The use of Magallanic peat as non-conventional sorbent for EDTA removal from wastewater

Kraft mills are responsible for large volumes discharges of highly polluted effluents. Application of new bleaching processes (i.e. total chlorine-free (TCF) process) is already a feasible option to reduce environmental impacts. The current trend in the increase in the production of TCF pulp will proportionally increase the consumption of chelating agents. The most commonly used chelants, ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DPTA) are supposed to be relatively persistent substances, poorly degradable in biological treatment facilities and are subsequently considered as environmentally critical compounds. Adsorption could be used as a treatment technique to remove recalcitrant compounds from wastewaters. However, in most cases, sorbent and regeneration costs can make the whole process not economically feasible. The goal of this study was to evaluate the use of Magallanic peat as non-conventional sorbent for EDTA removal from wastewater. Adsorption studies were carried out considering a 2(3) factorial design. pH, temperature and sorbent/sorbate (S/S) relationship effects were evaluated in EDTA adsorption onto Magallanic peat. In addition, adsorption isotherm constants were determined according to the Langmuir and Freundlich models. The results showed that the optimal conditions for EDTA adsorption onto Magallanic peat were 20 degrees C, acid pH (4.0) and a low sorbent/sorbate ratio (0.1/100). At these conditions Magallanic peat showed an adsorption capacity for EDTA (Cs(sat)) of 128.2mg/g, comparable and even better than activated carbon (Cs(sat) 56.5mg/g). EDTA adsorption data at 60 degrees C obtained are not shown due to Magallanic peat degradation phenomena.     

Extracellular glycosyl hydrolase activity of the clostridia producing acetone, butanol, and ethanol

Production of acetone, butanol, ethanol, acetic acid, and butyric acid by three strains of anaerobic bacteria, which we identified as Clostridium acetobutylicum, was studied. The yield of acetone and alcohols in 6% flour medium amounted to 12.7-15 g/l with butanol constituting 51.0-55.6%. Activities of these strains towards xylan, beta-glucan, carboxymethylcellulose, and crystalline and amorphous celluloses were studied. C. acertobutylicum 6, C. acetoburylicum 7, and C. acertobutylicum VKPM B-4786 produced larger amounts of acetone and alcohols and displayed higher cellulase and hemicellulase activities than the type strain C. acetobutylicum ATCC 824. It was demonstrated that starch in the medium could be partially substituted with plant biomass.     

Olfactory coding in a simple system: adaptation in Drosophila larvae.

Drosophila melanogaster larvae were pre-stimulated with high concentrations of six homologous alcohols (C4-C9) and then tested for adaptation and cross-adaptation using these same alcohols, four aliphatic n-acetates and three acids. Pre-stimulation with hexanol effectively reduced to zero (abolished) test responses to all six alcohols, whereas test responses to hexanol were only affected by pre-stimulation with hexanol. This substance appears to play a fundamental role in the organization of the larval olfactory system. Test responses to butanol and pentanol, and the effect of pre-stimulation with butanol and pentanol, were not significantly different, indicating that they are sensory equivalents. Heptanol, octanol and nonanol induce a complex set of responses among one another. Cross-adaptation between functional groups was observed, in particular following pre-stimulation with hexanol, but there was also evidence that functional groups are coded separately. A model of olfactory processing in the fruitfly maggot is presented that explains the data and provides predictions for future anatomical, genetic and electrophysiological studies.     

