Aqueous two-phase system (ATPS): an overview and advances in its applications

Integration of Aqueous Two-Phase Extraction as Cell Harvest and Capture Operation in the Manufacturing Process of Monoclonal Antibodies

Substantial improvements have been made to cell culturing processes (e.g., higher product titer) in recent years by raising cell densities and optimizing cultivation time. However, this has been accompanied by an increase in product-related impurities and therefore greater challenges in subsequent clarification and capture operations. Considering the paradigm shift towards the design of continuously operating dedicated plants at smaller scales—with or without disposable technology—for treating smaller patient populations due to new indications or personalized medicine approaches, the rising need for new, innovative strategies for both clarification and capture technology becomes evident. Aqueous two-phase extraction (ATPE) is now considered to be a feasible unit operation, e.g., for the capture of monoclonal antibodies or recombinant proteins. However, most of the published work so far investigates the applicability of ATPE in antibody-manufacturing processes at the lab-scale and for the most part, only during the capture step. This work shows the integration of ATPE as a combined harvest and capture step into a downstream process. Additionally, a model is applied that allows early prediction of settler dimensions with high prediction accuracy. Finally, a reliable process development concept, which guides through the necessary steps, starting from the definition of the separation task to the final stages of integration and scale-up, is presented.

Extractive Fermentation of Lactic Acid in Lactic Acid Bacteria Cultivation: A Review

Lactic acid bacteria are industrially important microorganisms recognized for their fermentative ability mostly in their probiotic benefits as well as lactic acid production for various applications. Nevertheless, lactic acid fermentation often suffers end-product inhibition which decreases the cell growth rate. The inhibition of lactic acid is due to the solubility of the undissociated lactic acid within the cytoplasmic membrane and insolubility of dissociated lactate, which causes acidification of cytoplasm and failure of proton motive forces. This phenomenon influences the transmembrane pH gradient and decreases the amount of energy available for cell growth. In general, the restriction imposed by lactic acid on its fermentation can be avoided by extractive fermentation techniques, which can also be exploited for product recovery.

Continuous laccase concentration in an aqueous two-phase system

An approach to describe continuous partitioning of Cerrena unicolor laccase in a PEG 6000—phosphate aqueous two-phase system was proposed. The laccase was separated from crude supernatant of C. unicolor-submerged culture, and all the experiments were carried out in 25 °C and pH 7 conditions. Masses of both phases and their compositions at phase equilibrium, as well as laccase activity concentrations at different mixing points, were measured in batch experiments. An empirical short-cut method was developed which allows for calculation of mass and volume fractions of the phases, laccase concentration factors, and laccase recoveries. Theoretical predictions were verified by several experiments carried out in a special mixer-settler unit with automatic substrate feed and continuous collection of separated phases. Required concentration of the laccase was possible to achieve in a one-step extraction process in the mixer-settler unit. The predictions of the short-cut method were compared to the results of experimental measurements of phase compositions, phase volume fractions, concentration factors and enzymatic yields at steady-state operation of the extraction unit. The values of experimental results lay well within the 10% error range of the predicted values.

Proteins recovery from wet microalgae using liquid biphasic flotation (LBF)

In this work, the extraction of microalgal protein from wet Chlorella sorokiniana species using alcohol/salt liquid biphasic flotation (LBF) with the aid of ultrasonication for cell rupturing was proposed. The effect of varying crude feedstock concentration, flotation time, salt type, salt concentration, alcohol type, alcohol concentration, initial volumes of salt and alcohol were investigated. After the optimization process, the highest proportion of protein recovered in the top phase was achieved with 250g/L ammonium sulphate, 60% (v/v) 2-propanol, 1.0V_R,initial, 20g/L crude biomass load, 4mm³/min air flowrate and 10min of flotation time. The recycling of phase components was introduced to minimize the use of alcohol and salt in the corresponding LBF. It was demonstrated that top phase (alcohol) recycling can achieve increasing performance for three consecutive recycling runs. Under optimized process conditions, the proportion of protein recovered in the top phase was 88.86% for the third recycle run.

