Semi-solid state fermentation: A promising method for production and optimization of tannase from bacillus gottheilii M2S2

Tannase is an important enzyme which finds commercial applications in food industry to reduce the level of tannins in fruit juices, preparation of instantaneous tea and production of gallic acid. Various low cost tannin rich residues such as coffee husk, tamarind seed powder, tea leaves and Triphala powder were studied in semi-solid state fermentation process. Triphala was found to be a prominent substrate which has exhibited maximum tannase activity of 29 ± 0.35 U/L. Thereafter, sequential statistical approach was used to optimize tannase production with Triphala in shake flask. The classical one-variable-at-a-time approach determined moistening media, tannic acid and inoculum volume which significantly influenced the tannase production. A central composite design showed that the optimal values of these factors were 6.2 mL, 1% (w/v) and 6.4 mL respectively. Subsequently, a 7-fold increase in corresponding tannase yield (106 ± 0.61 U/L) was obtained, compared with that produced in the submerged fermentation. The crude tannase showed optimum activity at 40°C and pH 4.0. Vmax and Km values were 1.404 μmol/ml.min and 1.24 mM respectively.