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Enzyme Research
Volume 2013 (2013), Article ID 438645, 7 pages
http://dx.doi.org/10.1155/2013/438645
Research Article

Purification and Properties of Polygalacturonase Produced by Thermophilic Fungus Thermoascus aurantiacus CBMAI-756 on Solid-State Fermentation

1Laboratório de Microbiologia, Universidade do Estado de Minas Gerais (UEMG), Avenida Prof. Mario Palmerio 1000, 38200-000 Frutal, MG, Brazil
2Faculdade de Ciências Biológicas e Ambientais (FCBA), Universidade Federal da Grande Dourados (UFGD), Rodovia Dourados-Itahum, Km 12, 79804-970 Dourados, MS, Brazil
3Laboratório de Bioquímica e Microbiologia Aplicada, Instituto de Biociências, Universidade Estadual Paulista (UNESP), Rua Cristovão Colombo 2265, Jd. Nazareth, 15054-000 São José do Rio Preto, SP, Brazil

Received 25 February 2013; Revised 9 August 2013; Accepted 11 August 2013

Academic Editor: Toshihisa Ohshima

Copyright © 2013 Eduardo da Silva Martins et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Polygalacturonases are enzymes involved in the degradation of pectic substances, being extensively used in food industries, textile processing, degumming of plant rough fibres, and treatment of pectic wastewaters. Polygalacturonase (PG) production by thermophilic fungus Thermoascus aurantiacus on solid-state fermentation was carried out in culture media containing sugar cane bagasse and orange bagasse in proportions of 30% and 70% (w/w) at 45°C for 4 days. PG obtained was purified by gel filtration and ion-exchange chromatography. The highest activity was found between pH 4.5 and 5.5, and the enzyme preserved more than 80% of its activity at pH values between 5.0 and 6.5. At pH values between 3.0 and 4.5, PG retained about 73% of the original activity, whereas at pH 10.0 it remained around 44%. The optimum temperature was 60–65°C. The enzyme was completely stable when incubated for 1 hour at 50°C. At 55°C and 60°C, the activity decreased 55% and 90%, respectively. The apparent molecular weight was 29.3 kDa, of 1.58 mg/mL and of 1553.1 μmol/min/mg. The presence of Zn+2, Mn+2, and Hg+2 inhibited 59%, 77%, and 100% of enzyme activity, respectively. The hydrolysis product suggests that polygalacturonase was shown to be an endo/exoenzyme.