Engineered bacteria that self-assemble ''bioglass'' polysilicate coatings display enhanced light focusing

Abstract

Photonic devices are cutting-edge optical materials that produce narrow, intense beams of light, but their synthesis typically requires toxic, complex methodology. Here we employ a synthetic biology approach to produce environmentally-friendly, living microlenses with tunable structural properties. We engineered Escherichia coli bacteria to display the silica biomineralization enzyme silicatein from aquatic sea sponges. Our silicatein-expressing bacteria can self-assemble a shell of polysilicate "bioglass" around themselves. Remarkably, the polysilicate-encapsulated bacteria can focus light into intense nanojets that are nearly an order of magnitude brighter than unmodified bacteria. Polysilicate-encapsulated bacteria are metabolically active for up to four months, potentially allowing them to sense and respond to stimuli over time. Our data demonstrate that engineered bacterial particles have the potential to revolutionize the development of multiple optical and photonic technologies. Significance StatementIn this work, we apply the principles of synthetic biology to create living optical devices. Utilizing the ability of sea sponges to polymerize bioglass from silica precursors in the ocean water using only a single enzyme, silicatein, we have fused this same enzyme to the surface of Escherichia coli bacterial cells. The modified bacteria can polymerize a layer of bioglass at their surface. This bioglass shell allows the bacteria to act as engineered optical devices that are able to scatter high intensity, focused light while also surviving for several months, opening the door to a wide range of sense-and-respond applications. ClassificationBiological Sciences, Applied Biological Sciences