Comparing flow cytometry with culture-based methods for microbial monitoring and as a diagnostic tool for assessing drinking water treatment processes

Cheswick, Ryan; Cartmell, Elise; Lee, Susan; Upton, A.; Weir, Paul; Moore, Graeme; Nocker, Andreas; Jefferson, Bruce; Jarvis, Peter

doi:10.1016/j.envint.2019.06.003

Cited by 39 publications

(35 citation statements)

References 26 publications

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“…At the network location, the concentrations of HPCs and total coliforms were still below the detection limit, while the bacterial cell concentrations from the FCM measurements were a factor 10 times higher compared to the water feeding the network. The analysis of HPC and total coliforms in drinking water has been utilized to determine biological stability in drinking water 19 . However, the limitations of HPC analysis, including the long incubation time required, variation in test results depending on experimental conditions, and detection of only a minute fraction of the total number of viable bacteria have been stated in previous studies 19,22,36,46 .…”

Section: Resultsmentioning

confidence: 99%

“…The analysis of HPC and total coliforms in drinking water has been utilized to determine biological stability in drinking water 19 . However, the limitations of HPC analysis, including the long incubation time required, variation in test results depending on experimental conditions, and detection of only a minute fraction of the total number of viable bacteria have been stated in previous studies 19,22,36,46 . Therefore, the direct bacterial quantification method, FCM, has been applied in this study for the drinking water samples to overcome the limitations of conventional bacterial culturedependent methods 26 .…”

Section: Resultsmentioning

confidence: 99%

“…Plate counting (i.e., HPC) and coliforms being the most applied methods that were proposed over 100 years ago 15,17,18 . However, the World Health Organization (WHO) acknowledges that HPC does not link to the health risk in people who are already healthy 19,20 , but HPC bacteria may pose a higher risk for the immunocompromised 21 . HPC only detects a fraction of total bacteria that can grow on the medium (<1% of bacteria) not including viable, but non-culturable bacteria (VBNC) 22,23 .…”

Section: Introductionmentioning

confidence: 99%

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Online characterization of bacterial processes in drinking water systems

2020

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The use of traditional drinking water microbial quality monitoring methods, including heterotrophic plate counts (HPCs) and total coliform counts, are not only laborious and time-consuming but also do not readily allow identification of risk areas in the network. Furthermore, if areas of concern are identified, and mitigation measures are taken, it takes days before the effectiveness of these measures is known. This study identified flow cytometry (FCM) as an online sensor technology for bacterial water quality monitoring in the distribution network. We monitored the total bacterial cell numbers and biodiversity in a drinking water distribution system (DWDS) using an online FCM. Two parallel online FCM monitoring systems were installed on two different locations at a drinking water treatment plant (DWTP; Saudi Arabia) supplying chlorinated water to the distribution and in the network 3.6 km away from the DWTP. The FCMs were operated at the same time in parallel to assess the biological stability in DWDSs. The flow cytometric data was compared with the conventional water quality detection methods (HPC and total coliforms). HPC and total coliforms were constantly below the detection limits, while the FCM provided detectable total cell count data and enabled the quantification of changes in the drinking water both with time and during distribution. Results demonstrate the value of FCM as a tool for compliance monitoring and risk assessment of DWDSs.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Online characterization of bacterial processes in drinking water systems

2020

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“…High‐throughput screening methods using enzymes have garnered continuous interest in pharmaceutical sciences [1–14], biochemistry [5], and biocatalysis [6,7]. Enzyme‐linked immunosorbent assay (ELISA) [8–10] and flow cytometry [11–13] are well‐known technologies for high‐throughput screening owing to their high sensitivity and throughput capacity; further, these methods require the use of fluorescence molecules. Traditional electrochemical approaches are capable of obtaining fast response times, have electrode arrays and simple instrumentation and operation, and enable electronic measurements without specially designed fluorescence molecules.…”

Section: Introductionmentioning

confidence: 99%

Light‐Addressable Amperometric Sensor with Counter and Working Electrodes of the Same Material

Kosugi

Hasegawa

Uchida

2021

IEEJ Transactions Elec Engng

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High‐throughput screening is important in various fields, and electrochemical approaches are effective because of advantages such as fast response time and electrode array. Hence, we developed a two‐dimensional electrochemical array sensor. However, its signal intensities for lower concentrations of the redox pair (100 μM–100 pM [Fe[CN]6]3−/4−) were unstable; Therefore, in this study, we investigated and demonstrated a method for improving the signal stability at lower concentrations. Two types of counter electrodes were prepared to assess their influence; the material of the first electrode was the same as that of the working electrode (same material condition), and the other was prepared from a different material (different material condition). First, the differences in the electric potentials between different materials were investigated at lower concentrations. Furthermore, the concentration dependence was investigated using our newly developed light‐addressable amperometric sensor for the two conditions. In the different condition, it was observed that differences in the electric potentials between the electrodes at lower concentrations. It was also observed that the signal intensity was more stable for the same material condition than the different material condition. Limit of detection(LOD) for the same material condition was lower than that under the different material condition. The proposed method using the same materials is thus an effective means to measure low concentrations of redox ions and expected to contribute to a fabrication of a smaller and more stable device without reference electrode. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

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“…In that context, flow cytometry (FCM) has emerged as a powerful and robust tool which allows for high-temporal-resolution monitoring (Egli and Stefan, 2015;Van Nevel et al, 2017b;Safford and Bischel, 2018). Several studies have been conducted on drinking water plants, as well as groundwater used for drinking water supply, to show the additional insights that are gained on the dynamics of the microbial communities compared to traditional cultivation methods (Cheswick et al, 2019;Kantor et al, 2019;Favere et al, 2020). The basic principle of flow cytometry measurements is the detection and counting of suspended particles present in a water samples by passing them one by one through a laser beam.…”

Section: Introductionmentioning

confidence: 99%