Date of Award

Winter 12-15-2019

Author's School

McKelvey School of Engineering

Author's Department

Energy, Environmental & Chemical Engineering

Degree Name

Doctor of Philosophy (PhD)

Degree Type



Nature has evolved a remarkable variety of high-performance materials based on multi-scale, polymeric assemblies of proteins (e.g. mussel byssus, insect silks, resilin, elastin, keratin, suckerin, and titin). These protein-based materials (PBMs) are biodegradable, produced from renewable feedstock through low energy processes, and mechanically equivalent to many synthetic plastics, making them appealing, eco-friendly alternatives to petroleum-based materials. Large scale productions of high-performance PBMs are currently limited by the impracticalities of harvesting from natural sources and the characteristically low yields of recombinant bioproduction. Low yields are primarily a result of the genetic instability and general metabolic burden associated with the highly repetitive, ultra-high molecular weight (UHMW, >300 kDa) proteins that typically compose high-performance PBMs. While little can be done to alter the economics of harvesting PBMs, continued advances in genetic engineering and synthetic biology can resolve the challenges restricting recombinant bioproduction. To address these challenges, this dissertation describes the development of a microbial platform termed "SI-Bricks" for efficient recombinant production of UHMW PBMs through post-translational polymerization of relatively small, genetically stable protein subunits. In this work, the SI-Bricks platform is successfully employed for microbial production of natural strength/toughness dragline spider silks as well as an entirely novel, high-toughness/damping capacity, muscle mimetic fiber. With continued development, SI-Bricks may enable large scale, commercially relevant production of both natural and engineered high-performance PBMs as environmentally friendly alternatives to a variety of petroleum-based plastics.


English (en)


Fuzhong Zhang

Committee Members

Jan Bieschke, Marcus Foston, Srikanth Singamaneni, Yinjie Tang,


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