Foam fractionation of exo-lipases from a growing fungus (<Emphasis Type="Italic">Pleurotus sapidus</Emphasis>)

Active lipases were isolated from the culture supernatant of the basidiomycetous fungus Pleurotus sapidus by foam fractionation. The pH value, the gas flow, and the foaming period were systematically varied to optimize the transport of the enzymes into the foam phase. On a 70-mL scale, a maximum recovery of hydrolytic activity of 95% was obtained at pH 7.0 and 60 mL N₂ min⁻¹ after 50 min. The procedure, with minor modifications, was also applicable to native pellet cultures of P. sapidus. The same recovery of 95% was achieved, with purification and enrichment factors of 11.6 and 28.0, respectively.     

Purification and identification of a novel cutinase from Coprinopsis cinerea by adsorptive bubble separation

A novel extracellular esterase was separated from culture supernatants of the basidiomycete Coprinopsis cinerea by means of foam fractionation. The parameters pH value, gas flow rate, addition of detergents, and the column design were varied to optimise the transport of the active enzyme into the foam phase. On the 70-mL scale, a recovery of activity of 79% with an enrichment factor of 10.5 was obtained at pH 7 and 20 mL air min⁻¹ within 15 min. The enriched enzyme was characterized biochemically by semi-native SDS-PAGE and IEF electrophoresis with activity staining. Peptide sequencing was performed after tryptic digestion by electrospray tandem mass spectrometry. Homology searches revealed significant similarities to cutinases of various ascomycetes and to C. cinerea genome data recently annotated as cutinases.     

螺旋构件强化排液的泡沫分离塔用于牛血清蛋白分离

引言 泡沫分离技术又称泡沫吸附分离技术[1],是以气泡作为分离介质,利用被分离组分在气液两相界面吸附性质的差异进行浓缩溶液中表面活性组分.在泡沫分离过程中,通过空气分布器在泡沫塔液相中产生气泡,气泡沿着轴向向上流动,被分离表面活性组分吸附在气泡的气液两相界面上,当吸附接近平衡后,气泡离开液相,在液相上方形成泡沫相.     

Enzymatic fractionation and enrichment of n−9 PUFA

A single-cell oil from a Mortierella alpina mutant (TGM17 oil) contains n−9 PUFA: 14.3 wt% 6,9-octadecadienoic acid (18∶2n−9; n−9 LnA) and 17.1 wt% Mead acid (20∶3n−9; MA). Lipase screening indicated that Pseudomonas aeruginosa lipase acted strongly on n−9 LnA and weakly on MA, and Candida rugosa lipase acted weakly on the two PUFA. Hence, fractionation and enrichment of the two FA were conducted with the lipases. The first step was selective hydrolysis of IGM17 oil with P. aeruginosa lipase. The hydrolysis fractionated the oil into FFA containing 20.4 wt% n−9 LnA and 6.3 wt% MA, and acylglycerols containing 10.7 wt% n−9 LnA and 23.7 wt% MA. The FFA fraction was used for preparation of n−9 LnA-rich FFA. After removal of saturated FA, the FFA were esterified with lauryl alcohol (LauOH) using C. rugosa lipase. Two selective esterifications increased the n−9 LnA content to 54.0 wt% with 38.2% recovery of the initial content of TGM17 oil. The acylglycerol fraction obtained in the hydrolysis with P. aeruginosa lipase was used for preparation of MA-rich FFA. The acylglycerol fraction was hydrolyzed under alkaline conditions, and saturated FA were eliminated by urea adduct fractionation. Two selective esterifications of the FFA with LauOH increased the MA content to 60.2 wt% with 53.5% recovery. Thus, the two-step enzymatic process was effective for fractionation and enrichment of n−9 LnA and MA.     

Separation of Bovine Serum Albumin by Foam Fractionation with Sieve Tray Column

A batch foam fractionation column with sieve trays was developed for enhancing the foam drainage. Effects of feeding concentration, air flow rate, number of stages, and sieve pore size on foam fractionation performances were investigated. The results indicated that the sieve trays enhanced the foam drainage effectively and improved enrichment ratio. At the liquid loading volume 490 mL, feeding concentration 0.1 g L^?1, and air flow rate 300 mL min^?1, the enrichment ratio reached 7.56 by using 10 stages of sieve trays with opening ratio of 38.25%, which was 1.84 times of that obtained by the control column.     

