Improving the Acid Resistance of Tannase TanBLp (AB379685) from Lactobacillus plantarum ATCC14917T by Site-Specific Mutagenesis

Tannin acyl hydrolase referred commonly as tannase catalyzes the hydrolysis of the galloyl ester bond of tannin to release gallic acid. The tannase TanBLp which cloned from Lactobacillus plantarum ATCC14917T has high activity in the pH range (7.0–9.0) at 40 °C, it would be detrimental to the utilization at acidic environment. The catalytic sites and stability of TanBLp were analyzed using bioinformatics and site-specific mutagenesis. The results reiterated that the amino acid residues Ala164, Lys343, Glu357, Asp421 and His451 had played an important role in maintaining the activity. The optimum pH of mutants V75A, G77A, N94A, A164S and F243A were shifted from 8.0 to 6.0, and mutant V75A has the highest pH stability and activity at acidic conditions than other mutants, which was more suitable for industrial application to manufacture gallic acid. This study was of great significance to promote the industrialization and efficient utilization of tannase TanBLp.