Removal of cytokines from HAS-containing solutions by adsorption onto silica

Septic shock syndrome is a potentially fatal medical condition that is associated with elevated blood levels of low molecular weight proteins known as cytokines. Adsorption was investigated as a potential method for removing cytokines from blood. Saline with 50 mg/mL human serum albumin (HAS) spiked with pathological concentrations (ng-pg/mL) of radiolabeled cytokine was used to study cytokine adsorption. Adsorption isotherms were linear in the pathological concentration range, with adsorption constants ranging from 33.0 mL/g to 173 mL/g for tumor necrosis factor (TNF-alpha), interleukin-8 (IL-8),interleukin-6 (IL-6), and C3a. Adsorption constants were also determined for interleukin-1alpha (IL-1alpha), IL-1beta, and interferon-gamma (IFN-gamma). The adsorption of cytokines by several different silica adsorbents was investigated. Increased concentrations of NaCl reduced cytokine adsorption, but did not completely eliminate adsorption even at high concentrations, suggesting that adsorption wads not entirely electrostatic in nature. Possible mechanisms of cytokine adsorption are discussed. Data for batch adsorption for TNF-alpha was used to estimate the minimum amount of silica required to treat septic shock. It was concluded that a silica adsorbent has a sufficiently high capacity to be used for hemoperfusion. Adsorption of myoglobin and cytochrome c was also investigated as possible marker proteins for future dynamic adsorption studies in hemoperfusion devices. (c) 1994 John Wiley & Sons, Inc.     

Metabolic engineering of Clostridium acetobutylicum for the enhanced production of isopropanol‐butanol‐ethanol fuel mixture

Butanol is considered as a superior biofuel, which is conventionally produced by clostridial acetone‐butanol‐ethanol (ABE) fermentation. Among ABE, only butanol and ethanol can be used as fuel alternatives. Coproduction of acetone thus causes lower yield of fuel alcohols. Thus, this study aimed at developing an improved Clostridium acetobutylicum strain possessing enhanced fuel alcohol production capability. For this, we previously developed a hyper ABE producing BKM19 strain was further engineered to convert acetone into isopropanol. The BKM19 strain was transformed with the plasmid pIPA100 containing the sadh (primary/secondary alcohol dehydrogenase) and hydG (putative electron transfer protein) genes from the Clostridium beijerinckii NRRL B593 cloned under the control of the thiolase promoter. The resulting BKM19 (pIPA100) strain produced 27.9 g/l isopropanol‐butanol‐ethanol (IBE) as a fuel alcohols with negligible amount of acetone (0.4 g/l) from 97.8 g/l glucose in lab‐scale (2 l) batch fermentation. Thus, this metabolically engineered strain was able to produce 99% of total solvent produced as fuel alcohols. The scalability and stability of BKM19 (pIPA100) were evaluated at 200 l pilot‐scale fermentation, which showed that the fuel alcohol yield could be improved to 0.37 g/g as compared to 0.29 g/g obtained at lab‐scale fermentation, while attaining a similar titer. To the best of our knowledge, this is the highest titer of IBE achieved and the first report on the large scale fermentation of C. acetobutylicum for IBE production. © 2013 American Institute of Chemical Engineers Biotechnol. Prog., 29:1083–1088, 2013     

Production of biofuels from C1-gases with Clostridium and related bacteria—Recent advances

Clostridium spp. are suitable for the bioconversion of C₁-gases (e.g., CO₂, CO and syngas) into different bioproducts. These products can be used as biofuels and are reviewed here, focusing on ethanol, butanol and hexanol, mainly. The production of higher alcohols (e.g., butanol and hexanol) has hardly been reviewed. Parameters affecting the optimization of the bioconversion process and bioreactor performance are addressed as well as the pathways involved in these bioconversions. New aspects, such as mixotrophy and sugar versus gas fermentation, are also reviewed. In addition, Clostridia can also produce higher alcohols from the integration of the Wood-Ljungdahl pathway and the reverse ß-oxidation pathway, which has also not yet been comprehensively reviewed. In the latter process, the acetogen uses the reducing power of CO/syngas to reduce C₄ or C₆ fatty acids, previously produced by a chain elongating microorganism (commonly Clostridium kluyveri), into the corresponding bioalcohol.     

