Basic Medium Research Articles

Stepwise Understanding on Hydrolysis Formation of the IrOx Nanoparticles as Highly Active Electrocatalyst for Oxygen Evolution Reaction

AbstractIn this study, we have investigated the synthesis of supported iridium oxide (IrOx) nanoparticles (NPs) through hydrolysis in a surfactant-free aqueous bath as a possible route for the large-scale production of highly active electrocatalyst for oxygen evolution reaction (OER) in acidic water electrolyzers. The process involves (i) formation of Ir-hydroxides complex from an Ir precursor in basic media followed by (ii) protonation in acidic media to form colloidal hydrated IrOx NPs and (iii) conversion and deposition of IrOx NPs on the surface of carbon or TiN support by probe sonication. The IrOx NPs produced through hydrolysis route form highly stable colloidal solution. Since it is essential to precipitate the catalyst NPs from the colloidal solution for their use in water electrolyzer electrode development, here, we investigate the optimal reaction conditions, e.g., pH, temperature, time, and presence of support, for efficient synthesis of the catalyst NPs. The reaction intermediates formed at different reaction steps are explored to get insights into the chemistry of the process. Under the optimal synthesis conditions, 100% precipitation of IrOx NPs was achieved. Further, the precipitated TiN supported IrOx NPs exhibited high OER activity, superior to that of the commercial benchmark IrO2 electrocatalyst. The study provides a scalable synthesis route for highly active, low Ir-content OER electrocatalysts for acidic water electrolyzers. Graphical Abstract

A facile strategy for tuning the density of surface-grafted biomolecules for melt extrusion-based additive manufacturing applications

AbstractMelt extrusion-based additive manufacturing (ME-AM) is a promising technique to fabricate porous scaffolds for tissue engineering applications. However, most synthetic semicrystalline polymers do not possess the intrinsic biological activity required to control cell fate. Grafting of biomolecules on polymeric surfaces of AM scaffolds enhances the bioactivity of a construct; however, there are limited strategies available to control the surface density. Here, we report a strategy to tune the surface density of bioactive groups by blending a low molecular weight poly(ε-caprolactone)5k (PCL5k) containing orthogonally reactive azide groups with an unfunctionalized high molecular weight PCL75k at different ratios. Stable porous three-dimensional (3D) scaffolds were then fabricated using a high weight percentage (75 wt.%) of the low molecular weight PCL5k. As a proof-of-concept test, we prepared films of three different mass ratios of low and high molecular weight polymers with a thermopress and reacted with an alkynated fluorescent model compound on the surface, yielding a density of 201–561 pmol/cm2. Subsequently, a bone morphogenetic protein 2 (BMP-2)-derived peptide was grafted onto the films comprising different blend compositions, and the effect of peptide surface density on the osteogenic differentiation of human mesenchymal stromal cells (hMSCs) was assessed. After two weeks of culturing in a basic medium, cells expressed higher levels of BMP receptor II (BMPRII) on films with the conjugated peptide. In addition, we found that alkaline phosphatase activity was only significantly enhanced on films containing the highest peptide density (i.e., 561 pmol/cm2), indicating the importance of the surface density. Taken together, these results emphasize that the density of surface peptides on cell differentiation must be considered at the cell-material interface. Moreover, we have presented a viable strategy for ME-AM community that desires to tune the bulk and surface functionality via blending of (modified) polymers. Furthermore, the use of alkyne–azide “click” chemistry enables spatial control over bioconjugation of many tissue-specific moieties, making this approach a versatile strategy for tissue engineering applications. Graphic abstract

Basic and acidic electrolyte mediums impact on MnO2-Mn2O3/Poly-2-methylaniline hexagonal nanocomposite pseudo-supercapacitor

