Process Intensification Of Fermentation Coupling With Foam Separation

Applications of fermentation coupling with foam separation technology show great advantages in many natural biosurfactants fermentation. There is a relatively large body of literature relevant to exploring its applicability into different products. However, only a few reports focus on process improvement, i.e. cells overflowing with foam and large amounts of foam due to aeration in the culture stage of coupling fermentation.Aiming at the above prob lems, fermentation coupling with foam separation technology was improved. As a result, the cells overflowing was avoid. Detrimental foam in culture stage was suppressed while favorable foam in separation stage was regenerated.At first, the conditions of coupling fermentation(pH, column height, air flow rate) were optimized. Cells were recycled through internal reflux. This strategy was characterized by enrichment, recovery percentage, and inactivity percentage for product and cells. The optimal condition for fermentation coupling with foam separation was determined(pH 5.5, column height 75 cm, air flow rate 100 mL/min, and temperature 30°C). The maximum total titer of polymyxin E reached 917932.31 U(1147.4 U/mL) using coupling strategy that was 1.36 times more than total titer in shaken- flask culture. Additionally, the adsorption mechanism for polymyxin E and cells was studied. The results indicated polymyxin E were mainly adsorbed on bubble, while the cells were partly in liquid, and partly adsorbed on undesired protein. Undesired protein can be considered as a stabilizer in foam separation of polymyxin E.Secondly, a novel method for foam mitigation and regeneration by adding nature oil as antifoaming agents was proposed. The optimal air flow rate for polymyxin E fermentation without the interference of detrimental foam was studied. The optimal types of natural oil and production process was determined. The maximum total titer of polymyxin E reached 1169054.26 U(1461.3 U/mL) using coupling strategy that was 1.74 times more than total titer in shaken-flask culture when the process that culture stage 100 mL/min, separation stage 300 mL/min was adopted.