ng/L) and the treatment process to remove them from drinking water is costly. Early assessment of T&O risk is crucial, but currently requires time-consuming and costly sampling as well as laboratory analysis which prevents real-time monitoring and a timely management response.Cyanobacterial species responsible for T&O production can be monitored with eDNA techniques and potentially provide an early warning of T&O episodes. Moreover, detection of the genes that are responsible for T&O production within the DNA of the freshwater community can help to speed up analysis. We show that qPCR methods can target the Geosmin synthase gene (geoA) and that this correlates significantly with Geosmin concentrations >15 ng/L. Alternatively, in-situ sensors that can be deployed remotely and transmit data, can provide real-time monitoring for early warning and potentially predictive capacity. Commercially available sensors do not currently exist for T&O compounds, but they do for many other water quality parameters. We consider the analytes that could be effective for T&O warning systems, using a Welsh reservoir as an exemplar case. Assessment of nutrient dynamics suggests N and P ratios are critical, hence we evaluate the sensors that are available for these compounds and associated environmental controls on their behaviour. We present recommendations for the design of an in-situ monitoring programme and introduce the planned tests that will evaluate it.

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In Situ Monitoring of the Nascent Pseudomonas fluorescens Biofilm Response to Variations in the Dissolved Organic Carbon Level in Low-Nutrient Water by Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy

Applied and Environmental Microbiology ◽

10.1128/aem.00838-07 ◽

2007 ◽

Vol 73 (18) ◽

pp. 5782-5788 ◽

Cited By ~ 50

Author(s):

Anne Delille ◽

Fabienne Quilès ◽

François Humbert

Keyword(s):

Drinking Water ◽

Fourier Transform ◽

Organic Carbon ◽

Dissolved Organic Carbon ◽

Pseudomonas Fluorescens ◽

Real Time ◽

Tap Water ◽

Attenuated Total Reflectance ◽

Total Reflectance

ABSTRACT Drinking water quality management requires early warning tools which enable water supply companies to detect quickly and to forecast degradation of the microbial quality of drinking water during its transport throughout distribution systems. This study evaluated the feasibility of assessing, in real time, drinking water biostability by monitoring in situ the evolution of the attenuated total reflectance-Fourier transform infrared (ATR-FTIR) fingerprint of a nascent reference biofilm exposed to water being tested. For this purpose, the responses of nascent Pseudomonas fluorescens biofilms to variations in the dissolved organic carbon (DOC) level in tap water were monitored in situ and in real time by ATR-FTIR spectroscopy. Nascent P. fluorescens biofilms consisting of a monolayer of bacteria were formed on the germanium crystal of an ATR flowthrough cell by pumping bacterial suspensions in Luria-Bertani (LB) medium through the cell. Then they were exposed to a continuous flow of dechlorinated sterile tap water supplemented with appropriate amounts of sterile LB medium to obtain DOC concentrations ranging from 1.5 to 11.8 mg/liter. The time evolution of infrared bands related to proteins, polysaccharides, and nucleic acids clearly showed that changes in the DOC concentration resulted in changes in the nascent biofilm ATR-FTIR fingerprint within 2 h after exposure of the biofilm to the water being tested. The initial bacterial attachment, biofilm detachment, and regrowth kinetics determined from changes in the areas of bands associated with proteins and polysaccharides were directly dependent on the DOC level. Furthermore, they were consistent with bacterial adhesion or growth kinetic models and extracellular polymeric substance overproduction or starvation-dependent detachment mechanisms.

