Efficient Vanillin Synthesis Through Engineering Auto-regulatory Genetic Circuits in Escherichia coli

View all posters

Tat-Ming Lo, Chueh-Loo Poh, Matthew Wook Chang

Nanyang Technological University, Singapore

Vanillin (4-hydroxy-3-methoxybenzaldehyde) is the key compound that contributes to the vanilla aroma which can be found in food and cosmetic products. Due to its heavy consumption, natural vanillin produced from the seed pods of Vanilla plantifola contributes to less than 1% of the total global supply, with the majority coming from chemical synthesis using petroleum based materials. Various attempts to biologically produce vanillin from renewable materials such as ferulic acid, eugenol and isoeugenol have been reported. However, the biological production of vanillin often requires inducers such as L-arabinose and IPTG. Artificial induction in many cases is less favorable due to high economic cost of inducers, inducer toxicity, incompatibilities with industrial scale-up and detrimental growth conditions. Hence, in this study, we have attempted to engineer E. coli that is capable of auto-inducing and self-regulating its protein expressions based on the presence of the substrate, ferulic acid and its cell population density. We aimed to demonstrate that by having controlled and self-regulated expression, E. coli could have improvements on its viability and growth rate, thereby enabling a larger population for bioconversion. By having a large bio-catalytic population in the shortest time, it could possibly lead to a more efficient production of vanillin from agro-industrial wastes that contain ferulic acid. To construct the ferulic acid sensing device, we implemented the sensing mechanism of Pseudomonas spp. in E. coli. Besides the ferulic acid sensing device, we also introduced a second regulatory device that is based indirectly on cell density. By combining the ferulic acid sensing device and the indirect cell density device for regulating vanillin genes, we demonstrated a highly efficient production of vanillin in our engineered E. coli.