A comparative evaluation of biochar and Paenarthrobacter sp. AT5 for reducing atrazine risks to soybeans and bacterial communities in black soil.

Application of biochar and inoculation with specific microbial strains offer promising approaches for addressing atrazine contamination in agricultural soils. However, determining the optimal method necessitates a comprehensive understanding of their effects under similar conditions. This study aimed to evaluate the effectiveness of biochar and Paenarthrobacter sp. AT5, a bacterial strain known for its ability to degrade atrazine, in reducing atrazine-related risks to soybean crops and influencing bacterial communities. Both biochar and strain AT5 significantly improved atrazine degradation in both planted and unplanted soils, with the most substantial reduction observed in soils treated with strain AT5. Furthermore, bioaugmentation with strain AT5 outperformed biochar in enhancing soybean growth, photosynthetic pigments, and antioxidant defenses. While biochar promoted higher soil bacterial diversity compared to strain AT5, the latter selectively enriched specific bacterial populations. Additionally, soil inoculated with strain AT5 displayed a notable increase in the abundance of key genes associated with atrazine degradation (trzN, atzB, and atzC), surpassing the effects observed with biochar addition, thus highlighting its effectiveness in mitigating atrazine risks in soil.

Synergistic mitigation of atrazine-induced oxidative stress on soybeans in black soil using biochar and Paenarthrobacter sp. AT5.

Atrazine, a widely used herbicide in modern agriculture, can lead to soil contamination and adverse effects on specific crops. To address this, we investigated the efficacy of biochar loaded with Paenarthrobacter sp. AT5 (an atrazine-degrading bacterial strain) in mitigating atrazine's impact on soybeans in black soil. Bacterially loaded biochar (BBC) significantly enhanced atrazine removal rates in both unplanted and planted soil systems. Moreover, BBC application improved soybean biomass, photosynthetic pigments, and antioxidant systems while mitigating alterations in metabolite pathways induced by atrazine exposure. These findings demonstrate the effectiveness of BBC in reducing atrazine-induced oxidative stress on soybeans in black soil, highlighting its potential for sustainable agriculture.

Material Design of Ultra-Thin InN/GaN Superlattices for a Long-Wavelength Light Emission.

GaN heterostructure is a promising material for next-generation optoelectronic devices, and Indium gallium nitride (InGaN) has been widely used in ultraviolet and blue light emission. However, its applied potential for longer wavelengths still requires exploration. In this work, the ultra-thin InN/GaN superlattices (SL) were designed for long-wavelength light emission and investigated by first-principles simulations. The crystallographic and electronic properties of SL were comprehensively studied, especially the strain state of InN well layers in SL. Different strain states of InN layers were applied to modulate the bandgap of the SL, and the designed InN/GaN heterostructure could theoretically achieve photon emission of at least 650 nm. Additionally, we found the SL had different quantum confinement effects on electrons and holes, but an efficient capture of electron-hole pairs could be realized. Meanwhile, external forces were also considered. The orbital compositions of the valence band maximum (VBM) were changed with the increase in tensile stress. The transverse electric (TE) mode was found to play a leading role in light emission in normal working conditions, and it was advantageous for light extraction. The capacity of ultra-thin InN/GaN SL on long-wavelength light emission was theoretically investigated.

Characteristics of bacterial community and extracellular enzymes in response to atrazine application in black soil.

