The degradation of gibberellic acid (GA3) by the strain Aspergillus niger TJ-1 was studied. Plackett-Burman Design was used to screen important factors affecting its degradation, and response surface analysis was applied to optimize its degradation condition. The properties of GA3 degradation by the strain were also investigated. The results showed that Aspergillus niger TJ-1 could degrade GA3. Incubation temperature and the concentrations of ammonium sulfate and magnesium sulfatein the system are the major factors influencing GA3 degradation. The degradation rate of GA3 is up to 56.90% under the optimized condition, which is close to the predictive value from response surface model (57.64%). A regular change of GA3 contents, biomass and pH in the system with incubation time was observed.
