Study on the process of fermentation coupling with foam fractionation and membrane module for nisin production

Abstract

Nisin, an antimicrobial peptide, is commercially used as a food preservative and a promising alternative in medical applications for inhibiting bacterial infection in both humans and livestock. It is produced by fermentation using certain strains of Lactococcus lactis ssp. lactis. In traditional fermentation, the yield of nisin has always been limited by adsorption of nisin onto its producer, enzymatic degradation and product inhibition. This limitation can be solved by fast removal of the product from the broth during fermentation. In the current work, a technology of fermentation coupling with foam fractionation and membrane module was developed to achieve in situ removal of nisin produced by L. lactis ssp. lactis ATCC 11454 from the broth. The effects of air flow rate, the initial aeration time and interval time on the performance of the technology were studied to increase the yield of nisin. The results showed that under the optimal conditions of air flow rate 60 mL/min, the initial aeration time of the fourth hour and regular 30-min interval, the total nisin titer reached 3946 IU/mL, increased by 24.2%, compared with the control group (3177 IU/mL). Therefore the coupling technology can effectively weaken the feedback inhibition and thus increase the yield of nisin by in situ fast removal of the product from broth during fermentation.

Surfactant‐assisted separation of ginkgo flavonoids from Ginkgo biloba leaves using leaching and foam fractionation

“…During the process of foam fractionation, the high SDS concentration in the leaching solution would result in the low foam drainage because of high viscosity and bad fluidity. Currently, changing column shape, increasing temperature and adding internal component were usually used for promoting foam drainage by increasing the fluidity of the loading solution . In this work, a column with a spherical part was used as the experimental column, and a cylindrical column was used as a control column.…”

“…Foam fractionation is a bubble adsorptive separation technology, and it has been widely used to separate a trace material with surface activity from its aqueous solution . Currently, foam fractionation has also aroused the interest of bioengineering researchers because of simple equipment, low cost and environmental compatibility . In this case, foam fractionation is continually developed to recover a non‐surface‐active material from the industrial effluents based on its specific interactions with a surfactant which is used as the collector .…”

Process improvement for fermentation coupling with foam separation: a convenient strategy for cell recycle

“…The loss of cells in FCFS was less than that in foam separation of part 1 because growth of cells offset the loss to some extent. The increase of polymyxin E was because on the one hand foam separation relieved the product inhibition; [13,33] on the other hand, the air inlet met the need of oxygen in aerobic fermentation. It cannot be ignored that FCFS technology not only increased polymyxin E total titer but also obtained two kinds of liquid-foamate and residual broth.…”

“…Heyd et al [3] reported that bacteria could be entrapped in magnetic alginate beads to prevent loss of the cell through foaming. Cui et al [13] developed a technology of fermentation coupling with foam fractionation and membrane module. However, previous studies were difficult to scale up because of complexity or being restricted to anaerobic fermentation (i.e.…”

“…However, previous studies were difficult to scale up because of complexity or being restricted to anaerobic fermentation (i.e. Cui's work [13] ). Furthermore, they all need additional power compared with traditional submerged fermentation.…”