Characterisation of bacteria by matrix-assisted laser desorption/ionisation and electrospray mass spectrometry

Abstract

Chemical analysis for the characterisation of micro‐organisms is rapidly evolving, after the recent advent of new ionisation methods in mass spectrometry (MS): electrospray (ES) and matrix‐assisted laser desorption/ionisation (MALDI). These methods allow quick characterisation of micro‐organisms, either directly or after minimum sample preparation. This review provides a brief introduction to ES and MALDI MS and a discussion of micro‐organism characterisation capabilities. Some attention is devoted to the analysis of mixtures of proteins, lipids and other compounds, to the combination of polymerase chain reaction technology and MS, and to the analysis of whole bacteria and their lysates. The review of results produced hitherto is concluded with an outlook on future developments.

Lipid fingerprinting of Gram‐positive lactobacilli by intact cells – matrix‐assisted laser desorption/ionization mass spectrometry using a proton sponge based matrix

“…Many of these issues have typically involved various chromatographic techniques, requiring high sample amounts together with time‐consuming sample pre‐treatments (e.g., hydrolysis, extraction, column purification) leading to unavoidable loss of sample. Among mass spectrometric techniques, matrix‐assisted laser desorption/ionization time‐of‐flight (MALDI‐TOF) mass spectrometry (MS) has shown its capability in providing useful information for identification of microorganisms and differentiation due to its speed and sensitivity that allow rapid analyses with minimal sample preparation . In the last decade, MALDI‐TOF MS analysis has been successfully applied for identification of bacteria, viruses, fungi, and insects, typically through peptide/protein fingerprinting.…”

Analysis of Four Human Microsporidian Isolates by MALDI‐TOF Mass Spectrometry

“…These physicochemical methods have been successfully used for detection of biomarkers from whole unfractionated microorganisms, including viruses, prokaryotes, and a few unicellular eukaryotes, after applying them directly to the sample target (Fenselau and Demi‐rev 2001). MALDI‐TOF MS is emerging as an important tool for the rapid identification of microorganisms because of short analysis time and the potential for a wealth of applications, such as monitoring bioremediation, detection of biowarfare agents, and identification of pathogenic species (van Baar 2000).…”

“…The microsporidian biomarkers detected in this study are possibly due to the desorption of ions from the spore wall when whole organisms were applied to the target, or from a mixture of cellular components generated after lysis. Both possibilities may occur (Evason et al 2001; Fenselau and Demirev 2001; van Baar 2000). The data presented here suggests that, since most of the proteins and peptides detected when intact spores were used were not present in the soluble fractions, they were most likely desorbed from the spore surface during the MALDI process.…”

“…Reproducibility of MALDI‐TOF MS spectra is an important concern that has been addressed in a number of studies (Fenselau and Demirev 2001; Lay 2001; Saenz et al 1999; van Baar 2000). Overall, the spectra of replicate samples in this study were similar, even in the spectra acquired in wells with different spore concentrations.…”

“…This has been possible because of the development of soft ionization methods in MS, coupled with the rapid evolution of the commercially available MALDI‐TOF MS equipment. These developments facilitated ionization and subsequent detection of biological molecules with a broad‐range molecular mass, thus demonstrating that unique peptides or biomarkers could be detected rapidly and directly with minimal sample preparation (reviewed by Dalluge 2000; Fenselau and Demirev 2001; Lay 2001; van Baar 2000).…”