Effect of surface species on the alcohol-acid adsorption from FTS wastewater on graphene: A structure-capacity study.

Fischer-Tropsch synthesis (FTS) wastewater retaining low-carbon alcohols and acids are organic pollutants as a limiting factor for FTS industrialization. In this work, the structure-capacity relationships between alcohol-acid adsorption and surface species on graphene were reported, shedding light into their intricate interactions. The graphene oxide (GO) and reduced graphene oxide (rGO) were synthesized via improved Hummers method with flake graphite (G). The physicochemical properties of samples were characterized via SEM, XRD, XPS, FT-IR, and Raman. The alcohol-acid adsorption behaviors and adsorption quantities on G, GO, and rGO were measured via theoretical and experimental method. It was revealed that the presence of COOH, C=O and CO species on graphene occupy the adsorption sites and increase the interactions of water with graphene, which are unfavorable for alcohol-acid adsorption. The equilibrium adsorption quantities of alcohols and acids grow in pace with carbon number. The monolayer adsorption occurs on graphene was verified via model fitting. rGO has the highest FTS modeling wastewater adsorption quantity (110 mg/g) due to the reduction of oxygen species. These novel findings provide a foundation for the alcohol-acid wastewater treatment, as well as the design and development of high-performance carbon-based adsorbent materials.

Source reduction and end treatment of acid mine drainage in closed coal mines of the Yudong River Basin.

After the closure of the Yudong coal mine, the pH value was approximately 3.0, and the Fe and Mn concentrations reached 380 and 69 mg/L, respectively, in the acid mine drainage (AMD), causing serious pollution to the water bodies in the nearby watershed. Combined with the formation conditions of AMD, the comprehensive treatment technology of source reduction-end treatment is adopted to treat the AMD. The treatment area of the goaf is 0.3 km3, the filling and grouting volume is about 6.7 m3, and the curtain grouting volume is 4,000 m3. Through the grouting and sealing treatment in the goaf, the water volume is reduced to less than 85% of the initial volume (100 m3/h). After the end treatment, the pH value of the effluent is around 7.0, the content of Fe and Mn is less than 0.1 mg/L, and the removal rate is above 99%. The project was subsequently operated at RMB 0.85 yuan/t. This project is aimed at the treatment of AMD from small coal mines in complex terrain conditions. It has the characteristics of low cost and high efficiency and can provide an effective treatment technology for AMD in southwestern China and areas with the same geological conditions.

Variability in the acid adaptation of ten different O157:H7 and non-O157 Escherichia coli strains in orange juice and the impact on UV radiation resistance.

This study aimed to assess the impact of adaptation of ten strains of O157:H7 and non-O157 Escherichia coli to low pH (acid shock or slow acidification) and the effects of this exposure or not on the resistance of E. coli strains to UV radiation in orange juice (pH 3.5). The acid-shocked cells were obtained through culture in tryptic soy broth (TSB) with a final pH of 4.8, which was adjusted by hydrochloric, lactic, or citric acid and subsequently inoculated in orange juice at 4 °C for 30 days. No significant differences (p > 0.05) in survival in orange juice were observed between the serotypes O157:H7 and non-O157:H7 for acid-shocked experiments. After slow acidification, where the cells were cultured in TSB supplemented with glucose 1% (TSB + G), a significant increase (p < 0.05) in survival was observed for all strains evaluated. The D-values (radiation dose (J/cm2) necessary to decrease the microbial population by 90%) were determined as the inverse of the slopes of the regressions (k) obtained by plotting log (N/N0). The results show that among the strains tested, E. coli O157:H7 (303/00) and O26:H11 were the most resistant and sensitive strains, respectively. According to our results, the method of acid adaptation contributes to increasing the UV resistance for most of the strains tested.

Rising Alkali-to-Acid Ratios in the Atmosphere May Correspond to Increased Aerosol Acidity.

