EtOH Production Research Articles

Incorporation anthracene and Cu to NH2-Zr-UiO-67 metal-organic framework: Introducing the simultaneous selectivity and efficiency in photocatalytic CO2 reduction to ethanol

Metal-organic frameworks (MOFs) are considered promising candidates for photocatalytic CO2 reduction (PCR) into valuable organic fuels. However, compared to numerous reports regarding CO, CH4, and CHOOH generation, the explored MOFs have shown limited success in producing alcohols, particularly EtOH, through the PCR strategy. Existing MOFs also suffer from insufficient selectivity and efficiency. This study addresses these limitations by implementing a dual modification strategy on NH2-Zr-UiO-67 MOFs. This strategy involves synthesizing four MOF derivatives with different ratios of redox-active metal sites (Cu) to light absorption antenna (anthracene): 1:1, 2:1, 1:2, and 1:3. The as-synthesized MOFs (denoted as Cu/An (X:X)@NZU67 exhibited a remarkable capability for PCR-to-EtOH, without requiring a photosensitizer. The optimal amount of anthracene plays a crucial role in several aspects: improving light absorption, enhancing CO2 adsorption capacity, and promoting charge transfer/separation. Efficient charge transfer is critical for facilitating the multi-step electron transfer pathway required for ethanol synthesis. Notably, Cu/An (1:2)@NZU67 achieved an ethanol productivity of 624.17 µmolh−1g−1 for EtOH, which is, to the best of our knowledge, the highest efficiency reported for MOFs in PCR-to-EtOH conversion so far. Besides significant performance, the MOF showed 100% selectivity for EtOH production. This work represents a significant milestone in the field of PCR-to-EtOH transformation by providing a new perspective for designing MOF photocatalysts that can simultaneously improve both selectivity and efficiency.

Simultaneous Hydrogen and Ethanol Production from Crude Glycerol by a Microbial Consortium Using Fed-Batch Fermentation

Simultaneous bioproduction of hydrogen and ethanol from cheaper waste feedstock has the potential for the development of a more cost-effective biofuel generation process. Crude glycerol (CG), a by-product of the biodiesel industry, is a renewable resource, abundant, sold at low prices and available worldwide. However, the main CG limitations in fermentation processes are mainly related to the presence of impurities and the lack of nitrogen sources, both acting on microbial activity. In this study, a fermentation process with CG was improved using a highly specific microbial consortium called GlyCeroL (GCL). The process was developed in fed-batch fermentation mode using not diluted substrate and carried out under non-sterile conditions and at increasing amounts of the substrate (from 20 to 80 gL−1 of glycerol). The results showed higher H2 (from 6 to 8 LL−1) and EtOH (from 13 to 20 gL−1) production by increasing glycerol concentration from 20 to 40 gL−1. On the other hand, a decrease in glycerol degradation efficiency (from 75 to 56%) was observed. Then, the nitrogen sparging strategy was applied. Using CG of 40 gL−1, process improvement was achieved, leading to the increased production of hydrogen (10 LL−1) but not that of ethanol (20 gL−1). A further increase to 60 gL−1 of glycerol produced a slight increment of EtOH (21 gL−1) and H2 (11 gL−1) but a sharp decrease in glycerol degradation efficiency (41%). Acetate, as the main impurity of CG, was an additional carbon source for GCL microorganisms contributing to EtOH production and increasing that of lactic acid to restore the redox balance. The Denaturing Gradient Gel Electrophoresis (DGGE) fingerprint at the end of all fed-batch fermentations supported the robustness of GCL functional units and their adaptability to fermentation conditions.