A highly efficient MnO2-Mn2O3/Poly-2-methylaniline (MnO2-Mn2O3/P2MA) hexagonal nanocomposite is synthesized using a one-pot technique involving oxidation polymerization. The hexagonal morphology and crystalline nature of this nanocomposite, as evidenced by the XRD pattern, affirm its exceptional characteristics. The electrical properties are assessed through charge/discharge behavior and cyclic voltammetry curves, elucidating the storage capabilities of this pseudo supercapacitor using different electrolytes NaOH and HCl. The fabricated supercapacitor exhibits impressive efficiency values of 22 F g−1 in a basic medium and a notably higher 72 F g−1 in an acidic medium at a current density of 0.2 A/g. Similarly, the power density values are calculated at 480 and 478 W.kg−1 for the basic and acidic electrolyte, correspondingly. In the basic medium, the series resistance (RS) and charge transfer resistance (RCT) are 5.2 and 0.7 Ω, respectively. In the acidic medium, these values are notably lower, with RS at 2.82 Ω and RCT at 0.2 Ω. Remarkably, even after 500 cycles, the supercapacitor stability remains high at 95% in both media, underscoring the enduring stability attributed to the oxides and polymer materials within the supercapacitor. The combination of cost-effectiveness, ease of fabrication, and potential for mass production positions this supercapacitor as a promising candidate for industrial applications of polymer-based supercapacitors.

Gd and Ni co-doped BiFeO3 ferrite/r-GO nanocomposite for photocatalytic environmental remediation applications

Synergistic effects of the co-doping of rare earth and transition metals on the structural, electrical and optical, in multi-ferroic BiFeO3 nanoferrites (NFs) combined with reduced graphene oxide (r-GO) nanosheets, photocatalytic degradation properties can be boosted. In this current study gadolinium and nickel-co-doped Bi1-xGdxFe1-yNiyO3 were synthesised via the tartaric acid-assisted sol-gel method and their composite Bi1-xGdxFe1-yNiyO3/r-GO with 10 % reduced graphene oxide (r-GO) via the ultra-sonication route. Phase and structural investigation were carried out using x-ray diffraction (P-XRD), Raman scattering, and Fourier transform infrared (FTIR) analysis, which confirms the successful fabrication of co-doping in the rhombohedral geometry of the perovskite-type Bi1-xGdxFe1-yNiyO3. Electrical conductivity of the fabricated composite material was observed to increase because of the co-doping and the addition of r-GO. Photoluminescence (PL) spectra of co-doped and r-GO composite material exhibited a decline in PL intensity because optical bandgap energies exhibited narrowing of 1.99 eV and 1.91 eV respectively, which indicates the excellent separation and stabilization of photo-excited charge pairs. Special conduction properties of r-GO nanosheets improved electrical and optical properties, a well-porous nature, large surface area, lower bandgap, and increased dye degradation in the Bi1-xGdxFe1-yNiyO3/r-GO photocatalyst showing excellent photo-degradation of cationic malachite green (M.G.) dye, achieving a degradation efficiency of 96.4 % under natural solar light. Hence, the photocatalyst shows excellent stability where quenching of radicals using selective scavengers shows that OH* radicals and e−/h+ pairs are primarily involved in the mechanism of photo-degradation in a basic pH medium, making the as-fabricated material a potential material for photo-catalytic environmental remediation.

8(S)-[(1R,2S,5R)-2-Isopropyl-5-methylcyclohexyloxy]-3,4-dihydro-2H-[1,4]dithiepino[2,3-c]furan-6(8H)-one

The interaction of propane-1,3-dithiol with the chiral bis-thioether, which combines two 2(5H)-furanone moieties, bridged through their carbon atoms C(4) by the propane-1,3-dithiol fragment, in DMF in the presence of potassium hydroxide or cesium carbonate resulted in the formation of an optically active fused bicyclic sulfur heterocycle, possessing 1,4-dithiepine and unsaturated γ-lactone moieties. The studied reaction follows an unexpected pathway in a basic medium with the thiolate–thiolate exchange. The structure of the novel heterocycle of the 1,4-dithiepinofuranone series is characterized by single-crystal X-ray diffraction.

