Acetate Degradation Research Articles

The role of gut microbiota and metabolomic pathways in modulating the efficacy of SSRIs for major depressive disorder

This study aims to explore the mechanism by which gut microbiota influences the antidepressant effects of serotonin reuptake inhibitors (SSRIs) through metabolic pathways. A total of 126 patients were analyzed for their gut microbiota and metabolomics. Patients received SSRI treatment and were categorized into responder and non-responder groups based on changes in their Hamilton Depression Rating Scale (HAMD-17) scores before and after treatment. The association between gut microbiota composition and the efficacy of SSRIs was investigated through 16S rRNA gene sequencing and metabolomic analysis, and a predictive model was developed. As a result, the study found significant differences in gut microbiota composition between the responder and resistant groups. Specific taxa, such as Ruminococcus, Bifidobacterium, and Faecalibacterium, were more abundant in the responder group. Functional analysis revealed upregulation of acetate degradation and neurotransmitter synthesis pathways in the responder group. The machine learning model indicated that gut microbiota and metabolites are potential biomarkers for predicting SSRIs efficacy. In conclusion, gut microbiota influences the antidepressant effects of SSRIs through metabolic pathways. The diversity and function of gut microbiota can serve as biomarkers for predicting the treatment response, providing new insights for personalized treatment.

Deciphering the role of biochar pseudocapacitance strengthening in promoting syntrophic methanogenesis: Microbial capacitance-tropism in propionate metabolism

The redox functional groups of biochar can act as pseudocapacitance, alleviating acid accumulation and facilitating electron transfer in anaerobic digestion. Fe modification further enhances its pseudocapacitance properties. However, the specific role of pseudocapacitance strengthening in the electron transfer of volatile fatty acid syntrophic methanogenesis, as well as the factors inducing the enrichment behavior and metabolic mechanisms of microbes on its surface, remain unclear. In this study, experiments using acetate and propionate as substrates were conducted with the addition of biochar and electro-enhanced biochar, while 16S rRNA gene amplicon sequencing and metagenomic analysis were employed to investigate the underlying mechanisms. The results demonstrate that strengthening biochar’s pseudocapacitance significantly facilitates the electron shunt by accepting electrons, accelerating NADH/NAD+ conversion and ATP synthesis. This further promotes the oxidative degradation of propionate and acetate through the methylmalonyl-CoA (MMC) and syntrophic acetate oxidation (SAO) pathways. During methanogenesis, biochar directly transfers electrons to methanogens, with the strengthened pseudocapacitance further accelerating electron transfer through the CO2 reduction pathway and specifically promoting the methanation of propionate rather than acetate. Moreover, during propionate metabolism, Coprothermobacter and Methanosarcina exhibit capacitance-tropism in their enrichment on biochar, serving as key functional contributors to the biochar-microbial aggregates. These findings provide valuable insights for selecting exogenous materials in engineering applications to alleviate acid accumulation in anaerobic digestion systems.

Impact of bioaugmentation on psychrophilic anaerobic digestion of corn straw

In order to investigate the mechanisms by which bioaugmentation affects psychrophilic anaerobic digestion (AD), this study introduced a psychrophilic methanogenic culture into the sequencing batch of psychrophilic AD systems. The findings demonstrated that bioaugmentation boosted the abundance of Smithella (23.2 times), Syntrophobacter (9.9 times), and Methanothrix (1.4 times) in the psychrophilic AD systems, accelerating acetate and propionate degradation and improving methane production (26 %). Metagenomic analysis showed that bioaugmentation increased the relative abundance of genes related to propionate degradation and methane production, such as propionyl-CoA synthetase (45 %) and acetyl-CoA synthetase (11 %). At the cellular level, genes related to prevention of cell damage and promotion of membrane fluidity were upregulated. This study revealed the effect of bioaugmentation on microbial metabolic activities related to conversion of propionate to methane and cold tolerance in psychrophilic AD.

