Affiliation:
1. Department of Paraclinical Sciences, Faculty of Veterinary Medicine Norwegian University of Life Sciences (NMBU) Ås Norway
2. Department of Physics Umeå University Umeå Sweden
3. Structural Biology Brussels Vrije Universiteit Brussel Brussels Belgium
4. Structural and Molecular Microbiology Structural Biology Research Center Brussels VIB Belgium
5. Umeå Centre for Microbial Research (UCMR) Umeå Sweden
Abstract
AbstractSpecies within the Bacillus cereus sensu lato group, known for their spore‐forming ability, are recognized for their significant role in food spoilage and food poisoning. The spores of B. cereus are adorned with numerous pilus‐like appendages, referred to as S‐ENAs and L‐ENAs. These appendages are thought to play vital roles in self‐aggregation, adhesion, and biofilm formation. Our study investigates the role of S‐ENAs and L‐ENAs, as well as the impact of various environmental factors on spore‐to‐spore contacts and the interaction between spores and vegetative cells, using both bulk and single‐cell approaches. Our findings indicate that ENAs, especially their tip fibrillae, play a crucial role in spore self‐aggregation, but not in the adhesion of spores to vegetative cells. The absence of L‐BclA, which forms the L‐ENA tip fibrillum, reduced spore aggregation mediated by both S‐ENAs and L‐ENAs, highlighting the interconnected roles of S‐ENAs and L‐ENAs. We also found that increased salt concentrations in the liquid environment significantly reduced spore aggregation, suggesting a charge dependency of spore‐spore interactions. By shedding light on these complex interactions, our study offers valuable insights into spore dynamics. This knowledge can inform future studies on spore behaviour in environmental settings and assist in developing strategies to manage bacterial aggregation for beneficial purposes, such as controlling biofilms in food production equipment.