Abstract: The effects of different factors on producing tannase have been studied,such as different carbon sources ,carbon source ratio,different nitrogen sources,nitrogen source ratio and initial pH value.The optimal mixture and the optimal culture conditions of liquid state fermentation to produce tannase have been obtained by making orthogonal tests.The results showed that the optimal mixture was soyabean meal (0.67%),tannin acid (1.2%) wheat flour (0.3%),NH4NO3(0.05%) ,KCl (0.05%),MgSO47H2O (0.05%),FeSO4 (0.001%),K2HPO4 (0.03%),and pH6.0.The tannin acid,the combination of soyabean meal and NH4NO3,and wheat flour have shown great effects on producing tannase.Moreover,the combination of soyabean meal and NH4NO3 has shown positive interaction with tannin acid,and the combination of soyabean meal and NH4NO3 has shown also very notable positive interaction with K2HPO4.pH6.0 of the mixture was benefit to producing tannase.The investigation on the strain’s growth and the time of producing tannase showed that the biomass,protein content and the yield of tannase reached maximum in 72 hours.Therefore,it could be concluded that the strain’s capacity to produce tannase was parallel to its growth.

Key words: Tannase Aspergillus niger Liquid State Fermentation