Blue Light Switchable Bacterial Cell-cell Adhesions Enable the Control of Multicellular Bacterial Communities.

Although the fundamental importance and biotechnological potential of multi-bacterial communities, also called biofilms, are well known, our ability to control them is limited. We present a new way of dynamically controlling bacteria-bacteria adhesions by using blue light and how these photoswitchable adhesions can be used to regulate multicellularity and associated bacterial behavior. To achieve this, the photoswitchable proteins nMagHigh and pMagHigh were expressed on bacterial surfaces as adhesins to allow multicellular clusters to assemble under blue light and reversibly disassemble in the dark. Regulation of the bacterial cell-cell adhesions with visible light provides unique advantages including high spatiotemporal control, tunability and non-invasive remote regulation. Moreover, these photoswitchable adhesions make it possible to regulate collective bacterial functions including aggregation, quorum sensing, biofilm formation and metabolic cross-feeding between auxotrophic bacteria with light. Overall, the photoregula-tion of bacteria-bacteria adhesions provides a new way of studying bacterial cell biology and will enable the design of biofilms for biotechnological applications.