Characterization of micro-organisms isolated from biofilms in food companies: Identification and biofilm-forming properties

Introduction: The importance and role of biofilms in persistent infections with spoilage organisms and pathogenic bacteria is still insufficiently known. Research about sampling, detection and characterization of biofilms in the food industry can help to provide new insights in this issue.
Purpose: The aim of this study was to sample biofilms in different food companies and to characterize the microbial population and matrix components of these presumptive biofilms.
Methods: Surfaces in 8 food companies were sampled after cleaning and disinfection. On the samples, different microbiological enumerations were performed and the dominant bacteria were identified using (GTG)5 clustering followed by 16S rRNA gene sequencing. Also, the biofilm matrix components proteins, carbohydrates and uronic acids were determined. The possibility of the collected dominant bacteria to form biofilm under lab conditions was evaluated in microtiter plates.
Results: The proportion of microbiological contaminated surfaces varied from 0 to 64% across the different food companies with values varying from 0.00 to 7.23 log CFU/100cm². For 0 to 33% of the sampled surfaces over the food companies, micro-organisms were found in combination with biofilm matrix components. Identification of the collected isolates showed a wide diversity but the most common identified species were Pseudomonas spp. (26,3%), Stenotrophomonas spp. (8,3%) and Microbacterium spp. (8,1%). Regarding the biofilm-forming properties, micro-organisms with the strongest possibility to form biofilms are part of the Pseudomonas, Acinetobacter and Stenotrophomonas family.
Significance: Detection and characterization of biofilms in the concerned food companies gave useful insights in the potential to cause food spoilage and foodborne infections and offered a basis for the development of more efficient cleaning and disinfection procedures.