Integrated Strain, Bioprocess, and Polymerization Development for Production of a Bio-Based 4-Hydroxyphenylacetic Acid Polymer

High Resolution Image Download MS PowerPoint Slide Bio-based polymer building blocks can offer new molecular functionalities with lower environmental impact, but new production processes and purification affect purity and therefore polymerizability. This study explores a complete process chain for microbial 4-hydroxyphenylacetic acid (4HPAA) production from glucose using Pseudomonas taiwanensis . Multiple biosynthetic pathways were engineered, enabling efficient 4HPAA production with a yield of up to 25% (Cmol Cmol –1 ). The process was optimized in shake flasks to enhance the productivity and scaled up to 30 and 1500 L stirred tank bioreactors, where product titers of 11 g L –1 were achieved in a fed-batch process. Downstream processing enabled kilogram-scale purification of 4HPAA but, more importantly, provided valuable insights into the effects of purification on subsequent polymerization of the monomer. The effects of strain engineering, scale-up, and purification on the purity of 4HPAA were assessed. Multiple 4HPAA samples from different downstream processing stages were polymerized and compared regarding the molecular weights and color of the resulting polymers. The use of bio-based 4HPAA with purities of ≥95% produced polymers comparable to a high-purity commercial 4HPAA. Overall, this study demonstrates the importance of an integrated approach of strain development, up- and downstream process engineering, and polymer science to enable sustainable production of bio-based monomers.