Flow Cytometry in Aquatic Research

Flow cytometry is a rapid, robust analytical technique that has been utilized in many different fields of biological research. This article will discuss the use of flow cytometry in aquatic research.

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What is Flow Cytometry?

Flow cytometry is a technology that has been around for approximately half a century. With this technique, researchers can analyze single cells in a population at the rate of thousands per minute. It is a multivariate, multiparametric technique that can provide data on a wealth of components such as:

• DNA
• RNA
• Cell size and numbers present
• Lipids
• Proteins
• Processes such as apoptosis and cell signaling
• The presence of pathogens including bacteria and viruses

Individual cells are concentrated in a flow cell (or tube) and then pass a laser, which detects a fluorescent signal. This is then analyzed by sophisticated software, producing data on the parameter under study. It has proven to be especially useful in aquatic research, providing data that can be used to improve water quality and inform environmental research.

The Importance of Aquatic Research

Aquatic research is vital for human health and food supply chains, as well as environmental monitoring and protection.

Aquatic microbiology has applications in many diverse industries such as fisheries, sewage and wastewater treatment, and pollution control. Aquatic microorganisms also play an important role in the environment by cycling nutrients, making them a crucial part of the food chain. Monitoring the presence and function of these vital organisms is therefore essential for human society.

For example, effluent runoff can increase the likelihood of algal blooms, due to an increase in available nutrients. This leads to oxygen depletion in the aquatic environment, leading to the death of other organisms present. This can cause immense environmental damage.

Flow Cytometry’s Advantages for Aquatic Research

Flow cytometry is a technique that has found numerous applications in aquatic research due to its advantages over other commonly used analytical methods. It has become a valuable tool due to three unique technical properties:

• The velocity of obtaining and processing data
• Superior sorting capacity
• High-speed multiparametric data acquisition and multivariate analysis.

With flow cytometry, sample preparation is faster, saving time and resources. Counting time is also significantly reduced to a couple of minutes and many more cells can be counted compared to other methods. Flow cytometry can count thousands of cells compared to, for example, optical microscopy that can count a few hundred in the same amount of time.

The development of new fluorescent markers, the growing use of quantum dots, and the introduction of new cytometric techniques are constantly driving the technology forward. Bacteria, viruses, algae, protozoa, and nanoparticles present in aquatic environments can all be analyzed at a rate and accuracy not possible with other methods. Their effects upon other organisms can be studied in detail which would otherwise be lacking.

Flow Cytometry Applications in Water Treatment

Effective water treatment is essential for the health of entire populations. Treatment, distribution, and reuse must be tightly monitored and controlled to ensure the quality of water used for drinking, industry, and agriculture. Treatment-plant discharge can also impact environments, leading to pollution and perturbation of marine ecosystems.

Other analytical methods in use today are lacking in several areas. They are limited by low sensitivity, high costs, are susceptible to interference from chemicals and inhibitory compounds, and cannot effectively distinguish between cells. Flow cytometry overcomes these problems with ease, making it an attractive alternative approach.

Flow cytometry can be used to monitor microbial populations that affect the quality of treated water and therefore inform better water management. Between 2010 and 2018 almost 300 studies were conducted which used flow cytometry for this purpose.

Whilst the technique has shown significant promise for water management, some issues do still exist. Areas for improvement include optimizing protocols for the study of water-borne viruses, improving instrumentation, and automating sample preparation and handling for real-time analysis. However, there is a large enough body of research that has documented the successful applications of flow cytometry that will aid wide-scale adoption.

Use of Online Flow Cytometry to Monitor and Survey Water Quality

Data gathered on cell concentration in an aquatic sample can fluctuate wildly due to both man-made and natural dynamics. This can lead to inaccurate detection of microbial anomalies as they can become obscured. This can present problems for real-time analysis. Better automated systems capable of surveilling microbial populations and detecting change are needed.

Cytometric fingerprinting tools are one method that can distinguish between normal and abnormal microbial changes in microbial communities. However, most rely on offline statistical computations which are problematic for real-time monitoring. Therefore, using online processes is advantageous. A team, publishing their research in 2020, developed a system called Microbial Community Change Detection.

The advantages of an online computational system are obvious: it can be used with automated flow cytometry to rapidly detect microbial contamination, which is especially useful in time-critical applications such as pollution control and monitoring. As such time-critical applications can have far-reaching consequences for food security and maintaining healthy natural environments, real-time surveillance of microbial contamination is crucial.

Flow Cytometry: A Key Analytical Technique for Aquatic Research

Flow cytometry is a vital tool for aquatic research. Already in common use worldwide, it is informing better water security, wastewater management, environmental monitoring, and food safety.

As new techniques are developed, technology improved, and flow cytometry is integrated with other technologies, the use of this robust analytical technique continues to be a central tool in aquatic research. Flow cytometry will continue to play an important role in the field for many years to come.

References:

• Safford, H.R & Bischel, H.N (2019) Flow cytometry applications in water treatments, distribution, and reuse: A review Water Research 151:15 pp. 110-133 [Accessed online 13^th August 2021] https://www.sciencedirect.com/science/article/abs/pii/S0043135418310339
• Sadler, M.C et al. (2020) Computational Surveillance of Microbial Water Quality with Online Flow Cytometry Front. Water. Vol 2 page 45 [Accessed online 13^th August 2021] https://www.frontiersin.org/articles/10.3389/frwa.2020.586969/full
• Vives-Rigo, J, Lebaron, P & Nebe-von Caron, G. (2000) Current and future applications of flow cytometry in aquatic microbiology FEMS Microbiology Reviews 24:4 pp. 429-448 [Accessed online 13^th August 2021] https://academic.oup.com/femsre/article/24/4/429/510325

Further Reading

• All Flow Cytometry Content
• Flow Cytometry Methodology, Uses, and Data Analysis
• Flow Cytometry Techniques used in Medicine and Research
• Flow Cytometry History
• Fluorescence-Activated Cell Sorting

Written by

Reginald Davey

Reg Davey is a freelance copywriter and editor based in Nottingham in the United Kingdom. Writing for News Medical represents the coming together of various interests and fields he has been interested and involved in over the years, including Microbiology, Biomedical Sciences, and Environmental Science.