Selective extraction of hemicelluloses from spruce using switchable ionic liquids

Switchable ionic liquids (SILs) made from alcohols, either hexanol or butanol, and CO₂ together with an amidine (1,8-diazabicyclo-[5.4.0]-undec-7-ene (DBU)) were investigated as dissolution/fractionation solvents for wood material. Both native spruce (Picea abies), and pre-extracted spruce were treated with either butanol SIL (SIL1) or hexanol SIL (SIL2) for 5 days at 55 °C under normal pressure. The SILs were formed by bubbling CO₂ through an equimolar mixture of either 1-hexanol or 1-butanol and DBU. The viscosity of the mixture increased from 7.1 mPa s to 2980 mPa s for SIL2 and 5.1 to 1600 mPa s for SIL1. Melting points of the SILs 1 and 2 were at 8 and 14 °C, respectively. After the treatment time (5 days), the undissolved fraction contained 38 wt.% less hemicelluloses compared to native spruce. There was an increase in the glucose content of the milled spruce treated with both SILs, since the milling step reduced the cellulose crystallinity of the wood and facilitated an easier SIL access into the wood. The solvents were very neutral in terms of lignin removal. Consequently, only about 2% of the lignin was removed from native wood. Moreover, a priori removal of the wood extractives did not influence the lignin removal.     

Access of cellulase to cellulose and lignin for poplar solids produced by leading pretreatment technologies

Adsorption of cellulase on solids resulting from pretreatment of poplar wood by ammonia fiber expansion (AFEX), ammonia recycled percolation (ARP), controlled pH, dilute acid (DA), flowthrough (FT), lime, and sulfur dioxide (SO₂) and pure Avicel glucan was measured at 4°C, as were adsorption and desorption of cellulase and adsorption of β‐glucosidase for lignin left after enzymatic digestion of the solids from these pretreatments. From this, Langmuir adsorption parameters, cellulose accessibility to cellulase, and the effectiveness of cellulase adsorbed on poplar solids were estimated, and the effect of delignification on cellulase effectiveness was determined. Furthermore, Avicel hydrolysis inhibition by enzymatic and acid lignin of poplar solids was studied. Flowthrough pretreated solids showed the highest maximum cellulase adsorption capacity (σ_solids = 195 mg/g solid) followed by dilute acid (σ_solids = 170.0 mg/g solid) and lime pretreated solids (σ_solids = 150.8 mg/g solid), whereas controlled pH pretreated solids had the lowest (σ_solids = 56 mg/g solid). Lime pretreated solids also had the highest cellulose accessibility (σ_cellulose = 241 mg/g cellulose) followed by FT and DA. AFEX lignin had the lowest cellulase adsorption capacity (σ_lignin = 57 mg/g lignin) followed by dilute acid lignin (σ_lignin = 74 mg/g lignin). AFEX lignin also had the lowest β‐glucosidase capacity (σ_lignin = 66.6 mg/g lignin), while lignin from SO₂ (σ_lignin = 320 mg/g lignin) followed by dilute acid had the highest (301 mg/g lignin). Furthermore, SO₂ followed by dilute acid pretreated solids gave the highest cellulase effectiveness, but delignification enhanced cellulase effectiveness more for high pH than low pH pretreatments, suggesting that lignin impedes access of enzymes to xylan more than to glucan, which in turn affects glucan accessibility. In addition, lignin from enzymatic digestion of AFEX and dilute acid pretreated solids inhibited Avicel hydrolysis less than ARP and flowthrough lignin, whereas acid lignin from unpretreated poplar inhibited enzymes the most. Irreversible binding of cellulase to lignin varied with pretreatment type and desorption method. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009     

Synthetic co-culture of autotrophic Clostridium carboxidivorans and chain elongating Clostridium kluyveri monitored by flow cytometry

Syngas fermentation with acetogens is known to produce mainly acetate and ethanol efficiently. Co-cultures with chain elongating bacteria making use of these products are a promising approach to produce longer-chain alcohols. Synthetic co-cultures with identical initial cell concentrations of Clostridium carboxidivorans and Clostridium kluyveri were studied in batch-operated stirred-tank bioreactors with continuous CO/CO₂-gassing and monitoring of the cell counts of both clostridia by flow cytometry after fluorescence in situ hybridization (FISH-FC). At 800 mbar CO, chain elongation activity was observed at pH 6.0, although growth of C. kluyveri was restricted. Organic acids produced by C. kluyveri were reduced by C. carboxidivorans to the corresponding alcohols butanol and hexanol. This resulted in a threefold increase in final butanol concentration and enabled hexanol production compared with a mono-culture of C. carboxidivorans. At 100 mbar CO, growth of C. kluyveri was improved; however, the capacity of C. carboxidivorans to form alcohols was reduced. Because of the accumulation of organic acids, a constant decay of C. carboxidivorans was observed. The measurement of individual cell concentrations in co-culture established in this study may serve as an effective tool for knowledge-based identification of optimum process conditions for enhanced formation of longer-chain alcohols by clostridial co-cultures.     

