Functional membranous structures can exist apart from cellular entities as exosomes or extracellular vesicles (EVs) in all kingdoms of life including bacteria. For bacteriophages (phages), the viruses of bacteria, association to bacterial surfaces is an essential step in their infection cycle. Consequently, by presenting bacterial surface parts that serve as phage receptors, bacterial extracellular vesicles (BEVs) provide potent bacterial decoys to reduce the number of infective bacteriophage particles within a bacterial population. In contrast, not much is known about the mechanisms, by which BEVs inactivate phages and what is the fate of a bacteriophage once bound to a vesicle. In addition, although BEV production has been established as a major bacterial stress response, molecular details of vesiculation triggered during bacteriophage infection are not well understood and need more investigation. Using Salmonella as a model, we are working on these open questions. Our work will substantially advance the fundamental knowledge on how OMVs modulate phage-host coexistence.

Bacterial viruses (bacteriophages) shuttle their genomes into bacterial cells as a key initial step for the infection of hosts. Many bacteriophages use a tail for adsorption and DNA translocation to the host’s cytosol. Tailed phages combine core tail architectures with diversified infection modules, reflecting the different envelope compositions encountered on their wide range of bacterial hosts. Long, non-contractile tailed siphoviruses are a predominant tailed phage type. However, the nature of the infection signal these phages receive from the bacterial envelope is not well understood and needs more investigations. With total internal reflection fluorescence (TIRF) microscopy, and new Gram-negative model membrane set-ups, we will study siphovirus 9NA’s time-resolved genome release mechanism on a single particle level, and analyze the influence of Gram-negative membrane properties on successful infection initiation. Exploring the dynamics in bacteriophage-envelope interactions will advance our view on phage tail structure rearrangements, leading to genome release as a key step in the phage life cycle.