Abstract：Coronatine (COR) is a kind of novel plant growth regulator, which is environmentally friendly and can be used to effectively control plant growth and enhance plant resistance. At present, coronatine is mainly produced by microbial fermentation, however low fermentation yield is the biggest problem that limits the application of coronatine. To improve the yield of coronatine, the method of semicontinuous fermentation using Pseudomonas syringae Z2-6 was established, and related fermentation conditions were optimized. Optimization includes the initial removal time, and removal volume. The results showed that the beginning of removal at the 10 d post inoculate (dpi) could extend the production cycle of coronatine, which extended for more than 4 d than the beginning at 8 or 9 dpi, and kept the synthesis of coronatine maintaining at a high level. Coronatine production efficiency with time interval of 1 d was higher than 2 d. When the amount of removal was not more than 30%, the growth of bacteria was not be affected. The highest coronatine yield was obtained at the amount of removal of 30%. In conclusion, when 30% of the fermentation broth was removed from 10 dpi every day and equal volume fresh medium was supplemented, the production of coronatine reached the highest level. The yield of coronatine was increased from 11.2 mg/(L·d) to 22.1 mg/(L·d), and the production efficiency was increased by 98%. This method of semicontinuous fermentation could be used to improve the production efficiency of coronatine, reduce the production cost, and provide support for the further popularization of coronatine.
