Preliminary studies on the biosynthesis of microbial inulinase by Aspergillus niger ICCF 92

Modern diets are high in fructans, which may lead to abdominal discomfort, particularly in sensitive individuals. Microbial inulinase, an enzyme that hydrolyzes inulin into fructose and fructo-oligosaccharides (FOS), has significant prebiotic potential and may contribute to the prevention of metabolic disorders by enhancing fructan digestion.

This study investigates inulinase production by the Aspergillus niger ICCF 92 strain under various growth conditions. Three carbon sources (inulin, molasses, and carob pod decoction), the time required for biosynthesis processes, and stirring speed were evaluated for their influence on inulinase activity.

For inoculum development, the microorganism was grown in liquid malt extract medium for 5 days at 30 °C. Fermentations were conducted in 500 mL Erlenmeyer flasks with 100 mL of medium, under both static and stirring (220 rpm) conditions. Nitrogen sources included yeast extract, ammonium nitrate, and ammonium phosphate. Process monitoring included pH measurement, protein quantification via the Bradford assay, and inulinase activity assessment using the 3,5-dinitrosalicylic acid method.

The optimal inulinase production (38.29 U/mL) and protein concentration (0.7548 mg/mL) were achieved after 14 days of static fermentation with carob pod decoction as the carbon source.

These findings highlight the potential of A. niger ICCF 92 as a viable producer of inulinase and its possible application in mitigating metabolic and nutritional disorders through improved dietary fructan processing.