Assessing the succinic acid production capabilities of Corynebacterium glutamicum using industrial feedstocks

BACKGROUND

The study focuses on succinic acid production in synthetic and industrial media using wild type Corynebacterium glutamicum, a known carboxylic acid producer. The South African sugar industry is facing many challenges, largely due to increased competition and the implementation of a sugar levy, which has resulted in a decrease in demand. Sugarcane material was selected as a cheap and abundant carbon source to assess the succinic acid production capabilities of C. glutamicum.

RESULTS

Small-scale flask studies (700 mL) showed that glucose was the favorable sugar source when compared to xylose, recording a maximum value of 18.87 ± 1.27 g L⁻¹ succinic acid. Evaluation of the industrial small-scale flask studies concluded that molasses was the top-performing sugarcane material in comparison to the sugarcane juice, reaching a succinic acid concentration of 20.31 ± 0.75 g L⁻¹. The productivities achieved in the small-scale studies when using molasses was 0.56 g L⁻¹ h⁻¹, which was less than that recorded for the glucose-based media, at 0.67 g L⁻¹ h⁻¹, which was an expected outcome due to the complexity of the molasses. These studies were then successfully scaled up to 30 L biostat reactors, where the fermentations were run to mimic the micro-aerobic conditions experienced in the flasks but in a more controlled environment.

CONCLUSION

The highest concentration of produced succinic acid was obtained when using molasses as the carbon source, reaching a maximum of 28.89 ± 0.10 g L⁻¹. The study recognizes the potential for the South African sugar industry to diversify its product offerings through the adoption of biochemical production. © 2025 Society of Chemical Industry (SCI).