Interactive deciphering electron-shuttling characteristics of Coffea arabica leaves and potential bioenergy-steered anti-SARS-CoV-2 RdRp inhibitor via microbial fuel cells.

Due to the pandemics of COVID-19, herbal medicine has recently been explored for possible antiviral treatment and prevention via novel platform of microbial fuel cells. It was revealed that Coffea arabica leaves was very appropriate for anti-COVID-19 drug development. Antioxidant and anti-inflammatory tests exhibited the most promising activities for C. arabica ethanol extracts and drying approaches were implemented on the leaf samples prior to ethanol extraction. Ethanol extracts of C. arabica leaves were applied to bioenergy evaluation via DC-MFCs, clearly revealing that air-dried leaves (CA-A-EtOH) exhibited the highest bioenergy-stimulating capabilities (ca. 2.72 fold of power amplification to the blank). Furthermore, molecular docking analysis was implemented to decipher the potential of C. arabica leaves metabolites. Chlorogenic acid (-6.5 kcal/mol) owned the highest binding affinity with RdRp of SARS-CoV-2, showing a much lower average RMSF value than an apoprotein. This study suggested C. arabica leaves as an encouraging medicinal herb against SARS-CoV-2.

Kinetic study of Reactive Black 5 degradation by Fe2+/S2O82- process via interactive model-based response surface methodology.

This study aimed to kinetically discover optimal conditions on characteristics of Reactive Black 5 decolorization/degradation via ferrous (Fe2+)-activated potassium persulfate (PS). Monod-like kinetics and interactive model-based response surface methodology (RSM) were applied to fitting and predict optimize treatment. Biodegradability of the intermediates was also tested by shaking culture with two species (Proteus hauseri ZMd44 and Shewanella sp. WLP72). Results showed that the optimal degradation efficiency was predicted (through RSM) as pH 3.72, (PS) = 0.39 mM, and (Fe2+) = 0.29 mM. The transformation products (dl-4-hydroxymandelic acid, benzoic acid, benzene, formic acid, oxalic acid and acetic acid) were less toxic than the original dye solution. According to those results, clean-up of dye pollutants by the Fe2+/S2O82- process is feasible as a pre-processing for the biodegradation, and the predicted optimal conditions are meaningful for further industry utilization.

Deciphering visible light photoreductive conversion of CO2 to formic acid and methanol using waste prepared material.

As gradual increases in atmospheric CO2 and depletion of fossil fuels have raised considerable public concern in recent decades, utilizing the unlimited solar energy to convert CO2 to fuels (e.g., formic acid and methanol) apparently could simultaneously resolve these issues for sustainable development. However, due to the complicated characteristics of CO2 reduction, the mechanism has yet to be disclosed. To clarify the postulated pathway as mentioned in the literature, the technique of electron paramagnetic resonance (ESR) was implemented herein to confirm the mechanism and related pathways of CO2 reduction under visible light using graphene-TiO2 as catalyst. The findings indicated that CO(-•) radicals, as the main intermediates, were first detected herein to react with several hydrogen ions and electrons for the formation of CH3OH. For example, the generation of CO(-•) radicals is possibly the vital rate-controlling step for conversion of CO2 to methanol as hypothesized elsewhere. The kinetics behind the proposed mechanism was also determined in this study. The mechanism and kinetics could provide the in-depth understanding to the pathway of CO2 reduction and disclose system optimization of maximal conversion for further application.

Exploring metal effects and synergistic interactions of ferric stimulation on azo-dye decolorization by new indigenous Acinetobacter guillouiae Ax-9 and Rahnella aquatilis DX2b.

The first-attempt study deciphered metal-interacting effects on dye-decolorizing capabilities of indigenous bioelectricity-generating strains, Acinetobacter guillouiae Ax-9 and Rahnella aquatilis DX2b. Most of the metallic ions were inhibitory to color removal capabilities of these strains. However, with supplementation of 5 mM ferric chloride, specific decolorization rate (SDR) of Ax-9 increased by 55.48% compared to Fe(3+)-free conditions. In contrast, SDR of DX2b decreased 75.35% due to the inhibition of ferric chloride. On the other hand, ferric citrate could stimulate SDR of DX2b for 21.5% at same dosage. Enzymatic assay indicated that Fe reductase activity was consistent with synergistic effects of ferric chloride on Ax-9, and ferric citrate on DX2b. Protein analysis via SDS-PAGE and identification of Tandem MS/MS afterwards showed that outer membrane protein (Omp) primarily deals with decolorization as a channeling regulation. Moreover, molecular modeling and bioinformatics data also provided detailed evidences to confirm the biological significance of Omp.

