Comparative studies on pectinases obtained from Aspergillus fumigatus and Aspergillus niger in submerged fermentation system using pectin extracted from mango, orange and pineapple peels as carbon sources.

Abstract

Pectinase was produced from Aspergillus species (A. fumigatus, and A. niger) in a submerged fermentation system after 4 and 5 days of fermentation, respectively using pectin extracted from different agro-wastes (mango, orange and pineapple peels) as the carbon sources. The pectin was extracted from mango, orange and pineapplepeels with extractionyields of 17%, 15.5% and 8.33%, respectively. The specific activitiesof the crude pectinases using mango, orange and pineapplepectin extract were found to be 11.20U/mg, 52.9U/mg and 11.14U/mg protein, respectively. The specific activities of precipitated and dialyzed pectinase from A. fumigates were found to be 11.78U/mg and 34.60U/mg, respectively, while that for the enzyme from A. niger using orange and pineapple pectin extract were found to be 33.56U/mg, 92.08U/mg, and 17.26U/mg, 49.42U/mg protein, respectively. The optimum pH for pectinase from A. Fumigates (mango) and A. niger (orange) were found to be 5.5 and 5, respectively with common optimum temperature of 40˚C while pectinase from A. niger (pineapple) had optimum activity at 55˚C, pH 5.5. The maximum velocity, V_max and Michealis constant, K_m obtained from Line weaver-Burk plots of initial velocity data at different concentrations of pectin were found to be625µmol/min and 45.5mg/ml for pectinase from A. fumigatus, 200 µmol/min and 18mg/ml for pectinase from A. niger on orange pectin and 5000µmol/min and 89.5mg/ml for pectinase from A. niger using pineapple pectin, respectively. The result suggests that peels of mango, orange and pineapple can be used for value added synthesis of pectinase, an important enzyme in fruit juice clarification. 

Keywords: Agro-wastes, pectinase, pectin, Aspergillus fumigatus, Aspergillus niger, submerged fermentation, partial purification and characterization