title: Microencapsulated mycelium-bound tannase from Aspergillus niger: an efficient catalyst for esterification of propyl gallate in organic solvents.
abstract: Microencapsulated Aspergillus niger with mycelium-bound tannase activity was employed to investigate the esterification of propyl gallate from gallic acid and propanol in organic solvents. The effects of various organic solvents (log P: -1.0 to 6.6) on the enzymatic reactions showed that benzene (log P: 2.0) was the suitable solvent, for which the conversion reached 26.8%. The optimum catalyst concentration and water concentration was found at 25 capsules in 10 mL of benzene and 0.04 g of water/capsule. The external mass transfer effect could be eliminated at stirring speeds of 180 rpm or higher. Both substrates 1-propanol and gallic acid had significant inhibition effects on the tannase activity. Maximum molar conversion (36.2%) was achieved with 9.1% (v/v) 1-propanol and 8 mM gallic acid and decreased with increasing amounts of substrates.
authors.affiliation: Zhejiang University, College of Life Science, Yuquan Campus, Hangzhou 310027, P.R. China.
authors.forename: Xiao-Wei
authors.initials: XW
authors.lastname: Yu
authors.forename: Yong-Quan
authors.initials: YQ
authors.lastname: Li
mesh_terms: D000433:1-Propanol / Q000378:metabolism; D001234:Aspergillus niger / Q000201:enzymology*; D002265:Carboxylic Ester Hydrolases / Q000378:metabolism*; D004339:Drug Compounding; D004951:Esterification; D005656:Fungal Proteins / Q000378:metabolism*; D005707:Gallic Acid / Q000378:metabolism; D015394:Molecular Structure; D025282:Mycelium / Q000378:metabolism*; D011435:Propyl Gallate / Q000737:chemistry / Q000378:metabolism*; D012997:Solvents / Q000737:chemistry*; D014867:Water / Q000737:chemistry
chemical_list: D005656:Fungal Proteins; D012997:Solvents; D014867:Water; D005707:Gallic Acid; D011435:Propyl Gallate; D000433:1-Propanol; D002265:Carboxylic Ester Hydrolases; C022711:tannase