MALDI-TOF for Yeast

The principle of MALDI-TOF (Matrix-Assisted Laser Desorption/Ionization – Time of Flight) mass spectrometry is based on analyzing the mass-to-charge ratio (m/z) of ionized molecules to identify them, which is commonly used for the rapid identification of microorganisms.

Core Principle

1. Sample Preparation:

   • A microbial sample is mixed with a chemical matrix (usually a small organic acid) and applied to a metal plate.

   • The matrix absorbs UV laser energy and assists in the desorption and ionization of the sample.

2. Laser Ionization:

   • A laser pulse excites the matrix, which causes it to vaporize along with the sample and ionize the sample molecules (usually proteins, especially ribosomal proteins).

3. Acceleration:

   • The ionized molecules are accelerated in an electric field toward a detector. All ions receive the same kinetic energy.

4. Time-of-Flight (TOF) Analysis:

   • Lighter ions travel faster and reach the detector sooner than heavier ones.

   • The time taken to reach the detector is recorded and used to calculate the mass-to-charge ratio (m/z).

5. Spectrum Generation:

   • A mass spectrum is generated—a plot of intensity vs. m/z—representing the molecular fingerprint of the organism.

6. Identification:

• The obtained spectrum is compared with a reference database to identify the organism.