Strategy for Mitigating Antibiotic Resistance by Biochar and Hyperaccumulators in Cadmium and Oxytetracycline Co-contaminated Soil

Sewage Sludge Promotes the Accumulation of Antibiotic Resistance Genes in Tomato Xylem

Xylem serves as a conduit linking soil to the aboveground plant parts and facilitating the upward movement of microbes into leaves and fruits. Despite this potential, the composition of the xylem microbiome and its associated risks, including antibiotic resistance, are understudied. Here, we cultivated tomatoes and analyzed their xylem sap to assess the microbiome and antibiotic resistance profiles following treatment with sewage sludge. Our findings show that xylem microbes primarily originate from soil, albeit with reduced diversity in comparison to those of their soil microbiomes. Using single-cell Raman spectroscopy coupled with D2O labeling, we detected significantly higher metabolic activity in xylem microbes than in rhizosphere soil, with 87% of xylem microbes active compared to just 36% in the soil. Additionally, xylem was pinpointed as a reservoir for antibiotic resistance genes (ARGs), with their abundance being 2.4-6.9 times higher than in rhizosphere soil. Sludge addition dramatically increased the abundance of ARGs in xylem and also increased their mobility and host pathogenicity. Xylem represents a distinct ecological niche for microbes and is a significant reservoir for ARGs. These results could be used to manage the resistome in crops and improve food safety.

Variations in antibiotic resistomes associated with archaeal, bacterial, and viral communities affected by integrated rice-fish farming in the paddy field ecosystem

Antibiotic resistance genes (ARGs) serving as a newly recognized pollutant that poses potential risks to global human health, which in the paddy soil can be potentially altered by different agricultural production patterns. To elucidate the impacts and mechanisms of the widely used and sustainable agricultural production pattern, namely integrated rice-fish farming, on the antibiotic resistomes, we applied metagenomic sequencing to assess ARGs, mobile genetic elements (MGEs), bacteria, archaea, and viruses in paddy soil. There were 20 types and 359 subtypes of ARGs identified in paddy soil. The integrated rice-fish farming reduced the ARG and MGE diversities and the abundances of dominant ARGs and MGEs. Significantly decreased ARGs were mainly antibiotic deactivation and regulator types and primarily ranked level IV based on their potential threat to human health. The integrated rice-fish farming decreased the alpha diversities and altered microbial community compositions. MGEs, bacteria, archaea, and virus exhibited significant correlations with ARGs, while integrated rice-fish farming effectively changed their interrelationships. Viruses, bacteria, and MGEs played crucial roles in affecting the ARGs by the integrated rice-fish farming. The most crucial pathway by which integrated rice-fish farming affected ARGs was through the modulation of viral communities, thereby directly or indirectly influencing ARG abundance. Our research contributed to the control and restoration of ARGs pollution from a new perspective and providing theoretical support for the development of clean and sustainable agricultural production.

Almond shell-derived biochar decreased toxic metals bioavailability and uptake by tomato and enhanced the antioxidant system and microbial community

The effectiveness of almond shell-derived biochar (ASB) in immobilizing soil heavy metals (HMs) and its impact on soil microbial activity and diversity have not been sufficiently studied. Hence, a pot study was carried out to investigate the effectiveness of ASB addition at 2, 4, and 6 % (w/w) on soil biochemical characteristics and the bioavailability of Cd, Cu, Pb, and Zn to tomato (Solanum lycopersicum L.) plants, as compared to the control (contaminated soil without ASB addition). The addition of ASB promoted plant growth (up to two-fold) and restored the damage to the ultrastructure of chloroplast organelles. In addition, ASB mitigated the adverse effects of HMs toxicity by decreasing oxidative damage, regulating the antioxidant system, improving soil physicochemical properties, and enhancing enzymatic activities. At the phylum level, ASB addition enhanced the relative abundance of Actinobacteriota, Acidobacteriota, and Firmicutes while decreasing the relative abundance of Proteobacteria and Bacteroidota. Furthermore, ASB application increased the relative abundance of several fungal taxa (Ascomycota and Mortierellomycota) while reducing the relative abundance of Basidiomycota in the soil. The ASB-induced improvement in soil properties, microbial community, and diversity led to a significant decrease in the DTPA-extractable HMs down to 41.0 %, 51.0 %, 52.0 %, and 35.0 % for Cd, Cu, Pb, and Zn, respectively, as compared to the control. The highest doses of ASB (ASB6) significantly reduced the metals content by 26.0 % for Cd, 78.0 % for Cu, 38.0 % for Pb, and 20.0 % for Zn in the roots, and 72.0 % for Cd, 67.0 % for Cu, 46.0 % for Pb, and 35.0 % for Zn in the shoots, as compared to the control. The structural equation model predicts that soil pH and organic matter are driving factors in reducing the availability and uptake of HMs. ASB could be used as a sustainable trial for remediation of HMs polluted soils and reducing metal content in edible plants.