Boron-doped reduced graphene oxide as an efficient cathode in microbial fuel cells for biological toxicity detection.

Electrodes with superior stability and sensitivity are highly desirable in advancing the toxicity detection efficiency of microbial fuel cells (MFCs). Herein, boron-doped reduced graphene oxide (B-rGO) was synthesized and utilized as an efficient cathode candidate in an MFCs system for sensitive sodium dodecylbenzene sulfonate (SDBS) detection. Boron doping introduces additional defects and improves the dispersibility and oxygen permeability, thereby enhancing the oxygen reduction reaction (ORR) efficiency. The B-rGO-based cathode has demonstrated significantly improved output voltage and power density, marking improvements of 75 % and 58 % over their undoped counterparts, respectively. Furthermore, it also exhibited remarkable linear sensitivity to SDBS concentrations across a broad range (0.2-15 mg/L). Notably, the cathode maintained excellent stability within the test range and showed significant reversibility for SDBS concentrations between 0.2 and 3 mg/L. The highly sensitive and stable B-rGO-based cathode is inspiring for developing more practical and cost-effective toxicant sensing devices.

Interactive network pharmacology and electrochemical analysis reveals electron transport-mediating characteristics of Chinese medicine formula Jing Guan Fang.

Background: Jing Guan Fang (JGF) is an anti-COVID-19 Chinese Medicine decoction comprised of five medicinal herbs to possess anti-inflammatory and antiviral properties for treatment. This study aims to electrochemically decipher the anti-coronavirus activity of JGF and show that microbial fuel cells may serve as a platform for screening efficacious herbal medicines and providing scientific bases for the mechanism of action (MOA) of TCMs. Methods: Electrochemical techniques (e.g., cyclic voltammetry) and MFCs were adopted as the bioenergy-based platforms to assess the bioenergy-stimulating characteristics of JGF. Phytochemical analysis correlated polyphenolic and flavonoid content with antioxidant activity and bioenergy-stimulating properties. Network pharmacology on the active compounds was employed to identify anti-inflammatory and anti-COVID-19 protein targets, and molecular docking validated in silico results. Significant findings: This first-attempt results show that JGF possesses significant reversible bioenergy-stimulation (amplification 2.02 ± 0.04) properties suggesting that its antiviral efficacy is both bioenergy-steered and electron mediated. Major flavonoids and flavone glycosides identified by HPLC (e.g., baicalein and baicalin, respectively) possess electron-shuttling (ES) characteristics that allow herbal medicines to treat COVID-19 via (1) reversible scavenging of ROS to lessen inflammation; (2) inhibition of viral proteins; and (3) targeting of immunomodulatory pathways to stimulate the immune response according to network pharmacology.

Deciphering Houttuynia cordata extract as electron shuttles with anti-COVID-19 activity and its performance in microbial fuel cells.

Background: Traditional herbal medicines usually contain electron shuttle (ES)-like structures compounds which are potential candidates for antiviral compounds selection. Houttuynia cordata is applied as a biomaterial to decipher its potential applications in bioenergy extraction in microbial fuel cells (MFCs) and anti-COVID-19 via molecular docking evaluation. Methods: H. cordata leaves extracts by water and 60% ethanol solvent were analyzed for total polyphenols, antioxidant activity, cyclic voltammetry (CV), and MFCs. The bioactive compounds of H. cordata leaves extracts were assayed via LC/MS analysis. Identification of the marker substances for potential antiviral activity using a molecular docking model was provided. Significant findings: 60% ethanol extract exhibits the highest total polyphenols and antioxidant activity compared with water extracts. Bioenergy extraction in MFCs showed that 60% ethanol extracts could give 1.76-fold more power generation compared to the blank. Flavonoids and their sugar-to-glycan ratios increased after CV scanning and they are expected to be effective ES substances. Quercitrin, from the H. cordata extract that shares an ES-like structure, was found to exhibit strong binding affinities towards ACE2 and RdRp. This indicated the potential of H. cordata leaves as a promising antiviral herb.

