Synthesis Of Acetic Acid Research Articles

Direct Photocatalytic Synthesis of Acetic Acid from Methane and CO at Ambient Temperature Using Water as Oxidant

Direct functionalization of methane selectively to value-added chemicals is still one of the main challenges in modern science. Acetic acid is an important industrial chemical produced nowadays by expensive and environmentally unfriendly carbonylation of methanol using homogeneous catalysts. Here, we report a new photocatalytic reaction route to synthesize acetic acid from CH4 and CO at room temperature using water as the sole external oxygen source. The optimized photocatalyst consists of a TiO2 support and ammonium phosphotungstic polyoxometalate (NPW) clusters anchored with isolated Pt single atoms (Pt1). It enables a stable synthesis of 5.7 mmol·L-1 acetic acid solution in 60 h with the selectivity over 90% and 66% to acetic acid on liquid-phase and carbon basis, respectively, with the production of 99 mol of acetic acid per mol of Pt. Combined isotopic and in situ spectroscopy investigation suggests that synthesis of acetic acid proceeds via a photocatalytic oxidative carbonylation of methane over the Pt1 sites, with the methane activation facilitated by water-derived hydroxyl radicals.

On the way to potential antifungal compounds: synthesis and in vitro activity of 2-benzofuranylacetic acid amides.

Crop losses caused by microbial infections are a significant global issue, especially in tropical regions. The development of novel antimicrobial agents, particularly antifungal agents, has been explored from various perspectives, including chemical synthesis. However, conventional approaches typically involve synthesizing new and potent compounds on a small scale (a few milligrams), making the scale-up of the reaction a major challenge. In this manuscript, we present a method for the synthesis of new and active (against Fusarium oxysporum) benzofuranyl acetic acid amides. Our strategy allows us to synthesize the key precursor on the gram scale, enabling the production of sufficient quantities of other active compounds within short timeframes for conducting biological studies. All the reactions used in this manuscript are recognized by their industrial application.

Impact of plant growth promoting rhizobacteria Serratia nematodiphila RGK and Pseudomonas plecoglossicida RGK on secondary metabolites of turmeric rhizome

Plant growth promoting rhizobacteria (PGPR) are diverse group of soil bacteria that live in the rhizosphere of plants. The current research focuses on the plant growth promoting potential of two strains, Serratia nematodiphila RGK and Pseudomonas plecoglossicida RGK isolated from the rhizospheric soil of the turmeric plant. Both of these bacterial strains found to have the capacity to solubilize phosphate, zinc and potassium as well as potential to produce indole acetic acid, siderophores, nitrogen fixation, ammonia, hydrogen cyanide (HCN) and exopolysaccharide synthesis. Further, they showed the salinity tolerance up to the 6–7% NaCl and antibiotic sensitivity to Gentamycin, Kanamycin, Streptomycin, Tobramycin, and Amikacin. The isolate Pseudomonas plecoglossicida RGK also has shown antifungal activity against fungal pathogen of turmeric Pythium aphanidermatum. Treatment of turmeric rhizomes with separate and by combination of both strains demonstrated remarkable increase growth parameters of turmeric as compared to control. They improved the growth metrics of the plant such as the number of leaves, shoot height, rhizome biomass as well as phenolic, flavonoid content, and free-radical (DPPH) scavenging ability. As compared to the untreated plants, PGPR treated rhizomes showed higher amounts of secondary metabolites, primarily curcumin and additional compounds such 4-Hydroxy-2-methylacetophenone, 2,4-Di-tertbutyl phenol, aR-Turmerone, and (Z) -gamma-Atlantone. The detection of a phenolic compound, 4-Hydroxy-2-methylacetophenone, in a consortium-treated turmeric plant, which has significant biological activity is reported for first time. The use of different microbial strains in a single formulation is a new and developing trend for sustainable agriculture.