Distinct Assembly Patterns of Soil Antibiotic Resistome Revealed by Land-Use Changes over 30 Years

Compared with the ever-growing information about the anthropogenic discharge of nutrients, metals, and antibiotics on the disturbance of antibiotic resistance genes (ARGs), less is known about how the potential natural stressors drive the evolutionary processes of antibiotic resistance. This study examined how soil resistomes evolved and differentiated over 30 years in various land use settings with spatiotemporal homogeneity and minimal human impact. We found that the contents of soil organic carbon, nitrogen, soil microbial biomass, and bioavailable heavy metals, as well as related changes in the antibiotic resistome prevalence including diversity and abundance, declined in the order of grassland > cropland > bareland. Sixty-nine remaining ARGs and 14 mobile genetic elements (MGEs) were shared among three land uses. Multiple factors (i.e., soil properties, heavy metals, bacterial community, and MGEs) contributed to the evolutionary changes of the antibiotic resistome, wherein the resistome profile was dominantly driven by MGEs from both direct and indirect pathways, supported by a partial least-squares path model analysis. Our results suggest that pathways to mitigate ARGs in soils can coincide with land degradation processes, posing a challenge to the common goal of managing our environment sustainably.

Food waste compost and digestate as novel fertilizers: Impacts on antibiotic resistome and potential risks in a soil-vegetable system

As a novel agricultural practice, the reuse of food waste compost and digestate as fertilizers leads to a circular economy, but inevitably introduces bio-contaminants such as antibiotic resistance genes (ARGs) into the agroecosystem. Moreover, heavy metal and antibiotic contamination in farmland soil may exert selective pressures on the evolution of ARGs, posing threats to human health. This study investigated the fate, influencing mechanisms and potential risks of ARGs in a soil-vegetable system under different food waste fertilization and remediation treatments and soil contamination conditions. Application of food waste fertilizers significantly promoted the pakchoi growth, but resulted in the spread of ARGs from fertilizers to pakchoi. A total of 56, 80, 84, 41, and 73 ARGs, mobile genetic elements (MGEs) and metal resistance genes (MRGs) were detected in the rhizosphere soil (RS), bulk soil (BS), control soil (CS), root endophytes (RE), and leaf endophytes (LE), respectively. Notably, 7 genes were shared in the above five subgroups, indicating a specific soil-root-endophytes transmission pathway. 36 genes were uniquely detected in the LE, which may originate from airborne ARGs. The combined application of biochar and fertilizers reduced the occurrence of ARGs and MGEs to some extent, showing the remediation effect of biochar. The average abundance of ARGs in the RS, BS and CS was 3.15 × 10-2, 1.31 × 10-2 and 2.35 × 10-1, respectively. Rhizosphere effects may reduce the abundance of ARGs in soil. The distribution pattern of ARGs was influenced by the types of soil, endophyte and contaminant. MGEs is the key driver shaping ARGs dynamics. Soil properties and pakchoi growth status may affect the bacterial composition, and consequently regulate ARGs fate, while endophytic ARGs were more impacted by biotic factors. Moreover, the average daily doses of ARGs from pakchoi consumption is 107-109 copies/d/kg, and its potential health risks should be emphasized.

