Isolation and screening of pectinase-producing Aspergillus niger and use ofwhey in optimizing enzyme production

Background and Objective: Pectinase is a pectinolytic enzyme that can break down pectin in plant cellwalls, which is a polysaccharide substrate. In addition, pectinase is considered one of the most importantindustrial enzymes in the world, which can be isolated from a wide range of microorganisms such asbacteria and fungi. Therefore, considering the importance and many uses of this enzyme in foodprocessing, agriculture, and industry, the purpose of this research is to investigate a method for isolatingand screening pectinase-producing fungi from all kinds of rotten fruits and vegetables, as well asoptimizing its further production.methods: In this research, first, isolation and identification of fungi producing pectinase enzyme fromrotten fruits (peach, plum, and apple) and vegetables (onion) were done. Then, methods such ascultivation on specific media containing pectin, staining with lactophenol cotton blue, and slide culturemethod were used to identify and screen the most capable fungal strains producing pectinase enzyme.Also, in order to identify the isolated fungi more accurately, the molecular technique of ۱۸S rRNAsequencing was also used. In order to optimize the production rate of the pectinase enzyme, together withpectin substrate, Permit cheese juice was used as one of the ingredients of the basic culture medium underdifferent temperatures and pH, and the activity of this enzyme was also measured by the standard DNSmethod.Results: The results showed that after identifying and screening the fungi in rotten fruits and vegetables,only one Aspergillus niger fungus-producing pectinase enzyme was isolated from the onion. Theinvestigation of production optimization conditions also shows that the identified strain, in the presence ofpermeate cheese juice (as a basic medium composition) along with pectin substrate and also underincubation at ۲۵ C° with ۱۴۰ rpm and pH=۶.۵, the highest It had amount of production and enzymeactivity (۱۰۳/۰۱۸ IU/ml). While, with fungus cultivation in the vicinity of pure pectin substrate andincubation at ۲۵ C° with the same shaker revolution and pH = ۷, the amount of pectinase production andenzyme activity was lower (۹۲.۷۱۷ IU/ml).Conclusion: In this research, it was shown that the Aspergillus niger strain is capable of producing morepectinase enzyme in the culture medium containing pectin substrate and permeated whey as thecomposition of the production base medium and at the optimum temperature, acidity, and shakerrevolution. Therefore, the results of this study can be a significant achievement in the field of pectinaseproduction in terms of cost-effectiveness in economic conditions.

Keywords:

Aspergillus niger , DNS method , Pectinase enzyme , Whey