Purification and characterization of pectinase produced by Aspergillus niger LFP-1 using citrus waste as substrate via solid substrate fermentation




*Taufiq, M. M. J. and Darah, I.

Industrial Biotechnology Research Laboratory (IBRL), School of Biological Sciences, Universiti Sains Malaysia, 11800, Penang, Malaysia. *Corresponding author: fiqz04@yahoo.com.sg

Abstract

Pectinase is one of the valuable enzymes in industry especially in fruit juices and beverages, paper making and textile industries. Therefore, the present study was emphasized on the pectinase production by local fungal isolate, A. niger LFP-1 using citrus wastes, pamelo peels as a sole carbon source under solid substrate fermentation. The purification and characterization of crude pectinase were done in order to purify pectinase and to know the physiochemical characteristics of the purified enzyme. The purification process started with the concentration of crude enzyme using ammonium sulphate precipitation and followed by purification using anion exchange column chromatography (DEAE-sephadex) and subsequently using gel filtration column chromatography (Sephadex G-100) until a single band of protein was obtained. The molecular weight of purified pectinase was determined using SDS-PAGE method and the results revealed that the molecular weight of the purified pectinase was 48 kDa. Under purification process, the crude enzyme was purified about 75.89 folds with specific activity of 61.54 U/mg and the final yield obtained was 0.01%. The purified pectinase had optimum temperature of 50oC and it was stable at temperature ranges from 40oC to 50oC upon characterization process. Moreover, it has optimum pH at pH 3.5 and its pH stability was in the range of pH 3.5 to pH 4.5. Meanwhile, pectin from citrus fruit was observed as the best substrate for purified pectinase and other substrate such as mandarin peels, pamelo peels, xylan from oat spelt, oat and starch from potato were assumed as potential pectin substrate. In addition, metal ion (Co2+) was observed as a good inducer to enhance pectinase yield.

Key words: Pectinase, solid substrate fermentation, A. niger LFP-1, purification, characterization

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