Engineering of Multiple Modules to Improve Amorphadiene Production in Bacillus subtilis Using CRISPR-Cas9

Engineering strategies to improve terpenoids production in Bacillus subtilis mainly focus on 2C-methyl-D-erythritol-4-phosphate (MEP) pathway overexpression. To systematically engineer the chassis strain for higher amorphadiene (precursor of artemisinin) production, a clustered regularly interspaced short palindromic repeat-Cas9 (CRISPR-Cas9) system was established in B. subtilis to facilitate precise and efficient genome editing. Then, this system was employed to engineer three more modules to improve amorphadiene production, including the terpene synthase module, the branch pathway module, and the central metabolic pathway module. Finally, our combination of all of the useful strategies within one strain significantly increased extracellular amorphadiene production from 81 to 116 mg/L after 48 h flask fermentation without medium optimization. For the first time, we attenuated the FPP-derived competing pathway to improve amorphadiene biosynthesis and investigated how the TCA cycle affects amorphadiene production in B. subtilis. Overall, this study provides a universal strategy for further increasing terpenoids' production in B. subtilis by comprehensive and systematic metabolic engineering.

Automated summary

This study focused on improving terpenoids production in Bacillus subtilis by establishing a CRISPR-Cas9 system for precise genome editing, which led to increased amorphadiene production. By modifying three modules related to terpene synthase, branch pathway, and central metabolic pathway, extracellular amorphadiene production was significantly enhanced without medium optimization. This research provides a universal strategy for enhancing terpenoids production in B. subtilis through comprehensive and systematic metabolic engineering.