Optimization of Pectinase Production by a Potent Fungal Isolate Obtained from Spoiled Fresh Produce

Fungal pectinases are extracellular enzymes associated with the degradation of pectic substances in plant tissues and have applications in biotechnological processing. This study assessed the pectinolytic activity of fungi isolated from spoiled fresh produce and examined the effects of assay temperature, pH and reaction time on a selected crude enzyme preparation. Five fungal groups—Aspergillus, Penicillium, Fusarium, Rhizopus and Alternaria—were screened on pectin-containing medium using hydrolysis-zone diameter. The most active isolate was subsequently identified as Aspergillus niger. Screening and quantitative assays were performed in triplicate, and differences between treatments were assessed using one-way analysis of variance and Tukey's test. Aspergillus niger produced the largest hydrolysis zone (6.35 ± 0.15 mm), exceeding those of the other four groups (p < 0.05). Its measured pectinase activity increased from 2.23 ± 0.10 U/mL at 10°C to 9.86 ± 0.25 U/mL at 40°C, before decreasing at 50°C. The highest activity in the pH experiment was 10.04 ± 0.20 U/mL at pH 7. Activity in the reaction-time experiment reached 18.74 ± 0.16 U/mL at 20 min and did not improve significantly at 25 min (p = 0.653). Overall effects of temperature, pH and reaction time were significant (p < 0.001). These findings identify assay-specific conditions associated with the highest observed crude pectinase activity within the evaluated ranges, without establishing optimum enzyme-production conditions during fungal cultivation.