The ecological functioning of black soil largely depends on the activities of various groups of microorganisms. However, little is known about how atrazine, a widely used herbicide with known harmful effects on the environment, influences the microbial ecology of black soil, and the extracellular enzymes related to the carbon, nitrogen and phosphorus cycles. Here, we evaluated the change in extracellular enzymes and bacterial community characteristics in black soil after exposure to various concentrations of atrazine. Low concentrations of applied atrazine (10 - 20 mg kg-1) were almost completely degraded after 120 days. At high concentrations (80 - 100 mg kg-1), about 95% of the applied atrazine was degraded over the same period. Additionally, linear fitting of data indicated that the total enzymatic activity index (TEI) and bacterial α-diversity index were negatively correlated with atrazine applied concentration. The atrazine had a greater effect on bacterial beta diversity after 120 days, which differentiated species clusters treated with low and high atrazine concentrations. Soil bacterial community structure and function were affected by atrazine, especially at high atrazine concentrations (80 - 100 mg kg-1). Key microorganisms such as Sphingomonas and Nocardioides were identified as biomarkers for atrazine dissipation. Functional prediction indicated that most metabolic pathways might be involved in atrazine dissipation. Overall, the findings enhance our understanding of the factors driving atrazine degradation in black soil and supports the use of biomarkers as indicators of atrazine dissipation.

Transcriptome Analysis of Native Kentucky Bluegrass (Poa pratensis L.) in Response to Osmotic Stress.

Kentucky bluegrass (Poa pratensis L.) is an important cool season turfgrass species with a high cold tolerance, but it is sensitive to drought. It is valuable for the applications of Kentucky bluegrass to improve its drought tolerance. However, little is known about the underlying drought mechanism. In the present study, transcriptomic profiling in the roots and leaves of the Kentucky bluegrass cultivar 'Qinghai', in response to osmotic stress in the form of treatment with 2 h and 50 h of 25% (v/v) PEG-6000, was analyzed. The results showed that a large number of genes were significantly up-regulated or down-regulated under osmotic stress. The majority of genes were up-regulated in leaves but down-regulated in roots after 2 h and 50 h of osmotic stress, among them were 350 up-regulated DEGs and 20 down-regulated DEGs shared in both leaves and roots. GO and KEGG analysis showed that carbohydrate metabolism, polyamine and amino acid metabolism and the plant hormone signaling pathway were enriched in the leaves and roots of 'Qinghai' after osmotic stress. The genes involving in carbohydrate metabolism were up-regulated, and sucrose, trehalose and raffinose levels were consistently increased. The genes involved in polyamine and amino acid metabolism were up-regulated in leaves in response to osmotic stress and several amino acids, such as Glu, Met and Val levels were increased, while the genes involved in photosynthesis, carbon fixation and citrate cycle in leaves were down-regulated. In addition, the genes involved in plant hormone biosynthesis and signal transduction were altered in leaves after osmotic stress. This study provided promising candidate genes for studying drought mechanisms in 'Qinghai' and improving the drought tolerance of Kentucky bluegrass and drought-sensitive crops.

Magnetic biochar/quaternary phosphonium salt reduced antibiotic resistome and pathobiome on pakchoi leaves.

Antibiotic resistance genes (ARGs) and human pathogenic bacteria (HPB) in leafy vegetable is a matter of concern as they can be transferred from soil, atmosphere, and foliar sprays, and poses a potential risk to public health. While traditional disinfection technologies are effective in reducing the presence of ARGs and HPB in soil. A new technology, foliar spraying with magnetic biochar/quaternary ammonium salt (MBQ), was demonstrated and applied to the leaf surface. High-throughput quantitative PCR targeting 96 valid ARGs and 16 S rRNA sequencing were used to assess its efficacy in reducing ARGs and HPB. The results showed that spraying MBQ reduced 97.0 ± 0.81% of "high-risk ARGs", associated with seven classes of antibiotic resistance in pakchoi leaves within two weeks. Water washing could further reduce "high-risk ARGs" from pakchoi leaves by 19.8%- 24.6%. The relative abundance of HPB closely related to numerous ARGs was reduced by 15.2 ± 0.23% with MBQ application. Overall, this study identified the potential risk of ARGs from leafy vegetables and clarified the significant implications of MBQ application for human health as it offers a promising strategy for reducing ARGs and HPB in leafy vegetables.

Effects of atrazine on microbial metabolic limitations in black soils: Evidence from enzyme stoichiometry.

