Chemical Engineering Seminar

Diverse challenges in human and environmental health can be addressed by harnessing the power of biocatalysis to create unnatural building block chemicals - efficiently, selectively, and potentially in distributed contexts by autonomous cells. Our lab is expanding the biological repertoire of building blocks by engineering metabolism, proteins, and genomes. In this talk, I will present glimpses of our work in three related research directions. First, we have designed biochemical routes to add amine functionality to carboxylic acids and aldehydes derived from plastic or biomass waste. Our mono- and diamine monomers should allow for polymer upcycling. Second, we are advancing the biosynthesis of non-standard amino acids (nsAAs) by live cells, with an emphasis on introducing heteroatom functionality onto aromatic amino acid sidechains. One example is the biosynthesis of an immunogenic amino acid that contains a nitroaromatic sidechain. We demonstrate the design of live bacterial cells that biosynthesize para-nitro-L-phenylalanine and that insert it within specific sites of target proteins. This technology may serve as a foundation for live bacterial vaccines that produce recombinant antigens for better recognition by the immune system. To enable a more generalizable approach to nsAA biosynthesis for diverse applications, we also report new and improved
members of an enzyme family that produces diverse beta-hydroxylated aromatic amino acids from aromatic aldehyde precursors. Finally, I will briefly discuss the ability to use unnatural building blocks for biological containment of engineered microbes. The ability to effectively contain engineered microbes through engineered dependency on unnatural building blocks could unlock the potential of microbial synthetic biology for use in the field. Here, I review our published efforts in designing effective containment for E. coli strains.