Aerosol acidity (or pH) is one central parameter in determining the health, climate, and ecological effects of aerosols. While it is traditionally assumed that the long-term aerosol pH levels are determined by the relative abundances of atmospheric alkaline to acidic substances (referred to as RC/A hereinafter), we observed contrasting pH─RC/A trends at different sites globally, i.e., rising alkali-to-acid ratios in the atmosphere may unexpectedly lead to increased aerosol acidity. Here, we examined this apparently counterintuitive phenomenon using the multiphase buffer theory. We show that the aerosol water content (AWC) set a pH "baseline" as the peak buffer pH, while the RC/A and particle-phase chemical compositions determine the deviation of pH from this baseline within the buffer ranges. Therefore, contrasting long-term pH trends may emerge when RC/A increases while the AWC or nitrate fraction decreases, or vice versa. Our results provided a theoretical framework for a quantitative understanding of the response of aerosol pH to variations in SO2, NOx versus NH3, and dust emissions, offering broad applications in studies on aerosol pH and the associated environmental and health effects.

The Influence of Barley Proteome on Hop Bitter Acid Yield during Brewing.

A persistent challenge in brewing is the efficient utilization of hop bitter acids, with about 50% of these compounds precipitating with trub during wort boiling. This study aims to uncover the correlation between the barley cultivar proteome and hop bitter acid utilization during wort boiling. Therefore, comparative experiments were conducted using two cultivars, Liga and Solist, with varying proteomes to identify specific proteins' role in hop bitter acids precipitation. High-performance liquid chromatography (HPLC) was used to measure hop bitter acid content, while liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used to quantify and identify proteins. The 107 protein groups, particularly enzymes linked to barley metabolic defense mechanisms, exhibited significant differences between the two cultivars. Results revealed significantly lower α- and iso-α-acid content in wort produced from the barley cultivar Liga. This study highlights the critical role of the barley proteome in optimizing process efficiency by enhancing hop utilization through barley cultivar selection.

Breeding for an elite malting barley cultivar with acid soil tolerance.

Barley (Hordeum vulgare L.) is the fourth most produced cereal crop in the world, but its productivity on acid soil has been restricted due to its high sensitivity to aluminum (Al) toxicity. The major gene controlling Al tolerance in barley is HvAACT1 (Al-activated citrate transporter 1), which is involved in citrate secretion from the roots for Al detoxification. Here we bred a malting barley cultivar with enhanced acid soil tolerance by introgression of a 1-kb transposon regulating the expression of HvAACT1 into an elite malting cultivar through multiple backcrossing and marker-assisted selection. The line selected showed increased expression of HvAACT1, enhanced citrate secretion from the roots and decreased Al binding to the roots. This line produced more than two to three times the grain yield compared with the original cultivar when grown on acidic soil, providing a potentially sustainable and economic way to boost productivity of malting barley cultivars in areas with acidic soil.

Heterologous expression of the Oenococcus oeni two-component signal transduction response regulator in the Lactiplantibacillus plantarum WCFS1 strain enhances acid stress tolerance.

BACKGROUND: Oenococcus oeni is a commercial wine-fermenting bacterial strain, owing to its high efficiency of malolactic fermentation and stress tolerance. The present study explored the function of key genes in O. oeni to enhance stress resistance by heterologous expression of these genes in another species. RESULTS: The orf00404 gene that encodes a two-component signal transduction response regulator in O. oeni was heterologously expressed in Lactiplantibacillus plantarum WCFS1. The expression of orf00404 significantly enhanced the growth rate of the recombinant strain under acid stress. At 60 h, 72 h, and 108 h of culture at pH 4.0, the recombinant strain had 1562, 641, and 748 differentially expressed genes compared to the control strain, respectively. At all three time points, 20 genes were upregulated in the recombinant strain, including the lamA-D operon-coding genes of the quorum-sensing two component signal transduction system and the spx5 RNA polymerase-binding protein coding gene, which may help adaptation to acid stress. In addition, 47 genes were downregulated in the recombinant strain at all three time points, including the hsp1 heat shock protein-coding gene, the trxA1 thioredoxin-coding gene, and the dinP, mutY, umuC, and uvrB DNA damage repair-related protein-coding genes, potentially indicating that the recombinant strain was less susceptible to stress and had less DNA damage than the control strain in acid stress conditions. The recombinant strain had higher membrane fluidity, permeability, and integrity at an early stage of logarithmic growth (72 h), suggesting that it had a more complete and active cell membrane state at this stage. The intracellular ATP content was significantly reduced in the recombinant strain at the beginning of logarithmic growth (60 h), implying that the recombinant strain consumed more energy at this stage to resist acid stress and growth. CONCLUSIONS: These results indicated that the recombinant strain enhances acid stress tolerance by regulating a gene expression pattern, increasing ATP consumption, and enhancing cell membrane fluidity, membrane permeability, and membrane integrity at specific growth stages. Thus, the recombinant strain may have potential application in the microbial biotechnology industry.