Effect of modifiers on the stability of 1‑butyl‑3-methylimidazolium-based ionic liquids

The distinctive capabilities of 1‑butyl‑3-methylimidazolium (bmim) cation-based ionic liquids (ILs) to dissolve lignocellulosic biomass offer the potential for the development of novel green bioprocessing technologies based on their utilization as green solvents. The limited range of thermal stability of ILs necessitates the use of various co-solvents to maintain solubility. In the present study, an original approach to determine the degree of degradation of alkylimidazolium ILs was proposed, based on the application of gravimetric analysis method to determine the content of volatile degradation products and high-performance liquid chromatography-high-resolution mass spectrometry (HPLCHRMS) to determine the total degree of degradation. The proposed approach, as well as the combination of HPLCHRMS with gas chromatography-mass spectrometry (GC–MS), was employed to comprehensively characterize the impact of additives and impurities (water, dimethyl sulfoxide, hydrochloric and acetic acids, diethylamine) on the degradation of bmim acetate, chloride, and methyl sulfate during thermal treatment under typical biomass dissolution conditions (150 °C, 24 h). The presence of additives or impurities in the composition of ILs has been found to predominantly contribute to a decrease in the number of volatile compounds formed, while increasing the variety and relative content of non-volatile degradation products. The use of protic solvents and acids results in a decrease in the overall degree of degradation of ionic liquids and in the fraction of volatile compounds formed. This allows for the classification of binary mixtures based on these additives as "green" solvents at temperatures below 150 °C.

Isotopic evidence of acetate turnover in Precambrian continental fracture fluids

The deep continental crust represents a vast potential habitat for microbial life where its activity remains poorly constrained. Organic acids like acetate are common in these ecosystems, but their role in the subsurface carbon cycle - including the mechanism and rate of their turnover - is still unclear. Here, we develop an isotope-exchange ‘clock’ based on the abiotic equilibration of H-isotopes between acetate and water, which can be used to define the maximum in situ acetate residence time. We apply this technique to the fracture fluids in Birchtree and Kidd Creek mines within the Canadian Precambrian crust. At both sites, we find that acetate residence times are <1 million years and calculated a rate of turnover that could theoretically support microbial life. However, radiolytic water-rock reactions could also contribute to acetate production and degradation, a process that would have global relevance for the deep biosphere. More broadly, our study demonstrates the utility of isotope-exchange clocks in determining residence times of biomolecules with possible applications to other environments.

Atmospheric Degradation Mechanism of Isoamyl Acetate Initiated by OH Radicals and Cl Atoms Revealed by Quantum Chemical Calculations and Kinetic Modeling.

Isoamyl acetate is one of the volatile organic compound class molecules relevant to agricultural and industrial applications. With the growing interest in isoamyl acetate applications in industry, the atmospheric fate of isoamyl acetate must be considered. Reaction mechanisms, potential energy profiles, and rate constants of isoamyl acetate reaction with atmospheric relevant oxidant OH radicals and Cl atoms have been obtained from the quantum chemical calculations and kinetic modeling. The geometry optimizations were conducted using M06-2X/6-311++G(3df,3pd) followed by single point-energy calculations at the DLPNO-CCSD(T) method with an extrapolated complete basis set. The rate constants were calculated by solving the master equation. A hydrogen-abstraction reaction dominates the first step of isoamyl acetate degradation, while the addition-substitution reaction plays a small role in the degradation products. The kinetic study was conducted to evaluate the rate constants within a temperature range of 200-400 K. The total rate constants for the isoamyl acetate degradation reactions initiated by the OH radical and Cl atom were determined to be 6.96 × 10-12 and 1.27 × 10-10 cm3 molecule-1 s-1, respectively, under standard temperature and pressure conditions. The product degradation mechanism, ozone formation potential, and atmospheric impacts were discussed.

Metagenomic insights into the enhanced methane production by hydrochar at varied propionate concentrations

Propionate is a crucial intermediate product in anaerobic digestion (AD), but its degradation is thermodynamically unfavorable. Its accumulation in the AD system can significantly reduce methane production efficiency and may lead to severe acidification. The present study investigated the methane production at various propionate concentrations (15, 30 and 60 mM) with and without hydrochar and also explored the microbial shifts by metagenomic analysis. The findings revealed that higher propionate concentrations reduced methane production and propionate degradation efficiency, leading to acetate accumulation. The addition of hydrochar mitigated the inhibitory effects of increased propionate concentrations, notably reduced the lag phase by 20.13 % and enhanced the methane production rate by 138.43 % under 30 mM propionate. This also resulted in faster degradation of propionate and acetate. Hydrochar impacted the microbial communities’ functional potentials, enhancing methane metabolic potential in all conditions. Genomic-centric analysis revealed that hydrochar selectively enriched syntrophic propionate-oxidizing bacteria (SPOB) candidate MAG79 Syntrophopropionicum sp., which could participate in DIET, across different concentrations of propionate, with the most pronounced effect at 30 mM propionate. This was distinct from the dominant species in the control groups, MAG63 Syntrophosphaera sp. and MAG69 Syntrophobacteraceae sp.. Hydrochar further supported the growth of another DIET candidate MAG4 Methanosarcina mazei and increased the abundance of proposed syntrophic acetate-oxidizing bacterium (SAOBs), across all propionate concentrations. These effects collectively led to more efficient propionate degradation and methane production.