Interactive deciphering electron-shuttling characteristics of agricultural wastes with potential bioenergy-steered anti-COVID-19 activity via microbial fuel cells.

Background: This first-attempt study explored indigenous herbs from agricultural waste with bioenergy and biorefinery-stimulating potentials for possible anti-COVID-19 drug development. As prior novel study revealed, medicinal herbs abundant in ortho-dihydroxyl substituents and flavonoid-bearing chemicals were likely not only electron shuttle (ES)-steered, but also virus transmission-resisted. Methods: Herbal extract preparation from agricultural wastes were implemented via traditional Chinese medicine (TCM) decoction pot. After filtration and evaporation, a crude extract obtained was used for evaluation of bioenergy-stimulating and electron-mediating characteristics via microbial fuel cells (MFCs). Combined with cyclic voltammetric analysis, MFCs provided a novel platform to distinguish electron shuttles from antioxidants with electron-transfer steered antiviral potentials of herbal extracts. Significant findings: After 50 serial cyclic voltammogram traces, considerable ES activities of herbal extracts still stably remained, indicating that possible medication-associated capabilities could be persistent. This work also extended to explore bioenergy-stimulating herbs from agricultural waste recycling for bioenergy and biorefinery applications. Water extract of Coffea arabica was more biotoxic than ethanolic extract, resulting in its lower power-generating capability. The findings revealed that water extract of Trichodesma khasianum and Euphorbia hirta could exhibit considerable bioenergy-enhancing effects. For cradle-to-cradle circular economy, agricultural waste could be specifically screened for possible regeneration of value-added anti-COVID-19 drugs via bioenergy selection.

Synergistic deciphering of bioenergy production and electron transport characteristics to screen traditional Chinese medicine (TCM) for COVID-19 drug development.

Background: Traditional Chinese medicine (TCM) has been used as an "immune booster" for disease prevention and clinical treatment since ancient China. However, many studies were focused on the organic herbal extract rather than aqueous herbal extract (AHE; decoction). Due to the COVID-19 pandemics, this study tended to decipher phytochemical contents in the decoction of herbs and derived bioactivities (e.g., anti-oxidant and anti-inflammatory properties). As prior works revealed, the efficacy of Parkinson's medicines and antiviral flavonoid herbs was strongly governed by their bioenergy-stimulating proficiency. Methods: Herbal extracts were prepared by using a traditional Chinese decoction pot. After filtration and evaporation, crude extracts were used to prepare sample solutions for various bioassays. The phytochemical content and bioactivities of AHEs were determined via ELISA microplate reader. Microbial fuel cells (MFCs) were used as a novel platform to evaluate bioenergy contents with electron-transfer characteristics for antiviral drug development. Significant findings: Regarding 18 TCM herbal extracts for the prevention of SARS and H1N1 influenza, comparison on total polyphenol, flavonoid, condensed tannins and polysaccharides were conducted. Moreover, considerable total flavonoid contents were detected for 11 herb extracts. These AEHs were not only rich in phytonutrient contents but also plentiful in anti-oxidant and anti-inflammatory activities. Herbs with high polyphenol content had higher antioxidant activity. Forsythia suspensa extract expressed the highest inhibition against nitric oxide production for anti-inflammation. MFC bioenergy-stimulating studies also revealed that top ranking COVID-19 efficacious herbs were both bioenergy driven and electron mediated. That is, electron transfer-controlled bioenergy extraction was significant to antiviral characteristics for anti-COVID-19 drug development.

Exploring characteristics of bioelectricity generation and dye decolorization of mixed and pure bacterial cultures from wine-bearing wastewater treatment.

This study uncovered microbial characteristics of bioelectricity generation and dye decolorization in single-chamber microbial fuel cells (MFCs) using activated sludge for wine-containing wastewater treatment. Phylogenetic tree analysis on 16S rRNA gene fragments indicated that the predominant strains on anodic biofilm in acclimatized MFCs were Gamma-Proteobacteria Aeromonas punctata NIU-P9, Pseudomonas plecoglossicida NIU-Y3, Pseudomonas koreensis NIU-X8, Acinetobacter junii NIU-Y8, Stenotrophomonas maltophila NIU-X2. Our findings showed that the current production capabilities of these pure strains were only ca. 10% of those of their mother activated sludge, indicating that synergistic interactions among microbes might be the most influential factor to maximize power generation in MFCs. Plus, these electrochemically active strains also performed reductive decolorization of C.I. reactive blue 160, suggesting that bioelectricity generation might be directly associated to azo dye decolorization to deal with electron transfer on anodic biofilm in MFCs.