Long-term input of agricultural chemicals such as pesticides into the soil can increase soil pollution, thereby affecting the productivity and quality of black soil. Triazine herbicide atrazine has been shown to have long-lasting residual effects in black soil. The atrazine residues affected soil biochemical properties, further leading to microbial metabolism restriction. It is necessary to explore the strategies to mitigate the limitations on microbial metabolism in atrazine-contaminated soils. Here, we evaluated the effect of the atrazine on microbial nutrient acquisition strategies as indicated by extracellular enzyme stoichiometry (EES) in four black soils. Atrazine degradation in soil followed the first-order kinetics model across various concentrations ranging from 10 to 100 mg kg-1. We found that the atrazine was negatively correlated with the EES for C-, N-, and P-acquisition. Vector lengths and angles decreased and increased significantly with an increase of atrazine concentration in tested black soils except for Lishu soils. Moreover, the vector angles were >45° for tested four black soils, indicating that atrazine residue had the greatest P-limitation on soil microorganisms. Interestingly, microbial C- and P-limitations with different atrazine concentrations showed a strong linear relationship, especially in Qiqihar and Nongan soils. Atrazine treatment significantly negatively affected microbial metabolic limitation. Soil properties and EES interaction explained up to 88.2% for microbial C-/P-limitation. In conclusion, this study confirms the EES as a useful method in evaluating the effects of pesticides on microbial metabolic limitations.

Effects of ball milling on biochar adsorption of contaminants in water: A meta-analysis.

Reckless release of contaminants into the environment causes pollution in various aquatic systems on a global scale. Biochar is potentially an inexpensive and environmentally friendly adsorbent for removing contaminants from water. Ball milling has been used to enhance biochar's functionality; however, global analysis of the effect of ball milling on biochar's capacity to adsorb contaminants in aqueous solutions has not yet been done. Here, we conducted a meta-analysis to investigate the effects of ball milling on the adsorption/removal capacity of biochar for contaminants in aqueous solutions, and to investigate whether ball milling effects are related to biochar production, ball milling, and other experimental variables. Overall, ball milling significantly increased biochar adsorption capacity towards both inorganic and organic contaminants, by 69.9% and 561.9%, respectively. This could be attributed to ball milling increasing biochar surface area by 2.05-fold, pore volume by 2.39-fold, and decreasing biochar pH by 0.83-fold. The positive adsorption effects induced by ball milling varied widely, with the most effective being ball milling for 12 to 24 h at 300 to 400 rpm with a biochar:ball mass ratio of 1:100 on biochars produced at 400-550 °C from wood residues. Based on this meta-analysis, we conclude that ball milling could effectively enhance biochar's ability to remove organic and inorganic contaminants from aquatic systems.

Genome-Wide Identification and Expression Analysis of Calmodulin-Like Gene Family in Paspalums vaginatium Revealed Their Role in Response to Salt and Cold Stress.

The calmodulin-like (CML) family is an important calcium (Ca2+) sensor in plants and plays a pivotal role in the response to abiotic and biotic stresses. As one of the most salt-tolerant grass species, Paspalums vaginatum is resistant to multiple abiotic stresses, such as salt, cold, and drought. However, investigations of PvCML proteins in P. vaginatum have been limited. Based on the recently published P. vaginatum genome, we identified forty-nine PvCMLs and performed a comprehensive bioinformatics analysis of PvCMLs. The main results showed that the PvCMLs were unevenly distributed on all chromosomes and that the expansion of PvCMLs was shaped by tandem and segmental duplications. In addition, cis-acting element analysis, expression profiles, and qRT-PCR analysis revealed that PvCMLs were involved in the response to salt and cold stress. Most interestingly, we found evidence of a tandem gene cluster that independently evolved in P. vaginatum and may participate in cold resistance. In summary, our work provides important insight into how grass species are resistant to abiotic stresses such as salt and cold and could be the basis of further gene function research on CMLs in P. vaginatum.

Transcriptomic and metabolomic changes in lettuce triggered by microplastics-stress.

