Partitioning of biomolecules in aqueous two-phase systems of polyethylene glycol and nonionic surfactant

Advances in Separation and Purification of Bioactive Polysaccharides through High-speed Counter-Current Chromatography

Polysaccharides, with an extensive distribution in natural products, represent a group of natural bioactive substances having widespread applications in health-care food products and as biomaterials. Devising an efficient system for the separation and purification of polysaccharides from natural sources, hence, is of utmost importance in the widespread applicability and feasibility of research for the development of polysaccharide-based products. High-speed counter-current chromatography (HSCCC) is a continuous liquid-liquid partitioning chromatography with the ability to support a high loading amount and crude material treatment. Due to its flexible two-phase solvent system, HSCCC has been successfully used in the separation of many natural products. Based on HSCCC unique advantages over general column chromatography and its enhanced superiority in this regard when coupled to aqueous two-phase system (ATPS), this review summarizes the separation and purification of various bioactive polysaccharides through HSCCC and its coupling to ATPS as an aid in future research in this direction.

Efficiency of Ionic Liquids-Based Aqueous Two-phase Electrophoresis for Partition of Cytochrome c

Cytochrome c is a small water-soluble protein that is abundantly found in the mitochondrial intermembrane space of microorganism, plants and mammalians. Ionic liquids (ILs)-based aqueous two-phase electrophoresis system (ATPES) was introduced in this study to investigate the partition efficiency of cytochrome c to facilitate subsequent development of two-phase electrophoresis for the separation of cytochrome c from microbial fermentation. The 1-Hexyl-3-methylimidazolium bromide, (C₆mim)Br and potassium citrate salt were selected as the phase-forming components. Effects of phase composition; position of electrodes; pH and addition of neutral salt on the partition efficiency of cytochrome c in the ATPES were evaluated. Highest partition coefficient (K = 179.12 ± 0.82) and yield of cytochrome c in top phase (Y_T = 99.63% ± 0.00) were recorded with IL/salt ATPES composed of 30% (w/w) (C₆mim)Br and 20% (w/w) potassium citrate salt of pH 7 and 3.0% (w/w) NaCl addition with anode at the bottom phase and cathode at the top phase. The SDS-PAGE profile revealed that cytochrome c with a molecular weight of 12 kDa was preferably partitioned to the IL-rich top phase. Present findings suggested that the single-step ATPES is a potential separation approach for the recovery of cytochrome c from microbial fermentation. Graphical Abstract.

Extractive Fermentation for Process integration and amplified pullulan production by A. pullulans in Aqueous Two Phase Systems

Extractive fermentation technique or in situ product recovery process is a novel technique to segregate the desired product simultaneously in a fermentation process. For economic and high yield production of pullulan, Extractive fermentation process was applied fermentation process of A. pullulans. Aqueous Two Phase system (ATPS) systems were designed with various molecular mass of PEG (400, 600, 4000 and 6000) and dextran or mono/bi-sodium phosphate salts. Systems with short Tie Line length (TLL) 6.7 and 7.5% w/w for PEG-Salt and PEG-dextran respectively were chosen. Volume ratio for all the systems was kept constant at 1.0 and pH 7.0 for PEG-dextran and PEG-NaH2PO4 was maintained, whereas pH 9.0 was kept for PEG-Na2HPO4. A. pullulans, was found to be viable with PEG-NaH2PO4 and PEG-dextran systems. The biomass partitioned in the PEG rich top phase and the exopolysaccharide pullulan shown affinity towards the bottom phase. A maximum yield (36.47 g/L) was found with PEG 4000-Dextran 500 system of extractive fermentation process. The proposed process aptly integrates upstream and downstream process for continuous production and recovery of pullulan from the biomass, thus reducing the time quotient of the whole process.

Development of aqueous two-phase systems comprising poly ethylene glycol and dextran for purification of pullulan: Phase diagrams and fiscal analysis

Pullulan is a commercially important Exopolysaccharide (EPS) with wide-spread applications which is produced by Aureobasidium pullulans. The alternative α (1 4) & α (1 6) configuration in pullulan provides it the specific structural and conformational properties. Pullulan is currently being exploited in food, health care, pharmacy, lithography, cosmetics. The fermented broth is processed by organic solvent precipitation for isolation and purification of pullulan. In this study, we have tried to analyze the potential of aqueous two phase system as an alternate technique to extract pullulan from fermented broth. Including this viability of ATPS was also compared with conventional organic solvent precipitation system in terms of cost and time. It was found that ATPS process produced a higher yield of pullulan (80.56%) than organic solvent precipitation method (71.6%). ATPS was also found more economical and less time consuming method.

A multiplexed microfluidic toolbox for the rapid optimization of affinity-driven partition in aqueous two phase systems

Antibodies and other protein products such as interferons and cytokines are biopharmaceuticals of critical importance which, in order to be safely administered, have to be thoroughly purified in a cost effective and efficient manner. The use of aqueous two-phase extraction (ATPE) is a viable option for this purification, but these systems are difficult to model and optimization procedures require lengthy and expensive screening processes. Here, a methodology for the rapid screening of antibody extraction conditions using a microfluidic channel-based toolbox is presented. A first microfluidic structure allows a simple negative-pressure driven rapid screening of up to 8 extraction conditions simultaneously, using less than 20μL of each phase-forming solution per experiment, while a second microfluidic structure allows the integration of multi-step extraction protocols based on the results obtained with the first device. In this paper, this microfluidic toolbox was used to demonstrate the potential of LYTAG fusion proteins used as affinity tags to optimize the partitioning of antibodies in ATPE processes, where a maximum partition coefficient (K) of 9.2 in a PEG 3350/phosphate system was obtained for the antibody extraction in the presence of the LYTAG-Z dual ligand. This represents an increase of approx. 3.7 fold when compared with the same conditions without the affinity molecule (K=2.5). Overall, this miniaturized and versatile approach allowed the rapid optimization of molecule partition followed by a proof-of-concept demonstration of an integrated back extraction procedure, both of which are critical procedures towards obtaining high purity biopharmaceuticals using ATPE.

Partitioning of cerrena unicolor laccase activity in an aqueous two-phase system

Culture supernatant containing laccase produced by Cerrena unicolor strain was used to examine laccase partitioning between phases in an aqueous two-phase system. The investigated system consisted of polyethylene glycol 3000 and sodium phosphate buffer adjusted to pH = 7. Influence of several parameters on partitioning was measured, including phase forming components’ concentrations, tie line lengths, phase volume ratio, supernatant dilution, process temperature and halogen salt supplementation. Partitioning coefficients up to 78 in the bottom phase were achieved with yields of over 90%. Tie line length and phase volume ratio had significant effect on enzyme partitioning.

Surfactant-Amino Acid and Surfactant-Surfactant Interactions in Aqueous Medium: a Review

An overview of surfactant-amino acid interactions mainly in aqueous medium has been discussed. Main emphasis has been on the solution thermodynamics and solute-solvent interactions. Almost all available data on the topic has been presented in a lucid and simple way. Conventional surfactants have been discussed as amphiphiles forming micelles and amino acids as additives and their effect on the various physicochemical properties of these conventional surfactants. Surfactant-surfactant interactions in aqueous medium, various mixed surfactant models, are also highlighted to assess their interactions in aqueous medium. Finally, their applied part has been taken into consideration to interpret their possible uses.