Impact of additives on syntrophic propionate and acetate enrichments under high-ammonia conditions

High ammonia concentrations in anaerobic degradation systems cause volatile fatty acid accumulation and reduced methane yield, which often derive from restricted activity of syntrophic acid-oxidising bacteria and hydrogenotrophic methanogens. Inclusion of additives that facilitate the electron transfer or increase cell proximity of syntrophic species by flocculation can be a suitable strategy to counteract these problems, but its actual impact on syntrophic interactions has yet to be determined. In this study, microbial cultivation and molecular and microscopic analysis were performed to evaluate the impact of conductive (graphene, iron oxide) and non-conductive (zeolite) additives on the degradation rate of acetate and propionate to methane by highly enriched ammonia-tolerant syntrophic cultures derived from a biogas process. All additives had a low impact on the lag phase but resulted in a higher rate of acetate (except graphene) and propionate degradation. The syntrophic bacteria ‘Candidatus Syntrophopropionicum ammoniitolerans’, Syntrophaceticus schinkii and a novel hydrogenotrophic methanogen were found in higher relative abundance and higher gene copy numbers in flocculating communities than in planktonic communities in the cultures, indicating benefits to syntrophs of living in close proximity to their cooperating partner. Microscopy and element analysis showed precipitation of phosphates and biofilm formation in all batches except on the graphene batches, possibly enhancing the rate of acetate and propionate degradation. Overall, the concordance of responses observed in both acetate- and propionate-fed cultures highlight the suitability of the addition of iron oxide or zeolites to enhance acid conversion to methane in high-ammonia biogas processes.Key points• All additives promoted acetate (except graphene) and propionate degradation.• A preference for floc formation by ammonia-tolerant syntrophs was revealed.• Microbes colonised the surfaces of iron oxide and zeolite, but not graphene.Graphical

Mutual effects of CO and benzene oxidation over Cu catalysts: The role of surface oxygen species and reaction pathways

CuMn, CuMnCe, and CuCe metal oxide catalysts were prepared and applied in oxidizing CO and benzene as representative volatile organic compounds (VOCs). Various characterization methods and in situ diffuse reflectance infrared Fourier transform spectra (DRIFTS) were used to explore mutual effects between CO and benzene oxidation and the role of reactive oxygen species. CuMn shows the highest activity in independent and simultaneous oxidation of CO and benzene due to its spinel Cu1.5Mn1.5O4 structure, which gives abundant Cu+ sites, acidic sites, Oα, and Oβ. Cu+ sites and Oα benefit CO oxidation, while acidic sites, Oα, and Oβ contribute to benzene oxidation, producing intermediates decomposable at low temperatures. Mechanism study reveals that benzene inhibits CO oxidation by competing for Oα at low temperatures to retard carbonate intermediates formation. CO enhances benzene oxidation by promoting benzene preliminary oxidation and intermediates deep degradation. On CuMn, the formation and degradation of maleate and acetate are facilitated, while maleate and formate degradation are promoted on CuMnCe and CuCe, respectively.

Enhancing cellulose acetate biodegradability in cigarette filters: an in-depth analysis of thermal alkaline pretreatment, microbial dynamics, and breakdown pathway prediction

