Abstract
Synthetic communities (SynComs) are valuable tools for addressing microbial community assembly and function, towards their manipulation for clinical, biotechnological and agricultural applications. However, SynCom design is complicated since interactions between microbes cannot be predicted based on their individual properties. Here we aimed to assemble a functionally cohesive SynCom displaying high-order interactions, as a model to study the community-level beneficial functions of seed-endophytic bacteria from native maize landraces, including strains from the Bacilli class, and the Burkholderia and Pseudomonas genera. We developed a partial combinatorial, bottom-up strategy that was followed by the detection of complex colony architecture as an emergent property in co-cultures. Using this simplified approach, we tested less than 400 co-cultures from a pool of 27 strains, resulting in the assembly the Xilonen SynCom, which includes Bacillus pumilus NME155, Burkholderia contaminans XM7 and Pseudomonas sp. GW6. In this community, higher-order interactions result in complex colony architecture, which is considered a proxy of biofilm formation. Additionally, we generated protocols for absolute quantification of each member from a complex mixture. The Xilonen SynCom will serve as a model to study biofilm formation in community settings, and will aid in the study of the molecular and ecological basis mediating maize fertility.