Endophytic fungi Aspergillus spp. reduce fusarial wilt disease severity, enhance growth, metabolism and stimulate the plant defense system in pepper plants

Plants in various republics of the world face many dangers, including diseases that threaten crop productivity. The development and increase of novel species of infectious pathogens have made plant growth threatened. Fusarium wilt is one of the fiercest diseases affecting vegetables, which causes a great loss in the quality and quantity of pepper plants all over the world. In this study, stimulation of physiological immune responses in pepper plant using ecofriendly inducers (Aspergillus alabamensis, Aspergillus oryzae, and Aspergillus tubingensis) against Fusarium wilt had been studied. Endophytic fungi were assayed for their capability to synthesize hydrocyanic acid, phosphate solubilization, siderophores, and indole acetic acid synthesis, and the antifungal potential of ecofriendly inducers against F. oxysporum was also examined. A notable antifungal potential antifusarial with a supreme activity of A. tubingensis was found. More ultrastructure by TEM of Fusarium showed that sharp changes occurred in the cell wall, mycelium, and conidia as a result of treatment with A. tubingensis, A. oryzae, and A. alabamensis. The results demonstrated the high severity of F. oxysporum on pepper seedlings. Infected seedlings showed a high reduction in all vegetative parameters, photosynthesis, entire protein, and total carbohydrate. In the current study, the potential of endophytic fungi through foliar and soil application was applied to the Fusarium-infected pepper plants under pot conditions. Disease index, vegetative growth, photosynthetic pigments, osmolyte content, stress markers, and antioxidant isozymes were assessed. The achieved result indicates that tested endophytes through two modes (foliar and soil) lowered PDI and produced high protection, with the most protection influence represented by A. tubingensis (through the soil) by 83.33%. It was concluded that use of A. tubingensis, A. alabamensis, and A. oryzae could be commercially used as eco-friendly agents for the defense of pepper seedlings against Fusarium wilt disease.

Structural characterization and bifidogenic activity of polysaccharide from Dictyophora indusiata

Dictyophora indusiata is an edible and medicinal fungi with various nutritious, especially higher in carbohydrates. In this work, polysaccharide from Dictyophora indusiate (DIP) was extracted by the hot-water, and four polysaccharide fractions (DIP0, DIP1, DIP2 and DIP3) were obtained using cellulose DE-52 column. The objective of this study was to investigate the structure and bifidogenic activity of four polysaccharide fractions from Dictyophora indusiate. Structure of DIP was evaluated by HPLC, FT-IR and SEM, and the results indicated that four polysaccharide fractions from Dictyophora indusiate were consisted of mannose, glucose and galactose with almost the same functional groups. Remarkably, the DIP3 had significant differences in monosaccharide compositions, which additionally contains glucuronic acid. In addition, DIP0 exhibited a three-dimensional network structure formed by crosslinked chains, while DIP1, DIP2 and DIP3 displayed the irregular flake structure. During the periods of fermentation in vitro, a strong increase of Bifidobacterium longum was observed in the presence of DIP0, DIP1 and DIP2. In particular, Bifidobacterium longum produced more acetic acid in the medium with DIP0 as the carbon source during the fermentation, probably due to the fact that DIP0 contained higher mannose and lower glucose. These results suggest that DIP0 promoted the growth of Bifidobacterium longum and its metabolic synthesis of acetic acid, which would provide necessary information for the prebiotic studies of DIP.

Rational Design of Metal-Alkoxide-Functionalized Metal-Organic Frameworks for Synergistic Dual Activation of CH4 and CO2 toward Acetic Acid Synthesis.