BackgroundThe demand for bioplastics has increased exponentially as they have emerged as alternatives to petrochemical plastics. However, there is a substantial lack of knowledge regarding bioplastic degradation. This study developed a novel pretreatment method to improve the accessibility of a bioplastic substrate for biodegradation. In this study, cellulose acetate, a bioplastic found in the world’s most littered waste, e.g. cigarette filters, was selected as a potential substrate. Before anaerobic digestion, three thermal alkaline pretreatments: TA 30 °C, TA 90 °C, and TA 121 °C, were used to evaluate their effects on the chemical alterations of cellulose acetate.ResultThe ester groups in cellulose acetate were significantly reduced by the TA 30 °C pretreatment, as seen by a decrease in C = O stretching vibrations and shortening of C − O stretches (1,270 ∼ 1,210 cm− 1), indicating effective removal of acetyl groups. This pretreatment significantly enhanced cellulose acetate biodegradability to a maximum of 91%, surpassing the previously reported cellulose acetate degradation. Methane production increased to 695.0 ± 4 mL/g of volatile solid after TA 30 °C pretreatment, indicating enhanced cellulose acetate accessibility to microorganisms, which resulted in superior biogas production compared to the control (306.0 ± 10 mL/g of volatile solid). Diverse microbes in the anaerobic digestion system included hydrolytic (AB240379_g, Acetomicrobium, FN436103_g, etc.), fermentative, and volatile fatty acids degrading bacteria (JF417922_g, AB274492_g, Coprothermobacter, etc.), with Methanobacterium and Methanothermobacter being the sole hydrogenotrophic methanogens in the anaerobic digestion system. Additionally, an attempt to predict the pathway for the effective degradation of cellulose acetate from the microbial community in different pretreatment conditions.ConclusionsTo the best of our knowledge, this is the first study to estimate the maximum cellulose acetate degradation rate, with a simple and cost-effective pretreatment procedure. This approach holds promise for mitigating the environmental impact of cellulose acetate of cigarette filters and presents a sustainable and economically viable waste management strategy.

Corona discharge plasma-excited activation of MnZrLaCe/γ-Al2O3 catalyst for simultaneous degradation of meta-xylene and ethyl acetate: Effects and mechanism

The effects for the simultaneous degradation of meta-xylene (MX) and ethyl acetate (EA) by corona discharge plasma (CDP) combined with MnZrLaCe/γ-Al2O3 were investigated. The MnZrLaCe/γ-Al2O3 were characterized by SEM-EDS, XRD, BET, XPS, FT-IR and O2-TPD. The simultaneous degradation mechanism of the CDP combined catalyst for the mixed VOCs was discussed. Compared with degradation the single component, the degradation efficiency of MX and EA simultaneously is greatly higher than that of the CDP alone. The degradation efficiency of EA, MX and the mixture by the CDP combined with catalyst is up to 93.6 %, 94.5 % and 83.5 % at supply voltage 40 kV, and is 61.2 %, 43.3 % and 33.4 % higher than that of the NTP alone, respectively. The simultaneous degradation efficiency of MA and EA mixed pollutants is significantly improved after the addition of catalysts at the same supply voltage. The EY of all CDP combined with catalysis generally have a down ward trend with increasing of the supply voltage. The best EY for degrading MA and EA mixed pollutants simultaneously by the CDP combined with MnZrLaCe/γ-Al2O3 are up to 7.45 g/kWh at supply voltage 24 kV. The O3 concentration in the outlet gas of the CDP reactor is relatively low, and the NOx in the outlet gas is essentially absent. The main intermediate products of simultaneous degradation MX and EA by the CDP combined with MnZrLaCe/γ-Al2O3 are n-heptane, toluene and paraxylene, etc. Finally, the degradation mechanism for the MX and EA simultaneously by the CDP over the MnZrLaCe/γ-Al2O3 catalyst are proposed.

Degradation of Sodium Acetate by Catalytic Ozonation Coupled with MnOx/NiOOH-Modified Fly Ash.

Fly ash, a type of solid waste generated in power plants, can be utilized as a catalyst carrier to enhance its value-added potential. Common methods often involve using a large amount of alkali for preprocessing, resulting in stable quartz and mullite forming silicate dissolution. This leads to an increased specific surface area and pore structure. In this study, we produced a catalyst composed of MnOx/NiOOH supported on fly ash by directly employing nickel hydroxide and potassium permanganate to generate metal active sites over the fly ash surface while simultaneously creating a larger specific surface area and pore structure. The ozone catalytic oxidation performance of this catalyst was evaluated using sodium acetate as the target organic matter. The experimental results demonstrated that an optimal removal efficiency of 57.5% for sodium acetate was achieved, surpassing even that of MnOx/NiOOH supported catalyst by using γ-Al2O3. After loading of MnOx/NiOOH, an oxygen vacancy is formed on the surface of fly ash, which plays an indirect oxidation effect on sodium acetate due to the transformation of ozone to •O2- and •OH over this oxygen vacancy. The reaction process parameters, including varying concentrations of ozone, sodium acetate, and catalyst dosage, as well as pH value and the quantitative analysis of formed free radicals, were examined in detail. This work demonstrated that fly ash could be used as a viable catalytic material for wastewater treatment and provided a new solution to the added value of fly ash.