Electroanalysis of urinary l-dopa using tyrosinase immobilized on gold nanoelectrode ensembles

The performance of an amperometric biosensor constructed by associating tyrosinase (Tyr) enzyme with the advantages of a 3D gold nanoelectrode ensemble (GNEE) is evaluated in a flow-injection analysis (FIA) system for the analysis of l-dopa. GNEEs were fabricated by electroless deposition of the metal within the pores of polycarbonate track-etched membranes. A simple solvent etching procedure based on the solubility of polycarbonate membranes is adopted for the fabrication of the 3D GNEE. Afterward, enzyme was immobilized onto preformed self-assembled monolayers of cysteamine on the 3D GNEEs (GNEE-Tyr) via cross-linking with glutaraldehyde. The experimental conditions of the FIA system, such as the detection potential (−0.200 V vs. Ag/AgCl) and flow rates (1.0 mL min⁻¹) were optimized. Analytical responses for l-dopa were obtained in a wide concentration range between 1 × 10⁻⁸ mol L⁻¹ and 1 × 10⁻² mol L⁻¹. The limit of quantification was found to be 1 × 10⁻⁸ mol L⁻¹ with a resultant % RSD of 7.23% (n = 5). The limit of detection was found to be 1 × 10⁻⁹ mol L⁻¹ (S/N = 3). The common interfering compounds, namely glucose (10 mmol L⁻¹), ascorbic acid (10 mmol L⁻¹), and urea (10 mmol L⁻¹), were studied. The recovery of l-dopa (1 × 10⁻⁷ mol L⁻¹) from spiked urine samples was found to be 96%. Therefore, the developed method is adequate to be applied in the clinical analysis.     

Sensory Thresholds of Selected Phenolic Constituents from Thyme and their Antioxidant Potential in Sunflower Oil

The odor detection thresholds of carvacrol (5-isopropyl-2-methyl-phenol), thymol (2-isopropyl-5-methyl-phenol) and p-cymene 2,3-diol (2,3-dihydroxy-4-isopropyl-1-methyl-benzene) in sunflower oil, determined by the three-alternative, forced-choice procedure, were 30.97, 124 and 794.33 mg kg⁻¹, respectively. Sunflower oil containing 13, 70, or 335 mg kg⁻¹ of carvacrol, thymol or p-cymene 2,3-diol, respectively, was judged to be similar (P < 0.01) in taste and odor to its antioxidant-free counterpart. The rate constant of sunflower oil oxidation, measured from the increase in peroxide value during storage at 25 °C, was 9.2 × 10⁻⁹ mol kg⁻¹ s⁻¹ while the rate constants were 9.3 × 10⁻⁹, 9.8 × 10⁻⁹, and 4.3 × 10⁻⁹ mol kg⁻¹ s⁻¹ in the presence of 13 mg kg⁻¹ carvacrol, 70 mg kg⁻¹ thymol, and 335 mg kg⁻¹ p-cymene 2,3-diol, respectively. At a level of 335 mg kg⁻¹, p-cymene 2,3-diol did not impart flavor taints and effected a 46.7% reduction in the rate of oxidation of sunflower oil. These findings indicate that the diphenolic p-cymene 2,3-diol could potentially replace synthetic antioxidants and is a valuable addition to the antioxidants used by the food industry in its quest to meet consumer demands for synthetic-additives-free and ‘natural’ foods.     