Simultaneous achievement of removing bensulfuron-methyl and reducing CO2 emission in paddy soil by Acinetobacter YH0317 immobilized boron-doping biochar

Herbicide residue and greenhouse gas (GHG) emission are two main problems in the paddy rice field, which have barely been considered simultaneously. Herein, a bensulfuron-methyl (BSM)-degrading bacterium named Acinetobacter YH0317 was successfully immobilized on two kinds of biochars and subsequently applied in the paddy soil. The BSM removal rate of Acinetobacter YH0317 immobilized boron-doping biochar (BBC) was 80.42% after 30 d, which was significantly higher than that of BBC (39.05%) and Acinetobacter YH0317 (49.10%) applied alone. BBC acting as an immobilized carrier could enable Acinetobacter YH0317 to work in harsh and complex environment and thus improve the BSM removal efficiency. The addition of Acinetobacter YH0317 immobilized BBC (TP5) significantly improved the soil physicochemical properties (pH, SOC, and NH4+-N) and increased the diversity of soil microbial community compared to control group (CG). Meanwhile, Acinetobacter YH0317 immobilized BBC reduced the CO2-equivalent emission by 41.0%. Metagenomic sequencing results revealed that the decreasing CO2 emission in TP5 was correlated with carbon fixation gene (fhs), indicating that fhs gene may play an important role in reducing CO2 emission. The work presents a practical and supportive technique for the simultaneous achievement on the soil purification and GHG emission reduction in paddy soil.

Affecting factors and mechanism of removing antibiotics and antibiotic resistance genes by nano zero-valent iron (nZVI) and modified nZVI: A critical review

Antibiotics and antibiotic resistance genetic pollution have become a global environmental and health concern recently, with frequent detection in various environmental media. Therefore, finding ways to control antibiotics and antibiotic resistance genes (ARGs) is urgently needed. Nano zero-valent iron (nZVI) has shown a positive effect on antibiotics degradation and restraining ARGs, making it a promising solution for controlling antibiotics and ARGs. However, given the current increasingly fragmented research focus and results, a comprehensive review is still lacking. In this work, we first introduce the origin and transmission of antibiotics and ARGs in various environmental media, and then discuss the affecting factors during the degradation of antibiotics and the control of ARGs by nZVI and modified nZVI, including pH, nZVI dose, and oxidant concentration, etc. Then, the mechanisms of antibiotic and ARGs removal promoted by nZVI are also summarized. In general, the mechanism of antibiotic degradation by nZVI mainly includes adsorption and reduction, while promoting the biodegradation of antibiotics by affecting the microbial community. nZVI can also be combined with persulfates to degrade antibiotics through advanced oxidation processes. For the control of ARGs, nZVI not only changes the microbial community structure, but also affects the proliferation of ARGs through affecting the fate of mobile genetic elements (MGEs). Finally, some new ideas on the application of nZVI in the treatment of antibiotic resistance are proposed. This paper provides a reference for research and application in this field.

Rice husk and its derived biochar assist phytoremediation of heavy metals and PAHs co-contaminated soils but differently affect bacterial community

In order to evaluate the feasibility of rice husk and rice husk biochar on assisting phytoremediation of polycyclic aromatic hydrocarbons (PAHs) and heavy metals (HMs) co-contaminated soils, a 150-day pot experiment planted with alfalfa was designed. Rice husk and its derived biochar were applied to remediate a PAHs, Zn, and Cr co-contaminated soil. The effects of rice husk and biochar on the removal and bioavailability of PAHs and HMs, PAH-ring hydroxylating dioxygenase gene abundance and bacterial community structure in rhizosphere soils were investigated. Results suggested that rice husk biochar had better performance on the removal of PAHs and immobilization of HMs than those of rice husk in co-contaminated rhizosphere soil. The abundance of PAH-degraders, which increased with the culture time, was positively correlated with PAHs removal. Rice husk biochar decreased the richness and diversity of bacterial community, enhanced the growth of Steroidobacter, Bacillus, and Sphingomonas in rhizosphere soils. However, Steroidobacter, Dongia and Acidibacter were stimulated in rice husk amended soils. According to the correlation analysis, Steroidobacter and Mycobacterium may play an important role in PAHs removal and HMs absorption. The combination of rice husk biochar and alfalfa would be a promising method to remediate PAHs and HMs co-contaminated soil.

