February 4, 2025 - Joshua Scott, Ph.D. Candidate (Goddard Lab), Cornell University

Joshua Scott
Ph.D. Candidate, Goddard Lab (https://cals.cornell.edu/julie-m-goddard)
Department of Food Science, Cornell University

Speaker Bio

Joshua Scott is a 5th year Food Science Ph.D. candidate and National Science Foundation Graduate Research Fellow conducting research under the guidance of Professor Julie Goddard. His research focuses on the valorization of food byproduct and waste product streams using immobilized enzyme systems functionalized with protein stabilizing excipients. Before starting his PhD, Josh completed his Bachelor of Science in Chemical Engineering at the University of Illinois at Urbana-Champaign, during which, he completed internship roles at iBiocat, Inc. and Archer Daniels Midland. In his free time, Josh loves playing guitar, hiking, and spending quality time with his cat, Frank.

Immobilization of enzymes into solid nanobiocatalysts allows scientists and engineers to mediate a wide range of food waste transformations. However, enzyme stability is a challenge when using immobilized enzymes under extreme conditions (e.g., high temperature, low pH values) typical to food waste and byproduct streams. Nanomaterials enhance enzyme activity retention in immobilized enzyme systems by reducing denaturing enzyme-carrier interactions and improve enzyme stability in environmental extremes. Hierarchical biocatalytic nanocomplexes provide nanoscale environments for activity retention while containing microscale character to allow facile recovery. To create hierarchical biocatalytic nanocomplexes which enable cascade biocatalytic reactions and stabilization against extreme conditions, multiple enzymes may be co-immobilized by precipitation and cross-linking into combined cross-linked enzyme aggregates (Combi-CLEAs) containing nanostructure excipients having the enzyme stabilizing disaccharide, trehalose. Herein, we report the preparation and assessment of combi-CLEAs of β-galactosidase (β-Gal) and glucose isomerase (GI) containing trehalose-decorated poly(amidoamine) nanostructures for the conversion of lactose into lactose-fructose syrup. Combi-CLEAs of β-Gal and GI were prepared by precipitation of 100 mg/mL β-Gal and GI mixtures with 70% t-Butanol, followed by crosslinking with 100 mM glutaraldehyde. The effect of varying β-Gal and GI concentrations in Combi-CLEAs preparation on Combi-CLEAs conversion of lactose to fructose was evaluated, showing a maximum β-Gal and GI activity when preparing Combi-CLEAs with 100 mg/mL enzyme solutions with a β-Gal to GI activity ratio of 100 Uβ-Gal/ UGI. Trehalose nanostructures, prepared by carbodiimide coupling of succinylated trehalose to poly(amidoamine) and characterized by Fourier-transform infrared spectroscopy and nuclear magnetic resonance, was added to the combi-CLEA preparation, and the resulting combi-CLEAs exhibited 51% higher β-Gal activity and enhanced thermal stability while maintaining GI activity. Combi-CLEAs with trehalose decorated nanostructures were able to be recycled five times while maintaining 40% and 7% β-Gal and GI activity, respectively. This work has shown potential to perform cascade biocatalytic reactions to valorize D-lactose and improve enzyme performance in environmental extremes through use of multi-enzyme biocatalytic nanomaterials containing trehalose nanostructures.