Improved catalytic hydrolysis of carboxy methyl cellulose using cellulase immobilized on functionalized meso cellular foam

Cellulase from Penicillium funiculosum was immobilized on functionalized MCF (Meso Cellular Foam) silica by imine bond formation followed by reduction using NaBH₄. The specific activities of free and immobilized enzyme were measured for hydrolysis of soluble carboxymethyl cellulose (CMC). The highest activity of MCF immobilized and native enzyme was obtained at optimum pH 5 and 4.5 respectively. Kinetic parameters, Michaelis–Menten constant (Km) and maximum reaction velocity (Vmax), were calculated as Km = 0.025 × 10⁻² mg/mL, Vmax = 5.327 × 10⁻³ U/mg for the free enzyme and Km = 0.024 × 10⁻² mg/mL, Vmax = 9.794 × 10⁻³ U/mg for MCF immobilized enzyme respectively. The reusability of immobilized enzymes showed that 66% of its activity is retained even after 15 cycles. The availability of polar groups (–NH–, –OH) and large pore size of surface modified MCF could be electrostatically stabilizing the cellulase. Functionalized MCF was found to be a promising material for stabilizing cellulase with 16.4 wt% loading of enzyme.     

Effect of temperature programming on the performance of urea inclusion compound-based free fatty acid fractionation

The effect of cooling rate on the degree of removal of saturated acyl groups from FFA derived from canola oil and the isolation of di- and polyunsaturated acyl groups from FFA derived from vegetable and fish oil, respectively, during urea inclusion compound (UIC)-based fractionation was investigated. Traditionally, slow cooling has been used (ca.−1°C min⁻¹). A more rapid cooling rate (−47°C min⁻¹) produced UIC crystals of similar morphology and thermodynamic properties, but of a size an order of magnitude smaller than the UIC formed during slow cooling. Fractionations used only renewable materials (urea, FFA, and 95% ethanol as solvent) and benign operating conditions (ambient pressure, 25–75°C, and neutral pH). When the recovery of FFA (in the solvent-rich phase) was relatively high (>60%), the selectivity of UIC-based fractionation toward the inclusion of saturated FFA and against polyunsaturated FFA was not affected by the cooling rate. In contrast, when the FFA recovery was low, representing cases in which an increase of the PUFA purity is a more important economic goal, a slower cooling rate resulted in a significantly greater discrimination against PUFA groups, hence to a FFA product with a measurably greater purity. This paper was presented at the 96th AOCS Anual Meeting and Expo, Salt Lake City, Utah, on May 4, 2005.     

Electrocatalytic oxidation of glutathione at carbon paste electrode modified with 2,7-<Emphasis Type="Italic">bis</Emphasis> (ferrocenyl ethyl) fluoren-9-one: application as a voltammetric sensor

Electrooxidation of glutathione (GSH) was studied at the surface of 2,7-bis (ferrocenyl ethyl) fluoren-9-one modified carbon paste electrode (2,7-BFEFMCPE). Cyclic voltammetry (CV), double potential-step chronoamperometry, and differential pulse voltammetry (DPV) were used to investigate the suitability of this ferrocene derivative as a mediator for the electrocatalytic oxidation of GSH in aqueous solutions with various pH. Results showed that pH 7.00 is the most suitable pH for this purpose. At the optimum pH, the oxidation of GSH at the surface of this modified electrode occurs at a potential of about 0.410 V versus Ag|AgCl|KCl_sat. The kinetic parameters such as electron transfer coefficient, α = 0.61, and rate constant for the chemical reaction between GSH and redox site in 2,7-BFEFMCPE, k _h = 1.73 × 10³ cm³ mol⁻¹ s⁻¹, were also determined using electrochemical approaches. Also, the apparent diffusion coefficient, D _app, for GSH was found to be 5.0 × 10⁻⁵ cm² s⁻¹ in aqueous buffered solution. The electrocatalytic oxidation peak current of GSH showed a linear dependence on the glutathione concentration, and linear calibration curves were obtained in the ranges of 5.2 × 10⁻⁵ M to 4.1 × 10⁻³ M and 9.2 × 10⁻⁷ M to 1.1 × 10⁻⁵ M with cyclic voltammetry and differential pulse voltammetry methods, respectively. The detection limits (3σ) were determined as 1.4 × 10⁻⁵ M and 5.1 × 10⁻⁷ M for the CV and DPV methods, respectively. This method was also examined as a selective, simple, and precise new method for voltammetric determination of GSH in real sample such as hemolysed erythrocyte.     