Inhibition of quorum sensing serves as an effective strategy to mitigate the risks of human bacterial pathogens in soil

The coexistence of antibiotic resistance genes (ARGs), mobile genetic elements (MGEs), and virulence factor genes (VFGs) in human bacterial pathogens (HBPs) increases their risks to ecological security and human health and no effective strategy is available. Herein, we demonstrated two typical quorum sensing (QS) interfering agents, 4-nitropyridine-N-oxide (4-NPO, a QS inhibitor) and Acylase Ⅰ (a quorum quenching (QQ) enzyme), effectively decreased the abundance of HBPs by 48.30% and 72.54%, respectively, which was accompanied by the reduction of VFGs, ARGs, and MGEs. The decrease in QS signals mediated by QS interfering agents disturbed bacterial communication and inhibited biofilm formation. More importantly, QS interfering agents reduced the intra-species and inter-species conjugation frequencies among bacteria, considerably inhibiting the dissemination of ARGs and VFGs via horizontal gene transfer. Furthermore, the QS interfering agents did not significantly affect the metabolic function of other nonpathogenic microorganisms in the soil. Collectively, our study provides an effective and eco-friendly strategy to mitigate the risks of HBPs in soil.

A comprehensive review on the preparation of biochar from digestate sources and its application in environmental pollution remediation

The preparation of biochar from digestate is one of the effective ways to achieve the safe disposal and resource utilization of digestate. Nevertheless, up to now, a comprehensive review encompassing the factors influencing anaerobic digestate-derived biochar production and its applications is scarce in the literature. Therefore, to fill this gap, the present work first outlined the research hotspots of digestate in the last decade using bibliometric statistical analysis with the help of VOSviewer. Then, the characteristics of the different sources of digestate were summarized. Furthermore, the influencing factors of biochar preparation from digestate and the modification methods of digestate-derived biochar and associated mechanisms were analyzed. Notably, a comprehensive synthesis of anaerobic digestate-derived biochar applications is provided, encompassing enhanced anaerobic digestion, heavy metal remediation, aerobic composting, antibiotic/antibiotic resistance gene removal, and phosphorus recovery from digestate liquor. The economic and environmental impacts of digestate-derived biochar were also analyzed. Finally, the development prospect and challenges of using biochar from digestate to combat environmental pollution are foreseen. The aim is to not only address digestate management challenges at the source but also offer a novel path for the resourceful utilization of digestate.

Impact of biochar on the antibiotic resistome and associated microbial functions in rhizosphere and bulk soil in water-saving and flooding irrigated paddy fields

The addition of biochar in paddies under the condition of water-saving irrigation can simultaneously achieve soil improvement and water conservation, but little is known about the role of these two regulations in mediating the fate of antibiotic resistome in paddy soils. Here, metagenomic analysis was conducted to investigate the effects and intrinsic mechanisms of biochar application and irrigation patterns on propagation of antibiotic resistance genes (ARGs) in paddy soils. The addition of biochar in paddy soil resulted in a reduction of approximately 1.32%-8.01% in the total absolute abundance of ARGs and 0.60%-22.09% in the numbers of ARG subtype. Compared with flooding irrigation, the numbers of detected ARG subtype were reduced by 1.60%-22.90%, but the total absolute abundance of ARGs increased by 0.06%-5.79% in water-saving irrigation paddy soils. Moreover, the combined treatments of flooding irrigation and biochar could significantly reduce the abundance of ARGs in paddy soils. The incremental antibiotic resistance in soil induced by water-saving irrigation was likewise mitigated by the addition of biochar. Correlation analyses indicated that, the differences in soil physicochemical properties under biochar addition or irrigation treatments contributed to the corresponding changes in the abundance of ARGs. Moreover, the variations of microbial community diversity, multidrug efflux abundance and transport system-related genes in paddy soil were also important for mediating the corresponding differences in the abundance of ARGs under the conditions of biochar addition or irrigation treatments. The findings of this study demonstrated the effectiveness of biochar application in mitigating antibiotic resistance in paddy soils. However, it also highlighted a potential concern relating to the elevated antibiotic resistance associated with water-saving irrigation in paddy fields. Consequently, these results contribute to a deeper comprehension of the environmental risks posed by ARGs in paddy soils.

