Detection of Pathogenic and Non-pathogenic Bacteria by Matrix-assisted Laser Desorption/ Ionization Time-of-flight Mass Spectrometry (CAT#: STEM-ST-0303-LJX)

Introduction

The proteins isolated from the whole cells of bacterial pathogens and related non-pathogenic simulants were analyzed directly, with minimal sample preparation by matrix-assisted laser desorption/ionization (MALDI) time-of-flight mass spectrometry. Inspection of mass spectrometric profiles obtained from direct MALDI-MS analysis of the protein extracts revealed specific biomarkers for individual bacterial cells. The observed biomarkers enabled us not only to detect pathogenic bacteria (Bacillus anthracis, Yersinia pestis and Brucella melitensis), but also to distinguish them from the corresponding non-pathogenic species. By examining a series of strains of several Bacillus species (anthracis, thuringiensis, cereus and subtilis), it was possible to derive genus, species and strain-specific biomarkers from the measured molecular masses of the intact proteins. Additional series of biomarkers were obtained from direct mass spectrometric analysis of tryptic digests of the protein extracts. The application of this technique for rapid chemotaxonomic classification of microorganisms is demonstrated.

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Principle Applications Procedure Materials Notes Related Products

Principle

In a very small area and a very short time interval (ns order of magnitude), the laser delivers high-intensity pulse energy to the sample under test, causing it to desorption and ionize instantaneously without thermal decomposition. MALDI is a mass spectrometry ionization method for direct evaporation and ionization of non-volatile samples.

Applications

For measuring the molecular weight of biological macromolecules, such as the molecular weight distribution of peptides, proteins, nucleic acids, polymers and oligomer analysis.

Procedure

1. Mix the sample with the appropriate matrix material and load it onto the metal plate.
2. Pulsed laser light is used to irradiate the sample and trigger ablation and desorption of the sample and matrix materials.
3. Analyte molecules are ionized by protonation or deprotonation in the thermal plume of the ablated gas and are then accelerated to a mass analyzer for analysis.

Materials

• Sample Type:
Pathogenic and non-pathogenic bacteria

Notes

1. During shutdown, if the nitrogen is not turned off, the pressure should be properly lowered to avoid moisture.
2. Keep an eye on instrument drift during manual measurement. If there is drift, the instrument needs to be calibrated with standard peptide or standard protein.

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