Comparative analysis of milk bacteria by two MALDI-MS systems

Area of Science:

• Microbiology
• Analytical Chemistry
• Mass Spectrometry

Background:

• Accurate bacterial identification is crucial in food safety and diagnostics.
• Matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) is a rapid and effective technique for bacterial identification.
• Comparative studies of different MALDI-TOF MS systems are essential for optimizing diagnostic workflows.

Purpose of the Study:

• To compare the identification accuracy of two MALDI-TOF MS systems: Bruker Microflex LT Biotyper and Zybio EXS2600 Ex-Accuspec.
• To evaluate the performance of both systems at the genus and species levels for bacterial isolates from raw milk.
• To assess the agreement between the two systems in bacterial identification.

Main Methods:

• Comparative analysis of bacterial strains isolated from raw milk.
• Identification using two MALDI-TOF MS systems: Bruker Microflex LT Biotyper and Zybio EXS2600 Ex-Accuspec.
• Utilized the in-tube extraction method for sample preparation.
• Identified a total of 1,130 bacterial isolates.

Main Results:

• Bruker system achieved 94.6% genus-level identification; Zybio system achieved 91.3% genus-level identification.
• Approximately 75% agreement at the species level between the Bruker and Zybio systems.
• Discrepancies at both genus and species levels were observed in approximately 25% of cases.

Conclusions:

• Both Bruker and Zybio MALDI-TOF MS systems demonstrate high performance for bacterial identification from raw milk.
• The systems show comparable effectiveness for routine microbiological diagnostics.
• Further investigation may be needed to resolve discrepancies in approximately 25% of identifications.