The concurrent conversion of CH4 and CO2 into acetic acid is an ideal route to migrate the two greenhouse gases and manufacture a high-value-added C2 product with an atom economy of 100% but remains challenging due to the chemical inertness of both gases. By leveraging density functional theory (DFT) calculations, we report herein the computational design of metal-alkoxide-functionalized metal-organic framework (MOF) UiO-67 with well-defined dual sites that can activate CH4 and CO2 cooperatively to boost acetic acid synthesis. The dual sites are distributed on two adjacent functionalized organic linkers originating from the same node and feature a metal-metal distance of about 6-7 Å. Initially, a total of 13 single-site metal-alkoxide-functionalized UiO-67s (including three alkaline earth metals and 10 transition metals) are examined; then, favorable metal-alkoxides are identified and further used to design dual-site metal-alkoxide-functionalized UiO-67s for converting CH4 and CO2 into acetic acid. Detailed mechanistic investigation predicts that the dual-site UiO-67s functionalized with Mn-, Fe-, Co-, Ni-. and Zn-alkoxide are highly promising catalysts for this reaction. Compared to the single-site counterparts, the metal pair-site UiO-67s provide a subtle microenvironment for synergistic dual activation of CH4 and CO2, thus efficiently stabilizing the transition state and substantially reducing the reaction barrier for C-C coupling. The microscopic insights and design strategies in this work might advance the development of efficient MOF-based catalysts with built-in cooperative active sites toward direct acetic acid synthesis from CH4 and CO2.

Insights into Genomic Evolution and the Potential Genetic Basis of Klebsiella variicola subsp. variicola ZH07 Reveal Its Potential for Plant Growth Promotion and Autotoxin Degradation.

The accumulation of autotoxins in soil causes continuous cropping obstacle stress in crops, and the bioremediation of autotoxins by microorganisms is an efficient process. In this study, strain ZH07 was isolated from the peanut rhizosphere and was found to be utilizing multiple autotoxins as its carbon sources. Based on its genomic characteristics and a phylogenetic analysis, ZH07 represents a member of Klebsiella variicola subsp. variicola. A comparative genomic analysis exhibited evolutionary dynamics exhibited by mobile genetic elements (MGEs), strain-specific genes, potential horizontal genes, and evolutionary constraints driven by purifying selection, which facilitated its genomic adaptation to rhizosphere soil. Genome mining revealed the potential genomic properties associated with plant growth promotion, such as nitrogen fixation, indole acetic acid synthesis, phosphonate solubilization and assimilation, siderophore production, and secondary metabolite synthesis. Moreover, abundant genes putatively responsible for the biodegradation of aromatic xenobiotics, including benzoic acid, cinnamic acid, vanillic acid, protocatechuic acid, phenylacetic acid, and p-hydroxybenzoic acid were also observed in the ZH07 genome. Compared to autotoxin stress alone, the combination of ZH07 application promoted peanut germination and seedling growth. Our analysis revealed the genetic adaptation of ZH07 to the rhizosphere environment and the potential genetic basis and effectiveness of the isolate to serve as a plant growth stimulator. IMPORTANCE Continuous cropping obstacles reduce the production and quality of agricultural products, and the application of rhizosphere beneficial microbes is an important strategy. Strain ZH07 showed autotoxin-degrading and plant growth-promoting capacities. The objectives of this study were to characterize its genomic evolution and the potential genetic basis of the autotoxin degradation and plant growth promotion. ZH07 represents a member of Klebsiella variicola subsp. variicola, based on genomic and phylogenetic analyses. Its genomic components have undergone different degrees of purifying selection, and the disparity in the evolutionary rate may be associated with its niche adaptation. A systematic analysis of the ZH07 genome identified the potential genetic basis that contributes to plant growth promotion and to aromatic xenobiotic biodegradation. This study demonstrates that plant growth-promoting rhizobacteria (PGPR) play important roles in autotoxin biodegradation and can be used as biofertilizers to enhance the growth of peanuts in response to continuous cropping obstacle stress.

Fermentation Conditions Affect the Synthesis of Volatile Compounds, Dextran, and Organic Acids by Weissella confusa A16 in Faba Bean Protein Concentrate.

