Pectinase production by fungal-based solid-state fermentation of selected agricultural wastes

Abstract

Agricultural waste is the residues from growing and processing raw agricultural products. They can be properly managed using fungi to produce economical materials such as pectinase enzymes that act as biological agents which are applicable in many areas. This research was aimed at producing pectinase by fungal-based solid-state fermentation of agricultural wastes. Fungi were isolated from dump sites soil using the pour plate method. These fungal isolates were inoculated into the pretreated agricultural waste, including watermelon, mango, and pineapple peels. The degradation period was 15 days on mineral salt solid media using separate flasks for each waste and fungus. They were incubated at room temperature (28°C). The pectinase was assayed using pectin and DNSA (dinitrosalicyclic acid). Fungal isolates were identified and screened for pectinase production using standard methods. The pH and temperature were optimized to study the effect on pectinase activities using standard procedures and pectinase was purified using column sephadex G-100. Molecular identifications were carried out on the isolates using 18srRNA gene primers. The fungi were identified as Aspergillus niger strain AGF3 (OM273994), Penicillium Chrysogenum strain AGF2 (OM273982) and Cladosporium tenuissimum strain AGF1 (OM273981). Aspergillus niger strain AGF3 (OM273994) produced the highest specific pectinase activities in mango waste (2400 U/mg. protein/ mL and it can be compared to what was produced by Cladosporium tenuissimum strain AGF1 (OM273981) (1590 U/mg. protein/mL). High specific pecrtinase activity was also obtained from pineapple peels (2200 U/mg. protein/mL) produced by Cladosporium tenussimum strain AGF1 (OM273981). It can be concluded in this study that Aspergillus niger strain AGF3 (OM273994) and Cladosporium tenuissimum strain AGF1 (OM273981) were the best producers of pectinase using mango and pineapple peels, while Penicillium chrysogenum strain AGF2 (OM273982) produced substantial pectinase in all the three agricultural wastes but not at higher levels.