Fluorescence spectroscopy as a tool for determining microbial quality in potable water applications

Cumberland, Susan A.; Bridgeman, John; Baker, Andy; Sterling, Mark; Ward, David M.

doi:10.1080/09593330.2011.588401

Cited by 63 publications

(67 citation statements)

References 30 publications

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“…This suggests that Peak T fluorescence intensity can be attributed to an increase in E. coli population size, in accordance with previous studies Cumberland et al, 2012;Dartnell et al, 2013;Deepa and Ganesh, 2017;Sohn et al, 2009). However, as tryptophan is an essential amino acid, necessary for protein formation during growth and other metabolic pathways, it will be produced as a result of cell multiplication and metabolic processing (Coble et al, 2014;Hogg, 2005).…”

Section: Resultssupporting

confidence: 79%

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The in situ bacterial production of fluorescent organic matter; an investigation at a species level

et al. 2017

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a b s t r a c tAquatic dissolved organic matter (DOM) plays an essential role in biogeochemical cycling and transport of organic matter throughout the hydrological continuum. To characterise microbially-derived organic matter (OM) from common environmental microorganisms (Escherichia coli, Bacillus subtilis and Pseudomonas aeruginosa), excitation-emission matrix (EEM) fluorescence spectroscopy was employed. This work shows that bacterial organisms can produce fluorescent organic matter (FOM) in situ and, furthermore, that the production of FOM differs at a bacterial species level. This production can be attributed to structural biological compounds, specific functional proteins (e.g. pyoverdine production by P. aeruginosa), and/or metabolic by-products. Bacterial growth curve data demonstrates that the production of FOM is fundamentally related to microbial metabolism. For example, the majority of Peak T fluorescence (> 75%) is shown to be intracellular in origin, as a result of the building of proteins for growth and metabolism. This underpins the use of Peak T as a measure of microbial activity, as opposed to bacterial enumeration as has been previously suggested. This study shows that different bacterial species produce a range of FOM that has historically been attributed to high molecular weight allochthonous material or the degradation of terrestrial FOM. We provide definitive evidence that, in fact, it can be produced by microbes within a model system (autochthonous), providing new insights into the possible origin of allochthonous and autochthonous organic material present in aquatic systems.

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Section: Resultssupporting

confidence: 79%

“…Recent literature suggests that Peak T fluorescence may act as a surrogate for microbial and bacterial activity Cumberland et al, 2012), as first highlighted by Hudson et al (2008). Recent surface freshwater research has also attempted to use Peak T fluorescence to determine enumeration of specific species.…”

Section: Introductionmentioning

confidence: 99%

The in situ bacterial production of fluorescent organic matter; an investigation at a species level

et al. 2017

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“…Standard methods used to test for the presence of heterotrophic bacteria (HB), total coliforms (TC), faecal coliforms (FC) and E. coli include, inter alia, the multiple tube method (presence of gas and acid at 44°C), membrane filtration (MF), and colony-forming units (cfu) on agar media (Great Britain Department of Environment, 1983;Cumberland et al, 2011). The genera enumerated by any of these methods are highly variable since the cultivation medium of choice, incubation temperature and time, origin (river, surface water reservoir, treated and disinfected drinking water, etc.…”

Section: Current Methods Of Organic and Microbial Determinationmentioning

confidence: 99%

Portable LED fluorescence instrumentation for the rapid assessment of potable water quality

Bridgeman

Baker²,

Brown

et al. 2015

Science of The Total Environment

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Characterising the organic and microbial matrix of water are key issues in ensuring a safe potable water supply. Current techniques only confirm water quality retrospectively via laboratory analysis of discrete samples. Whilst such analysis is required for regulatory purposes, it would be highly beneficial to monitor water quality in-situ in real time, enabling rapid water quality assessment and facilitating proactive management of water supply systems. A novel LED-based instrument, detecting fluorescence peaks C and T (surrogates for organic and microbial matter, respectively), was constructed and performance assessed. Results from over 200 samples taken from source waters through to customer tap from three UK water companies are presented. Excellent correlation was observed between the new device and a research grade spectrophotometer (r(2)=0.98 and 0.77 for peak C and peak T respectively), demonstrating the potential of providing a low cost, portable alternative fluorimeter. The peak C/TOC correlation was very good (r(2)=0.75) at low TOC levels found in drinking water. However, correlations between peak T and regulatory measures of microbial matter (2 day/3 day heterotrophic plate counts (HPC), E. coli, and total coliforms) were poor, due to the specific nature of these regulatory measures and the general measure of peak T. A more promising correlation was obtained between peak T and total bacteria using flow cytometry. Assessment of the fluorescence of four individual bacteria isolated from drinking water was also considered and excellent correlations found with peak T (Sphingobium sp. (r(2)=0.83); Methylobacterium sp. (r(2)=1.0); Rhodococcus sp. (r(2)=0.86); Xenophilus sp. (r(2)=0.96)). It is notable that each of the bacteria studied exhibited different levels of fluorescence as a function of their number. The scope for LED based instrumentation for in-situ, real time assessment of the organic and microbial matrix of potable water is clearly demonstrated.

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“…In particular, the development of short-wave ultra-violet light emitting diodes (LEDs) has permitted the excitation of dissolved organic matter at~280 nm using portable instrumentation (Cumberland et al, 2012). At this wavelength, the intensity of fluorescence emitted at~350 nm (often referred to as peak T or peak T2) has been shown to relate to the water quality in sewage-impacted rivers (Baker, 2001).…”

Section: Introductionmentioning

confidence: 99%

“…Cumberland et al (2012) tested a portable fluorescence spectrometer to measure fluorescence intensity at these excitation and emission wavelengths and sought to determine whether there was a relationship with bacterial numbers. Their pilot-study, of 24 samples from four urban river and sewerage sites in the UK, demonstrated a linear correlation between fluorescence intensity and microbial water quality as determined by bacterial enumerations, over a three-log range of bacterial counts.…”

Section: Introductionmentioning

confidence: 99%

To what extent can portable fluorescence spectroscopy be used in the real-time assessment of microbial water quality?

Baker¹,

Cumberland

Bradley

et al. 2015

Science of The Total Environment

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The intrinsic fluorescence of aquatic organic matter emitted at 350 nm when excited at 280 nm correlates widely with water quality parameters such as biochemical oxygen demand. Hence, in sewage-impacted rivers and groundwater, it might be expected that fluorescence at these wavelengths will also correlate with the microbial water quality. In this paper we use a portable fluorimeter to assess the relationship between fluorescence intensity at this wavelength pair and Escherichia coli enumeration in contrasting river catchments of poor water quality: in KwaZulu-Natal, S. Africa and the West Midlands, UK. Across all catchments we demonstrate a log correlation (r = 0.74) between fluorescence intensity and E. coli over a seven-log range in E. coli enumerations on non-perturbed (unfiltered) samples. Within specific catchments, the relationship between fluorescence intensity and E. coli is more variable, demonstrating the importance of catchment-specific interference. Our research demonstrates the potential of using a portable fluorimeter as an initial screening tool for indicative microbial water quality, and one that is ideally suited to simple pollution scenarios such as assessing the impact of faecal contamination in river or groundwater at specific sites.

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Fluorescence spectroscopy as a tool for determining microbial quality in potable water applications

Cited by 63 publications

References 30 publications

The in situ bacterial production of fluorescent organic matter; an investigation at a species level

The in situ bacterial production of fluorescent organic matter; an investigation at a species level

Portable LED fluorescence instrumentation for the rapid assessment of potable water quality

To what extent can portable fluorescence spectroscopy be used in the real-time assessment of microbial water quality?

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