Project Details
Projekt
Engineered Living Actuators from Filamentous Cyanobacteria
Subject Area
Biomaterials
Biophysics
Biophysics
Term
since 2024
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 541299352
In this project, we propose a combined experimental and theoretical work with the goal to engineer living actuators from gliding filamentous cyanobacteria. These phototrophic organisms play an important role in the carbon cycle of Earth, both in the present and the past, generating, for instance, atmospheric oxygen and large parts of our fossil fuel record. Filaments consist of many linearly stacked cells. They are only a few microns in diameter but can grow up to millimeters in length. In contact with each other or solid surfaces, they self-propel along their contour and respond to gradients in light intensity by reversing their gliding direction. The mechanisms behind gliding motility and direction reversals remain incompletely understood. In natural habitats, this motility leads to aggregation into dense colonies that may contract or disperse again, depending on ambient conditions, which is considered an evolutionary advantage, allowing for a collective acclimatization. We will harness these properties to develop an adaptive living material with actuating capacity, i.e. a material that can change shape on demand by stimulation with light. Bacteria will be embedded in a matrix or scaffold structure, typically a gel- or fiber-based material with tailored properties and structure, which will be developed in this project. The scaffold couples to the forces generated by gliding motility. Guiding and aligning filamentous cyanobacteria by light patterns, we intend to build an active network in the scaffold, capable of contracting upon stimulation by switching light patterns. Forces from the active network will be transduced to the matrix either by adhesion or by mechanical interlocking between active and passive constituents. By tuning the mutual alignment of active and passive networks, their anisotropy, and their mechanical properties, we aim for a control of the actuation direction. On long timescales, the material is supposed to be adaptive, because long-term exposure to light patterns may induce a reassembly of the active network into different topologies, allowing it to switch between actuation modes. Designing manipulation strategies capable of extracting mechanical work requires knowledge of the spatio-temporal organization of the gliding force generation of individual filaments and their ensembles, which is currently unavailable and will be determined here. In contrast to most previously studied living actuators, our system is based on long, flexible and motile polymeric constituents that are exceedingly robust and inherently stimulatable by light: The fiber-like nature of the living constituents allows us to create strongly entangled networks that dwell in a wide range of ambient conditions. Their motility and responsivity allows for an actuation of the network itself, without the need for sophisticated modifications of the living constituents.
DFG Programme
Priority Programmes