Fermentation with Weissella confusa A16 could improve the flavor of various plant-based sources. However, less is known about the influence of fermentation conditions on the profile of volatile compounds, dextran synthesis and acidity. The present work investigates the synthesis of potential flavor-active volatile compounds, dextran, acetic acid, and lactic acid, as well as the changes in viscosity, pH, and total titratable acidity, during fermentation of faba bean protein concentrate with W. confusa A16. A Response Surface Methodology was applied to study the effect of time, temperature, dough yield, and inoculum ratio on the aforementioned responses. Twenty-nine fermentations were carried out using a Central Composite Face design. A total of 39 volatile organic compounds were identified: 2 organic acids, 7 alcohols, 8 aldehydes, 2 alkanes, 12 esters, 3 ketones, 2 aromatic compounds, and 3 terpenes. Long fermentation time and high temperature caused the formation of ethanol and ethyl acetate and the reduction of hexanal, among other compounds linked to the beany flavor. Levels of dextran, acetic acid, and lactic acid increased with increasing temperature, time, and dough yield. Optimal points set for increased dextran and reduced acidity were found at low temperatures and high dough yield. Such conditions would result in hexanal, ethyl acetate and ethanol having a relative peak area of 35.9%, 7.4%, and 4.9%, respectively.

Metagenomics of Virus Diversities in Solid-State Brewing Process of Traditional Chinese Vinegar.

Traditional Chinese vinegar offers an exceptional flavor and rich nutrients due to its unique solid-state fermentation process, which is a multiple microbial fermentation system including various bacteria, fungi and viruses. However, few studies on the virus diversities in traditional Chinese vinegar have been reported. In this paper, using Zhenjiang aromatic vinegar as a model system, we systemically explored the viral communities in the solid-state brewing process of traditional Chinese vinegar using bacterial and viral metagenomes. Results showed that the viral diversity in vinegar Pei was extensive and the virus communities varied along with the fermentation process. In addition, there existed some interactions between viral and bacterial communities. Moreover, abundant antibiotic resistance genes were found in viromes, indicating that viruses might protect fermentation bacteria strains from the stress of antibiotics in the fermentation environment. Remarkably, we identified abundant auxiliary carbohydrate metabolic genes (including alcohol oxidases, the key enzymes for acetic acid synthesis) from viromes, implying that viruses might participate in the acetic acid synthesis progress of the host through auxiliary metabolic genes. Taken together, our results indicated the potential roles of viruses in the vinegar brewing process and provided a new perspective for studying the fermentation mechanisms of traditional Chinese vinegar.

The rhizosphere microbiome improves the adaptive capabilities of plants under high soil cadmium conditions.

Cadmium (Cd) contamination of agricultural soils poses a potential public health issue for humans. Phytoremediation-based accumulating plants are an effective and sustainable technology for Cadmium remediation of contaminated agricultural soil. The rhizosphere microbiome can promote the growth and Cadmium accumulation in hyperaccumulators, but its taxonomic and functional traits remain elusive. The present study used two ecotypes of Sedum alfredii, an accumulating ecotype (AE) and a non-accumulating ecotype (NAE), as model plants to investigate the rhizosphere microbiome assemblages and influence on plant growth under high cadmium conditions. Our results showed that distinct root microbiomes assembled in association with both ecotypes of S. alfredii and that the assemblages were based largely on the lifestyles of the two ecotypes. In addition, we demonstrated that the functions of the microbes inhabiting the rhizosphere soils were closely associated with root-microbe interactions in both ecotypes of S. alfredii. Importantly, our results also demonstrated that the rhizosphere microbiome assembled in the AE rhizosphere soils contributed to plant growth and cadmium uptake under high cadmium conditions through functions such as nitrogen fixation, phosphorus solubilization, indole acetic acid (IAA) synthesis, and siderophore metabolism. However, this phenomenon was not clearly observed in the NAE. Our results suggest that the rhizosphere microbiome plays important roles in biogeochemical nutrient and metal cycling that can contribute to host plant fitness.

Biofertilizing effect of putative plant growth promoting rhizobacteria in vitro and in tomatillo seedlings (Physalis ixocarpa Brot.)

