Functional Materials Grown from Engineered Bacteria

Abstract

Nature has produced living materials with wonderful properties, including the ability to self-regenerate, to sense and respond to a changing environment, and to harvest energy from the sun. Inspired by this, researchers in the field of engineered living materials (ELMs) seek to use the tools of synthetic biology to create artificial materials with similar functional properties. In this dissertation, I describe our efforts to advance the goals of ELM research through the development of novel biofilm-based materials.

We developed a co-culture system which leveraged the strengths of two different microbes to produce robust, bacterial cellulose materials with highly programmable functions. One bacteria (Gluconacetobacter hansenii) produced a bacterial cellulose matrix which was colonized by a second bacteria (Escherichia coli) upon media transfer. In our scheme, the G. hansenii served as a “materials factory” while the E. coli offered a vast array of functionality, including the ability to sense external analytes and secrete recombinant proteins. We explored the potential of this system by programming the material with several functions, including biomolecule sequestration, enzymatic catalysis, and biomineralization. Considering the attractive material properties of bacterial cellulose, this enhancement of its functionality represents an exciting step forward in the field of ELMs.

We also used engineered curli fibers – functional amyloid protein fibers found in the biofilms of E. coli – to sequester viruses from wastewater to improve methods for disease surveillance. Due to their amyloid nature, curli fibers are self-assembled from a single protein, CsgA. Using modified curli fibers in which CsgA was genetically fused to single-domain antibodies targeting viral antigens, we demonstrated a simple and rapid protocol for concentrating viruses from wastewater and efficiently recovering viral RNA for downstream detection via quantitative polymerase chain reaction (qPCR). The versatility of curli fibers as a platform for multi-functional ELMs suggests that further development and optimization of this sequestration system is warranted.

In both cases, functional materials were produced entirely through simple bacterial culture without the use of an artificial scaffold. We believe this work represents a meaningful step forward in the design and development of bio-fabricated, functional ELMs.