Bacteria are ubiquitous in complex, three-dimensional, porous environments such as biological tissues and gels and subsurface soils and sediments. Here we develop a method to 3D print dense colonies of bacteria into jammed granular hydrogel matrices to study their growth and motility in complex environments. Studies have revealed previously unknown differences in spreading characteristics of bacteria inhabiting porous environments compared to those in liquid cultures on flat surfaces.
The development of using granular hydrogel matrices comprised of jammed biocompatible hydrogel particles swollen in liquid bacterial culture as porous Petri dishes to confine cells in 3D. Previous studies were limited to small sample volumes about one ml, and therefore short experimental time scales, and were also limited in their ability to define inocula geometries with high spatial resolution. We have established that the cell-spreading characteristics of the bacteria depend on the pore size and the motility of the cell.
