Enhanced direct gaseous CO2 fixation into higher bio-succinic acid production and selectivity.

Utilizing CO2 for bio-succinic acid production is an attractive approach to achieve carbon capture and recycling (CCR) with simultaneous production of a useful platform chemical. Actinobacillus succinogenes and Basfia succiniciproducens were selected and investigated as microbial catalysts. Firstly, the type and concentration of inorganic carbon concentration and glucose concentration were evaluated. 6 g C/L MgCO3 and 24 g C/L glucose were found to be the optimal basic operational conditions, with succinic acid production and carbon yield of over 30 g/L and over 40%, respectively. Then, for maximum gaseous CO2 fixation, carbonate was replaced with CO2 at different ratios. The "less carbonate more CO2" condition of the inorganic carbon source was set as carbonate: CO2 = 1:9 (based on the mass of carbon). This condition presented the highest availability of CO2 by well-balanced chemical reaction equilibrium and phase equilibrium, showing the best performance with regarding CO2 fixation (about 15 mg C/(L·hr)), with suppressed lactic acid accumulation. According to key enzymes analysis, the ratio of phosphoenolpyruvate carboxykinase to lactic dehydrogenase was enhanced at high ratios of gaseous CO2, which could promote glucose conversion through the succinic acid path. To further increase gaseous CO2 fixation and succinic acid production and selectivity, stepwise CO2 addition was evaluated. 50%-65% increase in inorganic carbon utilization was obtained coupled with 20%-30% increase in succinic acid selectivity. This was due to the promotion of the succinic acid branch of the glucose metabolism, while suppressing the pyruvate branch, along with the inhibition on the conversion from glucose to lactic acid.

Efficient degradation of organic compounds in landfill leachate via developing bio-electro-Fenton process.

Efficient and harmless disposal of landfill leachate has attracted increasing attention. In this study, the bio-electro-Fenton method was investigated and developed to degrade the organic compounds in landfill leachate by hydroxyl radical oxidation. The optimal operational parameters (i.e., pH and external voltage) of the bio-electro-Fenton system were detected. Under the conditions of pH 2, 0.6 V, the highest total chemical oxygen demand (COD) decrement efficiency was obtained (about 70%), with apparent removal constant at 6 h (kapp-6h) of about 0.12 h-1. Subsequently, to further increase the degradation efficiency, functionalized carbon black and functionalized carbon nanotube (FCNT) were prepared as catalysts for the cathode electrode modification. With 0.4 mg/cm2 FCNT coated on the cathode electrode, 91.3% of the organic compounds were degraded, remaining only 84 mg/L COD (kapp-6h = 0.24 h-1). In all the reactors, the COD was mainly decreased in 0-6 h, contributing to over 68% of the total degradation efficiency. In the bio-electro-Fenton system, the bio-anode electrode could enhance H2O2 production and the conversion between Fe2+ and Fe3+ by strengthening electrons generation and transportation via the oxidation of organics by biofilms (dominant with Geobacter) covered on the carbon brush.

Lipid metabolism-related genes as biomarkers and therapeutic targets reveal endometrial receptivity and immune microenvironment in women with reproductive dysfunction.

BACKGROUND: In recent years, alterations in lipid metabolism are currently considered a hallmark feature of many diseases. However, the role in women with reproductive dysfunction (WRD) remains to be fully elucidated. Here, this study aimed to explore the effect of lipid metabolism-related genes (LMRGs) on endometrial receptivity of WRD. METHODS: This study retrospectively analyzed endometrial receptivity array (ERA) in GEO database. The differential expression genes (DEGs) were obtained by limma differential analysis, and the core genes and corresponding predicted microRNA were obtained through protein-protein interaction (PPI) analysis and TargetScan database, so as to predict the chemical targets of drug therapy. Through the intersection of DEGs and LMRGs, the target gene expression profile was obtained for subsequent consensus clustering analysis and immune analysis. In addition, the immune cell infiltration was assessed by applying the ESTIMATE and MCPcounter algorithm and potential drug targets were obtained from the HERB website. RESULTS: 1473 genes showed differential expression between the groups of WRD and fertile women, and then a large number of lipid metabolism-related pathways and immune-related pathways were enriched. Twelve core genes and corresponding predicted miR-134-3p were obtained; most importantly, we found that these 12 genes were all LMRGs. Through drug target prediction, we obtained three drugs that regulate lipid metabolism and improve blood circulation, namely lovastatin, estrogen, and quercetin. EHHADH (AUC = 0.85) and PTEN (AUC = 0.82) have the best diagnostic performance. UMAP and heatmap revealed large differences between three clusters. LMRGs revealed specific manifestations of WRD in endometrial receptivity and immune microenvironment. CONCLUSIONS: Our study explored the expression pattern of LMRGs in endometrium of WRD, screened the corresponding biomarkers, and proposed the combination of traditional Chinese and Western medicine to improve the endometrial receptivity.

