Bacteriocin partitioning from a clarified fermentation broth of Lactobacillus plantamm ST16Pa in aqueous two-phase systems with sodium sulfate and choline-based salts as additives

摘要

The partitioning of bacteriocin, a promising alternative to chemical preservatives, in a novel inexpensive and stable aqueous two-phase system (ATPS) comprising poly(ethylene glycol) (PEG) and sodium polyacrylate (NaPA) was studied. The ATPS was generated by mixing both polymers with Na2SO4 or choline chloride ([Ch]Cl) and a bacteriocin extract from the fermented broth of Lactobacillus plantarum ST16Pa. Bacteriocin showed stability at different pH values (3.0-8.0) and temperatures (50-80 degrees C), as well as in the presence of ATPS components. Hydrophobic and electrostatic interactions were found to be the major driving forces for bacteriocin partitioning. The peptide partitioned preferentially to the PEG-rich phase (partition coefficient, K-Bact 1). However, the highest partition coefficient was achieved in the polymeric-based ATPS using [Ch]Cl as additive, as follows: 8 wt% PEG 10,000 g/mol/8 wt% NaPA 8,000 g/mol/0.5 M [Ch]Cl, resulting in a K-Bact equal to 32. Moreover, these conditions promoted high selectivity (S = 62.7), since the greater part of total proteins partitioned into the NaPA-rich phase (K-prot = 0.51). In conclusion, ATPS composed of PEG/NaPA using choline-based salts as additive can be considered mainly as a first step for bacteriocin extraction from fermented broth by applying low polymer content and mild conditions.