Controlling the Formation of Foams in Broth to Promote the Co-Production of Microbial Oil and Exopolysaccharide in Fed-Batch Fermentation

Abstract

A large amount of foam is generated in the production of microbial oil and exopolysaccharide (EPS) by Sporidiobolus pararoseus JD-2, which causes low efficiency in fermentation. In this study, we aimed to reduce the negative effects of foams on the co-production of oil and EPS by controlling the formation of foams in broth. As we have found, the formation of foams is positively associated with cell growth state, air entrapment, and properties of broth. The efficient foam-control method of adding 0.03% (v/v) of the emulsified polyoxyethylene polyoxypropylene pentaerythritol ether (PPE) and feeding corn steep liquor (CSL) at 8–24 h with speed of 0.02 L/h considerably improved the fermentation performance of S. pararoseus JD-2, and significantly increased the oil and EPS concentrations by 8.7% and 12.9%, respectively. The biomass, oil, and EPS concentrations were further increased using a foam backflow device combined with adding 0.03% (v/v) of the emulsified PPE and feeding CSL at 8–24 h, which reached to 62.3 ± 1.8 g/L, 31.2 ± 0.8 g/L, and 10.9 ± 0.4 g/L, respectively. The effective strategy for controlling the formation of foams in fermentation broth reported here could be used as a technical reference for producing frothing products in fed-batch fermentation.

Glycolipid Biosurfactants in Skincare Applications: Challenges and Recommendations for Future Exploitation

“…However, excessive foaming during the sophorolipid fermentation process resulting from culture aeration and agitation can cause a significant loss of products. Additionally, fermentation culture heterogenicity caused by the formation of a highly viscous second layer in cultures often reduces cellular exposure to oxygen and nutrients [40,112]. Nonetheless, the recent decade has seen the development of integrated sophorolipid production and separation techniques composed of foam fractioning, membrane, and gravity separation, which are capable of improving the recovery of sophorolipids after fermentation, even at an industrial scale [24,40].…”

Thermal and ultrasound foam control in biotechnology: a mini-review

“…Additionally, it has been reported by Zaky et al that in biofuel production, foam formation can be controlled using seawater [27,28]. Although these methods of preventing foam have achieved positive results, there is still a need to optimize resource use (e.g., energy, chemicals) without compromising on foam control in industrial fermentation processes resulting in, i.e., final titer, high carbon yield, and productivity [29]. Here, thermal methods and ultrasound foam destruction, two unconventional physical defoaming procedures, are reviewed.…”