Performance and Reaction Mechanisms of Catalytic Combustion of Toluene and Ethyl Acetate Over Fe‐Mn Oxides

AbstractIn this paper, Fe−Mn oxide catalysts were prepared by the co‐precipitation method. (Fe2O3)‐(Mn3O4)‐3 : 1 showed the best catalytic activity in the degradation of toluene and ethyl acetate, with the removal rate reaching 90 % at 166 °C and 156 °C respectively. The XRD, SEM, TEM, and XPS characterizations revealed that the interaction between Fe and Mn and the higher surface adsorption of oxygen in the (Fe2O3)‐(Mn3O4)‐3 : 1 catalyst may be the main factors promoting the catalytic oxidation. (Fe2O3)‐(Mn3O4)‐3 : 1 exhibited a better removal rate in ethyl acetate than toluene at different space velocities, concentrations and water contents. Under the same conditions, the degradation rate of (Fe2O3)‐(Mn3O4)‐3 : 1 in ethyl acetate was also greater than that in xylene and butyl acetate, which was related to their oxidation processes. FT‐IR and GC‐MS characterizations of fresh and used (Fe2O3)‐(Mn3O4)‐3 : 1 catalysts revealed intermediates in the oxidation of volatile organic compounds, and the reaction mechanisms were analyzed: Firstly, VOCs molecules were adsorbed on the catalyst surface, then decomposed into organic intermediates and oxidized to CO2 and H2O finally.

A novel g-C3N4@La:Y2O3 nanocomposite fluorescence sensor for simultaneous determination and photocatalytic degradation of Ulipristal acetate and Tacrolimus using Doehlert design optimization

Graphitic carbon nitride nanocomposite doped with La:Y2O3 was used as a new sensor for detection and determination of two hazardous active pharmaceutical compounds, Tacrolimus and Ulipristal acetate, by fluorescence spectrophotometry. This novel nanosensor has a fantastic ability to detect these drugs quickly, accurately, and simultaneously. The effect of Tacrolimus on this nanosensor is the quenching of fluorescence emission intensity at the wavelength of 369 nm while the Ulipristal acetate increases the fluorescence emission at 433 nm. Doehlert design was used to optimize the effective factors to reach the maximum fluorescence emission intensity of the nanosensor. Factors including pH, buffer solution concentration and the ratio of La:Y2O3 dopant in the nanocomposite structure. Under optimal conditions, the limit of detection of 17 nM and the limit of qualification of 58 nM for Tacrolimus and the limit of detection of 11 nM and the limit of qualification of 36 nM for Uipristal acetate were obtained with good accuracy. The prepared g-C3N4@La:Y2O3 nanocomposite has a reasonable ability to photodegrade these two drugs. In this regard, the process of photocatalytic degradation of Tacrolimus and Ulipristal acetate was investigated under visible light irradiation. The effect of active species in photocatalytic degradation was evaluated in order to determine the exact degradation mechanism, and the effect of Fenton factors on analytes degradation was also investigated.

Magnetite particles accelerate methanogenic degradation of highly concentrated acetic acid in anaerobic digestion process

The anaerobic digestion (AD) process has become significant for its capability to convert organic wastewater into biogas, a valuable energy source. Excessive acetic acid accumulation in the anaerobic digester can inhibit methanogens, ultimately leading to the deterioration of process performance. Herein, the effect of magnetite particles (MP) as an enhancer on the methanogenic degradation of highly-concentrated acetate (6 g COD/L) was examined through long-term sequential AD batch tests. Bioreactors with (AM) and without (AO) MP were compared. AO experienced inhibition and its methane production rate (qm) converged to 0.45 L CH4/g VSS/d after 10 sequential batches (AO10, the 10th batch in a series of the sequential batch tests conducted using bioreactors without MP addition). In contrast, AM achieved 3–425% higher qm through the sequential batches, indicating that MP could counteract the inhibition caused by the highly-concentrated acetate. MP addition to inhibited bioreactors (AO10) successfully restored them, achieving qm of 1.53 L CH4/g VSS/d, 3.4 times increase from AO10 after 8 days lag time, validating its potential as a recovery strategy for inhibited digesters with acetate accumulation. AM exhibited higher microbial populations (1.8–3.8 times) and intracellular activity (9.3 times) compared to AO. MP enriched Methanosaeta, Peptoclostridium, Paraclostridium, OPB41, and genes related to direct interspecies electron transfer and acetate oxidation, potentially driving the improvement of qm through MP-mediated methanogenesis. These findings demonstrated the potential of MP supplementation as an effective strategy to accelerate acetate-utilizing methanogenesis and restore an inhibited anaerobic digester with high acetate accumulation.

