“…By studying bacteria in complex, spatially structured communities instead of homogeneous planktonic populations, we have advanced the understanding of emergent properties and interactions (Tan et al, 2017;Madsen et al, 2018). When studying multi-species biofilms, it is of great importance to choose the right consortium for the research inquiry (for example processes, spatial patterns and mechanisms) and determine whether to consider the community as a unit or evaluate activity, fitness and functional contribution of individual species (Johns et al, 2016;Liu et al, 2016;Blasche et al, 2017;Tan et al, 2017). Many studies investigating the fundamental mechanisms behind interactions use model strains, such as Escherichia coli and Pseudomonas aeruginosa, which have been adapted to laboratory growth conditions and are easily genetically engineered.…”