De novo biosynthesis of sex pheromone components of Helicoverpa armigera through an artificial pathway in yeast

Abstract

The cotton bollworm, Helicoverpa armigera, causes severe damage to the yields of cotton and other crops. (Z)-11-Hexadecenal (Z11–16 : Ald) and (Z)-9-hexadecenal (Z9–16 : Ald), as the main components of H. armigera sex pheromones, have been used as attractants, which is widely considered one of the environmentally friendly approaches for pest control. To achieve a more sustainable and economical synthesis of Z11–16 : Ald and Z9–16 : Ald, here we present artificial biosynthetic pathways for these two compounds to demonstrate the artificial de novo synthesis from glucose by engineered yeasts. First, a Saccharomyces cerevisiae strain with increased titers of free fatty acids was designed and constructed by knocking out several genes. Then de novo production of (Z)-11-hexadecenoic acid was achieved by functional screening and introduction of several lepidopteran Δ11 fatty-acyl desaturases (FADs) into the strain. A further engineered yeast strain equipped with FAD from H. armigera combined with downregulation of the native yeast OLE1 gene produced 47.4 mg L⁻¹ (Z)-11-hexadecenoic acid and 87.6 mg L⁻¹cis-9 isomer. A derivative strain capable of producing Z11–16 : Ald and Z9–16 : Ald was subsequently constructed by introduction of a heterologous carboxylic acid reductase (CAR). Through fed-batch fermentation, its production of Z11–16 : Ald and Z9–16 : Ald could reach 22.7 mg L⁻¹ and 45.9 mg L⁻¹, respectively. Finally, biological effectiveness assays demonstrated that the sex pheromone components purified from the fermentation liquid of the engineered yeast and even the raw extracts without purification exhibited similar biological activity to commercial standards. Our work achieved de novo biosynthesis of aldehyde components of H. armigera sex pheromone in a yeast cell factory, which makes it feasible to produce these sex pheromone components on a large scale with low costs, and thus facilitate the application of aldehyde pheromones for pest management.