Stress-induced ethanol affects endocytic vesicle recycling and F-actin organisation in arabidopsis root apex cells

Ethanol (EtOH) is a short-chain alcohol that is abundant in nature. EtOH is endogenously produced by plants under hypoxic conditions, and exogenously applied EtOH improves plant stress tolerance at low concentrations (<1%). However, no direct observations have shown how EtOH affects cellular events in plants. In intact Arabidopsis roots, 0.1% EtOH promoted reactive oxygen species production in root apex cells. EtOH also accelerated exocytic vesicle recycling and altered F-actin organisation, both of which are closely related to cell membrane properties. In addition to exogenous EtOH application, hypoxic treatment resulted in EtOH production in roots and degradation of the cross-wall actin cytoskeleton in root epidermal cells. We conclude that hypoxia-induced EtOH production affects endocytic vesicle recycling and associated signalling pathways. • EtOH unbalances endocytic and exocytic vesicle recycling pathways in root apex transition zone cells • EtOH induces dispersion of F-actin bundles at root apex transition zone cross-walls • Hypoxia induces endogenous EtOH production and depletion of F-actin in cells of Arabidopsis root apex transition zone

Boosting ethanol production rates from carbon dioxide in MES cells under optimal solventogenic conditions

Microbial Electrosynthesis (MES) has been widely applied for acetic acid (HA) production from CO2 and electricity. Ethanol (EtOH) has a higher market value than HA, and wide application in industry and as a biofuel. However, it has only been obtained sporadically and at low concentrations, probably due to sub-optimal operating conditions. This study aimed at enhancing EtOH productivity in MES cells by jointly optimising key operation parameters, including pH, H2 and CO2 partial pressure (pH2 and pCO2), and HA concentration, to promote solventogenesis. Two H-type cells were operated in fed-batch mode at −0.8 V vs. SHE with CO2 as the sole carbon source. A mixed culture, enriched with Clostridium ljungdahlii was used as the biocatalyst. The combination of low pH (<4.5) and pCO2 (<0.3 atm), along with high HA concentration (about 6 g L−1) and pH2 (>3 atm), were mandatory conditions for maintaining an efficient solventogenic culture, dominated by Clostridium sp., capable of high-rate EtOH production. The maximum EtOH production rate was 10.95 g m−2 d−1, and a concentration of 5.28 g L−1 was achieved. Up to 30 % of the electrons and 15.2 % of the carbon provided were directed towards EtOH production, and 28.1 kWh were required for the synthesis of 1 kg of EtOH from CO2. These results highlight that strict conditions are required for a continuous, reliable, EtOH production in MES cells. Future investigation should focus on improving cell configuration to achieve EtOH production at higher current densities while minimizing the electric energy input.

Pulse Electrodeposition of Cu on Porous Ag Framework for Electrochemical CO2 Conversion to Ethanol

Electrochemical conversion of carbon dioxide (CO2) gas is a simple and cost-benefit method to produce economically valuable materials such as carbon monoxide (CO), multi-carbon (C2+) oxygenate, and hydrocarbons. In particular, ethanol (EtOH) production is attractive to be applied for conventional transport fuels. However, there has been a lack of techniques to yield predominant EtOH from CO2. Copper (Cu), as the well-known and exclusive C2+ catalyst, thermodynamically prefers the production of (C2H4) compared to EtOH. Previous studies suggested that increased concentration of carbon monoxide (CO) as the intermediate of CO2 ameliorated the EtOH selectivity.1,2 Because the solubility of CO is very little in an aqueous electrolyte solution, surface diffusion of CO has been considered to enhance the local CO concentration. It suggests that catalyst interface is crucial to increasing EtOH yield, while little knowledge was developed.We prepared porous Ag inverse opal (AgIO) frameworks with a uniform pore size of ~ 600 nm. The CO2 gas was electrochemically reduced to CO with > 90% selectivity at -1.05 V vs. RHE. In addition, the CO settled in the pore, providing an opportunity for sequential electrochemical/chemical reactions. We deposited the ultra-thin Cu layer (2~10 nm) upon the Ag surface through the pulse electrodeposition technique (PED). This catalyst, indicated as PEDCu/AgIOs, performed ~33 % Faradaic efficiency (FE) of EtOH at -1.05 V vs. RHE. Moreover, PEDCu/AgIOs showed a high oxygenates ratio relative to hydrocarbons (FEoxygenate/FEC2H4) of 2.28, while H2 evolution was significantly suppressed. These results suggested that as-prepared thin Cu film was partially segregated, and the Ag surface was exposed, forming the mixed Ag and Cu interfaces in the given electrochemical condition. This hypothesis was confirmed by negligible EtOH from the Ag-free CuIOs structure. More importantly, the resulting EtOH selectivity outperformed Cu nanoparticles (~7 nm diameter) dispersed on AgIOs (7.45 % FE) and aggregated Cu nanostructures on AgIOs (17.65 % FE) prepared by the constant current mode of electrodeposition. We, therefore, anticipated that CO spillover was promoted by the remaining and ultra-thin Cu layer. Further experiments were conducted by controlling of the thickness, pore size, and interpore size of AgIO frameworks to understand their roles. PEDCu/AgIOs with larger AgIOs thickness and smaller pore size showed higher EtOH selectivity, while the interpore size did not significantly affect the product selectivity. In the presentation, I will discuss key parameters to determine EtOH selectivity and the presumable pathway of EtOH production in details. References Ting, L. R. L.; Piqué, O.; Lim, S. Y.; Tanhaei, M.; Calle-Vallejo, F.; Yeo, B. S., Enhancing CO2 Electroreduction to Ethanol on Copper–Silver Composites by Opening an Alternative Catalytic Pathway. ACS Catal. 2020, 10 (7), 4059-4069.Gurudayal; Perone, D.; Malani, S.; Lum, Y.; Haussener, S.; Ager, J. W., Sequential Cascade Electrocatalytic Conversion of Carbon Dioxide to C-C Coupled Products. ACS Appl. Energy Mater. 2019, 2 (6), 4551-4559.

