Extended Spectra Database for Quality Indicators and Other Spoilers Identification By MALDI-TOF: A Never-Ending Story...

Introduction: Indicator organisms are employed to reflect the microbiological quality of foods and beverages. They are most often used as a measure of the hygienic or sanitary conditions, but they are as well used to describe an organism whose presence or level indicates the potential for future spoilage or as a “surrogate” organism; for example, those organisms that model the behavior of pathogens under certain conditions. In addition, some “indicators” are not specific organisms but assays for groups of organisms, such as Enterobacteriaceae (EB).

Purpose: Opening lines to develop the database is to focus on groups of micro-organisms, one after another. This helps in creating a road map, starting with the most commonly encountered then also moving to spoiler species linked to more specific industrial processes or formulations.

Methods: In that step-by-step database implementation program, isolates from dairy, meat and malt fermentation processes and strains collections were characterized using both 16S rDNA sequencing and Maldi-Tof Mass Spectrometry (MS). A minimum of 20 MS Profiles (MSPs) were obtained for each isolates to set up a Reference MSPs. Ideally, whenever possible, three different isolates or more are analyzed per species.

Results: The global database contains currently 104 species of lactic acid bacteria, species of 155 Enterobacteriaceae, 396 species of the main spore-forming bacteria spoilers including Alicyclobacilliaceae, Bacilliaceae, Paenibacilliaceae and Clostridia, and as well 193 yeasts. Blind isolates were analyzed and were accurately identified and distinguished from over 7311 other microorganisms present in the overall database.

Significance: The integration of Maldi-Tof MS combined to a fit-for-purpose database into existing food and beverage production processes helps to improve quality assurance practices, providing accurate identification and short-time to result. This high-throughput routine platform is as well a promising technology to identify quickly the origins of product spoilage, or to develop a strategy for quality indicators profile’s and other spoiler’s surveillance.