Matrix-assisted laser desorption/ionization (MALDI) is an ionization technique that uses a laser energy-absorbing matrix to create ions from large molecules, such as proteins, with minimal damages or distortions. It has been applied to the analysis of biomolecules (biopolymers such as DNA, proteins, peptides and carbohydrates) and various organic molecules since MALDI typically produces far fewer multi-charged ions than other similar techniques. MALDI methodology is a three-step process. First, the sample is mixed with a suitable matrix material and applied to a metal plate. Second, a pulsed laser irradiates the sample, triggering ablation and desorption of the sample and matrix material. Finally, the analyte molecules are ionized by being protonated or deprotonated in the hot plume of ablated gases, and then they can be accelerated into whichever mass spectrometer is used to analyse them.

This method describes the preparation of bacterial strains and plate preparation to be read in MALDI-TOF machine.

This analysis, for now, can be applied only to isolated colonies.

The present document describes a standard technique, the High Resolution Melting (HRM) real-time Polymerase Chain Reaction (PCR) to identify the species and five biovars of Brucella in animal / human samples.

High-resolution melting (HRM) is a post-PCR technique that determines with high precision the melt profile of PCR products. A new generation dye is incorporated into a double-stranded DNA. Using a slow constant increase in temperature, fluorescence acquisition allows the distinction between two different populations of amplicons. The method can be used to interrogate small number of SNPs.

Scientific references
Guillaume GIRAULT, Ludivine PERROT, Virginie MICK, Claire PONSART (2022). High-Resolution Melting PCR as Rapid Genotyping Tool for Brucella Species, Microorganisms 10 (336)