(520g) Micro-Biogeography Matters Greatly for Competition: Continuous Chaotic Bioprinting of Spatially Controlled Bacterial Microcosms

Cells do not work alone but function as collaborative micro-societies. The spatial distribution of different bacterial strains (micro-biogeography) in a shared volumetric space, and their degree of intimacy, will greatly influence their societal behavior. Current microbiological techniques, which are commonly focused on the culture of single bacterial strains or well-mixed bacterial communities, fail to reproduce the micro-biogeography of polybacterial societies. Moreover, the production of micro-spatially controlled scaffolds at high resolution is currently challenging.

In this contribution, we use chaotic flows induced by a printhead containing a static mixer to bioprint fine-scale bacterial microcosms. This straightforward approach allows us to intercalate layers of two bacterial strains in these constructs to analyze how their spatial distributions affect their social behavior and/or survival abilities. We demonstrate that these biological microsystems engage in either cooperation or competition, depending on the degree of shared interface between the microcolonies. Remarkably, the extent of inhibition in predator-prey scenarios increases when they are in greater intimacy. Furthermore, competition between two E. coli strains was observed in well-mixed microenvironments, whereas viability was similar in spatially structured consortia. In addition, the cell stationary phase was maintained for 12 h in two-striation scaffolds, allowing bacterial communities to achieve a collective functionality probably not possible in other scenarios. Finally, we modified the inlet port of our printhead for simultaneous extrusion of four inks from the same nozzle in predetermined deposition patterns. This development anticipates further scenarios, such as four-bacteria microcosms or physically isolated consortia, which may find applications in basic or applied science.

We envision that this technique will contribute to the development of a greater complexity of polybacterial microsystems, gut-microbiota models, and biomanufactured materials that will allow printing of fiber-like scaffolds 1 mm in diameter containing striations as large as 500 µm or as small as 7 µm.

Keywords: bioprinting, Kenics, bacteria, static mixer, chaotic, micro-biogeography.