Plant In Vitro Cultures of Coleus scutellarioides (L.) Benth. “Electric Lime” and Possibilities of Modification in the Biosynthesis of Volatile Compounds

Coleus scutellarioides (L.) Benth. is a globally spread species, known for its characteristic spectacularly colorful leaves of decorative value. Thanks to its rich chemical composition, the plant is used in ethnopharmacology, and it is also regarded as having high medicinal potential. The application of in vitro cultures enables the acquisition of homogeneous certified material of high quality. Additionally, excluding the effect of biotic and abiotic factors on the plants is a way to fully recognize the influence of phytohormones on the plant morphology and the biosynthetic pathways of compound production. The best way to grow C. scutellarioides “Electric Lime” under in vitro conditions is to use the basic MS medium (Murashige and Skoog medium), enriched with naphthyl-1-acetic acid at a concentration of 0.5 mg dm−3. The analysis of volatile compounds demonstrated that the content of volatile compounds in the plants cultivated under in vivo conditions was expressed at a level of 2848.59 µg g−1, whereas in the plants bred in vitro without supplementation with phytohormones, the level was 8191.47 µg g−1. The highest content was noted for copaene, α-pinene, 1-octene-3-ol, α-selinene, sabinen, γ- and δ-cadinene, 3-octanol, and β-pinene. Aroma profiling revealed a lack of boranyl acetate, 2-hexenal, and 2-hexen-1-ol in the plants cultivated under in vivo conditions. Differences were found in the volatile composition between plants bred in vivo and in vitro, with the most significant recorded for the contents of 1-octen-3-ol and 3-octanol. The addition of plant growth regulators into the basic medium under in vitro conditions affected the percentage ratio and contents of specific compounds in plant tissues. The most intense biosynthesis of volatile compounds took place in the plants cultivated on the medium enriched with NAA at 10,579.11 µg g−1, whereas the least intense was noted for plants cultivated on the medium supplemented with BA, where it was recorded at the level of 5610.02 µg g−1. So far, there has been no research published which would pertain to the profiling of volatile compounds performed using the SPME (solid-phase microextraction) technique. Moreover, the very few studies conducted on the chemical composition of these compounds do not mention the specific variety of C. scutellarioides under analysis.

COVID-19, Internet and Education: Loss of a Generation

Various international instruments and municipal laws have reiterated the importance of education as a basic human right in itself as well as a means to achieve other human rights. The Internet is the most useful tool that has revolutionized the entire system of education. All across the globe, the internet serves as a basic medium of sharing knowledge and research. In Jammu & Kashmir, however, we see a completely contrasting situation as it leads India’s internet shutdown statistics. The article aims to analyze the impact of the 7 months long lockdown and internet suspension in the region after the revocation of J&K’s constitution, followed by the COVID-19 pandemic, on the education of children in the region. Being the longest internet shutdown in the history of any democracy, this paper elucidates how the shutdown left millions of students in J&K without access to their fundamental right to education during this digital lockdown. The paper first analyzes the importance of and the right to education, as well as the role of the internet on education. It then moves on to discuss the 7-month long internet shutdown in the valley of Kashmir and mentions interviews to elucidate the human impact of such shutdown on education. The paper finally discusses the multi-fold impact of the internet shutdown on education in general and the life of students in particular.

Micropropagation of Turmeric (Curcuma longa L.) on Large-Scale

Aim: Turmeric (Curcuma longa L.) is a slow-to-reproduce perennial herb that is propagated from ground rhizomes. Despite its well-known medicinal and culinary uses, its supply for propagation is limited due to disease susceptibility and slow rhizome development. Methodology: To optimize turmeric bud cluster development and determined appropriate concentrations of BAP (6-benzyl aminopurin) and NAA (α-naphthalene acetic acid) for enhancing shoot multiplication and rooting rates. Results: The results indicated that MS (Murashige and Skoog, 1962) was basic media for turmeric; shoot clusters formation on media supplemented with 1 mg L-1BAP and 0.5 mg L-1 NAA; for shoot multiplication was 3 mg L-1 BAP and 0.5 mg L-1 NAA; and 0.5 mg L-1 NAA was favored for root induction Conclusion: This research contributed to advancing our knowledge of valuable plants in Vietnam, particularly turmeric production on large-scale.

