Ionic liquid-based multi-stage sugaring-out extraction of lactic acid from simulated broth and actual lignocellulosic fermentation broth

In this study, ionic liquid-based sugaring-out extraction was developed to separate lactic acid from the synthetic solution and actual lignocellulosic fermentation broth. Except for [EOHmim]BF4, the ILs with BF4− and OTF− anion can form aqueous two-phase system (ATPS) with the aid of saccharides. With the same kind of saccharides, the ATPS formation ability of ILs could be promoted by increasing the side-chain length of ILs in the order of [Hmim]BF4 ≈ [Bmim]BF4 ˃ [Emim]BF4 due to the decrease in ILs’ kosmotropicity. On the other hand, for the same type of ILs, an ATPS was formed more easily with glucose than with xylose. When IL concentration varied from 35% (w/w) to 40% (w/w) at a low glucose concentration of 15% (w/w), an interesting phase reversal was observed. When lactic acid was undissociated at pH 2.0, 51.8% LA and 92.3% [Bmim]BF4 were partitioned to the top phase, and 97.0% glucose to the bottom phase using an ATPS consisting of 25% (w/w) glucose and 45% (w/w) IL. The total recovery of LA would increase to 89.0% in three-stage sugaring-out extraction from synthetic solution. In three-stage sugaring-out extraction from the filtered and unfiltered fermentation broth obtained via simultaneous saccharification and co-fermentation (SSCF) of acid-pretreated corn stover by the microbial consortium, the total recovery of LA was 89.5% and 89.8%, respectively. Furthermore, the total removal ratio of cells and pigments from the unfiltered broth was 68.4% and 65.4%, respectively. The results support IL-based sugaring-out extraction as a potential method for the recovery of lactic acid from actual fermentation broth. Graphical Abstract

Organic Ion-Associate Phase Microextraction/Back-Microextraction for Preconcentration: Determination of Nickel in Environmental Water Using 2-Thenoyltrifluoroacetone via GF-AAS

An ion-associate phase (IAP) microextraction/ back-microextraction system was applied for the enrichment, separation, and detection of trace amounts of nickel from environmental water samples. Thenoyltrifluoroacetone (HTTA) acted not only as a chelating reagent for nickel, but also as a component of the extraction phase, i.e., IAP. Nickel in a 40 mL sample solution was pH-adjusted with phenolsulfonate (PS−) and tetramethylammonium hydroxide and converted by chelation reaction in the presence of thenoyltrifluoroacetonate (TTA−). When benzyldodecyldimethylammonium ion (C12BzDMA+) was added, a suspension of IAP formed in the solution. The IAP consisted of TTA−, a chelating reagent, the PS−, a component of pH buffer, and C12BzDMA+, which helps extract the chelating complex. When the solution was centrifuged, the IAP separated from the suspension and the nickel-TTA chelate was extracted into the bottom phase of the centrifuge tube. After the aqueous phase was taken away, 100 µL of nitric acid (2 M) solution containing phosphate was used to back-microextract nickel from the IAP. The acid phase was measured via graphite-furnace atomic-absorption spectrometry (GF-AAS). The proposed method facilitated a 400-fold enrichment. The limit of detection was 0.02 µg L−1. The proposed method was applied for the determination of nickel in river water and seawater samples.

Using Salivary Biomarkers for Stress Assessment in Offshore Saturation Diving: A Pilot Study

Health monitoring during offshore saturation diving is complicated due to restricted access to the divers, the desire to keep invasive procedures to a minimum, and limited opportunity for laboratory work onboard dive support vessels (DSV). In this pilot study, we examined whether measuring salivary biomarkrers in samples collected by the divers themselves might be a feasible approach to environmental stress assessment. Nine saturation divers were trained in the passive drool method for saliva collection and proceeded to collect samples at nine time points before, during, and after an offshore commercial saturation diving campaign. Samples collected within the hyperbaric living chambers were decompressed and stored frozen at −20°C onboard the DSV until they were shipped to land for analysis. Passive drool samples were collected without loss and assayed for a selection of salivary biomarkers: secretory immunoglobulin A (SIgA), C-reactive protein (CRP), tumor necrosis factor (TNF)-α, interleukins IL-6, IL-8, IL-1β, as well as cortisol and alpha-amylase. During the bottom phase of the hyperbaric saturation, SIgA, CRP, TNF-α, IL-8 and IL-1β increased significantly, whereas IL-6, cortisol and alpha-amylase were unchanged. All markers returned to pre-dive levels after the divers were decompressed back to surface pressure. We conclude that salivary biomarker analysis may be a feasible approach to stress assessment in offshore saturation diving. The results of our pilot test are consonant with an activation of the sympathetic nervous system related to systemic inflammation during hyperbaric and hyperoxic saturation.

