Research on Conditions of Solid-State Fermentation and Characters of Tannase by Aspergillus Niger B0201 with Gallnut

Abstract

Study is on the solid-state fermentation of tannase with the Gallnut by Aspergillus niger B-0201.The experiments involved in the process and conditions of solid-state fermentation and factors influencing characters of tannase. The results indicated that the unpasteurized method before fermentation was in favor of the higher enzymic activity than the sterilized method. With the unpasteurized method, the tannase activity got the best level(51.2U/gds) ,when 5.0g of culture medium containing the 1g of Gallnut powder, 4g of the bran powder, 1% (w/w) of (NH4)2SO4, 0.1%(w/w) of NaCl, 0.1%(w/w) of MgSO4·7H2O, 8ml of water, 1.6:1 of the solid-to-liquid ratio and 1ml（1×108spores per milliliter）of inoculum size to a 250 ml conical flask was incubated at 30°C, initial pH6.0 for 96 hours. At the same time, the conditions of fermentation were further optimized using the Response Surface Design(RSM). The tannase activity got at 56.2U/gds with the .Gallnut(17%,w/w) and the solid-to-liquid ratio(1.5：1) in the medium under 32°C. The optimum temperature and pH of tannase was respectively 40°C and 5.0. Fe3+，Cu2+，Fe2+, Ba2+，Mn2+，Ca2+，Al3+were the inhibitor of tannase at 2.0mM concentration. The optimum concentration of propylgallate as the substrate catalyzed by Tannase was 1mM. The value of Kmwas 0.514mM and Vmaxwas 71.8μmol·(L·min)-1.