A biorefinery for Nannochloropsis: Induction, harvesting, and extraction of EPA-rich oil and high-value protein

Microalgae have been studied as biofactories for almost four decades. Yet, even until today, many aspects of microalgae farming and processing are still considered exploratory because of the uniqueness of each microalgal species. Thus, it is important to develop the entire process of microalgae farming: from culturing to harvesting, and down to extracting the desired high-value products. Based on its rapid growth and high oil productivities, Nannochloropsis sp. is of particular interest to many industries for the production of high-value oil containing omega-3 fatty acids, specifically eicosapentaenoic acid (EPA), but also several other products. This review compares the various techniques for induction, harvesting, and extraction of EPA-rich oil and high-value protein explored by academia and industry to develop a multi-product Nannochloropsis biorefinery. Knowledge gaps and opportunities are discussed for culturing and inducing fatty acid biosynthesis, biomass harvesting, and extracting EPA-rich oil and high-value protein from the biomass of Nannochloropsis sp.

All-Aqueous Assemblies via Interfacial Complexation: Toward Artificial Cell and Microniche Development

In nature, the environment surrounding biomolecules and living cells can dictate their structure, function, and properties. Confinement is a key means to define and regulate such environments. For example, the confinement of appropriate constituents in compartments facilitates the assembly, dynamics, and function of biochemical machineries as well as subcellular organelles. Membraneless organelles, in particular, are thought to form via thermodynamic cues defined within the interior space of cells. On larger length scales, the confinement of living cells dictates cellular function for both mammalian and bacterial cells. One promising class of artificial structures that can recapitulate these multiscale confinement effects is based on aqueous two-phase systems (ATPSs). This feature article highlights recent developments in the production and stabilization of ATPS-droplet-based systems, with a focus on interfacial complexation. These systems enable structure formation, modulation, and triggered (dis)assembly, thereby allowing structures to be tailored to fit the desired function and designed for particular confinement studies. Open issues for both synthetic cells and niche studies are identified.

Ionic Liquid-Liquid Chromatography: A New General Purpose Separation Methodology

Ionic liquids can form biphasic solvent systems with many organic solvents and water, and these solvent systems can be used in liquid-liquid separations and countercurrent chromatography. The wide range of ionic liquids that can by synthesised, with specifically tailored properties, represents a new philosophy for the separation of organic, inorganic and bio-based materials. A customised countercurrent chromatograph has been designed and constructed specifically to allow the more viscous character of ionic liquid-based solvent systems to be used in a wide variety of separations (including transition metal salts, arenes, alkenes, alkanes, bio-oils and sugars).

Recent Advances and Challenges towards Sustainable Polyhydroxyalkanoate (PHA) Production

Sustainable biofuels, biomaterials, and fine chemicals production is a critical matter that research teams around the globe are focusing on nowadays. Polyhydroxyalkanoates represent one of the biomaterials of the future due to their physicochemical properties, biodegradability, and biocompatibility. Designing efficient and economic bioprocesses, combined with the respective social and environmental benefits, has brought together scientists from different backgrounds highlighting the multidisciplinary character of such a venture. In the current review, challenges and opportunities regarding polyhydroxyalkanoate production are presented and discussed, covering key steps of their overall production process by applying pure and mixed culture biotechnology, from raw bioprocess development to downstream processing.

Tuning interfacial complexation in aqueous two phase systems with polyelectrolytes and nanoparticles for compound all water emulsion bodies (AWE-somes)

Compound AWE-somes with tunable shells generated by aqueous interfacial complexation of a polycation with a polyanion and anionic nanoparticle mixture.

Microcapsules with a permeable hydrogel shell and an aqueous core continuously produced in a 3D microdevice by all-aqueous microfluidics

We report the continuous production of microcapsules composed of an aqueous core and permeable hydrogel shell, made stable by the controlled photo-cross-linking of the shell of an all-aqueous double emulsion.

Phase separation in organic aerosol

Liquid–liquid phase separation is prevalent in aerosol particles composed of organic compounds and salts and may impact aerosol climate effects.