Microplastics (MPs) are a global threat to the environment, and plant uptake of MP particles (≤0.2 µm) is a particular cause for concern. However, physiological and molecular mechanisms underlying MP-induced growth inhibition need to be clarified. Towards this goal, we conducted a hydroponic experiment to investigate the accumulation of MPs, changes in physiology, gene expression, and metabolites in lettuce from a series of concentrations of fluorescence-labelled polystyrene MPs (0, 10, 20, 30, 40, 50 mg L-1, ∼0.2 µm). Our results showed that MPs accumulated in the lettuce root tips and leaf veins, resulting in the hypertonic injury of lettuce, and the down-regulation of genes related to ion homeostasis. Stress-related genes were up-regulated, and sphingolipid metabolism increased in response to MP additions, causing increased biosynthesis of ascorbic acid, terpenoid, and flavonoids in root exudates. Our findings provide a molecular-scale perspective on the response of leafy vegetables to MP-stress at a range of concentrations. This enables more comprehensive evaluation of the risks of MPs to human health and the ecological environment.

Manure- and straw-derived biochars reduce the ecological risk of PBDE and promote nitrogen cycling by shaping microbiomes in PBDE-contaminated soil.

Pyrolysis of agricultural waste into biochar for soil remediation is a useful solid waste management strategy. However, it is still unclear how different agricultural feedstocks affect the properties of biochars and their effectiveness in remediation of PBDE-contaminated soil. In this study, we systematically investigated dynamic alterations of soil properties, microbial communities, and PBDE dissipation and bioavailability induced by the application of biochars from manure (MBC) and straw (SBC) to PBDE-contaminated soil. The results showed that soil properties, microbial community structure, and diversity changed differently with the incorporation of the two biochars. MBC had a larger surface area (17.4 m2/g) and a higher nutrient content (45.1% ash content), making it more suitable for use as a soil additive to improve soil quality and nutrient conditions, as well as to stimulate microbial growth. SBC showed higher adsorption capacity for 2,2',4,4'-Tetrabromodiphenyl Ether (BDE-47) (26.73 ± 0.65 mg/g), thus lowering the bioavailability and ecological risk of BDE-47 in soil. BDE-47 was stepwise debrominated into lower brominated PBDE by PBDE-degrading bacteria. MBC accelerated the debromination of BDE-47 (10.1%) by promoting PBDE-degrading microorganisms, while this was inhibited by SBC (3.5%) due to strong adsorption of BDE-47. In addition, we found that both types of biochar favored Nitrospirae bacteria and promoted N cycling. Overall, biochars from manure and straw can positively shape soil microbial communities differently by altering soil properties, soil fertility and nutrient availability, and the fate and the effects of contaminants, which ultimately led to a difference in the potential of biochars for their use in soil remediation.

Visualizing the Distribution of Phthalate Esters and Plant Metabolites in Carrot by Matrix-Assisted Laser Desorption/Ionization Imaging Mass Spectrometry.

The accumulation of organic pollutants in vegetables is a major global food safety issue. The concentrations of pollutants in vegetables usually differ across different tissues because of different transport and accumulation pathways. However, owing to the limitations of conventional methods, in situ localization of typical organic pollutants such as phthalate esters (PAEs) in plant tissues has not yet been studied. Here, we developed a quick and efficient method for in situ detection and imaging of the spatial distribution of PAEs in a typical root vegetable, carrot, using matrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI-IMS). The use of a 2,5-dihydroxybenzoic acid matrix with a spray-sublimation coating method led to the successful identification of PAEs ion signals. The IMS results showed that a typical PAE-di-(2-ethylhexyl)phthalate (DEHP) was broadly distributed in the cortex, phloem, and metaxylem, but was barely detectable in the cambium and protoxylem. Interestingly, MALDI-IMS data also revealed for the first time the spatial distribution of sugars and ß-carotene in carrots. In summary, the developed method offers a new and practical methodology for the in situ analysis of PAEs and plant metabolites in plant tissues. As a result, it could provide a more intuitive understanding of the movement and transformation of organic pollutants in soil-plant systems.