Electrochemical pretreatment of distillery wastewater using aluminum electrode

Electrochemical (EC) oxidation of distillery wastewater with low (BOD₅/COD) ratio was investigated using aluminum plates as electrodes. The effects of operating parameters such as pH, electrolysis duration, and current density on COD removal were studied. At a current density of 0.03 A cm⁻² and at pH 3, the COD removal was found to be 72.3%. The BOD₅/COD ratio increased from 0.15 to 0.68 for an optimum of 120-min electrolysis duration indicating improvement of biodegradability of wastewater. The maximum anodic efficiency observed was 21.58 kg COD h⁻¹ A⁻¹ m⁻², and the minimum energy consumption observed was 0.084 kWh kg⁻¹ COD. The kinetic study results revealed that reaction rate (k) decreased from 0.011 to 0.0063 min⁻¹ with increase in pH from 3 to 9 while the k value increased from 0.0035 to 0.0102 min⁻¹ with increase in current density from 0.01 to 0.03 A cm⁻². This study showed that the COD reduction is more influenced by the current density. The linear and the nonlinear regression models reveal that the COD reduction is influenced by the applied current density.     

The shear force amendments on the slugging behavior of upflow Anammox granular sludge bed reactor

The granulation of Anammox sludge plays an important role in improving the efficiency of high-rate Anammox bioreactors. The present study involved the use of anaerobic granular sludge to start up the Anammox process to accomplish granulation in Anammox reactor. The accumulation of nitrogen gas and subsequent slugging behavior were observed in the upflow Anammox granular sludge bed (AGSB) reactor, resulting in deteriorated effluent quality. Based on shear force analysis of the gas column under the quasi-steady state, the liquid-induced shear force was increased by progressively shortening of hydraulic residence time (HRT) and implementing effluent recycling. It appeared to be the right strategy to eradicate the slugging behavior which disappeared completely when HRT was shortened to 1.10 h with liquid upflow velocity of 1.30 cm min⁻¹. The application of high shear stress enhanced the nitrogen removal performance to 15.40 kg-N m⁻³ d⁻¹. Thus the amendments in the liquid-induced shear force by shortening HRT may be an appropriate strategy to overcome slugging behavior of the Anammox reactor.     

Fumigant and Contact Toxicities of Monoterpenes to <Emphasis Type="Italic">Sitophilus oryzae</Emphasis> (L.) and <Emphasis Type="Italic">Tribolium castaneum</Emphasis> (Herbst) and their Inhibitory Effects on Acetylcholinesterase Activity

A comparative study was conducted to assess the contact and fumigant toxicities of eleven monoterpenes on two important stored products insects—, Sitophilus oryzae, the rice weevil, and Tribolium castaneum, the rust red flour beetle. The monoterpenes included: camphene, (+)-camphor, (−)-carvone, 1-8-cineole, cuminaldehyde, (l)-fenchone, geraniol, (−)-limonene, (−)-linalool, (−)-menthol, and myrcene. The inhibitory effect of these compounds on acetylcholinesterase (AChE) activity also was examined to explore their possible mode(s) of toxic action. Although most of the compounds were toxic to S. oryzae and T. castaneum, their toxicity varied with insect species and with the bioassay test. In contact toxicity assays, (−)-carvone, geraniol, and cuminaldehyde showed the highest toxicity against S. oryzae with LC₅₀ values of 28.17, 28.76, and 42.08 μg/cm², respectively. (−)-Carvone (LC₅₀ = 19.80 μg/cm²) was the most effective compound against T. castaneum, followed by cuminaldehyde (LC₅₀ = 32.59 μg/cm²). In contrast, camphene, (+)-camphor, 1-8-cineole, and myrcene had weak activity against both insects (i.e., LC₅₀ values above 500 μg/cm²). In fumigant toxicity assays, 1-8-cineole was the most effective against S. oryzae and T. castaneum (LC₅₀ = 14.19 and 17.16 mg/l, respectively). Structure-toxicity investigations revealed that (−)-carvone—, a ketone—, had the highest contact toxicity against the both insects. 1-8-Cineole—, an ether—, was the most potent fumigant against both insects. In vitro inhibition studies of AChE from adults of S. oryzae showed that cuminaldehyde most effectively inhibited enzyme activity at the two tested concentrations (0.01 and 0.05 M) followed by 1-8-cineole, (−)-limonene, and (l)-fenchone. 1-8-Cineole was the most potent inhibitor of AChE activity from T. castaneum larvae followed by (−)-carvone and (−)-limonene. The results of the present study indicate that (−)-carvone, 1,8-cineole, cuminaldehyde, (l)-fenchone, and (−)-limonene could be effective biocontrol agents against S. oryzae and T. castaneum.     

