Endopolygalacturonase and pectinesterase from Aspergillus Niger

Abstract

Endo-polymethylgalacturonase (endo-PMG) EC 3.2.1.41 was produced by submerged fermentation using a local Aspergillus niger strain's Aspergillus niger spores (1xl05 spores/ml medium) as inoculum. The only carbon source present in the fermentation medium was commercial citrus pectin. The enzyme was partially purified by precipitation with 20% ammonium sulphate, followed by chromatography in Sephadex G-75 and DEAE Sephadex A-50 columns. Pectinesterase yield was low in those fermentation conditions used. Fermentation crude extract presented two pH values (endo-PMG optimum pH 4.5 and 6.3). The enzymes were stable at pH values between 2.0 and 10.0. Optimum temperature was in the 40°C-45°C range. Enzymes became totally inactive at 70°C. It was also found that sodium ion concentrations greater than 0.1M inhibited endo-PMG.

Keywords

• Pectinasas
• poligalacturonasa polimetilgalacturonasa
• enzimas pectolíticas
• enzimas pécticas
• Aspergillus niger