Predicting the co-melting temperatures of municipal solid waste incinerator fly ash and sewage sludge ash using grey model and neural network.

A grey model (GM) and an artificial neural network (ANN) were employed to predict co-melting temperature of municipal solid waste incinerator (MSWI) fly ash and sewage sludge ash (SSA) during formation of modified slag. The results indicated that in the aspect of model prediction, the mean absolute percentage error (MAPEs) were between 1.69 and 13.20% when adopting seven different GM (1, N) models. The MAPE were 1.59 and 1.31% when GM (1, 1) and rolling grey model (RGM (1, 1)) were adopted. The MAPEs fell within the range of 0.04 and 0.50% using different types of ANN. In GMs, the MAPE of 1.31% was found to be the lowest when using RGM (1, 1) to predict co-melting temperature. This value was higher than those of ANN2-1 to ANN8-1 by 1.27, 1.25, 1.24, 1.18, 1.16, 1.14 and 0.81%, respectively. GM only required a small amount of data (at least four data). Therefore, GM could be applied successfully in predicting the co-melting temperature of MSWI fly ash and SSA when no sufficient information is available. It also indicates that both the composition of MSWI fly ash and SSA could be applied on the prediction of co-melting temperature.

Exploring kinetics of phenol biodegradation by Cupriavidus taiwanesis 187.

Phenol biodegradation in batch systems using Cupriavidus taiwanesis 187 has been experimentally studied. To determine the various parameters of a kinetic model, combinations of rearranged equations have been evaluated using inverse polynomial techniques for parameter estimation. The correlations between lag phase and phase concentration suggest that considering phenol inhibition in kinetic analysis is helpful for characterizing phenol degradation. This study proposes a novel method to determine multiplicity of steady states in continuous stirred tank reactors (CSTRs) in order to identify the most appropriate kinetics to characterize the dynamics of phenol biodegradation.

Waste brick's potential for use as a pozzolan in blended Portland cement.

This study investigated the pozzolanic reactions and engineering properties of waste brick-blended cements in relation to various replacement ratios (0-50%). The waste brick consisted of SiO(2) (63.21%), Al(2)O(3) (16.41%), Fe(2)O(3) (6.05%), Na(2)O (1.19%), K(2)O (2.83%) and MgO (1.11%), and had a pozzolanic activity index of 107%. The toxic characteristic leaching procedure (TCLP) results demonstrate that the heavy-metal content in waste bricks met the Environmental Protection Agency regulatory limits. Experimental results indicate that 10, 20, 30, 40 and 50% of cement can be replaced by waste brick, which causes the initial and final setting times to increase. Compressive strength development was slower in waste brick-blended cement (WBBC) pastes in the early ages; however, strength at the later ages increased significantly. Species analyses demonstrate that the hydrates in WBBC pastes primarily consisted of Ca(OH)(2) and calcium silicate hydrate (C-S-H) gel, like those found in ordinary Portland cement (OPC) paste. Pozzolanic reaction products formed in the WBBC pastes, in particular, various reaction products, including hydrates of calcium silicates (CSH), aluminates (CAH) and aluminosilicates (CASH), formed as expected, resulting in consumption of Ca(OH)(2) during the late ages of curing. The changes in the properties of WBBC pastes were significant as blend ratio increased, due to the pores of C-S-H gels and CAH filling via pozzolanic reactions. This filling of gel pores resulted in densification and subsequently enhanced the gel/space ratio and degree of hydration. Experimental results demonstrate waste brick can be supplementary cementitious material.

Exploring community evolutionary characteristics of microbial populations with supplementation of Camellia green tea extracts in microbial fuel cells.

