Biochemical study of the effect of Nephrolepis biserrata pretreatment on exo-polygalacturonase production by Aspergilllus niger in solid state fermentation

Abstract

The substrate plays an important role in solid state fermentation (SSF) in the production of exo-polygalacturonase (one type of the pectinase enzymes). The aim of this study was to investigate a pretreatment method on Nephrolepis biserrata leaves as a substrate for the production of exo-polygalacturonase. The pretreatment steps improved the decomposition of the lignocellulosic material in the structure of N. biserrata leaves as a substrate and allowed Aspergillus niger better access of the substrate to the enzymatic reaction. This optimised both exo-polygalacturonase activity and the growth of A. niger in SSF. Pretreatment was performed under alkali, acidic, autohydrolytic and control conditions. The highest exo-polygalacturonase activity was 39.16 U/g and biomass of A. niger was 0.39 mg/gdsf at 120 h was found for the autohydrolysis pretreatment, as compared to alkali pretreatment, acid pretreatment and control. Scanning electron microscope images showed a marked change in the physical appearance of treated N. biserrata leaves as compared to untreated N. biserrata leaves, especially following autohydrolysis pretreatment.