Removal of Trace Metal Impurities from Pretreated Phosphoric Acid by Foam Fractionation

Demands for phosphoric acid are growing rapidly in various industries. This has highlighted the importance of optimizing its production and purification methods. Phosphoric acid can be produced by a wet process. However, due to the presence of many organic and inorganic impurities in the wet product, purification of the resulting product is a major concern in this industry. Removal of trace metal impurities (such as magnesium, cadmium, chromium, zinc, etc.) from produced phosphoric acid in a wet process was investigated by foam fractionation in a semi-batch setup using sodium dodecyl sulfate (SDS) as the surfactant. Effects of inlet air velocity, surfactant concentration, and surfactant selectivity were investigated. The optimum air velocity and surfactant concentration were obtained as 0.020 cm/min and 0.7 g/L, respectively. At the optimum condition, the total removal efficiency and enrichment factor reached were 70.2% and 4.39, respectively, while the acid loss was 8.3%. The total metal removal efficiency was increased to 95.3% in a two-stage experimental run.     

Greenhouse gas emissions and final compost properties from co-composting bovine specified risk material and mortalities with manure

The increased disposal costs of cattle specified risk materials (SRM) have reduced the competitiveness of the Canadian beef industry. The SRM materials include the skull, brain, trigeminal ganglia, eyes, palatine tonsils, spinal cord and dorsal root ganglia. This study investigates greenhouse gas (GHG) emissions and final compost properties from open windrow co-composting of manure with bovine SRM and mortalities. There were two compost treatments with four replications: SRMC consisting of SRM, cattle manure and barley straw and COWC consisting of cattle mortalities, cattle manure and barley straw. Average windrow temperature was higher (P < 0.05) for SRMC (47.1°C) than for COWC (44.1°C) over the first 139 days. The final compost coliform count, moisture, pH and TC contents were not significantly different between treatments while TN and available N (NH₄ ⁺ + NO₃ ⁻ + NO₂ ⁻) were lower for SRMC than for COWC. The average surface GHG flux from SRMC were 24.3 g C day⁻¹ m⁻² and 0.17 g N day⁻¹ m⁻² for CO₂ and N₂O, respectively, and were not significantly different from those from COWC (31.6 g C day⁻¹ m⁻² and 0.17 g N day⁻¹ m⁻² for CO₂ and N₂O, respectively), but CH₄ emissions from SRMC (0.47 g C day⁻¹ m⁻²) were lower than from COWC (1.57 g C day⁻¹ m⁻²). While a few large bones were left in the cattle mortality treatment, composting decomposed all SRM suggesting that it may be a viable alternative to rendering for SRM disposal.     

Enhanced foam drainage using parallel inclined channels in a single-stage foam fractionation column

A single-stage vertical foam fractionation column was investigated under continuous steady-state experimental conditions. Using a simple power-law expression to describe the drainage velocity through the foam, and in conjunction with continuity arguments, a theoretical framework was developed to analyse the performance of the vertical column. A reduction in the degrees of freedom in the analysis was achieved by using a fixed feed to gas flux ratio to promote a reasonably constant surfactant recovery. It was then possible to measure the process performance by determining the change in the level of enrichment produced from a change in the gas flux, and corresponding change in the feed flux. For a constant recovery, the enrichment is directly proportional to the volume reduction (defined as the ratio of the feed volume processed to foamate volume produced in a given time). The analysis was found to be consistent with experimental data and demonstrated the need to limit the gas flux, and hence the feed flux, to relatively low values in order to produce satisfactory volume reductions, and in turn achieve high enrichment. To overcome this processing constraint, three parallel inclined channels¹ (PIC) were used to provide an effective increase in the vessel area, and hence facilitate the release of the entrained liquid within the foam. A significant increase in the volume reduction was obtained using the inclined channel arrangement. For the same processing rate, the PIC column achieved up to a 4 fold increase in enrichment compared to the vertical column. A slight decrease in recovery, however, was observed using the PIC column.     