Synthesis and fluorescence properties of a two-dimensional Cd-complex for the ratiometric fluorescence detection of Zn2+ ions

The two-dimensional complex [Cd3(L)(2,2'-bpy)2]n (1) was synthesized solvothermally from 4,5-di(3,5-dicarboxylphenoxy)phthalic acid (H6L) and 2,2'-bipyridine (2,2'-bpy) and fully characterized by elemental analysis, infrared spectroscopy, single crystal and powder X-ray diffraction. Complex 1 displays high stability in water and resistance towards acidic and basic media. Fluorescence studies revealed that it may be acted as a ratiometric fluorescence probe to detect Zn2+ ions in water with a superior detection limit of 3.48 nM. The fluorescence recognition mechanism stems from weak interactions between Zn2+ ions and complex 1. Its pronounced stability and recyclability suggest that the new material may be used for high-precision detection of Zn2+ ions in real-life aqueous samples, even under acidic and basic conditions.

Exploring Iridium's Catalytic Role in Redox Reactions: A Concise Review

Abstract:: Transition metals exhibit a remarkable capacity to catalyse redox processes, playing a crucial role in various natural, biological, and chemical transformations. Among all the elements in the periodic table, iridium stands out with the broadest range of oxidation states. With its electronic configuration of 5d76s2, iridium displays a range of oxidation states, fluctuating from —3 in [Ir (CO)3]3- to +9 in [IrO4]2+. The utilization of iridium as a catalyst stems from its capability to adopt these variable oxidation states. Notably, Iridium (III) complexes exhibit significant catalytic activity in both acidic and basic environments, facilitating a diverse array of organic and inorganic chemical transformations. The catalytic mechanism adapts according to the specific conditions under which the catalysts are employed. Iridium's catalytic efficiency is notably enhanced in an acidic environment, as highlighted in the review, compared to its performance in a basic medium. Iridium stands as the sole reported catalyst with the capability to harness sunlight and transform it into chemical energy, offering promising prospects for application in artificial energy systems. The high surface-to-volume ratio of IrNPs contributes to their excellent catalytic performance. As research in Nanocatalysis continues to evolve, iridium remains a key player in shaping the future of sustainable and efficient chemical processes.

Improving Student’s Descriptive Writing Skill through Silent Card Shuffle Strategy

This study aims to improve students’ descriptive writing skill by applying Silent Card Shuffle Strategy. The method used this research is action research. The subject was students on semester 3 from Management Class of UPI YPTK Padang. They are chosen because they are learning the English business subject on this semester and have learned simple present tense in previous semester. Writing English Skill is important for Management students for productive skill. One of them is creating the English brochure. English brochure can be as basic media for creating business for management students. Unfortunately, most of them have not master in writing English. So lecturer has chosen Silent Card Shuffle Strategy to improve the student’s English descriptive writing skill. The instruments were used to collect the data were observation, questionnaire, Students’ writing test. Then the qualitative data were grouped based on the indicators. In addition, quantitative data has analyzed by Anggoro Formula. Then the researcher interpreted the data to get the result of this research. The research shows that Silent Card Shuffle Strategy is quite good. It can improve the students ‘English descriptive writing skill. This is evidenced by the score of students’ writing test. It increases from the pretest, cycle I and cycle II. The increasing can be seen from of students ‘mean score on pretest, cycle I and II. The students mean ‘score are 50, 5 on pretest, 67, 7 on cycle I and 83, 8 on cycle 2. Thus, the application of Silent Card Shuffle Strategy can increase the students’ descriptive writing skill.