Biophysical insights into sugar-dependent medium acidification promoting YfaL protein-mediated Escherichia coli self-aggregation, biofilm formation and acid stress resistance.

The ability of bacteria to interact with their environment is crucial to form aggregates and biofilms, and develop a collective stress resistance behavior. Despite its environmental and medical importance, bacterial aggregation is poorly understood and mediated by few known adhesion structures. Here, we identified a new role for a surface-exposed Escherichia coli protein, YfaL, which can self-recognize and induce bacterial autoaggregation. This process occurs only under acidic conditions generated during E. coli growth in the presence of fermentable sugars. These findings were supported by electrokinetic and atomic force spectroscopy measurements, which revealed changes in the electrostatic, hydrophobic, and structural properties of YfaL-decorated cell surface upon sugar consumption. Furthermore, YfaL-mediated autoaggregation promotes biofilm formation and enhances E. coli resistance to acid stress. The prevalence and conservation of YfaL in environmental and clinical E. coli suggest strong evolutionary selection for its function inside or outside the host. Overall, our results emphasize the importance of environmental parameters such as low pH as physicochemical cues influencing bacterial adhesion and aggregation, affecting E. coli and potentially other bacteria's resistance to environmental stress.

Synergistic effects of oxidative and acid stress on bacterial membranes of Escherichia coli and Staphylococcus simulans.

Oxidative stress in combination with acid stress has been shown to inactivate a wide spectrum of microorganisms, including multi-resistant bacteria. This occurs e.g. in phagolysosomes or during treatment by cold atmospheric pressure plasmas (CAP) and possibly depends on the cell membrane. We therefore explored the effects of CAP-generated reactive oxygen and nitrogen species (RONS) on bacterial growth inhibition and membranes in neutral and acidic suspensions. We observed that growth inhibition was most efficient when bacteria were treated by a mix of short and long-lived RONS in an acidic environment. Membrane packing was affected mainly upon contact with short-lived RONS, while also acidity strongly modulated packing. Under these conditions, Gram-negative bacteria displayed large potassium release while SYTOX Green influx remained marginal. Growth inhibition of Gram-negative bacteria correlated well with outer membrane (OM) permeabilization that occurred upon contact with short and/or long-lived RONS in synergy with acidity. In Gram-positive bacteria, CAP impaired membrane potential possibly through pore formation upon contact with short-lived RONS while formation of membrane protein hydroperoxides was probably involved in these effects. In summary, our study provides a wide perspective on understanding inactivation mechanisms of bacteria by RONS in combination with acidity.

Hypoglycemic effect of orally administered resistant dextrins prepared with different acids on type 2 diabetes mice induced by high-fat diet and streptozotocin.

A comparative study was performed to investigate the physicochemical properties and protective effects of hydrochloric acid-resistant dextrin (H-RD), citric acid-resistant dextrin (C-RD) and tartaric acid-resistant dextrin (T-RD) on the metabolic disorders and intestinal microbiota for type 2 diabetes mellitus (T2DM) mice. T-RD had the minimum molecular weight, with the highest short chain (DP 6-12) proportion and resistant starch content. After 4-week intervention with the three resistant dextrins, the body weight and fasting blood glucose of T2DM mice were improved significantly, accompanied by the reduction of serum indexes (TG, TC, LDL-C, ALT, AST, CRE, BUN, FINS, and GSP), but the serum HDL-C and liver glycogen levels increased. Among the three RDs intervention groups, T-RD showed the most significant improvement, followed by C-RD and finally H-RD. The 16 s rDNA results indicated that oral administration of resistant dextrins favored the proliferation of specific gut microbiota, including Faecalibaculum, Parabacteroides and Dubosiella, and reduced the ratio of Firmicutes/Bacteroidota, which is beneficial for reducing insulin resistance. Herein, the findings supported that the resistant dextrins exhibited a remission effect on T2DM, providing a basis for the development of functional food adjuvants for T2DM treatment.