Zn<Superscript>2+</Superscript>-exchange kinetics and antimicrobial properties of synthetic zirconium umbite (K<Subscript>2</Subscript>ZrSi<Subscript>3</Subscript>O<Subscript>9</Subscript>·H<Subscript>2</Subscript>O)

Zirconium umbite, K₂ZrSi₃O₉·H₂O, is a microporous framework ion exchanger whose potential as a carrier for Zn²⁺ ions in antimicrobial formulations has not yet been investigated. Accordingly, batch Zn²⁺-exchange kinetics of synthetic zirconium umbite (K-UM) and the subsequent antimicrobial action of the zinc-bearing phase (Zn-UM) against Staphylococcus aureus and Escherichia coli are reported. Nonstoicheiometric over-exchange of Zn²⁺ for K⁺ was observed and attributed to hydrolysis and complexation reactions of Zn²⁺ within the umbite framework. The exchange process, which was described by a simple pseudo-first-order model (k ₁ = 2.69 × 10⁻⁴ min⁻¹, R ² = 0.992), did not achieve equilibrium within 120 h at 25 °C, by which time the uptake of zinc was found to be 1.04 mmol g⁻¹. The minimal bactericidal concentrations of Zn-UM for E. coli and S. aureus were found to be >10 g cm³ and <1.0 g cm³, respectively.     

Electrochemical determination of thiamazole at a multi-wall carbon nanotube modified glassy carbon electrode

A simple and convenient method is described for voltammetric determination of thiamazole, a commonly used anti-hyperthyroid drug, based on its electrochemical oxidation at a multi-wall carbon nanotube modified glassy carbon electrode. Under optimized conditions, the proposed method exhibited acceptable analytical performances in terms of linearity (over the concentration range from 1.0 × 10⁻⁷ to 5.0 × 10⁻⁴ mol L⁻¹, r = 0.9983), detection limit (3.0 × 10⁻⁸ mol L⁻¹) and reproducibility (RSD = 2.64%, n = 10, for 5.0 × 10⁻⁵ mol L⁻¹ thiamazole). To further validate its possible application, the method was used for the quantification of thiamazole in pharmaceutical formulations and biological fluids.     

Hydrophobic inorganic membranes for water/gas separation

Macroporous or mesoporous hydrophobic inorganic membranes are prepared by a simple one-pot synthesis method coupling the sol–gel process with fluorinated silanes as precursors and the use of alumina powders as fillers. The porosity of these intrinsically hydrophobic membranes can be tuned by the particle size distribution of the dispersed alumina powder. These membranes developed for water/gas separation applications are characterized in term of gas permeance and water breakthrough pressure. A value of air permeance equal to 1800 L min⁻¹ bar⁻¹ m⁻² associated with a water breakthrough pressure larger than 10 bar are measured for the effective sample.     

Pt film electrodes prepared by the Pechini method for electrochemical decolourisation of Reactive Orange 16

Electrochemical decolourisation of Reactive Orange 16 was carried out in an electrochemical flow-cell, using as working electrodes a Pt thin film deposited on a Ti substrate (Pt/Ti) prepared by the Pechini method and a pure platinum (Pt) foil. Using the Pt/Ti electrodes better results for dye decolourisation were obtained under milder conditions than those used for pure Pt. For the Pt electrode, colour removal of 93 % (λ = 493 nm) was obtained after 60 min, at 2.2 V vs. RHE, using 0.017 mol L⁻¹ NaCl + 0.5 mol L⁻¹ H₂SO₄ solution. For the Pt/Ti electrode there was better colour removal, 98%, than for the Pt electrode. Moreover, we used 0.017 mol L⁻¹ NaCl solution and the applied potential was 1.8 V. Under this condition after 15 min of electrolysis, more than 80% of colour was removed. The rate reaction constant, assuming a first order reaction, was 0.024 min⁻¹ and 0.069 min⁻¹, for Pt and Pt/Ti electrodes, respectively.