Calcium ion can alleviate ammonia inhibition on anaerobic digestion via balanced-strengthening dehydrogenases and reinforcing protein-binding structure: Model evaluation and microbial characterization.

Experimental investigation and model simulation was combined to identify the effect of metal ions on mitigating ammonia inhibition during anaerobic digestion. Five metal ions (Ca, Mg, Cu, Zn, Fe) were tested in reactors with 1 g-glucose/L/d and 5 g-N/L under fed batch operation. Ca addition was considered the optimal approach with a 25% increment in methane production via balanced-strengthening dehydrogenases and reinforcing protein-binding structure. Gene-sequencing results suggested 50% and 15% increment in acetotrophic-related and hydrogenotrophic-related dehydrogenases, respectively, after Ca addition. The Anaerobic Digestion Model No.1 was modified by introducing lactate-related reactions, syntrophic acetate oxidation process, and kinetic equation of metal ions, with satisfactory predictions of methane and intermediates (R2 > 0.80). The lowest affinity constant KI_MI value was obtained with Ca supplement, indicating the highest conversion rate of substrates to methane. The model evaluation revealed the balanced ratio on the enzyme contribution of acetotrophic to hydrogenotrophic methanogenesis.

Bioaugmentation with well-constructed consortia can effectively alleviate ammonia inhibition of practical manure anaerobic digestion.

Bioaugmentation is an attractive method to improve methane production (MP) in the anaerobic digestion (AD) process. In this study, to tackle the ammonia inhibition problem, a long-term (operating over 6 months) acclimatized consortia and a well-constructed consortia were selected as the bioaugmentation consortia for sequencing batch AD reactors fed with dairy manure and pig manure under mesophilic condition. Similar responses, in terms of the reactor performance and microorganisms structure to the different consortia, were observed with both manure kinds indicating that the effectiveness of bioaugmentation was mainly decided by the composition of the added consortia, not the feedstock. 39 - 49% increment in MP was obtained in the reactors bioaugmented with well-constructed consortia, which was higher than the acclimatized consortia (about 25% increment in MP). Both acetogenesis and methanogenesis (advantageous) steps were stimulated with well-constructed consortia bioaugmentation. According to key functional enzyme analysis, the increment of glycine hydroxymethyltransferase and phosphoglycerate mutase might be the critical point in the bioaugmented AD system. Based on the higher functional contribution rate of the well-constructed consortia bioaugmentation reactors, Methanosarcina could have expressed more comprehensive functions or performed stronger activities in different functions than Methanosaeta.

Methane production from acetate, formate and H2/CO2 under high ammonia level: Modified ADM1 simulation and microbial characterization.

This study evaluated the methanogenic performance of typical substrates (acetate, formate, H2/CO2, and glucose) under low and high ammonia levels and the Anaerobic Digestion Model No.1 (ADM1) was extended and modified for better simulation and understanding of the process. Formate-utilizing and hydrogen-utilizing methanogenesis showed stronger ammonia resistance than acetate-utilizing methanogenesis (13-23% vs. 34% decrease in methane production (MP)). Model extension, based on foundational experiments fed with three typical precursors (R2 > 0.92), was then validated with glucose degradation experiments, and satisfactory predictions of MP and total volatile fatty acids were obtained (R2 > 0.91). Based on the modified ADM1, the carbon fluxes of glucose degradation were determined, and formate-utilizing methanogenesis showed its importance with a 28-34% contribution of the total methanation, becoming the dominant pathway under high ammonia level. Formate-utilizing methanogenesis also had a thermodynamic advantage among the three pathways. 16S rRNA sequencing suggested a homology between the hydrogen-utilizing and formate-utilizing methanogens. Methanobacterium and Methanobrevibacter were found to be key methanogens, and their enrichment under high ammonia level confirmed the stronger ammonia tolerance of formate-utilizing and hydrogen-utilizing methanogenesis. The microbial characterization and modified ADM1 simulations supported each other.