Positively Charged Microplastics Induce Strong Lettuce Stress Responses from Physiological, Transcriptomic, and Metabolomic Perspectives.

Microplastics (MPs) can enter plants through the foliar pathway and are potential hazards to ecosystems and human health. However, studies related to the molecular mechanisms underlying the impact of foliar exposure to differently charged MPs to leafy vegetables are limited. Because the surfaces of MPs in the environment are often charged, we explored the uptake pathways, accumulation concentration of MPs, physiological responses, and molecular mechanisms of lettuce foliarly exposed to MPs carrying positive (MP+) and negative charges (MP-). MPs largely accumulated in the lettuce leaves, and stomatal uptake and cuticle entry could be the main pathways for MPs to get inside lettuce leaves. More MP+ entered lettuce leaves and induced physiological, transcriptomic, and metabolomic changes, including a decrease in biomass and photosynthetic pigments, an increase in reactive oxygen species and antioxidant activities, a differential expression of genes, and a change of metabolite profiles. In particular, MP+ caused the upregulation of circadian rhythm-related genes, and this may play a major role in the greater physiological toxicity of MP+ to lettuce, compared to MP-. These findings provide direct evidence that MPs can enter plant leaves following foliar exposure and a molecular-scale perspective on the response of leafy vegetables to differently charged MPs.

Integrating Biochar, Bacteria, and Plants for Sustainable Remediation of Soils Contaminated with Organic Pollutants.

The contamination of soil with organic pollutants has been accelerated by agricultural and industrial development and poses a major threat to global ecosystems and human health. Various chemical and physical techniques have been developed to remediate soils contaminated with organic pollutants, but challenges related to cost, efficacy, and toxic byproducts often limit their sustainability. Fortunately, phytoremediation, achieved through the use of plants and associated microbiomes, has shown great promise for tackling environmental pollution; this technology has been tested both in the laboratory and in the field. Plant-microbe interactions further promote the efficacy of phytoremediation, with plant growth-promoting bacteria (PGPB) often used to assist the remediation of organic pollutants. However, the efficiency of microbe-assisted phytoremediation can be impeded by (i) high concentrations of secondary toxins, (ii) the absence of a suitable sink for these toxins, (iii) nutrient limitations, (iv) the lack of continued release of microbial inocula, and (v) the lack of shelter or porous habitats for planktonic organisms. In this regard, biochar affords unparalleled positive attributes that make it a suitable bacterial carrier and soil health enhancer. We propose that several barriers can be overcome by integrating plants, PGPB, and biochar for the remediation of organic pollutants in soil. Here, we explore the mechanisms by which biochar and PGPB can assist plants in the remediation of organic pollutants in soils, and thereby improve soil health. We analyze the cost-effectiveness, feasibility, life cycle, and practicality of this integration for sustainable restoration and management of soil.

Attachment of positively and negatively charged submicron polystyrene plastics on nine typical soils.

Microplastics (MPs) have attracted increasing concern as emerging contaminants of global importance in recent years. Soil is considered an important sink for MPs. Due to environmental weathering, MP surfaces are often charged, but there are limited studies on the interaction of differentially charged MP with soils. This study constructed Derjaguin-Landau-Verwey-Overbeek (DLVO) potential energy profiles, investigated the interaction mechanism of polystyrene MPs (0.2 µm) with positive (MP+) and negative (MP-) charges on nine typical soils through quantitative analysis of fluorescence intensity. The attachment of MPs to different soils fitted the pseudo-second-order kinetic model well. The attachment isotherm data of MP+ fitted the linear model better, while the MP- data fitted the Langmuir model. The attachment capacity of MPs was significantly correlated with the zeta potential of soils. These results, as well as the fourier transform infrared spectroscopy (FTIR) spectra and scanning electronic microscopy (SEM) images of soils, indicated that electrostatic interactions and physical trapping were the dominant mechanisms for MP attachment to soils. These results showed a strong affinity for MPs attachment on soil and gave insights to predict the transport, fate and ecological effect of different charged MPs in soil.