Boosting electrocatalytic CO2–to–ethanol production via asymmetric C–C coupling

Electroreduction of carbon dioxide (CO2) into multicarbon products provides possibility of large-scale chemicals production and is therefore of significant research and commercial interest. However, the production efficiency for ethanol (EtOH), a significant chemical feedstock, is impractically low because of limited selectivity, especially under high current operation. Here we report a new silver–modified copper–oxide catalyst (dCu2O/Ag2.3%) that exhibits a significant Faradaic efficiency of 40.8% and energy efficiency of 22.3% for boosted EtOH production. Importantly, it achieves CO2–to–ethanol conversion under high current operation with partial current density of 326.4 mA cm−2 at −0.87 V vs reversible hydrogen electrode to rank highly significantly amongst reported Cu–based catalysts. Based on in situ spectra studies we show that significantly boosted production results from tailored introduction of Ag to optimize the coordinated number and oxide state of surface Cu sites, in which the *CO adsorption is steered as both atop and bridge configuration to trigger asymmetric C–C coupling for stablization of EtOH intermediates.

Scale-up of hydrogen and ethanol co-production by an engineered Escherichia coli

In this work, the scale-up from 0.01 to 10 L process for the co-production of hydrogen (H2) and ethanol (EtOH) by a genetically engineered Escherichia coli that utilizes hemicellulosic hydrolysates from wheat straw pretreated (WSP) as substrate is presented. Co-production of biofuels was performed through the redirection of carbon-flux to ethanol by deleting ldhA (D-lactate dehydrogenase) and frdD (fumarate reductase) genes in an H2-overproducer strain (E. coli WDH). Resulting strain, E. coli WDH-LF (ΔhycA ΔfrdD ΔldhA), increased up to 70% and 167% the H2 and EtOH production from glucose compared with the parenteral strain. Using WSP as substrate, the yields of H2 and EtOH remained constant at all the evaluated scales. In 10 L bioreactors, the production parameters such as maximum production, production rate and yield were 5,603.0 ± 233.5 mL H2/L, 41.4 ± 4.0 mL H2/L/h, 342.7 ± 14.3 mL H2/g TRS, 7.90 ± 0.28 g EtOH/L and 0.48 ± 0.01 g EtOH/g TRS, respectively. The results demonstrate the potential of the co-production of H2 and EtOH at different production scales by the engineered E. coli strain using lignocellulosic biomass as feedstock, such as wheat straw hydrolysates.