Boosted simultaneous removal of chlortetracycline and Cu (II) by Litchi Leaves Biochar: Influence of pH, ionic strength, and background electrolyte ions

The coexistence of heavy metals and antibiotics in the environment always results in greater toxicity compared to the individual precursors. Therefore, efficient and economic technology for the simultaneous removal of antibiotics and heavy metals is essential. Herein, litchi leaves biochar carbonized at 550 °C (L550) demonstrated high efficiency in co-removal of CTC (1838.1 mmol/kg) and Cu (II) (1212.9 mmol/kg) within wide range of pH (pH 4-7). Ionic strength obviously enhanced the Cu (II) removal but showed no significant effect on CTC removal. Although Al3+ and HPO42- decreased the adsorption capacities of CTC and Cu (II) on L550, the coexistence of Na+, K+, Mg2+, Cl-, NO3-, CO32- and SO42- showed a negligible effect on the simultaneous removal of CTC and Cu (II). Moreover, the adsorption capacities of CTC and Cu (II) on L550 were excellent in the river water, tap water, and lake water. In addition to electrostatic interactions, ion exchange governed Cu (II) adsorption, while surface complexation played a key role in CTC adsorption on L550. Our results demonstrated that litchi leaves biochar could be a promising adsorbent for remediating multi-contaminated environments.

Piriformospora indica colonization enhances remediation of cadmium and chromium co-contaminated soils by king grass through plant growth promotion and rhizosphere microecological regulation

Poor plant growth and low pollutant bioavailability in contaminated soils limit phytoremediation efficiency. Pot experiments were conducted to investigate the effects and mechanisms of Piriformospora indica inoculation on the phytoremediation of Cd-Cr co-contaminated soils from farmland using king grass. P. indica colonization increased plant biomass by 20.4-24.6% and enhanced Cd/Cr accumulation in root, stem and leave tissues. Root vascular cylinder and cortex were the major structures for Cd/Cr transportation in plants. The amounts of Cd and Cr extracted by king grass considerably increased in the presence of P. indica (by 31.5-88.9% and 22.4-38.4%, respectively), as did the removal efficiency of both metals from soils (by 13.2-32.2% and 23.2-33.5%, respectively). Cd/Cr phytoextraction was closely related to the contents of alkanes, lipids and acids in root exudates. Following inoculation, the respiration of microbial sulfur compounds was promoted in soils at low and medium pollution levels, whereas nitrogen fixation and nitrification were reduced at high pollution level. This study demonstrates that P. indica inoculation enhances the phytoremediation efficiency of king grass for Cd-Cr co-contaminated soils through multiple regulation of plant growth, rhizosphere environment, root exudation and soil microbial function.

Prevalence of antibiotic and metal resistance genes in phytoremediated cadmium and zinc contaminated soil assisted by chitosan and Trichoderma harzianum

Heavy metal in soil have been shown to be toxic with high concentrations and acts as selective pressure on both bacterial metal and antibiotic resistance determinants, posing a serious risk to public health. In cadmium (Cd) and zinc (Zn) contaminated soil, chitosan (Chi) and Trichoderma harzianum (Tri) were applied alone and in combination to assist phytoremediation by Amaranthus hypochondriacus L. Prevalence of antibiotic and metal resistance genes (ARGs and MRGs) in the soil was also evaluated using metagenomic approach. Results indicated that the phytoremediation of Cd and Zn contaminated soil was promoted by Chi, and Tri further reinforced this effect, along with the increased availability of Cd and Zn in soil. Meanwhile, combination of Chi and Tri enhanced the prevalence of ARGs (e.g., multidrug and β-lactam resistance genes) and maintained a high level of MRGs (e.g., chromium, copper) in soil. Soil available Zn and Cd fractions were the main factors contributing to ARGs profile by co-selection, while boosted bacterial hosts (e.g., Mitsuaria, Solirubrobacter, Ramlibacter) contributed to prevalence of most MRGs (e.g., Cd). These findings indicate the potential risk of ARGs and MRGs propagation in phytoremediation of metal contaminated soils assisted by organic and biological agents.

