The MALDI-TOF MS technique (matrix assisted laser desorption / ionization time-of-flight mass spectrometry) provides a characteristic protein profile of a microbial strain from biomolecular analysis (mainly of ribosomal proteins).

The protein profile obtained enables us to identify the species listed in the reference database and to characterize any microbial strain.

CECT offers identification and/or characterization of microbial strains by MALDI-TOF MS (consult, aruvira@cect.org)

Necessary material

Active culture of the strain (Petri dish with the Z-streaking method).

For fastidious strains or specific requirements, 20 mg of bacterial biomass resuspended on 1200 µl of a 1:3 water/ethanol suspension. Use only Eppendorf microtubes (consult).

Methodology

Protein profile is analyzed following the protocol recommended by Bruker Daltonics (http://www.bdal.de), which involves extracting ethanol / formic acid. Spectra are acquired using a mass spectrometer Microflex L20 (Bruker Daltonics) equipped with a N2 laser, positive linear ion mode. The acceleration voltage is 20 kV. The spectra are obtained as the sum of 240 shots per target. The mass range used for analysis is 2,000-20,000 Da. The program used for data processing is the BioTyper 3.1 (Bruker Daltonics) as described in Maier et al. (2006).

Bibliografía

Maier et al., (2006). T. Maier, S. Klepel, U. Renner and M. Kostrzewa, Fast and reliable MALDI-TOF MS-based microorganism identification, Nat Methods 22 (2006).