Lindsey Furness

Lindsey Furness

Author : Lindsey Furness, EngD student. Her host university is Newcastle University and her project, 'Advancing the use of flow cytometry (FCM) in the water sector' is sponsored by Northumbrian Water.

I have just begun a 4-year Engineering Doctorate programme funded by the EPSRC and Northumbrian Water as part of the STREAM programme. As someone with a background in microbiology and no particular reputation for engineering ingenuity, this has come as somewhat a surprise to myself, my family and my friends. The STREAM programme supports researchers through providing a number of technical and transferable skills modules designed to prepare us to ‘drive innovation in the water industry’. Myself and 11 others make up cohort IX of the STREAM programme. We have a diverse range of backgrounds that includes mechanical engineering, chemical engineering, biological sciences and geography, but our new occupations unite us neatly under the umbrella of environmental engineering.

And to refer back to the beginning of this blogpost: that’s how a microbiologist becomes a research engineer!

Cohort IX on a field trip to Cambridge sewage treatment works

Now all the acronyms are cleared up, it seems a reasonable time to introduce my research project. This will be based at Northumbrian Water (which resides mainly in the north-east of England but interestingly also owns Essex & Suffolk Water- I note this as I am very excited for the commute!), with additional support from Newcastle University. The title is ‘Advancing the use of flow cytometry (FCM) in the water industry’. This is a rather broad scope, something I hope to narrow very quickly as meetings with my industrial and academic supervisors progress.

Flow cytometry at its most basic is using a machine to count cells through suspending them in a stream of fluid and passing this through a laser beam (or other electronic detection mechanism). At a broader level, flow cytometry allows the instant collection of data on individual particles by applying fluorescent stains and using an array of different lasers. Additionally, some flow cytometers have cell sorting capabilities in order to isolate and retain populations of cells according to tailored parameters.

A BD Accuri C6 flow cytometer (picture taken at Severn Trent Water)

FCM can be used to detect individual bacterial cells in water samples. These are differentiated from other particles in the sample using dyes to stain their DNA, producing a specific measurable fluorescence. For each individual cell, information is given on its size and complexity. An additional dye can be applied to highlight live cells, allowing a ‘total count’ and ‘viable count’ of bacteria in a sample to be achieved.

Analysis of bacteria in water is currently through culture based methods. This involves mixing a selected range of nutrients in an agar or broth, applying the sample and incubating this in an environment the bacteria of interest would be expected to grow. A major disadvantage of this is that bacteria do not always grow; in fact, we are able to grow only ~1% of bacteria that are found in water. There is also time-lag in results acquisition, as bacteria can take from 16 hours to 1 week to grow, depending on the organism. The pros and cons of this method are extensive and perhaps a subject for another blogpost.

Example of culture based methods using chromogenic media. Picture source FischerScientific.

The advantage of using flow cytometry for analysis is that a true representation of bacterial populations in a water sample can be acquired. Additionally, after ~15minutes sample preparation, results can be seen in real time. This should allow a much more reactive approach to bacterial control through the water treatment process.

I hope that my research will help highlight areas in both water and wastewater treatment where flow cytometry could help control and solve bacterial issues in processing, by providing a more accurate and rapid methodology. Application of FCM can also be used to optimise processes such as disinfection, reducing over-processing of water.

I could go on but I think that’s enough introduction for now! More posts may or may not follow.