Top-down proteomics for rapid identification of intact microorganisms

Area of Science:

• Microbiology
• Analytical Chemistry
• Biochemistry

Background:

• Accurate identification of Bacillus spore species is crucial for various applications.
• Traditional methods for microorganism identification can be time-consuming and labor-intensive.
• There is a need for rapid and reliable methods for spore identification.

Purpose of the Study:

• To develop and validate a MALDI-TOF/TOF MS-based method for rapid and high-confidence identification of intact Bacillus spore species.
• To demonstrate the utility of intact protein biomarkers without extensive sample processing.
• To evaluate factors influencing the method's performance for broader microorganism identification.

Main Methods:

• Utilized MALDI-TOF/TOF mass spectrometry for direct analysis of intact Bacillus spores.
• Employed laser-induced dissociation (LID) for fragmentation of precursor ions (>5 kDa).
• Developed in-house software for comparing experimental MS/MS spectra with in silico proteome databases to identify unique protein biomarkers.

Main Results:

• Successfully identified pure and mixed samples of Bacillus atrophaeus and Bacillus cereus spores with high confidence.
• Demonstrated unambiguous identification based on species-specific small, acid-soluble spore proteins.
• Evaluated key experimental parameters including mass accuracy, fragment ion count, and precursor ion charge state.

Conclusions:

• MALDI-TOF/TOF MS provides an efficient workflow for the rapid identification of intact Bacillus spores.
• The method eliminates the need for biomarker prefractionation, digestion, separation, and cleanup.
• This technique serves as an effective tool for in situ confirmation and verification of microorganism identification in a laboratory setting.