MALDI-TOF MS Analysis of Anaerobic Bacteria Isolated from Biofilm-Covered Surfaces in Brewery Bottling Halls

Abstract

Brewery filling equipment is continually exposed to moisture and nutrients during production runs and is therefore susceptible to microbial attachment and biofilm development. These biofilms play the role of reservoirs of beer spoilage microorganisms. We evaluated the usability of matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) analysis for direct identification of beer contaminants and direct analysis of biofilm. From a total of 58 isolates obtained from the beer filling hall environment, 47% were successfully assigned to the species level and 10% to the genus level when using the commercially available BioTyper (Bruker Daltonik) database. After homemade extension of the database by eight entries belonging to genera Pectinatus, Megasphaera, and Selenomonas, the identification success rate at the species level was increased to 85%. The possibility of direct biofilm analysis was also examined by testing four sample preparation procedures; however, identification of beer contaminants was not successful, as protein signals needed for microorganism identification were not detected by this approach. MALDI-TOF MS including the cultivation step in connection with a reference database containing relevant entries was found as a suitable method for identification of contaminants from brewery environment.