Degradation of mineral-immobilized pyrene by ferrate oxidation: Role of mineral type and intermediate oxidative iron species.

Ferrate (Fe(VI)) salts like K2FeO4 are efficient green oxidants to remediate organic contaminants in water treatment. Minerals are efficient sorbents of contaminants and also excellent solid heterogeneous catalysts which might affect Fe(VI) remediation processes. By targeting the typical polycyclic aromatic hydrocarbon compound - pyrene, the application of Fe(VI) for oxidation of pyrene immobilized on three minerals, i.e., montmorillonite, kaolinite and goethite was studied for the first time. Pyrene immobilized on the three minerals was efficiently oxidized by Fe(VI), with 87%-99% of pyrene (10 µM) being degraded at pH 9.0 in the presence of a 50-fold molar excess Fe(VI). Different minerals favored different pH optima for pyrene degradation, with pH optima from neutral to alkaline following the order of montmorillonite (pH 7.0), kaolinite (pH 8.0), and goethite (pH 9.0). Although goethite revealed the highest catalytic activity on pyrene degradation by Fe(VI), the greater noneffective loss of the oxidative species by ready self-decay in the goethite system resulted in lower degradation efficiency compared to montmorillonite. Protonation and Lewis acid on montmorillonite and goethite assisted Fe(VI) oxidation of pyrene. The intermediate ferrate species (Fe(V)/Fe(IV)) were the dominant oxidative species accountable for pyrene oxidation, while the contribution of Fe(VI) species was negligible. Hydroxyl radical was involved in mineral-immobilized pyrene degradation and contributed to 11.5%-27.4% of the pyrene degradation in montmorillonite system, followed by kaolinite (10.8%-21.4%) and goethite (5.1%-12.2%) according to the hydroxyl radical quenching experiments. Cations abundant in the matrix and dissolved humic acid hampered pyrene degradation. Finally, two different degradation pathways both producing phthalic acid were identified. This study demonstrates efficient Fe(VI) oxidation of pyrene immobilized on minerals and contributes to the development of efficient environmentally friendly Fe(VI) based remediation techniques.

Overexpression of SgDREB2C from Stylosanthes guianensis Leads to Increased Drought Tolerance in Transgenic Arabidopsis.

Stylosanthes guianensis is an excellent forage legume in subtropical and tropical regions with drought tolerance, but little is known about its drought tolerance mechanism. Dehydration responsive element binding proteins (DREBs) are responsive to abiotic stresses. A SgDREB2C was cloned from S. guianensis, while SgDREB2C protein was localized at nucleus. SgDREB2C transcript was induced by dehydration treatment. Transgenic Arabidopsis overexpressing SgDREB2C showed enhanced osmotic and drought tolerance with higher levels of relative germination rate, seedlings survival rate and Fv/Fm and lower levels of ion leakage compared with WT after osmotic and drought stress treatments. In addition, higher levels of superoxide dismutase (SOD) and ascorbate peroxidase (APX) activities and stress responsive gene (COR15A, COR47) transcripts were observed in transgenic Arabidopsis than in WT under drought stress. These results suggest that SgDREB2C regulated drought tolerance, which was associated with increased SOD and APX activities and stress-responsive gene expression under drought stress.

Sorption of N-acyl homoserine lactones on maize straw derived biochars: Characterization, kinetics and isotherm analysis.

