Optimization of the n-propanol concentration and feedback control strategy with electronic nose in erythromycin fermentation processes

N-propanol is an important precursor in industrial antibiotic erythromycin fermentation by Saccharopolyspora erythraea. However, the online control of n-propanol concentration is a challenging problem, and hardly any effective methods have been applied in the fermentation process. In this study, an innovative method developed for on-line detection and feedback control of n-propanol concentration in erythromycin fermentation process with electronic nose. The models for n-propanol detection based on the response of the electronic nose were established, and the on-line monitoring feedback system for n-propanol concentration controlling strategy was applied in erythromycin fermentation. The effects of different residual n-propanol concentration in fermentation broth on physiological metabolism of S. erythraea were investigated in a 50-L bioreactor. The results revealed that maintaining an n-propanol concentration of 1000 ± 38 ppm, detected by electronic nose, resulted in the highest erythromycin yield (8500 U/mL). In conclusion, real-time detection and feedback control of n-propanol concentration using electronic nose is an effective method for erythromycin fermentation processes and a new precursor adding optimization process was developed.