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Probing the Dynamic Self-Assembly Behaviour of Photoswitchable Wormlike Micelles in Real Time

10.26434/chemrxiv.7098695 ◽

2018 ◽

Author(s):

Elaine A. Kelly ◽

Judith E. Houston ◽

Rachel Evans

Keyword(s):

Real Time ◽

Absorption Spectroscopy ◽

Self Assembly ◽

Uv Light ◽

Wormlike Micelles ◽

Tetraethylene Glycol ◽

Light Illumination ◽

First Time ◽

Dependent Processes

Understanding the dynamic self-assembly behaviour of azobenzene photosurfactants (AzoPS) is crucial to advance their use in controlled release applications such asdrug delivery and micellar catalysis. Currently, their behaviour in the equilibrium cis-and trans-photostationary states is more widely understood than during the photoisomerisation process itself. Here, we investigate the time-dependent self-assembly of the different photoisomers of a model neutral AzoPS, <a>tetraethylene glycol mono(4′,4-octyloxy,octyl-azobenzene) </a>(C8AzoOC8E4) using small-angle neutron scattering (SANS). We show that the incorporation of in-situUV-Vis absorption spectroscopy with SANS allows the scattering profile, and hence micelle shape, to be correlated with the extent of photoisomerisation in real-time. It was observed that C8AzoOC8E4could switch between wormlike micelles (transnative state) and fractal aggregates (under UV light), with changes in the self-assembled structure arising concurrently with changes in the absorption spectrum. Wormlike micelles could be recovered within 60 seconds of blue light illumination. To the best of our knowledge, this is the first time the degree of AzoPS photoisomerisation has been tracked in-situthrough combined UV-Vis absorption spectroscopy-SANS measurements. This technique could be widely used to gain mechanistic and kinetic insights into light-dependent processes that are reliant on self-assembly.

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Enteric viruses in drinking water supplies

Water Science & Technology Water Supply ◽

10.2166/ws.2002.0080 ◽

2002 ◽

Vol 2 (3) ◽

pp. 17-22

Author(s):

A.P. Wyn-Jones ◽

J. Watkins ◽

C. Francis ◽

M. Laverick ◽

J. Sellwood

Keyword(s):

Drinking Water ◽

Heavy Rainfall ◽

Liquid Culture ◽

Plaque Assay ◽

Enteric Viruses ◽

Enteric Virus ◽

The Other ◽

Raw Water ◽

Rt Pcr ◽

Water Supplies

Two rural spring drinking water supplies were studied for their enteric virus levels. In one, serving about 30 dwellings, the water was chlorinated before distribution; in the other, which served a dairy and six dwellings the water was not treated. Samples of treated (40 l) and untreated (20 l) water were taken under normal and heavy rainfall conditions over a six weeks period and concentrated by adsorption/elution and organic flocculation. Infectious enterovirus in concentrates was detected in liquid culture and enumerated by plaque assay, both in BGM cells, and concentrates were also analysed by RT-PCR. Viruses were found in both raw water supplies. Rural supplies need to be analysed for viruses as well as bacterial and protozoan pathogens if the full microbial hazard is to be determined.

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The assessment of biofilm community composition on plumbing materials in filtered and unfiltered water distribution systems

Water Science & Technology Water Supply ◽

10.2166/ws.2003.0102 ◽

2003 ◽

Vol 3 (1-2) ◽

pp. 187-191

Author(s):

M.M. Critchley ◽

N.J. Cromar ◽

H.J. Fallowfield

Keyword(s):

Drinking Water ◽

Fatty Acid ◽

Community Composition ◽

Distribution Systems ◽

Water Distribution ◽

Water Distribution Systems ◽

Polymer Materials ◽

Fatty Acid Profiles ◽

Water Supplies ◽

Drinking Water Distribution Systems

Biofilms have been extensively characterised within drinking water distribution systems. However, the significance of materials on biofilm species diversity is not established. This study investigated the community composition of biofilms on plumbing materials receiving filtered and unfiltered water supplies. Biofilms were extracted from polybutylene, polyethylene, cross-linked polyethylene, unplasticised polyvinyl chloride and copper tubes in sampling rigs receiving Murray-Onkaparinga water before or after filtration. Biofilms were extracted and analysed for fatty acid composition using the FAME™ methodology. There were differences in the fatty acid profiles of biofilms and the respective water supplies, indicating differences in the attached and planktonic communities. The results also showed significant differences in the fatty acid profiles of biofilms on the polymer materials compared to copper, suggesting variations in biofilm populations on the different materials. The potential for materials to select for microbial populations has significant implications for the ecology of drinking water biofilms.

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