A high-performance anion-exchange chromatographic method for the fast analysis and precise determination of varied glucose-derived acids during biomass biorefinery.

Glucose-derived acids for the further production of value-added medicine, food additives, and polymers, will promote lignocellulosic biomass biorefinery industry. In response to the diversity and complexity, a new method was established by employing high performance anion exchange chromatography (HPAEC) coupled with a CarboPac™ PA200 column, for the precise and fast determination of glucose, gluconic acid, glucuronic acid, 2-ketogluconic acid, 5-ketogluconic acid and glucaric acid. Based on the analysis of tiny varieties in retention behavior, a gradient elution mode was designed and optimized for the quantitative and qualitative analysis. The protocol displayed acceptable linearity (R2 ≥ 0.995), commendable average recovery rate (95.28% âˆ¼ 99.89%), satisfactory precision (RSD% ≤ 1.5%), and sufficient resolution (R > 6). Additionally, this method was successfully applied to the high-value biorefining process, which confirmed the practicability and accuracy. The results demonstrated that HPAEC has good detection performance for glucose and its derivative acids, and provide key identification technical support for the high-value utilization of lignocellulose.

Oral microbiome insights: Tracing acidic culprits in dental caries with functional metagenomics.

OBJECTIVE: This study aimed to investigate the presence and abundance of acid-producing bacteria in dental caries samples using functional gene prediction techniques. DESIGN: A total of 24 dental caries samples were collected for analysis. DNA isolation was performed followed by shotgun metagenomic sequencing. Functional gene prediction techniques were used to identify enzymes responsible for acid production from primary metabolites. Enzymes responsible for converting primary metabolites into acids were identified from the KEGG database. Subsequently, 840 contigs were examined, and their genus and species were characterized. RESULTS: Analysis of the obtained data revealed 31 KEGG IDs corresponding to enzymes involved in the conversion of primary metabolites into acids. All 117 identified genera from the contig analysis were found to be part of the oral microbiome. In addition, A higher prevalence of acid-producing bacteria was noted in dental caries samples compared to earlier reports. CONCLUSION: The study indicates the significant role of acid-producing bacteria in the initiation and progression of dental caries. The findings highlight the importance of microbial activity in the demineralization process of tooth enamel. Methods for preventing dental decay may be promising if specific measures are implemented to reduce the amount of acid produced by oral bacteria.

Sour, but acceptable: Taste responsiveness to five food-associated acids in zoo-housed white-faced sakis, Pithecia pithecia.

White-faced sakis (Pithecia pithecia) are commonly considered as frugivores but are unusual among primates as they do not specialize on ripe fruits but rather include a high proportion of unripe fruits into their diet, even during seasons when ripe fruits are available. Using a two-bottle preference test of short duration we therefore assessed whether this dietary specialization affects the taste responsiveness and sour-taste tolerance of four adult white-faced sakis for five food-associated acids. We found taste preference thresholds of the sakis to be 1-10 mM for citric acid, 0.5-20 mM for ascorbic acid, 2-10 mM for malic acid, 0.1-1 mM for tannic acid, and 2-20 mM for acetic acid, respectively. When given the choice between a reference solution of 50 mM sucrose and mixtures containing varying concentrations of sucrose plus citric acid, the sakis displayed a high sour-taste tolerance and required only 100 mM of sucrose (when mixed with 10 mM citric acid) or 200 mM of sucrose (when mixed with 30 or 50 mM citric acid), respectively, to prefer the sweet-sour mixture over the purely sweet 50 mM sucrose reference solution. These results demonstrate that white-faced sakis have a well-developed taste sensitivity for food-associated acids which is not inferior to that of primates specializing on ripe fruits. Compared to other platyrrhine primates, the sakis displayed a markedly higher sour-taste tolerance. These results may therefore reflect an evolutionary adaptation to the dietary specialization of the white-faced sakis to sour-tasting unripe fruits.