The effect of bulk-biochar and nano-biochar amendment on the removal of antibiotic resistance genes in microplastic contaminated soil

Biochar amendment has significant benefits in removing antibiotic resistance genes (ARGs) in the soil. Nevertheless, there is little information on ARGs removal in microplastic contaminated soil. Herein, a 42-day soil microcosm experiment were carried out to study how two coconut shell biochars (bulk- and nano-size) eliminate soil ARGs with/without microplastic presence. The results showed that microplastic increased significantly the numbers and abundances of ARGs in soil at 14d of cultivation. And, two biochars amendment effectively inhibited soil ARGs spread whether or not microplastic was present, especially for nano-biochar which had more effective removal compared to bulk-biochar. However, microplastic weakened soil ARGs removal after applying same biochar. Two biochars removed ARGs through decreasing horizontal gene transfer (HGT) of ARGs, potential host-bacteria abundances, some bacteria crowding the eco-niche of hosts and promoting soil properties. The adverse effect of microplastic on ARGs removal was mainly caused by weakening mobile genetic elements (MGEs) removal, and by changing soil properties. Structural equation modeling (SEM) analysis indicated that biochar's effect on ARGs profile was changed by its size and microplastic presence through altering MGEs abundances. These results highlight that biochar amendment is still an effective method for ARGs removal in microplastic contaminated soil.

Unveiling the traits of dry and wet pre-magnetized zero-valent iron-activated peroxymonosulfate: Degradation of oxytetracycline

It has been previously reported that pre-magnetization could enhance the efficacy of zero-valent iron (ZVI) in removing contaminants. However, little is known about the effects and persistence of different magnetization methods on pre-magnetized ZVI (Pre-ZVI) when used in advanced oxidation processes (AOPs). Gaining a comprehensive understanding of the durability of various pre-magnetization methods in enhancing the removal efficiency of different pollutants will significantly impact the widespread utilization of Pre-ZVI in practical engineering. Herein, we investigated the efficiency of dry and wet Pre-ZVI-activated peroxymonosulfate (PMS) in eliminating oxytetracycline (OTC) and evaluated the durability of Pre-ZVI. Additionally, we examined several factors that influence the degradation process's efficiency. Our results found that the reaction constant k values corresponding to the dry Pre-ZVI/PMS system at the pH values of 3, 7, and 9 varied from approximately 0.0384, 0.0331, and 0.0349 (day 1) to roughly 0.0297, 0.0278, and 0.0314 (day 30), respectively. Meanwhile, the wet Pre-ZVI/PMS system exhibited k values ranging from approximately 0.0392, 0.0349, and 0.0374 (day 1) to roughly 0.0380, 0.0291, and 0.0322 (day 30), respectively. Moreover, we proposed four OTC degradation pathways using LC-MS/MS and density functional theory calculations. The toxicity of the degradation products was assessed using the ecological structure activity relationship and the toxicity estimation software tool. Overall, this study provides insights into the application of Pre-ZVI/PMS that can be selectively used to eliminate tetracycline antibiotics from water.

Biochar may alter plant communities when remediating the cadmium-contaminated soil in the saline-alkaline wetland

It is thought remediating cadmium pollution with biochar can affect plant traits. However, the potential impact of this practice on plant communities is poorly understood. Here, we established natural-germinated plant communities using soil seed bank from a saline-alkaline wetland and applied a biochar treatment in Cd-polluted wetland soil. The outcomes illustrated that Juglans regia biochar (JBC), Spartina alterniflora biochar (SBC), and Flaveria bidentis biochar (FBC) promoted exchangeable Cd transform into FeMn oxide bound Cd. Additionally, most biochar addition reduced species abundance, root-shoot ratio, biomass, diversity, and community stability, yet enhanced community height. Among all treatments, the 5 % SBC demonstrated the most significant reduction in species abundance, biomass, species richness and functional richness. Specifically, it resulted in a reduction of 92.80 % in species abundance, 73.80 % in biomass, 66.67 % in species richness, and 95.14 % in functional richness compared to the CK. We also observed changes in root morphological traits and community structure after biochar addition. Soil pH, salinity, and nutrients played a dominant role in shaping plant community. These findings have implications for biodiversity conservation, and the use of biochar for the remediation of heavy metals like cadmium should be approached with caution due to its potential negative impacts on plant communities.

