Nanostructured enzyme assemblies for lignocellulosic biomass breakdown for bioproduct and bioenergy applications

Authors: Lee, Charles; Wagschal, Kurt; PAAVOLA, CHAD - National Aeronautics And Space Administration (NASA)

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 5/27/2016
Publication Date: 6/5/2016
Citation: Lee, C.C., Wagschal, K.C., Paavola, C. 2016. Nanostructured enzyme assemblies for lignocellulosic biomass breakdown for bioproduct and bioenergy applications.[abstract]. USDA/NIFA Nanotechnology Meeting.

Interpretive Summary:

Technical Abstract: The continued reliance on fossil fuels to supply our chemical feedstock and energy requirements is unsustainable. However, it is estimated that there are greater than 220 billion tons of lignocellulosic biomass available globally which represents a tremendous renewable source for society’s chemical needs. In addition, the use of this waste biomass avoids conflicts that arise from the “food vs fuel” debate. However, the difficulty and costs associated with processing lignocellulose make the transition from fossil fuels to this renewable resource very challenging. Therefore, much effort has been focused on efficiently deriving value-added byproducts from the various fractions of biomass. One of the most efficient enzymatic strategies for hydrolyzing biomass substrates is the use of multienzyme complexes called cellulosomes produced by various anaerobic bacteria. These complexes are comprised of a protein scaffold containing multiple recognition sites called cohesins. Biomass-degrading enzymes with complementary recognition motifs called dockerins bind to the cohesins to form large complexes that are very effective at hydrolyzing cellulosic biomass. In this project, we created artificial designer cellulosomes to mimic these enzymatic complexes. We used an eighteen-subunit scaffold constructed from a chaperonin protein isolated from the thermophilic Sulfolobus shibatae bacterium. The scaffold protein was engineered to be capable of binding to mixtures of lignocellulases. These complexed enzymes were found to be significantly more active in cellulose hydrolysis than the enzymes free in solution. We also cloned and characterized other classes of enzymes and integrated them into our artificial cellulosomes. We demonstrated enhanced production of other value-added products, such as diacids, from different renewable substrates. Moreover, our work shows the effects that varying the specific enzyme ratios has upon overall product yield and levels of activity enhancement.