Repurposing Co-Fe LDH and Co-Fe LDH/Cellulose micro-adsorbents for sustainable energy generation in direct methanol fuel cells

Spent adsorbents need to be recycled as well as valorized to obtain long-term benefits from the adsorption of contaminants from wastewater. Co-Fe LDH and Co-Fe LDH/cellulose-layered double hydroxide (LDH) were prepared for crystal violet (CV) adsorption. FT-IR, XRD, SEM, TEM, and, zeta potential analyses confirmed the micro-composites. The parameters examined in this study were the initial pH, initial concentration, adsorbent dose, contact time, adsorption isotherm, and adsorption kinetics. The removal percent was 97.5 % and 88 % for Co-Fe LDH and Co-Fe LDH/cellulose, respectively. A maximum adsorption capacity was 69.4 and 50.0 mg g−1 for Co-Fe LDH and Co-Fe LDH/cellulose, respectively, at pH = 9. The Langmuir-Freundlich model can adequately explain the isotherm processes of LDH and LDH/cellulose; R2 was 0.96 and 0.95, respectively. The spent adsorbents (Co-Fe LDH/CV and Co-Fe LDH/Cellulose/CV) were applied once again as catalysts for electro-oxidation in direct-methanol fuel cells. Due to its high stability in the basic medium (NaOH), the waste material was exploited as an active catalyst to support methanol oxidation. It displayed a better efficiency of 74.75 % and a current density of 76 mA/cm2 at 50 mV/s in 1 M methanol for Co-Fe LDH/CV. The suggested technique opens up a completely new channel for reusing waste into high-value materials for application in electrocatalytic energy generation.

Palladium/coconut husk biochar composite material as an effective electrocatalyst for ethanol oxidation reaction

This study utilised coconut husk biochar as an alternative sustainable carbon support for Pd-based electrocatalyst for ethanol oxidation reaction in basic medium. Coconut husk biochar (BC) was prepared via slow pyrolysis at 800 °C for 1 h at a ramp rate of 5 °C min−1. The Pd/BC catalyst was prepared via borohydride-facilitated reduction of palladium chloride solution. TEM analysis revealed good dispersion of the Pd nanoparticles on the biochar support with particle size ranging from 1.9 to 3.4 nm. Cyclic voltammetry (CV) measurements of Pd/BC in 1.0 M ethanol in 0.1 M KOH gave an on-set potential of −0.615 V (versus Ag/AgCl) with a forward peak current density of 23.87 mA cm−2, which is slightly higher than the commercial Pd/C catalyst. The Pd/BC also has a higher electrochemical stability and durability than the commercial Pd/C catalyst based on chronoamperometry studies (i.e., 44.43% versus 39.64% current retention). The synthesised coconut husk biochar–supported Pd catalyst exhibited promising results for ethanol oxidation reaction for alkaline direct ethanol fuel cell application.

Exploration of Vitamin B6-Based Redox-Active Pyridinium Salts towards the Application in Aqueous Organic Flow Batteries.

Pyridoxal hydrochloride, a vitamin B6 vitamer, was synthetically converted to a series of diverse redox-active benzoyl pyridinium salts. Cyclic voltammetry studies demonstrated redox reversibility under basic conditions, and two of the most promising salts were subjected to laboratory-scale redox flow battery tests involving galvanostatic cycling at 10 mM in 0.1 M NaOH. In these tests, the battery was charged completely, corresponding to the transfer of two electrons to the electrolyte, but no discharge was observed. Both CV analysis and electrochemical simulations confirmed that the redox wave observed in the experimental voltammograms corresponds to a two-electron process. To explain the irreversibility in the battery tests, we conducted bulk electrolysis with the benzoyl pyridinium salts, affording the corresponding benzylic secondary alcohols. Computational studies suggest that the reduction proceeds in three consecutive steps: first electron transfer (ET), then proton-coupled electron transfer (PCET) and finally proton transfer (PT) to give the secondary alcohol. 1H NMR deuterium exchange studies indicated that the last PT step is not reversible in 0.1 M NaOH, rendering the entire redox process irreversible. The apparent reversibility observed in CV at the basic media likely arises from the slow rate of the PT step at the timescale of the measurement.

