Efficient strategy for enhancing aspergiolide A production by citrate feedings and its effects on sexual development and growth of marine-derived fungus Aspergillus glaucus

Aspergiolide A production enhancement by citrate and its effects on growth and sexual development of marine-derived fungus Aspergillus glaucus HB1-19 were investigated. In agar plate culture, 15 mM citric acid decreased colony radial growth and aspergiolide A production by 31.5% and 23.0%, respectively. It also improved sexual cleistothecium formation by 360% but depressed asexual conidiospore generation by 84.8%. In submerged culture, adding 40 mM citric acid finally promoted aspergiolide A production by 80.0%, which accompanied with 16.7% increase of biomass and 10.0% enhancement of sugar utilization. Differently, sodium citrate made no obvious or even opposite effects. Citrate and low pH could significantly improve pyruvate accumulation but inhibit succinate and fumarate production. Moreover, low pH was favorable to citrate utilization. Organic acids changes were closely related to aspergiolide A biosynthesis. Comparing to pH controls, effects of citric acid comprised pH decrease solicitation and citrate utilization enhancement.