Adsorption of Clostridium thermocellum cellulases onto pretreated mixed hardwood, avicel, and lignin

Adsorption of Avicel-hydrolyzing activity was examined with respect to: mixed hardwood flour pretreated with 1% sulfuric acid for 9 s at 220 degrees C (PTW220), lignin prepared from PTW220 by either acid or enzymatic hydrolysis, and Avicel. Experiments were conducted at 60 degrees C for all materials, and also at 25 degrees C for PTW220. Based on transient adsorption results and reaction rates, times were selected at which to characterize adsorption at 60 degrees C as follows: PTW220, 1 min; lignin, 30 min; and Avicel, 45 min. Similar results were obtained for adsorption of cellulase activity to PTW220 at 25 and 60 degrees C, and for lignin prepared by enzymatic and acid hydrolysis. For all materials, adsorption was described well by a Langmuir equation, although the reversibility of adsorption was not investigated. Langmuir affinity constants (L/g) were: PTW220, 109; lignin, 17.9; Avicel, 4.3; cellulose from PTW220, >/=187. Langmuir capacity constants were 760 for PTW220 and 42 for Avicel; the cellulase binding capacity of lignin appeared to be very high under the conditions examined, and could not be determined. At low and moderate cellulase loadings at least, the majority of cellulase activity adsorbed to PTW220 is bound to the cellulosic component. The results indicate that PTW220, and its cellulose component in particular, differ radically from Avicel with respect to adsorption. Avicel-hydrolyzing activity and CMC-hydrolyzing activities were found to bind to Avicel with a constant ratio of essentially one, consistent with adsorption of a multi-activity complex. (c) 1993 John Wiley & Sons, Inc.     

Bilirubin removal from human plasma by Cibacron Blue F3GA using immobilized microporous affinity membranous capillary method

A novel affinity sorbent system for direct bilirubin removal from human plasma was developed. These new adsorbents comprise Cibacron Blue F3GA as the specific ligand, and microporous membranous poly(tetrafluoroethylene) capillary (modified by coating with a hydrophilic layer of poly(vinyl alcohol) after activation) as the carrier matrix. The affinity adsorbents carrying 126.5 micromol Cibacron Blue F3GA/g polymer was then used to remove bilirubin in a flow-injection system. Non-specific adsorption on the poly(vinyl alcohol) coated capillary remains low, and higher affinity adsorption capacity, of up to 76.2 mg/g polymer was obtained after dye immobilization. The bilirubin adsorption capacity of the affinity capillary decreased with increase in the recirculation rate of plasma. The adsorption capacity increased with increase the temperature while decreased with increase the ionic strength. The maximum adsorption was only observed in neutral solution (pH 6-7). The adsorption isotherm fitted the Langmuir model well. These new adsorbents have higher velocity of mass transfer, better adsorption capacity, less fouling, longer service life and good reusability. The results of blood tests suggested the dye affinity capillary has good blood compatibility.     

In situ product recovery by adsorption in the butanol/isopropanol batch fermentation

Summary In the butanol/isopropanol batch fermentation adsorption of alcohols can increase the substrate conversion. The fouling of adsorbants by cells and medium components is severe, but this has no measured effect on the adsorption capacity of butanol in at least three successive fermentations. With the addition of some adsorbants it was found that the fermentation was drawn towards the production of butyric and acetic acid.     

