Making science more accessible for improved sample ID

Matrix-assisted laser-desorption and ionization time-of-flight mass spectrometry, known as MALDI-TOF MS, is a widely-recognised scientific technique used mainly to identify bacteria, particularly in clinical diagnostics. Although several MALDI-TOF MS sample-preparation methods are currently available, not all are suitable for insects and plants, particularly when working in the field.

Dr Mike Reeve, Head of Bioscience for CHAP partner CABI, has been using his long expertise in method development to overcome this hurdle, and to make MALDI-TOF MS methods more accessible for use across the globe.

“MALDI-TOF MS is a rapid and inexpensive method for discriminating between biological materials at species level, and can even differentiate between regional biotypes within a species. It works by obtaining a protein ‘fingerprint’, ready for screening against a database of reference spectra.

But there are limitations. Existing sample preparation methods aren’t really suitable for plant material or insects, particularly when taken on location or in the field. Also, it’s key that biological material is ‘fresh’, and sometimes the window before a sample degrades can be quite small. It’s therefore imperative that a low-cost, accessible method is developed.

When we first received the instrument at CABI, we were given the opportunity to investigate its capabilities. This, coupled with my background in method development, meant it soon became apparent that there was amazing potential in this relatively-simple instrument. We started to question each step and to ask can we redevelop it, and also make greater use of the instrument’s powerful algorithm for comparing spectra?

Though a strong desire to adapt and simplify, we were successful in finding a method for practical storage of field sample proteins, ready for use with MALDI-TOF MS. The method uses filter paper, impregnated with crushed biological material, which is then dried. By soaking in an alcoholic solution, this inactivates the microorganisms before being dried again ahead of storage.

After dry storage, the fingerprint proteins can be extracted from the paper, and analyzed in the usual manner.

This ability to ship and store opens up the world of sample preparation – from larger insects to tiny nematodes, both in the UK and internationally. Scientists can now study samples from other countries, making it far easier to help Developing Countries to overcome pest problems. As MALDI-TOF MS itself is low cost and very rapid, this is a great way to pre-screen samples before committing to expensive DNA sequencing.

Historically, MALDI-TOF MS has had greater success in medicine but here we are facilitating wider application of this valuable technology. We can work out differences in species when, to the naked eye, they may look the same. An example here is work we have undertaken with parasitoid wasps, broadening our understanding of these beneficial insects.

Our methodology is simple too, which makes it very easy for samples to be collected, improving the accessibility of science which is vital when working internationally.

We hope to secure future funding for MALDI-TOF MS so that we can further integrate this into a wide range of CHAP and CABI research projects.”


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For information about CHAP’s National Reference Collection facility, home of MALDI-TOF MS, visit here.

Please note, the opinions expressed in this article are the author’s own and do not necessarily reflect the views or opinions of CHAP.