Freeze-Dried-Conserved Bacteria Can Be Identified by Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry Without the Need of Prior Culturing

INTRODUCTION: Biobanking practices are continuously evolving to improve and accelerate sample preparation and analysis. OBJECTIVES: At the Biological Resource Center of the Institut Pasteur, our goal is to develop new and optimized methods for sample processing. In this study, we aimed to establish a culture-independent approach for identifying bacteria directly from their freeze-dried state. METHODS: Freeze-dried bacteria from 25 species were reconstituted in saline solution, mechanically lysed, and their proteins extracted with acetonitrile and formic acid, followed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry analysis. RESULTS: threshold, above which all strains were consistently and accurately identified. CONCLUSION: This approach provides a fast and robust alternative for the characterization of bacterial samples across diverse taxonomic groups.