Enhanced production of sabinene by engineered Saccharomyces cerevisiae from corn hydrolysates

Sabinene is a type of monoterpene that is widely used in flavors, fragrances and pharmaceuticals. Though sabinene biosynthesis has been investigated in a variety of microorganisms, application of sabinene is still limited due to its high production cost and lesser yielding strains. The baker's yeast Saccharomyces cerevisiae, which is generally recognized as safe (GRAS), is a suitable cell factory for the food and beverage industries. In this study, we aimed to enhance the production of sabinene from corn hydrolysates by employing genetic engineering techniques on S. cerevisiae. Here, we engineered S. cerevisiae for the production of sabinene by overexpressing sabinene synthase (SabS) and geranyl diphosphate synthase (GPPS) via CRISPR-Cas9, which is a simple and efficient tool for targeted and marker-free genome engineering. Subsequently, the culture medium and process conditions were optimized to enhance sabinene production and achieve ~ 23.6 mg/L under flask fermentation conditions. Based on the optimized culture conditions, we further investigated the production of sabinene from corn hydrolysates, which is a major source of dietary nutrients worldwide and an inexpensive source of sugars, and a high-level production of 60.0 mg/L was achieved in shake-flask fermentation. Our results implied that corn hydrolysates was a suitable medium for sabinene production and that CRISPR-Cas9 could boost the marker-free engineered yeast strain, which was more suitable for the food and beverage industry. Altogether, our work represents the progress in the bioproduction of food-grade sabinene from an inexpensive raw material.