It has been widely reported that rhizobacteria improve plant nutrition and growth. Therefore, they can be utilized to reduce the use of synthetic fertilizers. The mechanisms involved in rhizobacteria biofertilization includes phosphorus and potassium solubilization, nitrogen fixation, ammonia production, and phytohormones synthesis. In this study, 6 rhizobacteria strains were selected and identified based on a preliminary screening from wild plants of Physalis sp. and their biofertilization mechanisms were assessed in vitro. Of these isolates, four were further tested in tomatillo seedlings. The in vitro assays results indicated that the bacterium identified as Atlantibacter sp. showed activity in all biofertilization mechanisms evaluated, with the best results in phosphorus solubilization and indole acetic acid synthesis. In the seedlings experiment, the seedlings with bacterial treatments presented higher leaf weight (>349%) and root length (>11%) than the control. Seedlings treated with Priestia megaterium resulted in the highest height of seedlings, 140% compared to the control. In addition, P. megaterium and Acinetobacter calcoaceticus were significantly higher in the concentration of three minerals: K (54 and 37%), Ca (88 and 80%), and Mg (89 and 81%). Tested strains: P. megaterium, A. calcoaceticus, and Atlantibacter sp. demonstrated outstanding biochemical and agronomical characteristics in vitro and in vivo, making them excellent biofertilizers candidates for tomatillo crop production.

De novo biosynthesis of α-aminoadipate via multi-strategy metabolic engineering in Escherichia coli.

As a non‐protein amino acid, α‐aminoadipate is used in the fields of medicine, chemical engineering, food science, and others. For example, α‐aminoadipate is an important precursor for the production of β‐lactam antibiotics. Currently, the synthesis of α‐aminoadipate depends on chemical catalysis that has the disadvantages of high cost, low yield, and serious pollution. In this study, we construct a biosynthesis pathway of α‐aminoadipate in Escherichia coli using lysine as a precursor. In addition, we regulate the cell metabolism to improve the titer of α‐aminoadipate via multi‐strategy metabolic engineering. First, a novel synthetic pathway was constructed to realize de novo synthesis of α‐aminoadipate with titers of 82 mg/L. Second, the key enzymes involved in enhancing precursor synthesis were overexpressed and the CO2 fixation process was introduced, and these led to 80% and 34% increases in the α‐aminoadipate concentration, reaching 147 and 110 mg/L, respectively. Third, cofactor regulation was used to maintain the coupling balance of material and energy, with the intracellular α‐aminoadipate concentration reaching 140 mg/L. Fourth, the weakening of the synthesis of acetic acid was used to strengthen the synthesis of α‐aminoadipate, and this resulted in the enhancement of the α‐aminoadipate concentration by 2.2 times, reaching 263 mg/L. Finally, combination optimization was used to promote the production of α‐aminoadipate. The titers of α‐aminoadipate reached 368 mg/L (strain EcN11#) and 415 mg/L (strain EcN11##), which was 3.5 and 4 times higher than that of the parent strain. With these efforts, 1.54 g/L of α‐aminoadipate was produced under fed‐batch conditions by strain EcN11#. This study is the first to present the effective biosynthesis of α‐aminoadipate in E. coli using multi‐strategy metabolic engineering.

Ethyl acetate from nail polish remover inhalation in a case of fatal voluntary intoxication