Hydrazine metal complexes as a single source in the mechanochemical preparation of metallic magnetic nanoparticles and investigation of their magnetic hyperthermia properties

Ferromagnetic metallic cobalt and nickel nanoparticles were synthesized by intramolecular metal-hydrazine ligand oxidation reduction reaction in basic media and the solid state. Nickel nanoparticles Ni1 and Ni2 are obtained from two complexes, Ni(N2H4)2(C2O4) and Ni(N2H4)2(HCO2)2, respectively. X-ray powder diffraction (XRD) and energy-dispersive X-ray (EDX) data show pure fcc crystal structures of nanoparticles. Scanning electron microscopy (SEM) images revealed both Ni1 and Ni2 nanoparticles have agglomerated sphere morphologies. The crystallite size estimated by using the Scherer method for Ni1 and Ni2 were 18.7 and 6.2 nm. Vibrating sample magnetometer (VSM) data show the coercivity of metallic nickel samples Ni1 and Ni2 are 50 and 153 Oe, respectively. Both nanoparticles cause an increase in the temperature of water under applied alternative magnetic field and showed specific loss power (SLP) of 70 W/g and 104.8 W/g, respectively. The same method is used in preparation of cobalt nanoparticles from two complexes, Co(N2H4)2(C2O4) and Co(N2H4)2(HCO2)2. XRD analysis data show both nanoparticles have hcp crystal structure. SEM images show nanosheet structure with sheet thickness of 10 to 30 nm. Coercivity of Co1 and Co2 nanoparticles obtained by VSM and Hc are 182 and 171 Oe, respectively. In spite of high coercivity in both Co1 and Co2 nanoparticles, the magnetic hyperthermia heating effects are not observed in practice and specific loss power (SLP) is zero.

Microwave assisted synthesis of cobalt-doped copper selenite nanorice as bifunctional electrocatalyst for overall water splitting

In the research and development of noble-metal free catalysts, copper-based materials such as copper selenite have shown interest as electrocatalysts to drive the oxygen evolution reaction (OER) in basic medium, however their Hydrogen evolution reaction (HER) activity is still unexplored. Therefore, we have performed the synthesis of cobalt doped copper selenite nanoparticles which can robustly and effectively do electrocatalysis for both the OER and HER in basic medium electrolyte. The novelty lies in the fact that microwave synthesis procedure utilizing oxidizing agent as a key precursor is entirely new, this particular material was never employed in water splitting and catalyst need very low amount of binder. The results revealed that cobalt doped copper selenite have a relatively lower starting potential and a higher current density due to the synergistic effects of a large active area, quick charge, mass transport, and a three-dimensional conducting path, having OER and HER overpotentials of 359 mV and 226 mV at 10 mA/cm2 current densities, respectively. We found a novel doped structure featuring porous surfaces and distinctive rice like morphology which facilitate an efficient electron transportation during the water splitting thereby illustrating an exceptional performance of this system along with rapid synthesis and lower costs.

Fabrication of mechanically alloyed high entropy alloys (20-Fe-20Cr-20Ni-20Mn-20Ti) modified carbon paste electrode sensor for the cyclic voltammetric determination of methyl orange

We have successfully fabricated high entropy alloys (HEA) of composition 20-Fe-20Cr-20Ni-20Mn-20Ti by ball milling method for 20 h after optimizing the milling parameters. Generally, the HEAs are very popular for their multi-elemental cocktail effect and exhibit excellent high temperature oxidation resistance, high strength, electromagnetic, wear and corrosion resistance properties. But, HEAs also exhibit significant electrocatalytic properties due to their unique morphology, composition, and structure. Therefore, we have used planetary ball milled HEA powders for the electrochemical determination of methyl orange (MO). MO is recalcitrant and very difficult to degrade and can affect the humans as well as the environment. Therefore, we must determine the presence of MO. We have investigated the effect of scan rate, modifier and analyte concentration, and the pH variation on the anodic peak current (Ipa) of MO. The calculated active syrface area of bare carbon paste electrode (BCPE) and HEA-modified carbon paste electrode (HEA-MCPE) were found to be 0.041 cm2 and 0.137 cm2 respectively. We have obtained the maximum oxidation peak current for the 8 mg HEA-MCPE at a pH of 7.2 during the electrochemical oxidation of MO. The increased Ipa in basic medium is due to structural transformation of MO from quinoid form (in acidic medium) to azo structure (in basic medium). We have also calculated the number of electrons and the protons involved in the electrochemical reaction. The calculated values of detection limit (DL) and quantification limit (QL) of 8 mg HEA-MCPE was found to be 0.114 × 10−8 M and 0.38 × 10−8 M respectively.