Turning Carbon Dioxide and Ethane into Ethanol by Solar-Driven Heterogeneous Photocatalysis over RuO2- and NiO-co-Doped SrTiO3

The current work focused on the sunlight-driven thermo-photocatalytic reduction of carbon dioxide (CO2), the primary greenhouse gas, by ethane (C2H6), the second most abundant element in shale gas, aiming at the generation of ethanol (EtOH), a renewable fuel. To promote this process, a hybrid catalyst was prepared and properly characterized, comprising of strontium titanate (SrTiO3) co-doped with ruthenium oxide (RuO2) and nickel oxide (NiO). The photocatalytic activity towards EtOH production was assessed in batch-mode and at gas-phase, under the influence of different conditions: (i) dopant loading; (ii) temperature; (iii) optical radiation wavelength; (vi) consecutive uses; and (v) electron scavenger addition. From the results here obtained, it was found that: (i) the functionalization of the SrTiO3 with RuO2 and NiO allows the visible light harvest and narrows the band gap energy (ca. 14–20%); (ii) the selectivity towards EtOH depends on the presence of Ni and irradiation; (iii) the catalyst photoresponse is mainly due to the visible photons; (iv) the photocatalyst loses &gt; 50% efficiency right after the 2nd use; (v) the reaction mechanism is based on the photogenerated electron-hole pair charge separation; and (vi) a maximum yield of 64 μmol EtOH gcat−1 was obtained after 45-min (85 μmol EtOH gcat−1 h−1) of simulated solar irradiation (1000 W m−2) at 200 °C, using 0.4 g L−1 of SrTiO3:RuO2:NiO (0.8 wt.% Ru) with [CO2]:[C2H6] and [Ru]:[Ni] molar ratios of 1:3 and 1:1, respectively. Notwithstanding, despite its exploratory nature, this study offers an alternative route to solar fuels’ synthesis from the underutilized C2H6 and CO2.

Techno-Economic Feasibility of Biomass Washing in 1G2G Sugarcane Biorefineries

There are still bottlenecks to be overcome for the feasible industrial production of first- and second-generation ethanol (1G2G EtOH). One of them is the pretreatment stage. Washing is a candidate strategy to remove lignocellulose-derived byproducts from pretreated biomass, in order to reduce the negative effects of furaldehydes and phenolic compounds in the downstream biochemical reactions. However, the effectiveness of the removal of these inhibitors is highly influenced by the operational conditions of the washing process. Here, evaluation was made of the techno-economic impacts of including a washing operation after hydrothermally pretreating sugarcane bagasse for 2G EtOH production in an integrated 1G2G biorefinery. Different washing protocols were tested, considering their effects on the enzymatic hydrolysis and fermentation, and experimental data were used for simulation of process scale-up. The removal of inhibitors improved the glucose yield by 40%, followed by an increase of ~ 30% in EtOH productivity. These findings showed that washing is a cost-competitive option for a 1G2G biorefinery, with a net present value for the industrial unit of ~US$ 2.3E + 8, which was the highest among the 1G2G scenarios analyzed.

The stability of ethanol production from organic waste by a mixed culture depends on inoculum transfer time

• Ethanologenic community repeatably enriched from sheep rumen and anaerobic sludge. • High EtOH production (60 mM) from OMSW at pH ≤ 5.5 in batch microcosms. • Loss of activity and community composition across sequential inoculum transfers. • Interval of inoculum transfer critical to maintain ethanologenic activity. • 3-day transfers stable EtOH activity by enriching Clostridium and Pseudomonas . Mixed Culture Fermentation is a promising route for bioethanol production from organic wastes. Yet, achieving a stable ethanologenic activity in undefined mixed cultures remains a challenge. This work aimed to retain ethanol production from organic municipal solid waste by microbial communities enriched from sheep rumen and anaerobic sludge mixtures, under low process control (initially aerobic conditions and initial pH ≤ 5.5). To find a stable operating window, sequential inoculum transfer intervals were evaluated (14 and 3-days). Soluble fermentation product profiles and changes in the prokaryotic communities were monitored. The originally inoculated batches always produced high ethanol concentrations (60 mM; 0.070 L EtOH /Kg waste ), equivalent to 1/6 of the current corn grain-based ethanol industrial production process. Fermentative activity and community richness significantly decreased in both transfer times regimes tested. However, the 3-day transfer interval led to a stable community which consistently produced ethanol (30 mM) as its main soluble fermentation product. Originally inoculated and 3-day transferred communities consistently enriched for a solventogenic Clostridium and an acid-tolerant Pseudomonas species. Ethanologenesis, as a dominant catabolic process, is an inherent property of these mixed culture fermentations, and its maintenance across successive transfers is critically dependant on the inoculum transfer time.