Effect of microplastics on the degradation of tetracycline in a soil microbial electric field

The degradation of organic pollutants and the adsorption of organic pollutants onto microplastics (MPs) in the environment have recently been intensively studied, but the effects of biocurrents, which are widespread in various soil environments, on the environmental behavior of MPs and antibiotic pollutants have not been reported. In this study, it was found that polylactic acid (PLA) and polyvinyl chloride (PVC) MPs accelerated the mineralization of humic substances in microbial electrochemical systems (MESs). After tetracycline (TC) was introduced into the MESs, the internal resistance of the soil MESs decreased. Additionally, the presence of MPs enhanced the charge output of the soil MESs by 40% (PLA+TC) and 18% (PVC+TC) compared with a control group without MPs (424 C). The loss in MP mass decreased after TC was added, suggesting a promotion of TC degradation rather than MP degradation for charge output. MPs altered the distribution of the highest occupied molecular orbitals and lowest unoccupied molecular orbitals of TC molecules and reduced the energy barrier for the TC hydrolysis reaction. The microbial community of the plastisphere exhibited a greater ability to degrade xenobiotics than the soil microbial community, indicating that MPs were hotspots for TC degradation. This study provides the first glimpse into the influence of MPs on the degradation of TC in MESs, laying a theoretical and methodological foundation for the systematic evaluation of the potential risks of environmental pollutants in the future.

Uncovering the prevalence and drivers of antibiotic resistance genes in soils across different land-use types

The emergence and spread of antibiotic resistance genes (ARGs) in soil due to animal excreta and organic waste is a major threat to human health and ecosystems, and global efforts are required to tackle the issue. However, there is limited knowledge of the variation in ARG prevalence and diversity resulting from different land-use patterns and underlying driving factors in soils. This study aimed to comprehensively characterize the profile of ARGs and mobile genetic elements and their drivers in soil samples collected from 11 provinces across China, representing three different land-use types, using high-throughput quantitative polymerase chain reaction and 16S rRNA amplicon sequencing. Our results showed that agricultural soil had the highest abundance and diversity of ARGs, followed by tea plantation and forest land. A total of 124 unique ARGs were detected in all samples, with shared subtypes among different land-use patterns indicating a common origin or high transmission frequency. Moreover, significant differences in ARG distribution were observed among different geographical regions, with the greatest enrichment of ARGs found in southern China. Biotic and abiotic factors, including soil properties, climatic factors, and bacterial diversity, were identified as the primary drivers associated with ARG abundance, explaining 71.8% of total ARG variation. The findings of our study demonstrate that different land-use patterns are associated with variations in ARG abundance in soil, with agricultural practices posing the greatest risk to human health and ecosystems regarding ARGs. Our identification of biotic and abiotic drivers of ARG abundance provides valuable insights into strategies for mitigating the spread of these genes. This study emphasizes the need for coordinated and integrated approaches to address the global antimicrobial resistance crisis.

Effects of soil habitat changes on antibiotic resistance genes and related microbiomes in paddy fields

The changes of paddy soil habitat profoundly affect the structure and function of soil microorganisms, but how this process drives the growth and spread of manure- derived antibiotic resistance genes (ARGs) after entering the soil is unclear. Herein, this study explored the environmental fate and behavior of various ARGs in the paddy soil during rice growth period. Results showed that most ARG abundances in flooded soil was lower than that in non-flooded soil during rice growth (decreased by 33.4 %). And soil dry-wet alternation altered microbial community structure in paddy field (P < 0.05), showing that Actinobacteria and Firmicutes increased in proportion under non-flooded conditions, and Chloroflexi, Proteobacteria and Acidobacteria evolved into the dominant groups in flooded soil. Meanwhile, the correlation between ARGs and bacterial communities was stronger than that with mobile genetic elements (MGEs) in both flooded and non-flooded paddy soils. Furthermore, soil properties, especially oxidation reduction potential (ORP), were proved to be an essential factor in regulating the variability of ARGs in the whole rice growth stage by structural equation model, with a direct influence (λ = 0.38, P < 0.05), following by similar effects of bacterial communities and MGEs (λ = 0.36, P < 0.05; λ = 0.29, P < 0.05). This study demonstrated that soil dry-wet alternation effectively reduced the proliferation and dissemination of most ARGs in paddy fields, providing a novel agronomic measure for pollution control of antibiotic resistance in farmland ecosystem.