To describe a case of fatal voluntary intoxication involving ethyl acetate (EA) inhalation. A 57-year-old woman was found dead on her bed with a plastic bag over her head filled with cotton balls soaked with nail polish remover. Several empty nail polish remover bottles corresponding to a total volume of approximatly one liter of EA, were found near the body. Among her medical history, gastric banding, an orphan disease that required numerous orthopedic surgeries, depression and suicide attempts were notified. Medications were found at home such as venlafaxine, lorazepam, acetaminophen and zopiclone. At the autopsy, no traumatic injuries were observed. A non-specific asphyxia syndrome with organ congestion was notified with macroscopic lesions in favor of an acute or subacute pathological condition with obstruction of the upper airways by gastric contents up to the main bronchi resulting in pulmonary edema. Anoxia was confirmed by the findings of the microscopic examination. The following samples were available for toxicological analysis: peripheral and cardiac blood, urine, stomach content and bile. A comprehensive forensic toxicological expertise was carried out including investigation of illegal drugs, prescribed drugs, alcohol, volatile substances and other poisons like carbon monoxide with several screenings (immunoassay, gas chromatography-mass spectrometry and liquid chromatography-mass tandem) of various postmortem samples. Each substance detected was quantified by a validated method. Lorazepam, zopiclone and venlafaxine and metabolite were quantified by high-performance liquid chromatography with photodiode-array detection. EA, ethanol and methanol were quantified by gas chromatography and static headspace gas chromatography with flame ionization detector. Peripheral blood concentrations of lorazepam, zopiclone and venlafaxine and O-desmethyl-Venlafaxine were respectively at 55, 49, 414 and < 20 μg/L. EA and ethanol concentrations were at 0.033 and 2.58 g/L in peripheral blood, at 0.034 and 2.76 g/L in cardiac blood, at 0.069 and 2.33 g/L in urine, at 0.155 and 2.27 g/L in stomach content and at 0.014 and 2.87 g/L in bile. EA is commonly used as component in nail polish remover. After exposure to EA vapor, absorption is mainly respiratory and percutaneous. Distribution involves all organs but predominates in fatty tissues. EA is rapidly metabolized by plasma esterases resulting in ethanol and acetic acid synthesis. EA may cause drowsiness, sleepiness, unconsciousness, narcosis, stupor and central nervous system depression. These symptoms are potentiated with ethanol. In this case, the low ratio of EA to ethanol concentrations in all postmortem samples confirmed this rapid biotransformation. This was already mentioned in a case of accidental workplace exposure (Coopman. Forensic Sci Int 2005;154:92–95). Blood concentrations of prescribed drugs were here within the therapeutic range. An EA blood concentration of 0.033 g/L can therefore be considered lethal associated with an ethanol concentration around 2.6 g/L. To our knowledge, this is the first fatal case of voluntary intoxication with EA inhalation. The measured concentrations in all usual autopsy samples can be added to toxicological databases.

A "Power-to-X" Route to Acetic Acid via Palladium-Catalyzed Isomerization of Methyl Formate.

The synthesis of acetic acid by formal isomerization of methyl formate (MF) was investigated using molecular catalysts. The base‐catalyzed decarbonylation of MF, yielding CO and methanol in situ, was integrated with their palladium‐catalyzed recombination for the synthesis of acetic acid and methyl acetate in a one pot reaction. The complex [Pd(Cl)2(dppe)] [dppe=1,2‐bis(diphenylphosphino)‐ethane] in combination with NaI as iodide source and NaOMe as base were identified as promising molecular components to enable the overall conversion. Sequential application of the statistical methods design of experiments and simplex optimization was used in combination with thermodynamic analysis of the competing reaction pathways for experimental planning and data analysis. Starting from a proof‐of‐principle with a turnover number (TON) of 11, the catalytic system could thus be optimized to allow quantitative conversion of MF with a TON of 43000, whereby a yield of 83 % of acetate groups and a yield of 74 % for free acetic acid was obtained.

Hydroxycarbonylation of Alkenes with Formic Acid Catalyzed by a Rhodium(III) Hydride Diiodide Complex Bearing a Bidentate Phosphine Ligand

An improved catalytic system was developed for the Rh complex-catalyzed hydroxycarbonylation of alkenes using formic acid (HCOOH). Ligand screening revealed DPEphos, a bidentate phosphine ligand, to be effective, and the corresponding rhodium(III) hydride diiodide complex, RhHI2(CO)(DPEphos) (2), was applied as a catalyst. Complex 2 showed high activity and selectivity in the hydroxycarbonylation of alkenes using HCOOH without any additives and was applicable to a variety of alkene substrates. Analysis of the catalytic cycle using density functional theory calculations was used to elucidate the reaction steps. Initially, an alkyl group was formed by the insertion of an alkene into Rh–H with subsequent acyl group formation via the insertion of a CO ligand, similar to the reaction steps suggested for Rh-catalyzed alkene hydroformylation. The latter part of the catalytic cycle involved the reductive elimination of acyl iodide and subsequent hydrolysis to form a carboxylic acid, analogous to the reaction steps suggested for the synthesis of acetic acid from methanol and CO using a rhodium complex catalyst with hydroiodic acid as an auxiliary catalyst. These results indicate that the iodine atom in complex 2 acts as an auxiliary catalyst during the additive-free hydroxycarbonylation of alkenes using HCOOH.