Deciphering microbial metabolic interactions and their implications for community dynamics in acid mine drainage sediments.

The microbially-mediated reduction processes have potential for the bioremediation of acid mine drainage (AMD), which represents a worldwide environment problem. However, we know little about the microbial interactions in anaerobic AMD sediments. Here we utilized genome-resolved metagenomics to uncover the nature of cooperative and competitive metabolic interactions in 90 AMD sediments across Southern China. Our analyses recovered well-represented prokaryotic communities through the reconstruction of 2625 population genomes. Functional analyses of these genomes revealed extensive metabolic handoffs which occurred more frequently in nitrogen metabolism than in sulfur metabolism, as well as stable functional redundancy across sediments resulting from populations with low genomic relatedness. Genome-scale metabolic modeling showed that metabolic competition promoted microbial co-occurrence relationships, suggesting that community assembly was dominated by habitat filtering in sediments. Notably, communities colonizing more extreme conditions tended to be highly competitive, which was typically accompanied with increased network complexity but decreased stability of the microbiome. Finally, our results demonstrated that heterotrophic Thermoplasmatota associated with ferric iron and sulfate reduction contributed most to the elevated levels of competition. Our study shed light on the cooperative and competitive metabolisms of microbiome in the hazardous AMD sediments, which may provide preliminary clues for the AMD bioremediation in the future.

Comparison of acid and hydrothermal pretreatments of date waste for value creation.

The production of date syrup yields a substantial amount of date press cake (DPC), fibrous and moisturising material with great potential for generating value through bioprocessing. However, the recalcitrant structure of DPC affects the yield of products in bioprocesses. To boost the accessibility of the structure as well as increase the soluble fraction of carbohydrates and facilitate further enzymatic hydrolysis, hydrothermal and dilute acid (0.5% (v/v) sulfuric acid) pretreatments as cost-effective and feasible methods were applied on DPC at relatively low temperatures (80, 100, 120 and 140 °C) and reaction times (60 and 90 min). The success in pretreatment was then evaluated by a post-enzymatic treatment using an enzyme cocktail of cellulases and hemicelluloses. Based on total accessible sugar with minimum produced inhibitors, an optimal operating condition was considered acid pretreatment at 120 °C for 90 min with a 55.02% increase in total sugar yield. To explore the potential use of pretreated DPC, an anaerobic digestion was conducted on untreated and acid-pretreated DPC at 120 °C for 90 min. The results showed that pretreatment increased the total bioproduct yield, including hydrogen, ethanol, and volatile fatty acid yields, by 59.75%. This demonstrates the significant impact of pretreatment on product yields in a bioprocess.

Acidic preconditioning induced intracellular acid adaptation to protect renal injury via dynamic phosphorylation of focal adhesion kinase-dependent activation of sodium hydrogen exchanger 1.

