The project's objective was to enhance understanding of bacterial interspecies interactions in multispecies biofilms within the food industry, while preparing the researcher for future professional challenges through comprehensive training. The researcher underwent extensive training at the home institute ILVO in various transferable skills (e.g. presenting, grant writing, food regulations) and on food processing operations in the Food Pilot, such as milk powder production, plant protein processing, and fish feed manufacturing. During secondment periods, training through research was performed at KU Leuven (biosensor) and the University of Copenhagen (confocal microscopy). The research involved examining the biofilm-forming capabilities in vitro of approximately 100 bacterial strains isolated from biofilm samples in dairy, meat, and egg processing industries. The study then focused on interspecies interactions in biofilm models composed of various combinations of up to four species isolated from a dairy pasteurizer. From this, two 4-species biofilm models were selected based on their synergistic bacterial interactions for further studies.
It was discovered that various social interactions within these dairy communities are crucial for species coexistence within the biofilm, going from cooperation, over competition to even exploitation. The stability and population dynamics of each species were found to be influenced by these interactions. The concept of 'keystone species' (e.g. the dairy species Microbacterium lacticum) was introduced, emphasizing their critical role in biofilm stability. Targeting these keystone species could be pivotal in developing strategies for biofilm eradication. At KU Leuven, the researcher innovatively utilized biosensors to study interspecies interactions on metallic coated surfaces, revealing for the first time the possibility to follow in real time the attachment and release of bacterial cells in a biofilm. Confocal microscopy at the University of Copenhagen was successfully employed to understand the spatial organization of each bacterial species in biofilms using specific FISH (fluorescent in situ hybridization) probes. This study revealed how bacteria benefit from their spatial organization under abiotic stress conditions such as cleaning and disinfection. Furthermore, new metabolic pathways and expressed genes related to bacterial adaptation in various environments were identified, offering insights into controlling biofilms and understanding interspecies interactions at an unprecedented level.
The findings have been disseminated through general articles in popular and trade magazines, a school activity and social media, enhancing public and industry understanding. In the academic sphere, four scientific articles have already been published, and more are underway, as well as oral and poster presentations at four international conferences. Several food or supplier companies have expressed their interest in the findings which may lead to follow-up research or industrial innovation.
