Evaluation and optimization of food-grade tannin acyl hydrolase production by a probiotic Lactobacillus plantarum strain in submerged and solid state fermentation

Tannin acyl hydrolase (tannase) production by Lactobacillus plantarum MTCC1407 was studied in submerged and solid-state fermentation process. Sequential optimization strategy using Plackett-Burman screening and response surface methodology was adopted to optimize the submerged fermentation process. Eight medium components were evaluated initially by Plackett-Burman two level factorial designs to identify the most significant parameters that affect the tannase production. The significant variables affecting tannase production were found to be tannic acid, glucose and MnSO ₄·7H ₂O. These factors were further optimized by response surface methodology. Maximum tannase activity of 9.13 U ml ^-1 was observed at 30 h using the following medium composition (g l ^-1): tannic acid, 13.16; glucose, 1.5; NH ₄Cl, 1.0; CaCl ₂·2H ₂O, 1.0; K ₂HPO ₄, 0.5; KH ₂PO ₄, 0.5; MgSO4·7H ₂O, 0.5 and MnSO ₄·7H ₂O, 0.03. Among the various carbon sources examined for tannase production by L. plantarum, glucose and tannic acid combination was found to be decisive for enhancing tannase yield. Solid state fermentation was conducted using various solid substrates and agricultural residues. Maximum tannase activity of 5.319 U gds ^-1 was obtained using coffee husk as substrate.