Background: Various process intensifications are proposed to improve process efficiency, quality, and safety of fermented products. With the market significantly growing, the production process of L-leucine needs significant improvements to increased productivity and yield. Ultrasound, a process intensification, is an emerging and fast-growing technology due to its wide range of applications in food science and fermentation industry.
Results: By optimizing the time points and parameters of ultrasound, the biomass of Corynebacterium glutamicum CP was significantly improved. The response surface methodology was adopted to create prediction profiler model and optimize sonication conditions. C. glutamicum CP fermentation at conditions of ultrasonic power of 94 W/L, frequency of 25 kHz, interval of 31 min, and duration of 37 s produced 52.89 g/L of L-leucine in 44 h, increased by 21.6% compared with the control. The production performance of L-leucine was also improved under ultrasonic treatment. Moreover, the cell morphology of C. glutamicum CP were more irregular, elongated, and swollen cells under the ultrasonic condition. The cell permeability of C. glutamicum CP and the activity of key enzymes with ultrasonic treatment were significantly higher than the control.
Conclusions: We successfully obtain the optimum ultrasonic conditions to produce L-leucine in fed-batch culture. The results indicate that ultrasonication is an efficient intensification process for enhancing fermentation to produce L-leucine from C. glutamicum CP.