Metal-Chelate Affinity Precipitation with Thermo-Responsive Polymer for Purification of ε-Poly-l-Lysine

Abstract

ε-Poly-L-lysine (ε-PL) is a natural preservative for food processing industry. A thermo-responsive polymer, attached with Cu or Ni, was prepared for metal-chelate affinity precipitation for purification of ε-PL. The low critical solution temperatures (LCSTs) of these polymers were close to the room temperature (31.0-35.0 °C). The optimal adsorption conditions were as follows: pH 4.0, 0 mol/L NaCl, ligand density 75.00 μmol/g, and 120 min. The ligand Cu showed a stronger affinity interaction with ε-PL and the highest adsorption amount reached 251.93 mg/g polymer. The elution recovery of ε-PL could be 98.42% with 0.50 mol/L imidazole (pH = 8.0) as the eluent. The method could purify ε-PL from fermentation broth and the final product was proved as electrophoretic pure by SDS-PAGE. Moreover, these affinity polymers could be recycled after the purification of ε-PL and the recoveries were above 95.00%. Graphical Abstract Scheme for affinity precipitation of ε-PL.

Epsilon-poly-L-lysine: Recent Advances in Biomanufacturing and Applications

“…These workers subsequently developed the dipicrylamine anion (a yellow anionic dye) for precipitating polycationic ε-PL ( Katano et al, 2015 ). Metal-chelate affinity precipitation was also used to separate and purify ε-PL, which afforded electrophoretic purity with recovery as high as 98.42% ( Li et al, 2017a ). Although precipitation processes can obtain high ε-PL purification from small volumes of fermentation broth containing ε-PL, the heavy use of acetone can introduce food-safety problems in industrial production.…”

Extraction and purification of ε-poly-l-lysine from fermentation broth using an ethanol/ammonium sulfate aqueous two-phase system combined with ultrafiltration

“…12 Moreover, metal-chelate affinity precipitation was used for 3-PL purication, and this afforded 98.42% recovery with electrophoretic purity. 13 Unfortunately, these methods are only suitable for research purposes and are unsuitable for industrial application in terms of cost and food safety. Thus, it is necessary to continue to discover an efficient, high food safety and inexpensive strategy for 3-PL purication.…”

Effect of ion form of the ion-exchange resin on ε-poly-l-lysine purification from microbial fermentation broth

“…A metal-chelate affinity precipitation was used for 3-PL purication and achieved electrophoretic purity with a recovery ratio of 98.42%. 14 Although both novel methods could extract 3-PL from the fermentation broth, investigations are required before applying them in industry because of food-safety or cost-related concerns.…”