Industrial Waste based Bio-manufacturing of Synthetic Tandem Repeat Protein Fibers

Abstract

Protein-based fibers are lightweight, biodegradable, have excellent moisture and temperature regulation, and exceptional mechanical properties, but they are limited in production capacity. Biosynthetic protein-based fibers have the potential to overcome these concerns, but large-scale production with high yield (>1g/L) and purity (>%80), as well as low cost (<$50/kg), must be achieved. Here we developed an optimized expression and purification method for biosynthetic tandem repeat proteins, that are inspired from squid ring tooth (SRT) protein using three wetwaste feedstock, corn steep liquor, molasses, and soybean extract. SRT is composed of a highly stiff, naturally occurring bioplastic and these properties arise from the molecular architecture of the constituant proteins, which are segmented co-polymers with alternating semicrystalline and amorphous domains similar to silk. We have developed protocols to use liquid industrial and agricultural waste as feedstock for SRT production, which has the potential to divert waste streams into useful products. We also show that our biosynthetic protein powder, produced at 1 g/L yield and greater than 80% purity, can be manufactured into fibers using conventional split film or wet-spinning approaches.