Photoactivation of Cu Centers in Metal-Organic Frameworks for Selective CO2 Conversion to Ethanol.

CO2 hydrogenation to ethanol is of practical importance but poses a significant challenge due to the need of forming one C-C bond while keeping one C-O bond intact. CuI centers could selectively catalyze CO2-to-ethanol conversion, but the CuI catalytic sites were unstable under reaction conditions. Here we report the use of low-intensity light to generate CuI species in the cavities of a metal-organic framework (MOF) for catalytic CO2 hydrogenation to ethanol. X-ray photoelectron and transient absorption spectroscopies indicate the generation of CuI species via single-electron transfer from photoexcited [Ru(bpy)3]2+-based ligands on the MOF to CuII centers in the cavities and from Cu0 centers to the photoexcited [Ru(bpy)3]2+-based ligands. Upon light activation, this Cu-Ru-MOF hybrid selectively hydrogenates CO2 to EtOH with an activity of 9650 μmol gCu-1 h-1 under 2 MPa of H2/CO2 = 3:1 at 150 °C. Low-intensity light thus generates and stabilizes CuI species for sustained EtOH production.

Selective Formation of C2 Products from Electrochemical CO2 Reduction over Cu1.8Se Nanowires

Electrochemical reduction of CO2 into higher-value C2 products (e.g., C2H4 and EtOH) is desirable for applications in chemical and fuel industries. Herein, we report that Cu1.8Se nanowires supported on Cu foam can function as an efficient electrocatalyst for selective reduction of CO2 to C2 products, with the Faradaic efficiencies for C2H4 and EtOH production reaching 55% and 24% at −1.1 V, respectively. Additionally, these nanowires also demonstrate a good long-term stability. We believe that the high C2/C1 product selectivity exhibited by the resulting catalyst is more likely due to a high CO2 pressure and the presence of Se species.

Integrated techno-economic and environmental analysis of butadiene production from biomass

In this study, lignocellulose biorefineries annexed to a typical sugar mill were investigated to produce either ethanol (EtOH) or 1,3-butadiene (BD), utilizing bagasse and trash as feedstock. Aspen simulation of the scenarios were developed and evaluated in terms of economic and environmental performance. The minimum selling prices (MSPs) for bio-based BD and EtOH production were 2.9–3.3 and 1.26–1.38-fold higher than market prices, respectively. Based on the sensitivity analysis results, capital investment, Internal Rate of Return and extension of annual operating time had the greatest impact on the MSP. Monte Carlo simulation demonstrated that EtOH and BD productions could be profitable if the average of ten-year historical price increases by 1.05 and 1.9-fold, respectively. The fossil-based route was found inferior to bio-based pathway across all investigated environmental impact categories, due to burdens associated with oil extraction.

Self-dark fermentation of lipids rich wastewater for 2-biofuels (H2 and Et-OH) production

Abstract Food processing industry produces huge quantities of lipids rich wastewater which affect negatively on the environment. However, wastewater represents an attractive and sustainable source for biofuels production via robust anaerobic digestion process. Hydrogen (H2) and ethanol (Et-OH) production from lipids rich wastewater via up-flow anaerobic staged reactor (UASR) was investigated at different hydraulic retention times (HRTs) and organic loading rates (OLRs). H2 and Et-OH production significantly (p

Photocatalytic Reduction of CO2 with Water into Methanol and Ethanol Using Graphene Derivative–TiO2 Composites: Effect of pH and Copper(I) Oxide

Fuels derived from CO2 can contribute to neutralize the carbon balance in the atmosphere and can be converted into easily transportable liquid chemicals, such as methanol (MeOH) or ethanol (EtOH). In this work, a composite prepared from graphene oxide (GO) and titanium dioxide (TiO2) is applied to the photocatalytic water reduction of CO2 into renewable fuels under UV/vis light irradiation. The pH was identified as a key variable towards selective MeOH formation. The prepared GO–TiO2 composite exhibited superior photocatalytic activity for EtOH production (144.7 μmol g−1 h−1) at pH 11.0 and for MeOH production (47.0 μmol g−1 h−1) at pH 4.0. The effect of copper species in the GO–TiO2 composite is also assessed and its influence on the photocatalytic reaction inferred. The photocatalysts prepared with copper nitrate as copper precursor exhibited the highest rate of MeOH production at pH 11.0. Accordingly, a conceptual scheme in which the photogenerated electrons are used to reduce CO2 is proposed.