Actividad PGPR de bacterias solubilizadoras de carbón

Coal solubilizing bacteria (CSB) are microorganisms to able to bio transformed low rank coal, releasing humified organic matter in the process. On the other hand, these bacterial genera have reported previously as plant growth promoting bacteria. The aim of this work was to assess the Plant Growth Promoting Rhizobacteria (PGPR) capacity of five CSB strains: Bacillus pumilus (CSB05), B. mycoides (CSB25), Microbacterium sp. (CSB3), Acinetobacter sp. (CSB13) and B. amyloliquefaciens (CSB02). For this, the PGPR traits of CSB were evaluated under laboratory conditions: the biological nitrogen fixation capacity, the reduction of acetylene, the synthesis of indole acetic acid (IAA) and the solubilization of phosphates. In a second experiment under plant nursery conditions, PGPR activity of strain CSB05 was evaluated in common bean plants. Under laboratory conditions, it was evidenced that all the evaluated strains produced IAA, solubilized phosphate in a liquid medium, presented atmospheric nitrogen fixation capacity, and only the CSB3 and CSB13 strains reduced acetylene. In the plant nursery experiment, PGPR activity of strain CSB05 was detected in common bean plants, reflected in increases in the height of these plants. These results show that CSB are promising in the PGPR activity, which is interesting to the design of biological products with agricultural and environmental applications, for the management of crops in disturbed soils of the Colombian dry Caribbean.

Syngas fermentation and microbial electrosynthesis integration as a single process unit

Industrially relevant syngas (15 % CO, 15% H2, 20% N2 in 50% CO2) fermentation and microbial electrosynthesis were integrated as a single process unit in open and closed-circuit modes. This study examined the impact of electrochemical reducing power from –50 to –400 mV on the acetic acid synthesis and CO inhibition on fermentation. –150 mV vs. Ag/AgCl (3.0 NaCl) was identified as the lowest benchmark potential for improved acetic acid synthesis rate (0.263 mmol L−1h−1), which is 15-fold higher than the open circuit mode’s rate. No significant inhibition by CO in the fermentation was observed, while 60% of the gas was consumed. Anodic potential above 2.0 V substantially lowered the product formation. Superseding the fermentation medium with fresh inoculum through a fed-batch operation helped lower the anodic potential.

Proteome and Physiological Characterization of Halotolerant Nodule Endophytes: The Case of Rahnella aquatilis and Serratia plymuthica

Bacterial endophytes were isolated from nodules of pea and fava bean. The strains were identified and characterized for plant beneficial activities (phosphate solubilization, synthesis of indole acetic acid and siderophores) and salt tolerance. Based on these data, four strains of Rahnella aquatilis and three strains of Serratia plymuthica were selected. To shed light on the mechanisms underlying salt tolerance, the proteome of the two most performant strains (Ra4 and Sp2) grown in the presence or not of salt was characterized. The number of proteins expressed by the endophytes was higher in the presence of salt. The modulated proteome consisted of 302 (100 up-regulated, 202 down-regulated) and 323 (206 up-regulated, 117 down-regulated) proteins in Ra4 and Sp2, respectively. Overall, proteins involved in abiotic stress responses were up-regulated, while those involved in metabolism and flagellum structure were down-regulated. The main up-regulated proteins in Sp2 were thiol: disulfide interchange protein DsbA, required for the sulfur binding formation in periplasmic proteins, while in Ra4 corresponded to the soluble fraction of ABC transporters, having a role in compatible solute uptake. Our results demonstrated a conserved response to salt stress in the two taxonomically related species.

