Rational Enzyme Modification and Expression Enhancement Strategies for 1,8-cineole Production in Serratia marcescens...

Area of Science:

• Biotechnology
• Metabolic Engineering
• Synthetic Biology

Background:

• 1,8-cineole is a valuable monoterpenoid used in flavors, pharmaceuticals, and biofuels.
• Biosynthesis in model organisms like E. coli and S. cerevisiae is hindered by terpenoid cytotoxicity and low enzyme efficiency.

Purpose of the Study:

• To develop an efficient 1,8-cineole biosynthetic system using a non-model microorganism.
• To overcome the limitations of cytotoxicity and low enzyme activity in microbial terpene production.

Main Methods:

• Utilized Serratia marcescens HBQA7, a non-model bacterium with high terpene tolerance, as a microbial chassis.
• Performed heterologous expression and screening of six 1,8-cineole synthase genes, followed by enzyme engineering and tag fusion.
• Optimized fermentation conditions through shake flask and fed-batch bioreactor processes.

Main Results:

• Identified SoCinS from Salvia officinalis as the most active 1,8-cineole synthase.
• Achieved a 1,8-cineole titer of 2.1 g/L in shake flask fermentation within 72 hours.
• Reached a final 1,8-cineole titer of 10.2 g/L in a 5-L bioreactor via fed-batch fermentation.

Conclusions:

• Serratia marcescens serves as a robust chassis for efficient terpenoid biosynthesis.
• Non-model microorganisms offer significant advantages over traditional model systems for industrial natural product production.
• This study demonstrates a promising strategy for the scalable biosynthesis of 1,8-cineole.