Life cycle assessment of corn stover production for cellulosic ethanol in Quebec

Whitman, T., Yanni, S.F. and Whalen, J.K. 2011.Life cycle assessment of corn stover production for cellulosic ethanol in Quebec. Can. J. Soil Sci.91: 997–1012. The province of Quebec has a target of 5% ethanol (EtOH) content in fuel by 2012, which means the province will require about 400 million L of ethanol per year based on current consumption. Current research is focused on “second generation biofuels” such as cellulosic EtOH, which can be produced from agricultural by-products like corn stover. A life cycle assessment (LCA) evaluates the “cradle to gate” impact of corn stover feedstock production for cellulosic EtOH production in three corn-producing regions in Quebec for two impact categories: energy and greenhouse gas (GHG) impacts. The modelled system boundaries include in-field processes: corn stover production, collection, transport, soil organic carbon (SOC) loss, and N2O emissions, as well as background processes: herbicide, fertilizer, seed, and fuel production and transport. Sensitivity analyses vary the percentage of corn stover collected, contrast a multiple-pass with a one-pass stover-grain collection system, and compare mass, economic and system expansion allocation methods. Total energy impact is 931–1442 MJ t−1 dry stover collected under 15% stover collection, with stover harvest, transport, and field operationscontributing most strongly to the total impact. Total GHG emissions from corn stover production and transport of stover to the ethanol facility are320–488kg CO2e t−1 dry stover under 15% stover collection, with SOC loss, N2O emissions, and stover harvest contributing the most to the total impact. Sensitivity analysis reveals that the energy and GHG impacts of stover production are strongly influenced by the mass of stover collected, the use of a one-pass system, and the choice of allocation methods. Scaling-up results from the modelled system suggest that 100% of Quebec's EtOH targets could technically be supplied using corn stover feedstock, but this may come at the expense of GHG emissions and soil health.

Bioprospecting Thermophilic Microorganisms from Icelandic Hot Springs for Hydrogen and Ethanol Production

Fermentations can be used to produce sustainable energy carriers, such as hydrogen and ethanol (EtOH), from biomass or organic waste materials. The aim of this research was to prospect efficient H2- and EtOH-producing thermophilic microorganisms derived from hot spring environments in Iceland. Hydrogen- and EtOH-producing enrichment cultures were obtained from various hot spring samples over a temperature range of 50–78 °C. The temperature dependencies for the most promising enrichments were determined with a temperature-gradient incubator. One of the enrichments (33HL) produced 2.10 mol of H2/mol of glucose at 59 °C. Another enrichment (9HG), dominated by bacteria closely affiliated with Thermoanaerobacter thermohydrosulfuricus, produced 0.68 mol of H2/mol of glucose, and 1.21 mol of EtOH/mol of glucose at 78 °C. Hydrogen and EtOH production by 9HG was characterized further in a continuous-flow bioreactor at 74 °C. The highest H2 and EtOH yields of 9HG were obtained at pH 6.8 ± 0.3. Lactate production de...