Introducing a single secondary alcohol dehydrogenase into butanol-tolerant Clostridium acetobutylicum Rh8 switches ABE fermentation to high level IBE fermentation

ABSTRACT: BACKGROUND: Previously we have developed a butanol tolerant mutant of Clostridium acetobutylicum, Rh8, from the wild type strain DSM 1731. Strain Rh8 can tolerate up to 19 g/L butanol, with solvent titer improved accordingly, thus exhibiting industrial application potential. To test if strain Rh8 can be used for production of high level mixed alcohols, a single secondary alcohol dehydrogenase from Clostridium beijerinckii NRRL B593 was overexpressed in strain Rh8 under the control of constitutive thl promoter. RESULTS: The heterogenous gene sADH was functionally expressed in C. acetobutylicum Rh8. This simple, one-step engineering approach led to the complete conversion of acetone into isopropanol, achieving a total alcohol titer of 23.88 g/l (7.6 g/l isopropanol, 15 g/l butanol, and 1.28 g/l ethanol) with a yield to glucose of 31.42%. The acid (butyrate and acetate) assimilation rate in isopropanol producing strain Rh8(psADH) was increased. CONCLUSIONS: The improved butanol tolerance and the enhanced solvent biosynthesis machinery in strain Rh8 is beneficial for production of high concentration of mixed alcohols. Strain Rh8 thus can be considered as a good host for further engineering of solvent/alcohol production.     

直链脂肪醇对豚鼠乳头肌慢动作电位的影响

本工作用相平面法观察和分析了乙醇、丁醇、己醇和辛醇对豚鼠乳头肌慢动作电位(APA,APD50,APD90,(?)_(max),(?)′_(max))及其所对应的钙电流(I_(max))和钾电流(I′_(max))的影响。结果表明:这四种脂肪醇对钙电流均有抑制作用,而对钾电流的影响,随碳原子数的加大从增强(乙醇)逐渐转化为削弱(已醇,辛醇)。并且碳链越长,产生这些效应所需脂肪醇的浓度越低,这提示醇的作用可能与它们的疏水性相关。     

Kinetic modeling for enzymatic hydrolysis of pretreated creeping wild ryegrass

A semimechanistic multi‐reaction kinetic model was developed to describe the enzymatic hydrolysis of a lignocellulosic biomass, creeping wild ryegrass (CWR; Leymus triticoides). This model incorporated one homogeneous reaction of cellobiose‐to‐glucose and two heterogeneous reactions of cellulose‐to‐cellobiose and cellulose‐to‐glucose. Adsorption of cellulase onto pretreated CWR during enzymatic hydrolysis was modeled via a Langmuir adsorption isotherm. This is the first kinetic model which incorporated the negative role of lignin (nonproductive adsorption) using a Langmuir‐type isotherm adsorption of cellulase onto lignin. The model also reflected the competitive inhibitions of cellulase by glucose and cellobiose. The Matlab optimization function of “lsqnonlin” was used to fit the model and estimate kinetic parameters based on experimental data generated under typical conditions (8% solid loading and 15 FPU/g‐cellulose enzyme concentration without the addition of background sugars). The model showed high fidelity for predicting cellulose hydrolysis behavior over a broad range of solid loading (4–12%, w/w, dry basis), enzyme concentration (15–150 FPU/ g‐cellulose), sugar inhibition (glucose of 30 and 60 mg/mL and cellobiose of 10 mg/mL). In addition, sensitivity analysis showed that the incorporation of the nonproductive adsorption of cellulase onto lignin significantly improved the predictability of the kinetic model. Our model can serve as a robust tool for developing kinetic models for system optimization of enzymatic hydrolysis, hydrolysis reactor design, and/or other hydrolysis systems with different type of enzymes and substrates. Biotechnol. Bioeng. 2009;102: 1558–1569. © 2008 Wiley Periodicals, Inc.     

