Enhanced Citric Acid Production in Aspergillus niger Through D-Glucose Tolerance.

Abstract

This thesis focuses on optimizing citric acid production using Aspergillus niger, a fungus widely employed in industrial fermentation for its high efficiency and adaptability. Citric acid is a key compound in food, pharmaceutical, and cosmetic industries, primarily produced through microbial fermentation. The study investigates the impact of varying glucose concentrations on citric acid yield and fungal morphology. Experiments in manganese-free media showed that moderate glucose levels (180–260 g/L) supported optimal fungal growth with dense pellet formation and efficient citric acid production. Higher glucose levels (300 g/L and above) caused osmotic stress, leading to fragmented pellets and slower production rates. By analyzing glucose consumption and citric acid synthesis through high-performance liquid chromatography (HPLC), the research highlights the importance of controlling fermentation parameters like glucose levels, pH, temperature, and aeration. These insights contribute to developing sustainable, scalable, and cost-effective industrial processes, solidifying A. niger as a cornerstone organism in biotechnology.