BACKGROUND: Disruptions in intracellular pH (pHi) homeostasis, causing deviations from the physiological range, can damage renal epithelial cells. However, the existence of an adaptive mechanism to restore pHi to normalcy remains unclear. Early research identified H+ as a critical mediator of ischemic preconditioning (IPC), leading to the concept of acidic preconditioning (AP). This concept proposes that short-term, repetitive acidic stimulation can enhance a cell's capacity to withstand subsequent adverse stress. While AP has demonstrated protective effects in various ischemia-reperfusion (I/R) injury models, its application in kidney injury remains largely unexplored. METHODS: An AP model was established in human kidney (HK2) cells by treating them with an acidic medium for 12 h, followed by a recovery period with a normal medium for 6 h. To induce hypoxia/reoxygenation (H/R) injury, HK2 cells were subjected to hypoxia for 24 h and reoxygenation for 1 h. In vivo, a mouse model of IPC was established by clamping the bilateral renal pedicles for 15 min, followed by reperfusion for 4 days. Conversely, the I/R model involved clamping the bilateral renal pedicles for 35 min and reperfusion for 24 h. Western blotting was employed to evaluate the expression levels of cleaved caspase 3, cleaved caspase 9, NHE1, KIM1, FAK, and NOX4. A pH-sensitive fluorescent probe was used to measure pHi, while a Hemin/CNF microelectrode monitored kidney tissue pH. Immunofluorescence staining was performed to visualize the localization of NHE1, NOX4, and FAK, along with the actin cytoskeleton structure in HK2 cells. Cell adhesion and scratch assays were conducted to assess cell motility. RESULTS: Our findings demonstrated that AP could effectively mitigate H/R injury in HK2 cells. This protective effect and the maintenance of pHi homeostasis by AP involved the upregulation of Na+/H+ exchanger 1 (NHE1) expression and activity. The activity of NHE1 was regulated by dynamic changes in pHi-dependent phosphorylation of Focal Adhesion Kinase (FAK) at Y397. This process was associated with NOX4-mediated reactive oxygen species (ROS) production. Furthermore, AP induced the co-localization of FAK, NOX4, and NHE1 in focal adhesions, promoting cytoskeletal remodeling and enhancing cell adhesion and migration capabilities. CONCLUSIONS: This study provides compelling evidence that AP maintains pHi homeostasis and promotes cytoskeletal remodeling through FAK/NOX4/NHE1 signaling. This signaling pathway ultimately contributes to alleviated H/R injury in HK2 cells.

Association between Dietary Acid Load and Chronic Kidney Disease in the Chinese Population: A Comprehensive Analysis of the China Health and Nutrition Survey (2009).

BACKGROUND: Dietary acid load (DAL) is closely related to several chronic diseases. However, the link between DAL and chronic kidney disease (CKD) remains scarce and without data from the Chinese populations whose diet is quite different from people in Western countries. METHODS: This study evaluated DAL by potential renal acid load (PRAL) and net endogenous acid production (NEAP). We clarified the relationship between DAL and CKD by logistic regression analysis based on data from the China Health and Nutrition Survey (CHNS). RESULTS: The final analysis included 7699 individuals, of whom 811 (11.44%) were CKD patients. Although there was no notable link between PRAL and CKD, higher NEAP levels were independently correlated with CKD. As NEAP values rise, so does CKD prevalence. This trend remains highly significant even after adjustments. In subgroup analyses, the relationship between NEAP and CKD was more consistent in the elderly and subjects with a waistline of less than 82 cm and those without diabetes and heart disease. RCS analysis further confirmed the clear linear relationship between the OR of CKD and NEAP score. CONCLUSIONS: This study highlighted that higher NEAP was positively correlated with the risk of CKD.

Effect of solvent acids on the microstructure and corrosion resistance of chitosan films on MAO-treated AZ31B magnesium alloy.

This study evaluated the effect of solvent acids on the structure and corrosion resistance performance of chitosan (CS) film on MAO-treated AZ31B magnesium (Mg) alloy. Initially, CS solutions were prepared in four solvent acids: acetic acid (HAc), lactic acid (LA), hydrochloric acid (HCl), and citric acid (CA). The CS films were subsequently deposited on MAO-treated AZ31B Mg alloy via a dip-coating technique. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction analysis (XRD), Fourier-transform infrared spectroscopy (FT-IR), contact angle measurement, and atomic force microscopy (AFM) were employed to characterize the surface and cross-sectional morphology as well as chemical composition. Furthermore, the samples were subjected to potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) tests to assess their resistance against corrosion in simulated body fluid (SBF). These results indicated that the CS film prepared with LA exhibited the lowest surface roughness (Ra = 31.2 nm), the largest contact angle (CA = 98.50°), and the thickest coating (36 µm). Additionally, it demonstrated superior corrosion protection performance, with the lowest corrosion current density (Icorr = 3.343 × 10-7 A/cm2), highest corrosion potential (Ecorr = -1.49 V), and highest polarization resistance (Rp = 5.914 × 104 Ω·cm2) in SBF. These results indicated that solvent acid types significantly influenced their interactions with CS. Thus, the structure and corrosion protection performance of CS films can be optimized by selecting an appropriate solvent acid.