Extractive fermentation using aqueous two-phase systems for integrated production and purification of extracellular lipase derived from Burkholderia pseudomallei

Techniques for recovery and recycling of ionic liquids: A review

Due to beneficial properties like non-flammability, thermal stability, low melting point and low vapor pressure, ionic liquids (ILs) have gained great interest from engineers and researchers in the past decades to replace conventional solvents. The superior characteristics of ILs make them promising for applications in fields as wide-ranging as pharmaceuticals, foods, nanoparticles synthesis, catalysis, electrochemistry and so on. To alleviate the high cost and environmental impact of ILs, various technologies have been reported to recover and purify the used ILs, as well as recycling the ILs. The aim of this article is to overview the state-of-the-art research on the recovery and recycling technologies for ILs including membrane technology, distillation, extraction, aqueous two-phase system (ATPS) and adsorption. In addition, challenges and future perspectives on ILs recovery are discussed. This review is expected to provide valuable insights for developing effective and environmentally friendly recovery methods for ILs.

Sustainable production and preparative purification of thermostable alkaline α-amylase by Bacillus simplex (ON754233) employing natural deep eutectic solvent-based extractive fermentation

Using PEG-based deep eutectic solvents (PDES), the current study proposes extractive fermentation as a sustainable process integration for the production and purification of α-amylase from Bacillus simplex (ON754233). Glucose: PEG 400 outperformed five PDES in terms of tie lie length (58) and slope value (1.23) against sodium sulphatt. Apple cider pomace was used as a low-cost, sustainable carbon source to produce-amylase, with a maximum enzyme production of 2200.13 U/mL. PDES concentration (20% w/v), salt (12.75 w/v), and apple waste (2.75 g/mL) were all optimized using response surface methodology. When scaled upto 3 L benchtop bioreactor, extractive fermentation was proved to be better technology with maximum recovery of 92.4% with highest partition coefficient (3.59). The partially purified enzyme was further purified using a Sephadex G 100 followed by DEAE-Sephadex anion exchange chromatography with a purity fold of 33. The enzyme was found to be thermostable at the temperature (60 °C), remains alkaline (pH 8), and the activity was stimulated in the presence of Mg2+ ions. With SDS PAGE electrophoresis, the molecular weight was found to be around 140 kDa. Finally, the enzyme kinetics parameters were evaluated with observed Km (0.00396 mM) and Vmax (37.87 U/mL). Thus scaling up extractive fermentation entails increasing production capacity with improved extraction efficiency using green solvents.

Production and Recovery of Ectoine: A Review of Current State and Future Prospects

Ectoine (1,4,5,6-tetrahydro-2-methyl-4-pyrimidinecarboxylic acid) is a revolutionizing substance with vast applications in the cosmetic and food industries. Ectoine is often sourced from halobacteria. The increasing market demand for ectoine has urged the development of cost-effective and sustainable large-scale production of ectoine from microbial sources. This review describes the existing and potential microbial sources of ectoine and its derivatives, as well as microbial production and fermentation approaches for ectoine recovery. In addition, conventional methods and emerging technologies for enhanced production and recovery of ectoine from microbial fermentation with a focus on the aqueous biphasic system (ABS) are discussed. The ABS is a practically feasible approach for the integration of fermentation, cell disruption, bioconversion, and clarification of various biomolecules in a single-step operation. Nonetheless, the implementation of the ABS on an industrial-scale basis for the enhanced production and recovery of ectoine is yet to be exploited. Therefore, the feasibility of the ABS to integrate the production and direct recovery of ectoine from microbial sources is also highlighted in this review.

Application of Multiple Strategies to Improve the Production of the Potential Cancer Drug 4-Acetylantroquinonol B (4-AAQB) by the Rare Fungus Antrodia cinnamomea

4-Acetylantroquinonol B (4-AAQB) was identified in the rare fungus Antrodia cinnamomea and has been proven to be a potential therapeutic agent for cancer treatment. But the extraction of 4-AAQB from the fruit body led to a low yield and limited its further application in the pharmaceutical field. In this work, 4-AAQB production was enhanced in the submerged fermentation by the combination of exogenous additives, surfactants with the in situ extractive fermentation. 4-Methylbenzoic acid was proven to be an efficient additive for the accumulation of 4-AAQB by Antrodia cinnamomea, while 2% (w/v) Tween-80 added on the first day as surfactant and 30% (w/v) oleic acid added on the sixteenth day as extractant were the most available couples for 4-AAQB production in the in situ extractive fermentation. The combination of these multiple strategies resulted in the yield of 4-AAQB to 17.27 mg/g dry cell weight with a titer of 140 mg/L, which was the highest titer of 4-AAQB reported so far. It showed that the combination of these strategies had a significant promotion on 4-AAQB production by A. cinnamomea, which laid a good foundation for its large-scale production and also provided a viable method for the cultivation of other rare fungi.

