Systematic engineering for high-yield production of viridiflorol and amorphadiene in auxotrophic Escherichia coli.

Isoprenoids, widely used as pharmaceuticals, flavors and nutraceuticals, represent one of the largest groups of natural products. Yet the low availability of top-quality (enantiopure) products and high cost limit the wide application of many valuable terpenoids. An example being viridiflorol, currently used in cosmetics and personal care products, may have other unexplored applications (e.g. as insect repellents; anti-inflammatory supplements). Here, we systematically optimized an auxotrophic Escherichia coli to produce viridiflorol with transcription, translation, enzyme and strain engineering. The best strain achieved 25.7 g/L and a yield of 0.22 g-viridiflorol/g-glucose in 2.5 days. Statistical analysis revealed the correlation between viridiflorol yields with the transcriptional levels and translation initiation rates, which enabled better understanding of the isoprenoid pathway and guiding future strain optimization. As a proof-of-concept example, we applied the knowledge to amorphadiene, anti-malaria drug artemisinin precursor, achieved 30 g/L. Hence, this study paved the way for commercialization of microbial terpenoid production.