Soil amendment with biochar may trigger a series of positive and negative biological effects, partly because it interferes quorum sensing (QS) signals synthesized by microorganisms for communication. However, the mechanisms through which biochar interacts with these QS signals remain elusive. This study explored the mechanisms of interactions between N-acyl homoserine lactones (AHLs) and two maize straw-derived biochars (MBs) with different pyrolysis temperature. Pseudo-second-order equation model best depicted AHLs sorption kinetics on MBs. The intra-particle diffusion model revealed that AHLs sorption onto MBs consists of several stages. The sorption isotherms data of AHLs on MBs were in well agreement with both Langmuir and Freundlich models, indicating the occurrence of energetic distribution of active sites on the heterogeneous biochar with multilayer sorption. However, the AHLs sorption capacity on MBs varied, with biochar pyrolyzed at 600 °C displaying a higher AHLs sorption capacity compared with biochar pyrolyzed at 300 °C. It may be attributed to a variety of physiochemical interactions such as pore filling, functional groups complexation, hydrogen bond, and hydrophobic action. The adsorption/partitioning model results and thermodynamic parameters of Gibbs free energy (ΔG) confirmed that physical and chemical sorption occurred concurrently throughout the whole AHLs sorption process, with physical partitioning playing a greater role than surface sorption. The findings suggest that soil amendment with biochar may have a variety of effects on intra/inter-cellular communication, further implying biochar can be specially prepared to mediate soil processes related to microbial communication, like pollutant biodegradation, and carbon/nitrogen cycling.

Different performance of pyrene biodegradation on metal-modified montmorillonite: Role of surface metal ions from a bioelectrochemical perspective.

Microbial extracellular electron transfer (EET) at microbe-mineral interface has been reported to play a significant role in pollutant biotransformation. Different metals often co-exist with organic pollutants and are immobilized on mineral surfaces. However, little is known about the influence of mineral surface metal ions on organic pollutant biodegradation and the involved electron transfer mechanism. To address this knowledge gap, pyrene was used as a model compound to investigate the biodegradation of polycyclic aromatic hydrocarbon on montmorillonite mineral saturated with metal ions (Na(I), Ni(II), Co(II), Cu(II) and Fe(III)) by Mycobacteria strain NJS-1. Further, the possible underlying electron transfer mechanism by electrochemical approaches was investigated. The results show that pyrene biodegradation on montmorillonite was markedly influenced by surface metal ions, with degradation efficiency following the order Fe(III) > Na(I) ≈ Co(II) > Ni(II) ≈ Cu(II). Bioelectrochemical analysis showed that electron transfer activities (i.e., electron donating capacity and electron transport system activity) varied in different metal-modified montmorillonites and were closely related to pyrene biodegradation. Fe(III) modification greatly stimulated degrading enzyme activities (i.e., peroxidase and dioxygenase) and electron transfer activities resulting in enhanced pyrene biodegradation, which highlights its potential as a technique for pollutant bioremediation. The bacterial extracellular protein and humic substances played important roles in EET processes. Membrane-bound cytochrome C protein and extracellular riboflavin were identified as the electron shuttles responsible for transmembrane and cross extracellular matrix electron transfer, respectively. Additions of exogenetic electron mediators of riboflavin, humic acid and potassium ferricyanide accelerated pyrene biodegradation which further verified the critical role of EET in PAH transformation at bacteria-mineral interfaces. These results support the development of clay mineral based advanced bioremediation techniques through regulating the electron transfer processes at the microbe-mineral interfaces by mineral surface modification.

Technologies and perspectives for achieving carbon neutrality.

Global development has been heavily reliant on the overexploitation of natural resources since the Industrial Revolution. With the extensive use of fossil fuels, deforestation, and other forms of land-use change, anthropogenic activities have contributed to the ever-increasing concentrations of greenhouse gases (GHGs) in the atmosphere, causing global climate change. In response to the worsening global climate change, achieving carbon neutrality by 2050 is the most pressing task on the planet. To this end, it is of utmost importance and a significant challenge to reform the current production systems to reduce GHG emissions and promote the capture of CO2 from the atmosphere. Herein, we review innovative technologies that offer solutions achieving carbon (C) neutrality and sustainable development, including those for renewable energy production, food system transformation, waste valorization, C sink conservation, and C-negative manufacturing. The wealth of knowledge disseminated in this review could inspire the global community and drive the further development of innovative technologies to mitigate climate change and sustainably support human activities.