Rheology of the Environment Regulates Bacterial Growth

Many bacterial communities inhabit complex environments such as soils and biopolymer gels secreted by a host or the bacteria themselves. In these settings, the cellular surroundings are rheologically complex, subjected to flow, and frequently have limited nutrient availability. Within the human body alone, the rheological properties of a microbe's environment can change drastically depending on location in the body and host physiology. Here, by probing bacterial growth in granular hydrogel matrices with defined structural and rheological properties, we demonstrate that the rheology of the environment modulates flow-induced transport of essential nutrients—thereby regulating bacterial metabolism and cellular physiology. Our work thus reveals a new mechanism, beyond mechanosensing, by which mechanics modulates microbial behavior.