Surfactants in biorefineries: Role, challenges & perspectives

The use of lignocellulosic biomass (LCB) as feedstock has received increasing attention as an alternative to fossil-based refineries. Initial steps such as pretreatment and enzymatic hydrolysis are essential to breakdown the complex structure of LCB to make the sugar molecules available to obtain bioproducts by fermentation. However, these steps increase the cost of the bioproduct and often reduces its competitiveness against synthetic products. Currently, the use of surfactants has shown considerable potential to enhance lignocellulosic biomass processing. This review addresses the main mechanisms and role of surfactants as key molecules in various steps of biorefinery processes, viz., increasing the removal of lignin and hemicellulose during the pretreatments, increasing enzymatic stability and enhancing the accessibility of enzymes to the polymeric fractions, and improving the downstream process during fermentation. Further, technical advances, challenges in application of surfactants, and future perspectives to augment the production of several high value-added bioproducts have been discussed.

Extractive Fermentation for Recovery of Bacteriocin-Like Inhibitory Substances Derived from Lactococcus lactis Gh1 Using PEG2000/Dextran T500 Aqueous Two-Phase System

This work aimed to optimize the parameters affecting partitioning of a bacteriocin-like inhibitory substances (BLIS) from Lactococcus lactis Gh1 in extractive fermentation using polyethylene glycol (PEG)/dextran aqueous two-phase system (ATPS). This system was developed for the simultaneous cell cultivation and downstream processing of BLIS. Results showed that the molecular weight of PEG, PEG concentration, and dextran T500 affect the partition coefficient (K), purification factor (PF), and yield of BLIS partitioning. ATPS composed of 10% (w/w) PEG2000 and 8% (w/w) dextran T500, provided the greatest conditions for the extractive BLIS production. The K (1.00 ± 0.16), PF (2.92 ± 0.37) and yield (77.24 ± 2.81%) were increased at selected orbital speed (200 rpm) and pH (pH 7). Sustainable growth of the cells in the bioreactor and repeated fermentation up to the eighth extractive batch were observed during the scale up process, ensuring a continuous production and purification of BLIS. Hence, the simplicity and effectiveness of ATPS in the purification of BLIS were proven in this study.

In situ product recovery techniques aiming to obtain biotechnological products: A glance to current knowledge

Biotechnology and bioengineering techniques have been widely used in the production of biofuels, chemicals, pharmaceuticals, and food additives, being considered a "green" form of production because they use renewable and nonpolluting energy sources. On the other hand, in the traditional processes of production, the target product obtained by biotechnological routes must undergo several stages of purification, which makes these processes more expensive. In the past few years, some works have focused on processes that integrate fermentation to the recovery and purification steps necessary to obtain the final product required. This type of process is called in situ product recovery or extractive fermentation. However, there are some differences in the concepts of the techniques used in these bioprocesses. In this way, this review sought to compile relevant content on considerations and procedures that are being used in this field, such as evaporation, liquid-liquid extraction, permeation, and adsorption techniques. Also, the objective of this review was to approach the different configurations in the recent literature of the processes employed and the main bioproducts obtained, which can be used in the food, pharmaceutical, chemical, and/or fuel additives industry. We intended to elucidate concepts of these techniques, considered very recent, but which emerge as a promising alternative for the integration of bioprocesses.

