In This Issue

Bacteria in the human body often thrive within structured 3D communities that comprise multiple species. Mounting evidence suggests that relationships between structure and function in these microbial ecosystems mediate community attributes that influence human health, such as the virulence of infections within the cystic fibrosis lung and chronic wounds. Jodi Connell et al. (pp. 18380–18385) devised an approach that uses 3D microscopic printing to organize populations of mixed bacterial species within any structural arrangement. Based on a laser lithography system, the technique helps trap selected bacteria in sealed cavities of a highly porous gelatin that allows the enclosed cellular populations to rapidly grow and transmit biologically active molecules, including polypeptides, antibiotics, and chemical signals that trigger gene expression at certain population density thresholds. The authors also demonstrated that the 3D relationship between two bacterial species allows one pathogen’s resistance to an antibiotic to enhance the survival of a second species. The findings represent a tool that can help clarify mechanisms of cellular communication and the onset of social behaviors between microbes within aggregates, according to the authors. — T.J.