Engineering industrial fungus Aspergillus oryzae for the sustainable biosynthesis of ergot alkaloids

Abstract

Ergot alkaloids (EAs) are a class of indole derivatives used as prescription drugs for the treatment of neurological diseases. Due to the limited production of EAs by Claviceps and the enantioselective difficulties encountered in chemical synthesis, a sustainable supply of EAs remains challenging. Recently, numerous attempts have been made to produce EAs using heterologous hosts. However, these efforts have only resulted in the production of the precursor, lysergic acid (LA), with low efficiency. Here, we report the de novo high-efficient biosynthesis of LA and a series of LA-derived EAs in Aspergillus oryzae cell factories. Based on genome sequencing of the EA-producing strain, C. purpurea 22.07, an EA biosynthetic gene cluster was annotated and characterized. After introducing and optimizing the agroclavine (AG) biosynthetic pathway in A. oryzae, we constructed an efficient chassis strain for AG production. We then confirmed the function of the annotated CloA′ to catalyze the successive oxidation of AG into LA and isolysergic acid (ILA) in this AG-producing chassis and realize their de novo production with titers of 52.68 ± 1.49 and 6.32 ± 2.08 mg L⁻¹, respectively. The subsequent introduction of the downstream non-ribosomal peptide synthetase genes LpsB′ and LpsC′ enabled the complete biosynthesis of ergometrine and a series of its analogs, achieving a total titer of more than 160 mg L⁻¹. The unexpected biosynthesis of isolysergyl-glycine and lysergyl-glycine revealed a novel function of LpsC′, which utilizes glycine as a substrate. Our work successfully realized the complete biosynthesis of a series of EAs in an industrially feasible fungus, which will open new avenues for manufacturing EAs in a green and sustainable manner.