Structural characteristics and biological activity of lactic acid bacteria exopolysaccharides separated by ethanol/(NH4)2SO4 ATPS

Fractionation of Extracellular Polymeric Substances by Aqueous Three-Phase Partitioning Systems

“…Hence, EPS-PN yields benefit from salt concentrations high enough to maintain a relatively low water content in the ethanol-rich/top phase. Compared to the literature, a similar observation, regarding water content in the phase and the relative concentration of phase-forming compounds, has been reported by Jiang et al for the fractionation of EPS obtained by single microbial culture. The authors found that as (NH 4 ) 2 SO 4 concentration exceeded 18 wt %, the ability of the salt to capture water molecules was stronger than that of ethanol, resulting in a higher partition of EPS to the salt-rich phase.…”

“…Compared to the literature, the commonly reported TPP system (composed of butanol and sulfate salt) also shows precipitation of proteins at the interface. 73 In addition, Jiang et al 48 also reported that the polysaccharide fraction of the real EPS mixture obtained from lactic acid bacteria mostly partitioned to the salt-rich phase (yield at 75%) in an ethanol-based TPP system. It should be noted that, compared to commonly reported TPP systems (such as the ones based on ammonium sulfate and butanol), 73 using ethanol as the phase-forming compound is more beneficial as it is recognized as a less toxic solvent 74 and because of its lower boiling point, which reduces the energy demand in potential recycling processes involving evaporation.…”

“…43,44 The fractionation of EPS using ATPS offers several advantages over the conventional fractionation methods developed for analytical purposes, such as biocompatibility, use of greener chemicals, and easier scaling-up. 45 The effectiveness of ATPS for the fractionation of biopolymer, from a variety of sources, has been confirmed by studies using ionic liquid-, 34,41,46 polymer-, 35,47 and alcohol- 48,49 based ATPS. For instance, Kee et al 50 used a polymer-salt ATPS (PEG 1000/(NH 4 ) 2 SO 4 ) to recover keratinase (microbial exoenzyme) from its culture broth, and 78% of protein partitioned to the PEG-rich phase.…”

“…Aqueous two-phase systems (ATPS) represent a potential and scalable technique for the fractionation of EPS. , ATPS consist of a type of liquid–liquid extraction highly suitable for biomolecules since both coexisting phases are mostly composed of water. − The biphasic system is formed by mixing two water-soluble compounds that are incompatible together in solution above a certain concentration. − ATPS can be formed by combining a variety of compounds, such as ionic liquid, polymer, and alcohol, along with (in)­organic salts. , The fractionation of EPS using ATPS offers several advantages over the conventional fractionation methods developed for analytical purposes, such as biocompatibility, use of greener chemicals, and easier scaling-up . The effectiveness of ATPS for the fractionation of biopolymer, from a variety of sources, has been confirmed by studies using ionic liquid-, ,, polymer-, , and alcohol- , based ATPS. For instance, Kee et al used a polymer-salt ATPS (PEG 1000/(NH 4 ) 2 SO 4 ) to recover keratinase (microbial exoenzyme) from its culture broth, and 78% of protein partitioned to the PEG-rich phase.…”