Ionic liquid-based multi-stage sugaring-out extraction of lactic acid from actual lignocellulosic fermentation broth

In this study, ionic liquid-based sugaring-out extraction was developed to separate lactic acid from the synthetic solution and actual lignocellulosic fermentation broth. Except for [EOHmim]BF4, the ILs with BF4− and OTF− anion can form aqueous two-phase (ATP) systems with the aid of saccharides. With the same kind of saccharides, the ATP formation ability of ILs could be promoted by increasing the side-chain length of ILs in the order of [Hmim]BF4 ≈ [Bmim]BF4 ˃ [Emim]BF4 due to the decrease in ILs’ kosmotropicity. On the other hand, for the same type of ILs, an ATP system was formed more easily with glucose than with xylose. When IL concentration varied from 35% (w/w) to 40% (w/w) at a low glucose concentration of 15% (w/w), an interesting phase reversal was observed. When lactic acid was undissociated at pH 2.0, 51.8% LA and 92.3% [Bmim]BF4 were partitioned to the top phase, and 97.0% glucose to the bottom phase using an ATP system consisting of 25% (w/w) glucose and 45% (w/w) IL. The total recovery of LA would increase to 89.0% in three-stage sugaring-out extraction from synthetic solution. In three-stage sugaring-out extraction from the filtered and unfiltered fermentation broth obtained via simultaneous saccharification and co-fermentation (SSCF) of acid-pretreated corn stover by microbial consortium, the total recovery of LA was 89.5% and 89.8%, respectively. Furthermore, the total removal ratio of cells and pigments from the unfiltered broth was 68.4% and 65.4%, respectively. The results support IL-based sugaring-out extraction as a potential method for the recovery of lactic acid from actual fermentation broth.

Fractionation of phycocyanin and carbohydrate from Spirulina platensis using ionic liquid-based aqueous two-phase system

Microalgae have gained considerable attention due to their high-value biomolecules and potential applications in the pharmaceutical, food, medical and cosmeceutical field. However, the conventional biorefinery process of microalgae are costly, energy-intensive, and time-consuming. Aqueous two-phase system (ATPS) has emerged as a potential technique for the separation and fractionation of biomolecules in the biorefinery field. This study proposed the application of ionic liquid (IL) based ATPS for the fractionation of high-value phycocyanin and carbohydrates from a crude extract of Spirulina platensis.The biomass was first lysed by a high-speed homogenization with a solid to liquid ratio (S/L) of 1:10 and an operation time of 5 min to achieve optimum yields of multiple products. Next, the feasibility of several IL-based ATPS with phosphate/citrate buffer was evaluated by investigating the effects of cation, anion, and alkyl chain’s length of ILs. Among the IL-based ATPS, the system comprising of 1-butyl-1-methylpyrrolidinium dicyanamide and citrate buffer demonstrated the optimum phycocyanin extraction efficiency of 83.26 ± 0.05% at the top phase and a concurrent recovery of 73.89±0.06% carbohydrate at the bottom phase. In this work, the IL-based ATPS performed better than conventional polymer-based ATPS. This work suggests that IL-based ATPS allows efficient fractionation of phycocyanin and carbohydrates.

Glutathione Disulfide as a Reducing, Capping, and Mass-Separating Agent for the Synthesis and Enrichment of Gold Nanoclusters

Water-soluble nanoclusters, which are facilely enrichable without changes in the original properties, are highly demanded in many disciplines. In this contribution, a new class of gold nanoclusters (AuNCs) was synthesized using glutathione disulfide (GSSG) as a reducing and capping agent under intermittent heating mode. The as-prepared GSSG–AuNCs had a higher quantum yield (4.1%) compared to the conventional glutathione-protected AuNCs (1.8%). Moreover, by simply introducing the GSSG–AuNC solution to acetonitrile at a volume ratio of 1:7, a new bottom phase was formed, in which GSSG–AuNCs could be 400-fold enriched without changes in properties, with a percentage recovery higher than 99%. The enrichment approach did not need additional instruments and was potentially suitable for large-scale enrichment of nanoclusters. Further, density functional theory calculations indicated that the hydrogen bonding between GSSG and acetonitrile plays a key role for the bottom phase formation. Our work suggests that the highly emissive GSSG–AuNCs possess great potential not only in fluorescent measurements but also in other scenarios in which high-concentration AuNCs may be needed, such as catalysis, drug delivery, and electronic and optical industries.

