Journal of Bioscience and Bioengineering, Vol.123, No.6, 665-672, 2017
Identification of an acidic endo-polygalacturonase from Penicillium oxalicum CZ1028 and its broad use in major tropical and subtropical fruit juices production
Endo-polygalacturonases play an important role on depectinization in fruit juices industry. A putative endo-polygalacturonase gene PoxaEnPG2SA was cloned from Penicillium oxalicum CZ1028. PoxaEnPG28A consisted of a putative signal peptide and a catalytic domain belonging to glycoside hydrolase family 28, and it shared 72% identity with that of a functionally characterized endo-polygalacturonase from Trichoderma harzianum. Gene PoxaEnPG2SA was successfully expressed in Pichia pastoris with a high yield of 1828.7 U/mL. The purified recombinant enzyme PoxaEnPG28A hydrolyzed polygalacturonic acid in endo-manner releasing oligo-galacturonates. PoxaEnPG28A showed maximal activity at pH 5.5 and 55 degrees C, and was stable between pH 3.0 to 10.0 and below 45 degrees C. The kinetic constants Km and V-max of PoxaEnPG28A were calculated as 1.57 g/L, and 14,641.29 U/mg, respectively. PoxaEnPG28A significantly improved the yields of fruit juices from banana, plantain, papaya, pitaya and mango. The high production level of the recombinant enzyme PoxaEnPG28A by P. pastoris and remarkable catalytic activity of PoxaEnPG28A toward five kinds of fruit juices made the enzyme a potential application in agriculture and food industries. (C) 2017, The Society for Biotechnology, Japan. All rights reserved.
Keywords:Pectin;Endo-polygalacturonase;Penicillium oxalicum;Gene expression;Enzymatic characterization;Fruit juice