Identification by MALDI-TOF mass spectrometry
MALDI-TOF (Matrix-Assisted Laser Desorption/Ionization – Time of Flight) mass spectrometry is a cutting-edge analytical technique that enables the rapid, precise, and reliable identification of microorganisms (bacteria, yeasts, molds) based on their protein profile. Used in microbiology laboratories, this method is increasingly being integrated into industrial sectors (pharmaceutical, cosmetic, food processing, animal health) for contamination control and microbiological monitoring .
What is the MALDI-TOF method?
MALDI -TOF mass spectrometry method based on the desorption-ionization of a sample by a laser , assisted by a chemical matrix . The ions thus formed are then separated according to their time of flight (TOF) , that is, the time it takes them to travel a fixed distance in an electric field.
Each microorganism possesses a specific protein fingerprint , primarily composed of ribosomal proteins . This fingerprint is compared to a spectral database , enabling reliable identification down to the species level .
How the MALDI-TOF method works
The MALDI-TOF analysis follows these steps:
- Sample preparation : a bacterial colony is deposited on a target plate, mixed with a crystallizing matrix .
- Laser ionization : a UV laser vaporizes the matrix, releasing the sample proteins as ions.
- Time of flight (TOF) measurement : ions pass through a flight tube; their speed depends on their mass . They are detected upon arrival.
- Mass spectrum generation : the resulting profile (protein fingerprint) is compared to a database to identify the microorganism.
Technical specifications of the MALDI-TOF
- Spectrometry type : MALDI-TOF. This is a mass spectrometer combining a matrix-assisted laser ionization (MALDI) source and a time-of-flight (TOF) analyzer.
- Quick preparation : a few minutes
- Species identification : based on ribosomal proteins
- Matrix used : sinapinic acid or α-cyano-4-hydroxycinnamic acid (HCCA)
- Database : commercial or specific (environmental bacteria, typical contaminants)
- Detection limits : a few thousand cells are sufficient
- High reproducibility , validatable and traceable method
For which matrices?
MALDI-TOF mass spectrometry is applicable to microbial colonies cultured or isolated from various types of samples:
Main industrial applications
The MALDI-TOF method is widely used for microbiological diagnostics , but also in industry for critical quality control applications :
Léa Géréec
Technical and scientific expert
