The Principles, Applications and Pitfalls of Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry for Microbial Identification

Abstract

In recent years, Matrix Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) has been adopted as a method for routine microbial identification in clinical, pharmaceutical and food microbiology laboratories. In microbial identification by MALDI-TOF MS, bacteria and fungi are identified by acquiring mass spectra within the range of 2,000 to 20,000 Da, a range containing peaks derived from proteins of microbial cells. Compared to other technologies for microbial identification, this method brings results more rapidly by simpler sample preparation, at a lower cost. In addition, it has higher accuracy than the conventional methods, using the molecular method as the reference method. Since colonies on solid culture media are used as samples for spectra acquisition, not only differences in strains of the same species, but also differences in culture conditions result in differences in spectra. Moreover, each commercialized MALDI-TOF MS system for microbiology identification has different databases and algorithms. Users need to consider these characteristics of MALDI-TOF MS microbial identification, especially for adding species or strain information to a database and performing other microbiology applications. To utilize this technology as a method for microbial identification, it is important to understand its advantages and pitfalls to perform identification and further applications.