Collaborative Research: Engineering of Recoverable Cellulosomes for Biofuel Conversion

Collaborative Research: Engineering of Recoverable Cellulosomes for Biofuel Conversion, National Science Foundation

Project Summary

Cellulosomes from different organisms exhibit a wide variety of architectures but all localize a variety of cellulolytic enzymes to act synergistically. Natural cellulosomes are bound to a scaffoldin backbone through protein-binding dockerin regions. The scaffoldin may have 10-200 individual enzymes attached to it. The scaffoldin also has one or more carbohydrate binding modules that keeps the structure fixed to the substrate surface. The proposed engineered NBC will be used to advance knowledge of how composition of lignocellulolytic enzymes and structural organization of these enzymes in the carrier impact hydrolysis. Challenges to address include control and regulation of NBC structure, enzyme packing and mobility in the NBCs, selective binding of the nanocapsules to biomass substrates to enable rapid and scalable biomass hydrolysis, and NBC recycling using magnetic separation. Variations in spherical polymer brush composition and structure, composition of the loaded enzymes, enzyme interactions with the polymer brushes, including regulation of enzyme–brush interactions, and selective binding of artificial cellulosomes to cellulose vs lignin will be used to advance the understanding of synergy in natural cellulosomes to inform science-based engineering of effective recoverable cellulosomes.

Unlocking fermentable sugars from cellulosic biomass for use as an industrial processing feedstock is a key process in realizing the potential of biomass for sustainable liquid fuels and other bioproducts. Advances in rapid and inexpensive biomass hydrolysis in an industrial setting may be achieved through mimicry of natural biomass breakdown by microbial release of cellulases and complementary enzymes. While most bioconversion research uses free enzyme systems, the most efficient living systems have developed mechanisms to centralize diverse and complementary groups of enzymes into extracellular structures called cellulosomes. The strategic goal of this research is to engineer and study engineered recoverable cellulosomes as nanobiocatalytic capsules (NBCs) that accommodate diverse cellulolytic enzymes in a polymeric shell (spherical polymer brush) securing synergistic action of enzymes. The proposed research plan addresses challenging problems of improving bioconversion rates and yields through enzyme diversification and localization on natural cellulosome-inspired nanostructures. The research aims to produce NBCs that combine several biocatalytic enzymes in a polymer phase confined to the surface of superparamagnetic core particles. These artificial biocatalytically active nanostructures will mimic natural cellulosomes both in efficacy and diverse enzyme localization. Due to the superparamagnetic core, the NBCs can be extracted and recycled for multiple bioconversion cycles.

 

July,1,2016 – June,30,2019, $191,970 (in collaboration with Dr.S.Pryor at NDSU and University of Georgia)

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