Primary recovery of hyaluronic acid produced in Streptococcus equi subsp. zooepidemicus using PEG–citrate aqueous two-phase systems

Given its biocompatibility, rheological, and physiological properties, hyaluronic acid (HA) has become a biomaterial of increasing interest with multiple applications in medicine and cosmetics. In recent decades, microbial fermentations have become an important source for the industrial production of HA. However, due to its final applications, microbial HA must undergo critical and long purification processes to ensure clinical and cosmetic grade purity. Aqueous two-phase systems (ATPS) have proven to be an efficient technique for the primary recovery of high-value biomolecules. Nevertheless, their implementation in HA downstream processing has been practically unexplored. In this work, polyethylene glycol (PEG)–citrate ATPS were used for the first time for the primary recovery of HA produced with an engineered strain of Streptococcus equi subsp. zooepidemicus. The effects of PEG molecular weight (MW), tie-line length (TLL), volume ratio (VR), and sample load on HA recovery and purity were studied with a clarified fermentation broth as feed material. HA was recovered in the salt-rich bottom phase, and its recovery increased when a PEG MW of 8000 g mol−1 was used. Lower VR values (0.38) favoured HA recovery, whereas purity was enhanced by a high VR (3.50). Meanwhile, sample load had a negative impact on both recovery and purity. The ATPS with the best performance was PEG 8000 g mol−1, TLL 43% (w/w), and VR 3.50, showing 79.4% HA recovery and 74.5% purity. This study demonstrated for the first time the potential of PEG–citrate ATPS as an effective primary recovery strategy for the downstream process of microbial HA.

Efficacy of Alcohol/sugar Aqueous Biphasic System on Partition of Bovine Serum Albumin

A green bio-separation alternative can be performed with a non-toxic and biodegradable aqueous biphasic system (ABS) composed of short-chain aliphatic alcohol-based top phase (1-propanol and 2-propanol) and carbohydrate-based bottom phase (glucose, sucrose, and maltose). A model protein, bovine serum albumin (BSA) was adopted to determine the effects of types and concentration of phase-forming components; protein concentration; and system pH on the protein partition efficiency in the ABS. Results showed that the 1-propanol/maltose ABS gave an overall better partition efficiency of BSA to the alcohol-rich top phase compared to the 1-propanol/sucrose ABS, 1-propanol/glucose ABS, and 2-propanol/sugar ABS attributed to the lower hydrophilicity of 1-propanol and the stronger sugaring-out effect exerted by the maltose. A maximum partition coefficient (K) of 20.01 ± 0.05 and recovery yield (Y) of 95.42% ± 0.01 of BSA were obtained with the 35% (w/w) 1-propanol/22% (w/w) maltose ABS at pH 5.0 which contained 10% (w/w) BSA. The K and Y of BSA in 1-propanol/maltose ABS was further enhanced with the addition of 3% (w/w) of ionic liquids, 1-butyl-3-methylimidazolium bromide ([Bmim]Br) as the adjuvants which provides the protein stabilizing effect. The Fourier Transform Infrared Spectrum (FTIR) analysis revealed that the protein structure remained unaltered upon the separation process.

Rapid identification of capsulated Acinetobacter baumannii using a density-dependent gradient test

Background Gram-negative bacterial capsules are associated with production of carbohydrates, frequently resulting in a mucoid phenotype. Infections caused by capsulated or mucoid A. baumannii are associated with increased clinical severity. Therefore, it is clinically and epidemiologically important to identify capsulated A. baumannii. Here, we describe a density-dependent gradient test to distinguish between capsulated and thin/non-capsulated A. baumannii. Results Thirty-one of 57 A. baumannii isolates displayed a mucoid phenotype. The density-dependent gradient test was comprised of two phases, with silica concentrations of 30% (top phase) and 50% (bottom phase). Twenty-three isolates migrated to the bottom phase, indicating thin or non-capsulated strains, and 34 migrated to the top phase, suggesting strains suspected to be capsulated. There was agreement between the mucoid and the non-mucoid phenotypes and the density-dependent gradient test for all but three isolates. Total carbohydrates extracted from strains suspected to be capsulated were significantly higher. Transmission electron microscopy confirmed the presence of a capsule in the six representative strains suspected to be capsulated. Conclusions The density-dependent gradient test can be used to verify capsule presence in mucoid-appearing A. baumannii strains. Identifying capsulated strains can be useful for directing infection control measures to reduce the spread of hypervirulent strains.

A two-phase reaction system for selective oxidative degradation of lignin model compounds

Lignin depolymerization through an oxidation method could provide value-added products, but it is challenging in terms of recovering catalysts or separating products in time to avoid over-oxidation. In this study, a process of selectively oxidative degradation of lignin model compounds was operated in a two-phase reaction system. Lignin model compounds of 4-benzyloxyphenol (PBP) or guaiacylglycerol-β-guaiacyl ether (GGE) in a bottom phase of 1-butyl-3-methylimidazole chloride ([BMIM]Cl) ionic liquid were selectively oxidized by H2O2 in the presence of a solid acid (SO42-/Fe2O3-ZrO2), and the degradation products immediately diffused into the upper organic solvent phase (butyl acetate). In this kind of reaction system, the yield of the products was improved due to the prolonged life of ∙OH in ionic liquid, and the product selectivity was maintained due to the timely product separation, and the ionic liquid and the catalyst were easily recycled.