Utilizing A Tyrosine Exporter To Facilitate 4-Hydroxystyrene Biosynthesis In An E. Coli-E. Coli Co-Culture

4-hydroxystyrene is an important commodity chemical with recognized industrial values. In this study, 4-hydroxystyrene biosynthesis was achieved using engineered E. coli. An amino acid exporter protein PhpCAT was utilized in combination with a previously developed biosensor-assisted cell selection mechanism to strengthen the biosynthesis of the pathway intermediate tyrosine. When incorporated into an E. coli-E. coli co-culture, the exporter also improved tyrosine's mass transfer between the co-culture members to facilitate the streamlined 4-hydroxystyrene bioproduction. It was shown that the resulting co-culture produced 298 mg/L 4-hydroxystyrene from 5 g/L glucose, which is 96% higher than the control co-culture without the exporter. The achieved yield of 0.06 g/g glucose, to our knowledge, is the highest among previous studies on microbial biosynthesis. Our finding demonstrates that the utilization of the exporter protein for a pathway intermediate is an effective methodology for enhancing biosynthesis performance of microbial co-cultures.