High production of jasmonic acid by Lasiodiplodia iranensis using solid‐state fermentation: Optimization and understanding

Jasmonic acid (JA) is a plant hormone involved in regulating developmental and growth controls as well as photosynthesis. In addition, this hormone protects the plant against insects and has good applications in agriculture, the flavored industry and other fields. Filamentous fungus generally produces JA using liquid static culture. In the present study, a solid-state fermentation (SSF) method is developed for high production of JA using Lasiodiplodia iranensis.By selecting the solid substrate and optimizing the initial water content, inoculum volume, loading volume and other culture conditions, the maximum JA yield reached 5306.38 mg kg-1 when fermented for 12 days in a petri dish containing a medium with crushed wheat as the solid substrate and 75% initial water content. The logistic and Luedeking-Piret models were used to characterize the relationship between microbial growth and product synthesis in the SSF process, and the maximum JA production is predicted to be 5263.23 mg kg-1 , which is close to the experimental value. Liquid chromatography with tandem mass spectrometry (LC-MS/MS) is used to examine the metabolic changes that develop during fermentation. The results indicate that JA biosynthesis occurs in the α-linolenic acid metabolic pathway, of which 13(S)-HpOTrE is a key intermediate metabolite and both 13(S)-HOTrE and traumatic acid are byproducts of the branches of its synthesis.The results of this study provide a method for obtaining high JA yields by SSF, and offer new insights for understanding the production of JA by fungal fermentation.