(385q) Biocomposite Thermoplastic Polyurethanes Containing Evolved Bacterial Spores As Living Fillers to Facilitate Polymer Disintegration

The field of engineered living materials (ELMs) seeks to pair living organisms with synthetic materials to generate biocomposite materials with augmented function since living systems can provide highly-programmable and complex behavior. ELMs have typically been fabricated using techniques in benign aqueous environments, limiting their application. In this work, biocomposite fabrication was demonstrated in which spores from polymer-degrading bacteria, Bacillus subtilis, were incorporated into a thermoplastic polyurethane (TPU) using high-temperature melt processing. Bacteria were engineered using adaptive laboratory evolution to improve their heat tolerance to ensure nearly complete cell survivability during manufacturing at 135^o C. Mutation analysis of the multiple replicate evolutions identified the genetic basis for enhanced heat-shock tolerance of the Bacillus spores. Furthermore, the overall tensile properties of spore-filled TPUs were substantially improved, resulting in a significant improvement in toughness. The biocomposites facilitated disintegration in compost in the absence of a microbe-rich environment. Finally, spores retained a programmed function, expressing green fluorescent protein. This research provides a scalable method to fabricate advanced biocomposite materials in industrially-compatible processes.