Production of pectinases by Aspergillus niger in solid state fermentation at high initial glucose concentrations

Area of Science:

• Biotechnology
• Enzymology
• Microbial Fermentation

Background:

• Pectinases are crucial enzymes with diverse industrial applications.
• Aspergillus niger is a key microorganism for enzyme production.
• Solid-state fermentation (SSF) offers advantages for microbial enzyme production.

Purpose of the Study:

• To investigate the effect of initial glucose concentration on exopectinase (exo-p) and endopectinase (endo-p) production by Aspergillus niger CH4 in SSF.
• To determine the optimal glucose concentration for maximal pectinase yield.
• To elucidate the reasons behind reduced pectinase production at high glucose levels.

Main Methods:

• Solid-state fermentation of Aspergillus niger CH4 using varying initial glucose concentrations (100, 250, 350, 450 g/l).
• Assay of exopectinase and endopectinase activities at different time points.
• Monitoring of pH changes in the fermentation medium.

Main Results:

• Optimal exo-p production (35 U/g) occurred at 72h (100 g/l glucose) and 120h (250 g/l glucose).
• Maximum endo-p activity (9 U/g) was achieved at 72h with 250 g/l glucose.
• Pectinase production significantly decreased at 350 and 450 g/l glucose, primarily due to a drastic pH drop.

Conclusions:

• Initial glucose concentration critically influences pectinase production by Aspergillus niger CH4 in SSF.
• Low pH, rather than enzyme synthesis repression or glucose consumption rate, is the limiting factor for pectinase yield at high glucose concentrations.
• Optimizing glucose levels and controlling pH are essential for enhancing pectinase production in industrial applications.