Techno-Economic Evaluation of Novel Hybrid Biomass and Electricity-Based Ethanol Fuel Production

In order to limit climate change, fast greenhouse gas reductions are required already before 2030. Ethanol commonly produced by fermentation of sugars derived either from starch-based raw material such as corn, or lignocellulosic biomass is an established fuel decarbonizing the transport sector. We present a novel selective and flexible process concept for the production of ethanol with electricity and lignocellulosic biomass as main inputs. The process consists of several consecutive steps. First synthesis gas from gasification of biomass is purified by filtration and reforming and fed to methanol synthesis. The produced methanol is fed to acetic acid synthesis, together with a carbon monoxide-rich stream separated from the synthesis gas by membranes. Finally, acetic acid is hydrogenated to yield ethanol. With the exception of acetic acid hydrogenation, the overall process consists of technically mature subprocesses. Each process step was modelled in Aspen Plus to generate the mass and energy balances for the overall process. Additionally, the CO2 emissions and economic feasibility were assessed. Three separate cases were investigated. In the first two cases, the syngas carbon (CO and CO2) was split between methanol and acetic acid synthesis. The cases included either allothermal (case A) or electrically heated reforming (case B). In case C, maximum amount of CO was sent to acetic acid synthesis to maximize the acetic acid output, requiring a small additional carbon dioxide input to methanol synthesis. In all cases, additional hydrogen to methanol synthesis was provided by water electrolysis. Each case was designed at biomass input of 27.9 MW and the electrolyzer electricity requirement between 36 and 43.5 MW, depending on the case. The overall energy efficiency was calculated at 53–57%, and carbon efficiencies were above 90%. The lowest levelized cost of ethanol was 0.65 €/l, at biomass cost of 20 €/MWh and electricity cost of 45 €/MWh and production scale of approximately 42 kt ethanol per year. The levelized cost is competitive with the current biological route for lignocellulosic ethanol production. The ethanol price is very sensitive to the electricity cost, varying from 0.56 to 0.74 €/l at ±30% variation in electricity cost.

Electrochemical CO2 Reduction Catalyzed by Binuclear LRe2(CO)6Cl2 and LMn2(CO)6Br2 Complexes with an Internal Proton Source.

The synthesis of certain commodity chemicals, e.g., methanol and acetic acid, relies on CO, which is currently mainly produced by the combustion of carbon or natural gas. Photo- or electrochemical conversion of atmospheric CO2 to CO represents an attractive alternative strategy as this approach is carbon-neutral. Such photo- or electrochemically formed CO can also be used in the Fischer-Tropsch process forming liquid hydrocarbons for energy storage applications. The multiple electroreduction of CO2 is preferably coupled with proton transfer steps as this requires less energy than the single outer-sphere 1e- reduction of CO2.In 1984 and 2011, it was shown that [(Lbpy)Re(CO)3Cl] (1) and [(Lbpy)Mn(CO)3Br] (2), respectively, mediate the electrochemical 2e-/2H+ reduction of CO2 forming CO and water (Lbpy = 2,2'-bipyridine). Since proton management is crucial for catalysis, recently the impact of internal proton sources close to the axial position in such complexes has been investigated. However, binuclear complexes have been used rarely as mediators although it has been shown very early for 1 that electron management is also important: the 2e-/2H+ reduction pathway with 1 exhibits a higher reaction rate than going via the singly reduced species, though the pathway requires a higher overpotential. In this Account, we focus on recent developments of binuclear LMn2(CO)6 and LRe2(CO)6 mediators with an internal phenol group in the electroreduction of CO2. In contrast to mononuclear derivatives, for which the impact of the internal proton source on catalysis is very diverse, we always observed a higher reaction rate and for the Mn complexes also a lower overpotential with the binuclear complexes compared to the mononuclear variants. Spectroscopic, electrochemical, and computational studies on the mono- and binuclear complexes shed light on their reactivity under reductive conditions, elucidated the structure of reduced species, unraveled the kinetics for catalytically productive and unproductive (side) reactions, and allowed us to derive some hypothesis on the CO2 reduction mechanism. Finally, I emphasize that the electrohydrogenation of the polar double bonds by the binuclear complex LMn2(CO)6 with a central phenol unit is not restricted to CO2 but is also applicable to organic compounds with C═O bonds.