Pectinolytic complex production by <i>Aspergillus niger</i> URM 4645 using yellow passion fruit peels in solid state fermentation

Abstract

The activities of endo-polygalacturonase (endo-PG), exo-polygalacturonase (exo-PG), pectin lyase (PL), and pectin methylesterase (PE), produced by Aspergillus niger URM 4645, were studied in solid state fermentation (SSF) using yellow passion fruit peels as substrate. The effect of substrate amount, initial moisture content, and temperature on pectinase production was studied using a full factorial design (2³). Maximum endo-PG, exo-PG, PL, and PE activities were 31.35, 7.98, 551,299.39, and 447.93 U g⁻¹ dry substrate, respectively. Optimum activities of the four enzymes were obtained with 5.0 g of the substrate and an initial moisture content of 30% at 34°C with 96 h of fermentation. Optimum endo-PG activity was found at pH 7.5 at an optimum temperature of 40°C; exo-PG and PL at pH 7.0 at an optimum temperature of 80°C; and PE at pH 3.5 at an optimum temperature of 30°C. Endo-PG was stable at pH 7.0 to 8.0 at 40°C, and exo-PG and PL at pH 6.0 to 8.0 and 6.0 to 7.5, respectively at 60 to 70°C. PE was stable at pH 3.5 to 5.0 at 30 to 60°C. The enzyme production optimization clearly demonstrated the impact of process parameters on the yield of pectinolytic enzymes.

 Keywords: Aspergillus niger, residue, pectinolytic activities, solid state fermentation, characterization.

African Journal of Biotechnology, Vol 13(31) 3313-3322