Insights into the Origin of Postmortem Ethanol

Accurate interpretation of the blood ethanol (EtOH) concentration at the time of death presents a difficult task since the origin of detected EtOH in postmortem cases (either in corpses or in specimens after sample collection) may vary. Headspace gas chromatography is the choice method for detecting EtOH in blood or other specimens, due to the accuracy and sensitivity it provides. Possible sources of postmortem EtOH have been the ante-mortem ingestion, the ante-mortem endogenous production and the postmortem microbial neo-formation, which has been considered the most critical factor that could complicate the results. It has been reported that EtOH could be formed postmortem in variable and non-predictable amounts, as a function of the type and number of microorganisms present either in corpses or specimens collected at autopsy. The presence of other volatiles-mostly n-propanol-has been correlated to microbial EtOH production, although the quantitative pattern between them and EtOH still remains obscure. The factors most frequently implicated in the mechanism of postmortem EtOH production in corpses have been considered the number and nature of microbes present, the availability of various types of substrates, the temperature and the time. Complication in the interpretation of blood alcohol concentration could arise due to the atypical distribution of EtOH in the body compartments after death. Specimens to blood EtOH ratios reported in the literature are presented. All the aforementioned aspects are discussed in a comprehensive way, providing a deep insight into this essential problem.

Peach fruit ripening and quality in relation to picking time, and hypoxic and high CO2 short-term postharvest treatments

Peach fruits (Prunus persica L. Batsch, cv Springcrest) were harvested at two ripening stages (flesh firmness of 60 N, first harvest, and 45 N, second harvest) and maintained at 20°C in air (control) or for 24 and 48 h in streams of ultra low (<1%) oxygen (ULO) or high (30%) CO2 concentration and then transferred to air for up to 8 days. The decline in flesh firmness was strongly reduced by ULO and CO2 treatments in fruits of both harvests, although the effect was stronger in fruits picked earlier in which ethylene biosynthesis remained at the basal level. In fruits of the second harvest, endo β-1,4-glucanase (EGase) activity was lower in ULO- and CO2-treated fruits than in control fruits at the end of the 24 h treatment and the following two days in air. Acetaldehyde (AA) gradually accumulated in control fruit and the highest concentrations were detected during late ripening. Both treatments induced a strong accumulation of AA but, with the exception of the 24 and 48 h CO2 treatments performed on fruits of the second harvest, a decrease in AA content was observed when the fruits were transferred to air. A slight increase in ethanol (EtOH) was found throughout the ripening process in control fruits; ULO and CO2 strongly stimulated EtOH production. When fruits were transferred to air, EtOH concentration declined rapidly. Alcohol dehydrogenase (ADH) activity significantly increased in control fruit only in the late stages of ripening. Greater ADH activity was found throughout the experimental period in fruits of the first harvest treated for 24 h in ULO and CO2, whereas, at day 8, control and treated fruits of the second harvest showed similar ADH activity values. Hypoxic and, to a lesser extent, CO2-enriched atmospheres stimulated Adh gene expression.

Ethanol-Modulated Cytokine Production and Expression in Skin Cells Exposed to Methotrexate

Evidence suggests a link between alcohol consumption, psoriasis and the response of psoriatic patients to methotrexate (MTX) therapy. Ethanol (EtOH) may play a role in the pathogenesis of psoriasis by upregulating the expression and inducing the local secretion of proinflammatory cytokines, e.g. interleukins IL-1α, IL-6, chemokine IL-8 and tumor necrosis factor alpha (TNF-α). We investigated whether EtOH or MTX or their combination influence the secretion of these cytokines using normal human primary skin cells (NHPSC) and epidermoid cell line A431. The objectives of this study were: (1) to quantify the differences in cellular changes induced by MTX, (2) to measure the effect of EtOH on MTX toxicity and (3) to determine the relationship between MTX and EtOH exposure and production of proinflammatory cytokines. NHPSC and A431 were incubated with 0–10 mM MTX or α-MEM (control) in the presence or absence of 40 mM EtOH. A formazan 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) assay was used as a marker for cell viability (control was 100%). Significance was calculated by ANOVA. Cytokine release into media was quantitated by ELISA. After 24 h of MTX exposure, the release of IL-1α was unchanged. IL-6 increased 1.7 times in both cultures, and IL-8 increased 1.7 times in NHPSC and 2.1 times in A431. TNF-α release increased twice in A431 but not in NHPSC. Human recombinant IL-1α and IL-6 for 24 h had no effect, while TNF-α reduced cytoviability by 30% in NHPSC and 22% in A431. Anti-TNF-α reversed the effect produced by TNF-α in NHPSC and reduced it in A431 (11.8%, p < 0.05). We concluded that in vitro in normal human primary keratinocytes, toxicity and inflammatory responses are enhanced by EtOH.