1,2-Dibenzoylthiosemicarbazide

When 1-benzoylthiosemicarbazide (2) or thiosemicarbazide (1) were treated with benzoyl chloride in a basic medium, a mixture of two compounds was obtained: 1,2-dibenzoylthiosemicarbazide (3) and 1,4-dibenzoylthiosemicarbazide (4). To determine the structure of the novel compounds, 2D NMR spectroscopy techniques such as 1H-13C and 1H-15N were employed.

Practical and Selective Syntheses of S‐Acyl and N‐Acyl Glutathiones with N‐Acyl Imidazoles in Water

AbstractA selective, mild, convenient, and green protocol for the preparation of S‐acyl and N‐acyl glutathiones is described involving the chemical modification of glutathione (GSH) with N‐acyl imidazoles at room temperature in water. The syntheses of S‐acyl glutathiones were achieved in very high yields using 1 equiv. of an N‐acyl imidazole in water at room temperature, without the need of a base. Double acylation of GSH with various N‐acyl imidazoles in weakly basic aqueous media in the presence of N‐hydroxysuccinimide (HOSu) as the activating reagent followed by selective deprotection of the S‐acyl group with aqueous ammonia at room temperature gave high yields of N‐acyl glutathiones. Moreover, the reaction could accommodate a diverse range of carboxylic acids such as (hetero)benzoic acids, phenylacetic acids, aliphatic acids from short‐chain fatty acids (including acetic acid), long‐chain polyunsaturated fatty acids, secondary or tertiary amino acids, and carboxylic acids containing clickable functional groups, fluorescent probes, or drugs.

Gut microbial interactions based on network construction and bacterial pairwise cultivation.

Association networks are widely applied for the prediction of bacterial interactions in studies of human gut microbiomes. However, the experimental validation of the predicted interactions is challenging due to the complexity of gut microbiomes and the limited number of cultivated bacteria. In this study, we addressed this challenge by integrating in vitro time series network (TSN) associations and co-cultivation of TSN taxon pairs. Fecal samples were collected and used for cultivation and enrichment of gut microbiome on YCFA agar plates for 13 days. Enriched cells were harvested for DNA extraction and metagenomic sequencing. A total of 198 metagenome-assembled genomes (MAGs) were recovered. Temporal dynamics of bacteria growing on the YCFA agar were used to infer microbial association networks. To experimentally validate the interactions of taxon pairs in networks, we selected 24 and 19 bacterial strains from this study and from the previously established human gut microbial biobank, respectively, for pairwise co-cultures. The co-culture experiments revealed that most of the interactions between taxa in networks were identified as neutralism (51.67%), followed by commensalism (21.67%), amensalism (18.33%), competition (5%) and exploitation (3.33%). Genome-centric analysis further revealed that the commensal gut bacteria (helpers and beneficiaries) might interact with each other via the exchanges of amino acids with high biosynthetic costs, short-chain fatty acids, and/or vitamins. We also validated 12 beneficiaries by adding 16 additives into the basic YCFA medium and found that the growth of 66.7% of these strains was significantly promoted. This approach provides new insights into the gut microbiome complexity and microbial interactions in association networks. Our work highlights that the positive relationships in gut microbial communities tend to be overestimated, and that amino acids, short-chain fatty acids, and vitamins are contributed to the positive relationships.