Enhancing catalytic stability and cadaverine tolerance by whole-cell immobilization and the addition of cell protectant during cadaverine production

Abstract

A whole-cell (cadaverine-producing strain, Escherichia coli AST3) immobilization method was developed for improving catalytic activity and cadaverine tolerance during cadaverine production. Cell-immobilized beads were prepared by polyvinyl alcohol (PVA) and sodium alginate (SA) based on their advantages in biocatalyst activity recovery and mechanical strength. The following optimal immobilization conditions were established using response surface methodology: 3.62% SA, 4.71% PVA, 4.21% CaCl, calcification, 12 h, and freezing for 16 h at - 80 °C, with a cell concentration of 0.3% (g dry cell weight (DCW) per 100 mL) of immobilized beads. After a 2-h bioconversion, the immobilized beads maintained 85% of their original biocatalyst activity, which was 1.8-fold higher than that of free cells. Furthermore, the effects of cell protectants on immobilized biocatalyst activity were examined by fed-batch bioconversion experiments. The results showed that the addition of polyvinylpyrrolidone (PVP) into the immobilized matrix effectively protected biocatalyst activity, with 95% of the relative activity remaining after the 2-h bioconversion. The performance of PVA-SA-PVP-immobilized E. coli AST3 showed continuous production of cadaverine, with an average cadaverine yield of 29 ± 1 g gDCW h after 12 h, suggesting that this method is capable of industrial scale cadaverine production.

Synthetic engineering of Corynebacterium crenatum to selectively produce acetoin or 2,3-butanediol by one step bioconversion method

“…Therefore, the site-specific mutagenesis of butanol dehydrogenase ( butA ) gene might be further improved the AC and 2,3-BD yield and selectivity in C. creantum . In addition, although the repeated batch biocatalysis showed a high average productivity for AC and 2,3-BD production, the catalytic efficiency significantly deceased after only two batches, which can be further improved by cell immobilization to increase the cell viability and stability [44, 45]. On the other hand, process engineering, including buffer optimization, substrate concentration optimization, multiple biocatalysis strategies, and high cell density et al, can further improve AC and 2,3-BD production for commercial development.…”

Green chemical and biological synthesis of cadaverine: recent development and challenges

“…It was reported that E. coli AST3 can be entrapped and immobilized successfully in a mixture of 3.62% sodium alginate and 4.71% polyvinyl alcohol by dripping into 4.21% CaCl 2 . 99 The results showed that the activity of the cells was reduced by the high concentration of cadaverine. Then the cell protectant polyvinylpyrrolidone (PVP) was found to improve the stability of the immobilized cells in 2 h (1.8-fold higher than the free cells).…”

“…In the reactor, the PVA-SA-PVP-immobilized E. coli AST3 could produce 146 g L −1 cadaverine with an over 98% molar conversion yield of l -lysine. 99 The immobilization of free lysine decarboxylase could be another strategy to improve the catalytic efficiency. It is interesting to see that the CadA can be in situ immobilized by the molecular biology technology.…”

Ameliorating end-product inhibition to improve cadaverine production in engineered Escherichia coli and its application in the synthesis of bio-based diisocyanates

“…Recently, some researchers reported that the inhibitory effect of cadaverine significantly limits cadaverine production [ 16 ]. In E. coli , a high level of intracellular cadaverine was confirmed to induce closing of porins, causing inadequate cell absorption of nutrients, and reducing cell growth and metabolism [ 17 ].…”