Overexpression of Trp-related genes in Claviceps purpurea leading to increased ergot alkaloid production

Improving Ergometrine Production by easO and easP Knockout in Claviceps paspali

Ergometrine is widely used for the treatment of excessive postpartum uterine bleeding. Claviceps paspali is a common species for industrial production of ergometrine, which is often accompanied by lysergic acid α-hydroxyethylamide (LAH) and lysergic acid amide (LAA). Currently, direct evidence on the biosynthetic mechanism of LAH and LAA from lysergic acid in C. paspali is absent, except that LAH and LAA share the common precursor with ergometrine and LAA is spontaneously transformed from LAH. A comparison of the gene clusters between C. purpurea and C. paspali showed that the latter harbored the additional easO and easP genes. Thus, the knockout of easO and easP in the species should not only improve the ergometrine production but also elucidate the function. In this study, gene knockout of C. paspali by homologous recombination yielded two mutants ∆easOhetero-1 and ∆easPhetero-34 with ergometrine titers of 1559.36 mg∙L−1 and 837.57 mg∙L−1, which were four and two times higher than that of the wild-type control, respectively. While the total titer of LAH and LAA of ∆easOhetero-1 was lower than that of the wild-type control. The Aspergillus nidulans expression system was adopted to verify the function of easO and easP. Heterologous expression in A. nidulans further demonstrated that easO, but not easP, determines the formation of LAA.

Enhancement of Emodin Production by Medium Optimization and KH2PO4 Supplementation in Submerged Fermentation of Marine-Derived Aspergillus favipes HN4-13

Emodin is a widely distributed anthraquinone derivative with a variety of biological activities, one that can be efficiently produced by marine-derived fungus Aspergillus favipes HN4-13. However, its relatively low fermentation yield limits further development and pharmaceutical research work. In this study, Plaekett-Burman design and central composite design were adopted to optimize the fermentation conditions of A. favipes HN4-13. Optimal fermentation conditions in a 250-mL Erlenmeyer flask with 50 mL of medium were 59.3 g/L soluble starch, 10 g/L yeast extract paste, 30 g/L seawater salt, 1.04 g/L KH₂PO₄, 0.05 g/L MgSO₄·7H₂O, 0.01 g/L FeSO₄·7H₂O, seed culture 24 h, pH 5, inoculum size 18%, culture temperature 32 °C, and shaking at 160 rpm/min for 7 days. The production of emodin could achieve 132.40 ± 3.09 mg/L, with no significant difference from the predicted value (132.47 mg/L). Furthermore, KH₂PO₄ supplementation strategy was employed to regulate the mycelial morphology, upregulate the transcriptional level of biosynthesis gene cluster, and enhance emodin production (185.56 ± 4.39 mg/L).