Temperature sensitivity of aerobic and anaerobic organic carbon mineralization varies with climate and soil depth in riparian zones

The temperature sensitivity (Q10) of soil organic carbon (SOC) mineralization plays a vital role in predicting the global carbon cycle under climate change. Q10 has been extensively examined in various terrestrial ecosystems; however, in riparian zones where soil oxygen levels are highly dynamic owing to frequent flooding, Q10 should change with oxygen conditions and show spatial variation, but the mechanisms are still obscure. In this study, we collected topsoil and subsoil samples from riparian zones along a latitudinal gradient and conducted aerobic and anaerobic incubation experiments to determine the latitudinal and vertical patterns of Q10. The results showed that Q10 under anoxic conditions (average of 1.7) significantly exceeded that under oxic conditions (average of 1.4). In general, aerobic SOC mineralization is more sensitive to warming at higher latitudes than at lower latitudes, whereas the pattern is reversed under anoxic conditions. The Q10 in the topsoil was significantly higher than that in the subsoil only under oxic conditions. Metagenomics showed that the abundance of genes involved in the degradation of lignin, carbohydrate esters, and starch in the topsoil increased with latitude, whereas genes for acetate degradation were more abundant in warmer zones, regardless of soil depth. Q10 under oxic conditions was mainly influenced by soil physicochemical properties (e.g., pH and texture), whereas Q10 under anoxic conditions was jointly controlled by climate, soil texture, and acetate degradation genes. Together, anaerobic carbon (C) mineralization in riparian zones is more sensitive to temperature than aerobic metabolism, but the patterns of Q10 under oxic conditions were dependent on both latitude and depth. Our findings highlight that the discrepancies in aerobic and anaerobic C metabolism, and the C cycling process at different soil depths, might play a non-negligible role in affecting the assessment of global C emissions under climate change.

Unraveling the synergistic role of oxygen vacancy and Co dual-site pairs in MOFs-derived defect-engineered Co3O4 catalysts with a hollow architecture for photothermal OVOCs degradation: Formation of reactive oxygen species

Herein, we developed a solvent regulation strategy with dual organic ligands to synthesize a series of Co-MOF-74 isomer derivatives as model materials that were investigated the formation of reactive oxygen species (ROS) and photothermal OVOCs (methanol, acetone and ethyl acetate) degradation. As a result, the defect-engineered Co3O4-DIW-100 with hollow microsphere synthesized under an equivalent volume ratio of N, N-dimethylformamide (DMF), isopropanol and H2O, can efficiently improve the photothermal catalytic conversions for methanol (97 %), acetone (96 %) and ethyl acetate (93 %) oxidation under Xenon lamp irradiation, compared with unremarkable Co3O4-M catalyst. Thanks to its hollow architecture, the optimal Co3O4-DIW-100 possessed the enhanced low-temperature redox capability and more exposed Co3+ and VO sites. Furthermore, DFT and EPR results revealed that the VO and Co dual-site pairs at surrounding structural defects synergistically participated in the generation of abundant ROS (O2−) through a specific O2 activation configuration (Co2+=O–O–Co3+). Meanwhile, light irradiation could induce the separation and transfer of charge carriers to accelerate the formation of O2−. The superior absorption of visible light derived from the narrow Eg value on Co3O4-DIW-100 can boost a higher light-driven temperature to perform the photothermal OVOCs oxidation. The formation and transformation of sectional key reaction intermediates, such as CH3COOH, CH3OH and HCOOH, were accurately identified and investigated by in-situ DRIFTS results on the methanol, acetone and ethyl acetate oxidation.

