Synthesis of propyl gallate by mycelium-bound tannase from Aspergillus niger in organic solvent.

摘要

Aspergillus niger with mycelium-bound tannase (EC 3.1.1.20) activity was employed to investigate the synthesis of the antioxidant propyl gallate from gallic acid and 1-propanol in organic solvents. Effects of various organic solvents (log P from -1.0 to 6.6) on the enzymic reactions showed that benzene (log P of 2.0) was the most suitable solvent. The water content and protonation state of the mycelium-bound enzyme both had significant effects on the activity of tannase. The max. molar conversion (65%) was achieved with 7.3% (v/v) 1-propanol and 5.56mM gallic acid at stirring speeds of 200 rpm and a temp of 40 degrees C in presence of anhydrous sodium sulfate and PEG-10 000. Enzyme specificity for the alcohol portion (C1-C8) of the ester showed that the optimum synthesis occurred with alcohols of C3-C5.