MALDI-TOF MS: A return to phenotyping in microbial identification?

The Systematic and Applied Microbiology Executive Editors Team have engaged a dedicated issue on “Applications of Matrix-Assisted Laser Desorption/Ionisation Time-of-Flight Mass Spectrometry (MALDI-TOF MS) for the Identification and Typing of Microorganisms”. MALDI-TOF MS applied to microbial systematics is an emerging field with promising applications in microbial identification, typing and diversity studies. The articles that follow in this Special Issue present reports on the use of whole-cell MALDI-TOF MS for the identification of the members in a range of taxa. Here, we emphasise that the principle of utilising biomarkers for characterising microorganisms is still meaningful and compelling for diagnosing established taxa and for recognising novel ones. To this end, MALDI-TOF MS addresses the urgency for new protocols for identification, providing results with increased speed and with decreased effort and cost. As genotypic methods have become fixtures in the routine labs, with good reason, it is interesting to see that the rapid establishment of the phenotypic-based methodology of whole-cell protein profiling, by MALDI-TOF MS, appears poised to replace those and earlier protocols that have been applied for microbial identification. Readers should keep in mind that the focus in using MALDI-TOF MS, at least in most cases currently, is for identification purposes. The presentations in this Special Issue do not propose that this approach will replace methods that are used for establishing the framework of microbial systematics, but rather, the use of this methodology is seen as an added value to identification and the basic principles of taxonomy. It is anticipated that the use of MALDI-TOF MS in microbial systematics will lead to the generation of public, cumulative and interactive databases, in a similar way as the gene-based databases have evolved.Peer Reviewe