Differences in the gut microbiome of young adults with schizophrenia spectrum disorder: using machine learning to distinguish cases from controls

While an association between the gut microbiome and schizophrenia spectrum disorders (SSD) has been suggested, the existing evidence is still inconclusive. To this end, we analyzed bacteria and bacterial genes in feces from 52 young adult SSD patients and 52 controls using fecal shotgun metagenomic sequencing. Compared to controls, young SSD patients were found to have significantly lower α-diversity and different β-diversity both regarding bacterial species (i.e., taxonomic diversity) and bacterial genes (i.e., functional diversity). Furthermore, the α-diversity measures ‘Pielou’s evenness’ and ‘Shannon’ were significantly higher for both bacterial species, bacterial genes encoding enzymes and gut brain modules in young SSD patients on antipsychotic treatment (young SSD not on antipsychotics=9 patients, young SSD on antipsychotics=43 patients). We also applied machine learning classifiers to distinguish between young SSD patients and healthy controls based on their gut microbiome. Results showed that taxonomic and functional data classified young SSD individuals with an accuracy of ≥ 70% and with an area under the receiver operating characteristic curve (AUROC) of ≥ 0.75. Differential abundance analysis on the most important features in the classifier models revealed that most of the species with higher abundance in young SSD patients had their natural habitat in the oral cavity. In addition, many of the modules with higher abundance in young SSD patients were amino acid biosynthesis modules. Moreover, the abundances of gut-brain modules of butyrate synthesis and acetate degradation were lower in the SSD patients compared to controls. Collectively, our findings continue to support the presence of gut microbiome alterations in SSD and provide support for the use of machine learning algorithms to distinguish patients from controls based on gut microbiome profiles.

Metabolism of novel potential syntrophic acetate-oxidizing bacteria in thermophilic methanogenic chemostats.

Acetate is a major intermediate in the anaerobic digestion of organic waste to produce CH4. In methanogenic systems, acetate degradation is carried out by either acetoclastic methanogenesis or syntrophic degradation by acetate oxidizers and hydrogenotrophic methanogens. Due to challenges in the isolation of syntrophic acetate-oxidizing bacteria (SAOB), the diversity and metabolism of SAOB and the mechanisms of their interactions with methanogenic partners are not fully characterized. In this study, the in situ activity and metabolic characteristics of potential SAOB and their interactions with methanogens were elucidated through metagenomics and metatranscriptomics. In addition to the reported SAOB classified in the genera Tepidanaerobacter, Desulfotomaculum, and Thermodesulfovibrio, we identified a number of potential SAOB that are affiliated with Clostridia, Thermoanaerobacteraceae, Anaerolineae, and Gemmatimonadetes. The potential SAOB possessing the glycine-mediated acetate oxidation pathway dominates SAOB communities. Moreover, formate appeared to be the main product of the acetate degradation by the most active potential SAOB. We identified the methanogen partner of these potential SAOB in the acetate-fed chemostat as Methanosarcina thermophila. The dominated potential SAOB in each chemostat had similar metabolic characteristics, even though they were in different fatty-acid-fed chemostats. These novel syntrophic lineages are prevalent and may play critical roles in thermophilic methanogenic reactors. This study expands our understanding of the phylogenetic diversity and in situ biological functions of uncultured syntrophic acetate degraders and presents novel insights into how they interact with methanogens.IMPORTANCECombining reactor operation with omics provides insights into novel uncultured syntrophic acetate degraders and how they perform in thermophilic anaerobic digesters. This improves our understanding of syntrophic acetate degradation and contributes to the background knowledge necessary to better control and optimize anaerobic digestion processes.

Magnetite-boosted syntrophic conversion of acetate to methane during thermophilic anaerobic digestion.

Using a batch thermophilic anaerobic system established with 60 mL serum bottles, the mechanism on how microbial enrichments obtained from magnetite-amended paddy soil via repeated batch cultivation affected methane production from acetate was investigated. Magnetite-amended enrichments (MAEs) can improve the methane production rate rather than the methane yield. Compared with magnetite-unamended enrichments, the methane production rate in MAE was improved by 50%, concomitant with the pronounced electrochemical response, high electron transfer capacity, and fast acetate degradation. The promoting effects might be ascribed to direct interspecies electron transfer facilitated by magnetite, where magnetite might function as electron conduits to link the acetate oxidizers (Anaerolineaceae and Peptococcaceae) with methanogens (Methanosarcinaceae). The findings demonstrated the potential application of MAE for boosting methanogenic performance during thermophilic anaerobic digestion.