Concurrent Extraction and Purification of Gentiopicroside from Gentiana scabra Bunge Using Microwave-Assisted Ethanol-Salt Aqueous Two-Phase Systems

A potential method called microwave-assisted aqueous two-phase extraction (MA-ATPE) was developed for concurrent extraction and purification of gentiopicroside from Gentiana scabra Bunge. Formation characteristics of aqueous two-phase system (ATPS) composed of ethanol and 25 kinds of salts were investigated; K2HPO4 (w/w, 21.71%) and ethanol (w/w, 40.72%) were determined to be the optimal compositions of ATPS. Response surface methodology based on Box–Behnken design was used to investigate the extraction conditions, the optimal parameters were summarized as follows: 80°C of extraction temperature, 31 s of extraction time, 11:1 (mL/g) of liquid-to-solid ratio, 100 meshes of particle size and 806 W of microwave power. Under these conditions, the extraction yield of gentiopicroside was 65.32 ± 0.24 mg/g with a recovery of 96.51%. Compared with other four methods, the purity of gentiopicroside in the crude extracts reached 17.16 ± 0.25%, which was significantly higher than that of smashing tissue extraction, microwave assisted-extraction, ultrasonic-assisted extraction and heat reflux extraction, respectively. In addition, the phase-forming salt can be recyclable. Therefore, MA-ATPE was an excellent and alternative technique to the conventional extraction approaches of gentiopicroside.

Application of thermo-separating aqueous two-phase system in extractive bioconversion of polyhydroxyalkanoates by Cupriavidus necator H16

Polyhydroxyalkanoates (PHAs), a family of biodegradable and renewable biopolymers show a huge potential as an alternative to conventional plastics. Extractive bioconversion (in situ product recovery) is a technique that integrates upstream fermentation and downstream purification. In this study, extractive bioconversion of PHAs from Cupriavidus necator H16 was performed via a thermo-separating aqueous two-phase system to reduce the cost and environmental impacts of PHAs production. Key operating parameters, such as polymer concentration, temperature, and pH, were optimized. The strategy achieved a yield and PF of 97.6% and 1.36-fold, respectively at 5% EOPO 3900 concentration, 30 °C fermentation temperature and pH 6. The PHAs production process was also successfully scaled up in a 2 L bioreactor. To the best of our knowledge, this is the first report on extractive fermentation of PHAs from Cupriavidus necator utilizing a thermo-separation system to achieve a better productivity and purity of the target product.

Aqueous Two-Phase Systems at Large Scale: Challenges and Opportunities

Aqueous two-phase systems (ATPS) have proved to be an efficient and integrative operation to enhance recovery of industrially relevant bioproducts. After ATPS discovery, a variety of works have been published regarding their scaling from 10 to 1000 L. Although ATPS have achieved high recovery and purity yields, there is still a gap between their bench-scale use and potential industrial applications. In this context, this review paper critically analyzes ATPS scale-up strategies to enhance the potential industrial adoption. In particular, large-scale operation considerations, different phase separation procedures, the available optimization techniques (univariate, response surface methodology, and genetic algorithms) to maximize recovery and purity and economic modeling to predict large-scale costs, are discussed. ATPS intensification to increase the amount of sample to process at each system, developing recycling strategies and creating highly efficient predictive models, are still areas of great significance that can be further exploited with the use of high-throughput techniques. Moreover, the development of novel ATPS can maximize their specificity increasing the possibilities for the future industry adoption of ATPS. This review work attempts to present the areas of opportunity to increase ATPS attractiveness at industrial levels.

Integration process of fermentation and liquid biphasic flotation for lipase separation from Burkholderia cepacia

Liquid Biphasic Flotation (LBF) is an advanced recovery method that has been effectively applied for biomolecules extraction. The objective of this investigation is to incorporate the fermentation and extraction process of lipase from Burkholderia cepacia using flotation system. Initial study was conducted to compare the performance of bacteria growth and lipase production using flotation and shaker system. From the results obtained, bacteria shows quicker growth and high lipase yield via flotation system. Integration process for lipase separation was investigated and the result showed high efficiency reaching 92.29% and yield of 95.73%. Upscaling of the flotation system exhibited consistent result with the lab-scale which are 89.53% efficiency and 93.82% yield. The combination of upstream and downstream processes in a single system enables the acceleration of product formation, improves the product yield and facilitates downstream processing. This integration system demonstrated its potential for biomolecules fermentation and separation that possibly open new opportunities for industrial production.

