HPLC based characterization of citric acid produced from indigenous fungal strain through single and Co-Culture fermentation

Agro-based waste materials are primarily composed of complex polysaccharides that strengthen microbial growth to produce industrially relevant value-added products. Therefore, in the present study, solid state fermentation (SSF) was carried out using peanut shell, orange peel and mixture of both with 50:50 ratio as support for SSF to enhance citric acid production from single and co-culture consortia of Rhizopus stolonifera and Aspergillus niger. During initial trial, it was observed that growth media supplemented with orange peel under solid state fermentation (SSF) process of co-culture consortia revealed high yield (1593 μg/mL) of citric acid. On partial optimization of co-culture showed the maximum citric acid yields (7651 μg/mL) in the presence of orange peel base medium at 50% moisture content, 30 °C temperature, 5.5 pH and 25 g substrate concentration after 48th hours of solid-state fermentation. This amount of citric acid produced in the culture was estimated through reversed-phase High Performance Liquid Chromatography (HPLC) technique. Recent research activity revealed that a suitable addition of fermentative substrate to the solid-state fermentation media increased fungal growth, sugar utilization and citric acid production when used in lower concentration. [Display omitted] Statement of Novelty: The present study indicated that production of citric acid by co-culturing of Rhizopus stolonifera and Aspergillus niger using orange peel as a substrate which had enough polysaccharides that were efficient, safe, renewable inexpensive and abundantly available carbon and energy source for micro-organism. Analysis profile showed that the maximum production of citric acid was obtained using 25 g orange peel with 50% moisture content inoculated with 6 mL of inoculums, incubated for 48 h at pH 5.5 and temperature 30 °C. Citric acid production through solid state fermentation provided a key opportunity for achieving tremendous benefits of biomass utilization. Currently, two significant points of organic acid production technologies were reaction conditions and the production cost of the related system. In conclusion, the present research findings will be supportive in the improvement of low-cost system for hyper-production of citric acid for industrial application.