Date of Award
4-20-2017
Document Type
Dissertation
Degree Name
Molecular Biosciences, Ph.D.
First Advisor
Jianfeng Xu
Second Advisor
Brett Savary
Committee Members
Gregory Phillips; Maureen Dolan; Ya-Jane Wang
Call Number
LD251.A566d 2017 Z43
Abstract
There is a continuing need for new molecular and biochemical processing technologies to more sustainably utilize biomass such as sugar beet pulp for environmental and economic benefit. This research project addressed the overarching research hypothesis that innovative molecular and biochemical technologies can enable more efficient processing of plant biomass and generate renewable biobased products for food and industrial use. Specifically, this research investigated upstream processing technologies toward re-engineering the plant cell wall for improved biomass processability and downstream processing technologies for efficient cell wall-depolymerizing (CWD) enzyme production and biomass processing. There were two Specific Aims addressed in this project: 1.) Evaluate the design and function of hydroxyproline (Hyp)-O-glycosylated polypeptides (HypGPs) as a molecular carrier in directing the expression and localization of CWD enzyme(s) in the plant cell wall; and 2.) Investigate advanced enzymatic technologies for generating functional oligosaccharides, specifically feruloylated arabino-oligosaccharides (FAOs), from sugar beet pulp. Specific Aim 1 investigated Hyp-O-glycosylation of different designer HypGPs as molecular carriers in facilitating protein/enzyme apoplastic targeting and accumulation in both the in vitro hairy root culturesystem and whole plant model system. HypGPs representing two major types of plant cell wall glycoproteins: an extensin-type consisting of tandem repeats of “Ser-Hyp-Hyp-Hyp-Hyp” motif, and an arabinogalactan protein (AGP)-type consisting of tandem repeats of “X-Hyp” motif (X= Ser, Ala, Thr), were each engineered into tobacco hairy roots and/or whole plants. Both types of HypGP improved the accumulation of a conjoined protein. A new model describing the Hyp-O-glycosylation process of AGPs in planta was developed. Specific Aim 2 assessed bioproduction of a thermostable endo-1,5-α-L-arabinanase in Pichia pastoris for treatment of sugar beet soluble polysaccharide with the recombinant enzyme. FAOs were recovered and evaluated for modulating tight junctions of human colonic epithelial (T84) cells. Results indicated that FAOs could stabilize the tight junction-related proteins occludin and zonula occludens-1, while inhibiting loss of tight junction function following treatment by pro-inflammatory factor lipopolysaccharide. This research established proof-of-concept to further investigate direct expression of thermostable CWD enzymes in an economically important crop (e.g., sugar beets) for sustainable post-harvesting biomass processing towards cost-effective production of industrial sugars and functional oligosaccharides.
Rights Management
This work is licensed under a Creative Commons Attribution 4.0 International License.
Recommended Citation
Zhang, Ningning, "Molecular And Biochemical Technologies for Modifying Plant Cell Walls and Producing Functional Biobased Products" (2017). Student Theses and Dissertations. 565.
https://arch.astate.edu/all-etd/565
Included in
Genetics and Genomics Commons, Nanoscience and Nanotechnology Commons, Plant Sciences Commons