Synchronized separation, concentration and determination of trace sulfadiazine and sulfamethazine in food and environment by using polyoxyethylene lauryl ether-salt aqueous two-phase system coupled to high-performance liquid chromatography

Polyoxyethylene lauryl ether (POELE10)-Na2C4H4O6 aqueous two-phase extraction system (ATPES) is a novel and green pretreatment technique to trace samples. ATPES coupled with high-performance liquid chromatography (HPLC) is used to analyze synchronously sulfadiazine (SDZ) and sulfamethazine (SMT) in animal by-products (i.e., egg and milk) and environmental water sample. It was found that the extraction efficiency (E%) and the enrichment factor (F) of SDZ and SMT were influenced by the types of salts, the concentration of salt, the concentration of POELE10 and the temperature. The orthogonal experimental design (OED) was adopted in the multi-factor experiment to determine the optimized conditions. The final optimal condition was as following: the concentration of POELE10 is 0.027gmL(-1), the concentration of Na2C4H4O6 is 0.180gmL(-1) and the temperature is 35°C. This POELE10-Na2C4H4O6 ATPS was applied to separate and enrich SDZ and SMT in real samples (i.e., water, egg and milk) under the optimal conditions, and it was found that the recovery of SDZ and SMT was 96.20-99.52% with RSD of 0.35-3.41%. The limit of detection (LOD) of this method for the SDZ and SMT in spiked samples was 2.52-3.64pgmL(-1), and the limit of quantitation (LOQ) of this method for the SDZ and SMT in spiked samples was 8.41-12.15pgmL(-1).

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

Aqueous two-phase system (ATPS) is a liquid-liquid fractionation technique and has gained an interest because of great potential for the extraction, separation, purification and enrichment of proteins, membranes, viruses, enzymes, nucleic acids and other biomolecules both in industry and academia. Although, the partition behavior involved in the method is complex and difficult to predict. Current research shows that it has also been successfully used in the detection of veterinary drug residues in food, separation of precious metals, sewage treatment and a variety of other purposes. The ATPS is able to give high recovery yield and is easily to scale up. It is also very economic and environment friendly method. The aim of this review is to overview the basics of ATPS, optimization and its applications.

Miniaturization of aqueous two-phase extraction for biological applications: From micro-tubes to microchannels

Aqueous two-phase extraction (ATPE) is a biocompatible liquid-liquid (L-L) separation technique that has been under research for several decades towards the purification of biomolecules, ranging from small metabolites to large animal cells. More recently, with the emergence of rapid-prototyping techniques for fabrication of microfluidic structures with intricate designs, ATPE gained an expanded range of applications utilizing physical phenomena occurring exclusively at the microscale. Today, research is being carried simultaneously in two different volume ranges, mL-scale (microtubes) and nL-scale (microchannels). The objective of this review is to give insight into the state of the art at both microtube and microchannel-scale and to analyze whether miniaturization is currently a competing or divergent technology in a field of applications including bioseparation, bioanalytics, enhanced fermentation processes, catalysis, high-throughput screening and physical/chemical compartmentalization. From our perspective, both approaches are worthy of investigation and, depending on the application, it is likely that either (i) one of the approaches will eventually become obsolete in particular research areas such as purification at the preparative scale or high-throughput screening applications; or (ii) both approaches will function as complementing techniques within the bioanalytics field.

Thermoseparating aqueous two-phase systems: Recent trends and mechanisms

Having the benefits of being environmentally friendly, providing a mild environment for bioseparation, and scalability, aqueous two-phase systems (ATPSs) have increasingly caught the attention of industry and researchers for their application in the isolation and recovery of bioproducts. The limitations of conventional ATPSs give rise to the development of temperature-induced ATPSs that have distinctive thermoseparating properties and easy recyclability. This review starts with a brief introduction to thermoseparating ATPSs, including its history, unique characteristics and advantages, and lastly, key factors that influence partitioning. The underlying mechanism of temperature-induced ATPSs is covered together with a summary of recent applications. Thermoseparating ATPSs have been proven as a solution to the demand for economically favorable and environmentally friendly industrial-scale bioextraction and purification techniques.