This first-attempt study deciphered combined characteristics of species evolution and bioelectricity generation of microbial community in microbial fuel cells (MFCs) supplemented with Camellia green tea (GT) extracts for biomass energy extraction. Prior studies indicated that polyphenols-rich extracts as effective redox mediators (RMs) could exhibit significant electrochemical activities to enhance power generation in MFCs. However, the supplementation of Camellia GT extract obtained at room temperature with significant redox capabilities into MFCs unexpectedly exhibited obvious inhibitory effect towards power generation. This systematic study indicated that the presence of antimicrobial components (especially catechins) in GT extract might significantly alter the distribution of microbial community, in particular a decrease of microbial diversity and evenness. For practical applications to different microbial systems, pre-screening criteria of selecting biocompatible RMs should not only consider their promising redox capabilities (abiotic), but also possible inhibitory potency (biotic) to receptor microbes. Although Camellia tea extract was well-characterized as GRAS energy drink, some contents (e.g., catechins) may still express inhibition towards organisms and further assessment upon biotoxicity may be inevitably required for practice.

Deciphering Electron-Shuttling Characteristics of Neurotransmitters to Stimulate Bioelectricity-Generating Capabilities in Microbial Fuel Cells.

This first-attempt study used electrochemical methods to quantitatively assess electron-shuttling capabilities of different neurotransmitters crucial to catecholamine biosynthesis in human brain. As prior studies mentioned, aromatics bearing ortho- or para-dihydroxybenzenes could reveal promising electroactivities to stimulate bioenergy generation in microbial fuel cells (MFCs). This feasibility study extended to investigate the electrochemical characteristics of catecholamines and trace amines (e.g., 14 model compounds selected from neurotransmitters) synthesized by human brain via cyclic voltammetry methods (CVs) and MFCs. Dopamine (DA), levodopa (L-DOPA), epinephrine (EP), norepinephrine (NP), and 3,4-dihydroxyphenylacetic acid (DOPAC) would perform the electron-shuttling characteristics, and the rest would not. In particular, DA formed by decarboxylation of L-DOPA could exhibit relatively higher electrochemical activities than their precursors. In addition, carboxylic acids formed by deamination and carboxylation of trace monoamines would reveal more significant reductive potential (Epc); however, their oxidative electric currents seemed to be reduced. That is, chemical structure significantly influenced whether the electrochemical characteristics could be effectively expressed. This work also clearly revealed that neurotransmitters with ortho-dihydroxybenzenes exhibited promising stimulation to bioelectricity-generating capabilities of MFCs in the ranking of DA ~ EP > NP > L-DOPA > DOPAC. This was consistent with ES behaviors as CV analyses indicated.

Revealing microbial mechanism associated with volatile fatty acids production in anaerobic acidogenesis of waste activated sludge enhanced by freezing/thawing pretreatment.

This study investigated the association of volatile fatty acid (VFA) production with microbial mechanism in waste activated sludge (WAS) anaerobic acidogenesis enhanced by freezing/thawing (F/T) pretreatment. WAS solubilization was enhanced with 955.4 ± 10.0 mg/L soluble chemical oxygen demand (SCOD) release by a 50-h F/T pretreatment at -24 °C. The highest level of VFAs (4852 ± 156 mg COD/L) was obtained after a 12-day fermentation. Moreover, phyla of Proteobacteria, Bacteroidetes, Firmicutes, and Ignavibacteriae played vital roles in VFA generation, while high genera abundance of Clostridium, Macellibacteroides, Prevotella, and Megasphaera were positively associated with high yields of short-chain (C2-C5) fatty acids. A schematic diagram was drawn to illustrate the microbial mechanism of enhanced VFA generation by F/T pretreatment during WAS fermentation. This study provides an in-depth exploration of promoting bio-resource recycling from WAS with a low-cost approach (specially in high latitudes) and bring about some new thinking on future WAS management.

Sulfur doped-graphene for enhanced acetaminophen degradation via electro-catalytic activation: Efficiency and mechanism.

Although graphene exhibited excellent performance, its capability of electrochemical catalytic oxidation would significantly improve by modification via sulfur (S)-doping. However, due to the complicated doping species of heteroatoms, the detailed mechanism was still remained open for discussion. Thus, this first-attempt study tended to decipher such mechanism behind the direct and indirect oxidation by analyzing S species in S-graphene. The density functional theory (DFT) was adopted for reactive center calculation and confirmation of secondary active species, to discuss the degradation pathway. As the experimental and calculation results, the thiophene structure S was more favorable for electron acceptation in direct oxidation. Chloride reactive species, as the most effective secondary functionalities (rather than •OH), were favorably generated on the edge doped S position than thiophene structured S in defects, to further trigger the indirect oxidation. However, the extensive contents of reactive functionalities could act as trap for self-annihilation of chloride reactive species, resulting in poor electrocatalytic degradation of the pollutants. This study deepened the understanding of heteroatoms doping for electrochemical catalytic oxidation.