Extracellular glycosyl hydrolase activity of the Clostridium strains producing acetone, butanol, and ethanol

Production of acetone, butanol, ethanol, acetic acid, and butyric acid by three strains of anaerobic bacteria, which we identified as Clostridium acetobutylicum, was studied. The yield of acetone and alcohols in 6% wheat flour medium amounted to 12.7–15 g/l with butanol constituting 51.0–55.6%. Activities of these strains towards xylan, β-glucan, carboxymethylcellulose, and crystalline and amorphous celluloses were studied. C. acetobutylicum 6, C. acetobutylicum 7, and C. acetobutylicum VKPM B-4786 produced larger amounts of acetone and alcohols and displayed higher cellulase and hemicellulase activities than the type strain C. acetobutylicum ATCC 824 in lab-scale butch cultures. It was demonstrated that starch in the medium could be partially substituted with plant biomass.     

Impact of operating variables on the expanded bed adsorption of Saccharomyces cerevisiae cells using a concanavalin A derivatized perfluorocarbon

The use of fluidizable affinity adsorbents for the adsorption of cells in expanded mode is investigated. Affinity adsorbents have been synthesized by immobilizing the lectin Concanavalin A onto the surface of triazine-activated perfluorocarbon-solids. The adsorbents were found to adsorb Saccharomyces cerevisiae cells from solution with adsorption capacities of up to 6.8 x 10(9) cells mL(-1). Adsorption kinetics were rapid with a time constant of 相似文献   

In vitro evaluation of the capacity of zeolite and bentonite to adsorb aflatoxin B1 in simulated gastrointestinal fluids

Anin vitro study using single concentration and isotherm adsorption was carried out to evaluate the capacity of Vietnamese produced zeolite and bentonite to adsorb aflatoxin B₁ (AFB₁) in simulated gastrointestinal fluids (SGFs), and a commercial sorbent hydrated sodium calcium aluminosilicate (HSCAS) was used as reference. In this study, AFB₁ solution was mixed with sorbents (0.3, 0.4 and 0.5% w/v) in SGFs at pH 3 and pH 7 and shaken for 8 h, centrifuged and the supernatant measured by Vicam fluorometer. Adsorption of AFB₁ onto zeolite and bentonite varied according to the pH of SGFs and was lower than HSCAS. Linearity between the increased amount of AFB₁ adsorbed on sorbents and the decrease of sorbent concentration was observed for bentonite and HSCAS, except for zeolite in SGFs at pH 7. The observed maximum amounts of AFB₁ adsorbed on bentonite and HSCAS were 1.54 and 1.56 mg/g, respectively. The adsorption capacities of bentonite and HSCAS for AFB₁ were 12.7 and 13.1 mg/g, respectively, from fitting the data to the Freundlich isotherm equation. Improvement in processing and purification for bentonite is needed to enhance the surface area, which would probably result in better adsorptive capacity for this sorbent.     

Alcohol-induced biphasic inhibition of myosin subfragment 1 K-EDTA-ATPase

Butanol-induced inhibition of K-EDTA-ATPase of myosin subfragment 1 proceeded by biphasic kinetics, consisting of rapid and slow inactivations. The extent of the rapid inactivation, which was estimated by extrapolating the process of slow inactivation to zero time of the incubation period, was saturated with butanol concentration. Recovery of activity by dilution in the rapid phase indicates that the rapid process is reversible. The slow inactivation was concomitant with a partial denaturation of the 50 kDa domain of S1, which was detected by limited tryptic digestion. Other alcohols (methanol, ethanol, propanol and hexanol) also inhibited the K-EDTA-ATPase in the rapid phase. The Ki decreased with an increase in the number of methylene groups of alcohol. When K-EDTA-ATPase activity in the rapid phase was plotted against viscosity, surface tension or dielectric constant, the curves were different for each of the various alcohol solutions. The rapid inactivation appears to be caused by a binding of the alkyl group to S1, rather than by solvent effects. The kinetics of rapid butanol inhibitions indicate that butanol reduces the maximum activity of ATPase but enhances an apparent affinity of S1 with ATP. These indications suggest that alcohol stabilizes S1.KATP intermediate. The rapid K-EDTA-ATPase inhibition was observed at the same alcohol concentration where S1 Mg-ATPase was activated.