Novel lipase purification methods - a review of the latest developments

Microbial lipases are popular biocatalysts due to their ability to catalyse diverse reactions such as hydrolysis, esterification, and acidolysis. Lipases function efficiently on various substrates in aqueous and non-aqueous media. Lipases are chemo-, regio-, and enantio-specific, and are useful in various industries, including those manufacturing food, detergents, and pharmaceuticals. A large number of lipases from fungal and bacterial sources have been isolated and purified to homogeneity. This success is attributed to the development of both conventional and novel purification techniques. This review highlights the use of these techniques in lipase purification, including conventional techniques such as: (i) ammonium sulphate fractionation; (ii) ion-exchange; (iii) gel filtration and affinity chromatography; as well as novel techniques such as (iv) reverse micellar system; (v) membrane processes; (vi) immunopurification; (vi) aqueous two-phase system; and (vii) aqueous two-phase floatation. A summary of the purification schemes for various bacterial and fungal lipases are also provided.

A novel aqueous two phase system composed of a thermo-separating polymer and an organic solvent for purification of thermo-acidic amylase enzyme from red pitaya (Hylocereus polyrhizus) peel

The purification of thermo-acidic amylase enzyme from red pitaya (Hylocereus polyrhizus) peel for the first time was investigated using a novel aqueous two-phase system (ATPS) consisting of a thermo-separating copolymer and an organic solvent. The effectiveness of different parameters such as molecular weight of the thermo-separating ethylene oxide-propylene oxide (EOPO) copolymer and type and concentration of organic solvent on the partitioning behavior of amylase was investigated. In addition, the effects of phase components, volume ratio (VR), pH and crude load of purification factor and yield of amylase were evaluated to achieve the optimum partition conditions of the enzyme. In the novel ATPS method, the enzyme was satisfactorily partitioned into the polymer-rich top phase in the system composed of 30% (w/w) EOPO 2500 and 15% (w/w) 2-propanol, at a volume ratio of 1.94 and with a crude load scale of 25% (w/w) at pH 5.0. Recovery and recycling of components was also measured in each successive step of the ATPS process. The enzyme was successfully recovered by the method with a high purification factor of 14.3 and yield of 96.6% and copolymer was also recovered and recycled at a rate above 97%, making the method was more economical than the traditional ATPS method.

Extractive bioconversion of cyclodextrins by Bacillus cereus cyclodextrin glycosyltransferase in aqueous two-phase system

An extractive bioconversion with Bacillus cereus cyclodextrin glycosyltransferase (CGTase, EC 2.4.1.19) in aqueous two-phase system (ATPS) was investigated for the synthesis and recovery of cyclodextrins (CDs). Optimum condition for the extractive bioconversion of CDs was achieved in ATPS consisted of 7.7% (w/w) polyethylene glycol (PEG) 20,000 and 10.3% (w/w) dextran T500 with volume ratio (VR) of 4.0. Enzymatic conversion of starch occurred mainly in dextran-rich bottom phase whereas the product, CDs was transferred to top phase and a higher partition coefficient of CDs was achieved. Repetitive batch of CDs synthesis was employed by replenishment of the top phase components and addition of starch every 8h. An average total CDs concentration of 13.7 mg/mL, (4.77 mg/mLα-CD, 5.02 mg/mLβ-CD and 3.91 mg/mLγ-CD) was recovered in the top phase of PEG 20,000/dextran T500 ATPS. This study showed the effectiveness of ATPS application in extractive bioconversion of CDs synthesis with B. cereus CGTase.

Extraction and purification of anthraquinones derivatives from Aloe vera L. using alcohol/salt aqueous two-phase system

An alcohol/salt aqueous two-phase system (ATPS) composed of 1-propanol and (NH4)2SO4 was employed to purify anthraquinones (AQs) extracted from Aloe vera L. The main influencing system parameters such as type of alcohol, type and concentration of salt, temperature and pH were investigated in detail. Under the optimal extraction conditions, AQs can be extracted into alcohol-rich phase with high extraction efficiency, meanwhile majority polysaccharides, proteins, mineral substances and other impurities were extracted into salt-rich phase. Partitioning of AQs is dependent on hydrophobic interaction, hydrogen bond interaction, and salting-out effect in ATPS. Temperature also played a great role in the partitioning. After ATPS extraction, alcohol can be recycled by evaporation; moreover, salt can be recycled by dilution crystallization method. Compared with other liquid-liquid extractions, this alcohol/salt system is much simpler, lower in cost with easier recovery of phase-forming components, which has the potential scale-up in down-processing of active ingredients in plant.