Toxicity assessment upon augmented biostimulation source to indigenous rhizobium Cupriavidus taiwanensis.

This novel-attempt study used chemostat pulse technique (CPT) and transient dynamics of dissolved oxygen (DO) in CSTR to quantify stimulating or inhibitory effects of augmented nutrient sources in the presence of phenol upon Cupriavidus taiwanensis R186. With injected augmented nutrients, phenol degradation performance of R186 was directly dependent on combined toxicity between phenol and the augmented substrate and the biodegradability of phenol. The findings indicated that although phenol was toxic to R186, all augmented nutrient sources still exhibited stimulating effects to bacterial growth of R186 in the presence of phenol. The simulating rankings of augmented nutrients were (1) at 200 mg/L, acetic acid>gluconic acid>yeast extract>glycerol>>phenol alone, (2) at 1000 mg/L, gluconic acid>acetic acid>glycerol>yeast extract>>phenol alone. This stimulating effect clearly suggested that this combined toxicity was antagonistic. It was also revealed that transient responses of DO seemed to be in parallel with the findings from CPT. It was thus concluded that substrate consumption patterns would play the most significant role in biostimulation to cultures with dual energy sources. This study can help uncover the mysteries of optimal biostimulation for phenol degradation as proposed in previous studies. In addition, this study directly provided a kinetic model to quantify the relative stimulation ranking of augmented nutrients in the presence of phenol for practical bioremediation.

Comparative assessment upon dye removal capability of indigenous bacterial strains from Lanyang Plain in northeast Taiwan.

This study provides a first attempt from a geological and ecological perspective to look forward isolations of indigenous strains with the decolorization capability from the most biodiverse region in Taiwan for dye-laden wastewater treatment. Serial selections were conducted by a specific use of the fungicide nystatin and model azo dye C.I. reactive red 141 (RR141) during isolation. Several bacterial strains with the excellent capability of azo dye decolorization were predominantly isolated from river water and mud samples of Lanyang River Basin. Phase-curve profiles indicated that azo dye decolorization was found to be non-growth associated for both mixed cultures and isolated pure strains. The color removal efficiency of the mixed culture was nearly 10-fold to that of Pseudomonas luteola at ca. 600mgL(-1) RR141, indicating a promising feasibility of isolated cultures to be applicable for practical treatments. The decolorization performance of unacclimated and acclimated pure cultures was at most 20% and 70-80% to that of the mixed cultures, respectively. It might suggest that combined interactions among decolorizers were crucial for the optimal color removal. According to the results of physiological and 16S rRNA gene sequence examinations, the isolated strains should belong to Aeromonas species (very likely A. hydrophila).

Unraveling interactive characteristics of microbial community associated with bioelectric energy production in sludge fermentation fluid-fed microbial fuel cells.

This first-attempt study deciphered the interactive characteristics of anodophilic microbial community-associated bioelectricity production in waste activated sludge (WAS) fermentation fluid-fed microbial fuel cells (MFCs). A novel schematic elucidation for illustrating synergistic interactions in anodic microbial consortia towards electrogenesis was proposed. Moreover, the specific genera of Pseudomonas, Desulfovibrio, Phyllobacterium, Desulfuromonas, Chelatococcus and Aminivibrio were dominant in anodic biofilms, leading to an electrogenesis efficiency of 1.254 kWh/kg COD and peak power density of 0.182 W/m2 (at feeding level of 1.20 g COD/L). It was apparently higher than those MFCs fed with glucose/acetate. The fermentative species contributed positively in reorganizing microbial community structure in anodic biofilms, positively relating to electrogenesis via interactions with exoeletrogens in MFCs. Finally, a more electrogenesis was positively associated to larger anodic microbial diversity, relatively medium anodic community evenness, together with higher abundance of functional genes related to electrogenesis in functional species in MFCs fed with WAS fermentation fluid.