S133: Microbial production of 5-carbon polyamide building blocks

Microbial production of conventional monomer compounds could represent a sustainable path towards renewable bioplastics.  Recently, much attention has been given to the engineering of biocatalysts for the production of 4- through 6-carbon polyamide monomers, including succinic acid, adipic acid, putrescine, and cadaverine; each of which can be used to produce nylons and other plastics.  Here we report on the ‘bottom up’ engineering of a pathway and microbial biocatalysts for the production of two additional, 5-carbon polyamide monomers, namely 5-aminovaleric acid and glutaric acid.  This was achieved through the systematic over-expression of the natural lysine degradation pathway enzymes of Pseudomonas sp. (encoded by the davBADT operon of P. putida KT2440) in an Escherichia coli host engineered for lysine over-production. In addition to screening other sources of pathway isoenzymes, alternative expression strategies of the pathway enzymes were also investigated.  In shake flask cultures containing glucose in minimal media, current strains have already achieved 5-aminovaleric acid and glutaric acid titers surpassing 800 mg/L. Here we report an overview of our most recent findings in this project, including the implementation of strategies to support greater precursor availability and improved pathway flux, as well as the utilization of alternative and more sustainable substrates.