Production and partial characterization of pectinases from forage palm by Aspergillus niger URM4645

Abstract

The activity of endo-polygalacturonase (endo-PG), exo-polygalacturonase (exo-PG), pectin lyase (PL) and pectinesterase (PE) produced by Aspergillus niger URM4645 was studied in solid-state fermentation (SSF) using forage palm as the substrate. The effect of variable substrate amount, inoculum concentration and temperature on the pectinase production was studied using a full factorial design (2³). The maximum activity obtained was 66.19 U/g for endo-PG, 3.590 U/g for exo-PG and 40,615.62 U/g for PL at 96, 24 and 72 h of fermentation, respectively. PE showed no activity. The production of endo-PG and exo-PG was significantly influenced by varying substrate amount, inoculum concentration and temperature, but these variables had no influence on PL production. The best conditions for production of the three enzymes at the same time were obtained with 10.0 g of substrate, 107 spores/g at 28°C. Endo-PG and PL presented optimum activity at pH 5.0 and exo-PG at pH 7.0. The maximal activity of endo-PG and PL was determined at 50°C and exo-PG at 40°C. Endo-PG and exo-PG were stable at a pH range of 3.5 - 11.0 and at 50 and 80°C, respectively. PL showed stability only at pH 5.0 and at 50°C.

Key words: Aspergillus niger, pectinolytic activities, forage palm, solid-state fermentation.