Pig manure-derived fulvic acid more strongly drives the fate of arsenic and antibiotic resistance genes in paddy soil

Antibiotic resistance genes (ARGs) can threaten the clean production of rice owing to continuous selective pressure in heavy metal-antibiotic co-contaminated paddy soils. As an important soil carbon reservoir, the role of humic substances from different types of manure in the regulation of soil ARGs remains unclear. In this study, fulvic acid (FA) and humic acid (HA) were extracted from pig manure (PM), cow dung (CD), and chicken manure (CM). The influence of their characteristics and doses on the fate of ARGs was investigated in arsenic (As)-antibiotic co-contaminated paddy soils. The release of As and degradation of antibiotics were promoted in 1% PM-FA treatment, with increases of 4.8%-5.6% and 8.3%-8.8% compared with CM-FA and CD-FA treatments, respectively. The coexistence of FA/HA, Fe, As, and antibiotics in soil pore water affected the environmental behavior of ARGs, with FA showing a more positive effect. Species including Bacillus, Geobacter, Desulfitobacterium, and Christensenellaceae_R-7_group were considered potential hosts of ARGs, and their resistance to co-contamination increased after the addition of FA. Membrane transport is a potential strategy for host bacteria of ARGs to cope with As-antibiotic complex pressure. These results demonstrate the coupling mechanisms of As, antibiotics, and ARGs regulated by different humic substances in co-contaminated paddy soils, which could support the clean production of rice in agricultural practice.

Wheat straw pyrochar more efficiently decreased enantioselective uptake of dinotefuran by lettuce and dissemination of antibiotic resistance genes than hydrochar in an agricultural soil

Remediation of soils pollution caused by dinotefuran, a chiral pesticide, is indispensable for ensuring human food security. In comparison with pyrochar, the effect of hydrochar on enantioselective fate of dinotefuran, and antibiotic resistance genes (ARGs) profiles in the contaminated soils remain poorly understood. Therefore, wheat straw hydrochar (SHC) and pyrochar (SPC) were prepared at 220 and 500 °C, respectively, to investigate their effects and underlying mechanisms on enantioselective fate of dinotefuran enantiomers and metabolites, and soil ARG abundance in soil-plant ecosystems using a 30-day pot experiment planted with lettuce. SPC showed a greater reduction effect on the accumulation of R- and S-dinotefuran and metabolites in lettuce shoots than SHC. This was mainly resulted from the lowered soil bioavailability of R- and S-dinotefuran due to adsorption/immobilization by chars, together with the char-enhanced pesticide-degrading bacteria resulted from increased soil pH and organic matter content. Both SPC and SHC efficiently reduced ARG levels in soils, owing to lowered abundance of ARG-carrying bacteria and declined horizontal gene transfer induced by decreased dinotefuran bioavailability. The above results provide new insights for optimizing char-based sustainable technologies to mitigate pollution of dinotefuran and spread of ARGs in agroecosystems.

Effect of fertilizer type on antibiotic resistance genes by reshaping the bacterial community and soil properties

Conventional and bio-organic fertilizers play an important role in maintaining soil health and promoting crop growth. However, the effect of organic fertilizers on the prevalence of antibiotic resistance genes (ARGs) in the vegetable cropping system has been largely overlooked. In this study, we investigated the impacts of soil properties and biotic factors on ARG profiles by analyzing ARG and bacterial communities in vegetable copping soils with a long-term history of manure and bio-organic fertilizer application. The ARG abundance in the soil was significantly increased by 116% with manure application compared to synthetic NPK fertilizer application. This finding was corroborated by our meta-analysis that the longer the duration of manure application, the greater the response of increased soil ARG abundance. However, bio-organic fertilizers containing Trichoderma spp. Significantly reduced ARG contamination by 31% compared to manure application. About half of the ARG variation was explained by changes in bacterial abundance and structure, followed by soil properties. The mitigation of ARG by Trichoderma spp. Is achieved by altering the structure of the bacterial community and weakening the close association between bacteria and ARG prevalence. Taken together, these findings shed light on the contribution of bio-organic fertilizers in mitigating ARG contamination in agricultural soils, which can help manage the ecological risk posed by ARG inputs associated with manure application.

The ecological and molecular mechanism underlying effective reduction of antibiotic resistance genes pollution in soil by fermentation broth from fruit and vegetable waste

The strategies to relieve antibiotic resistance genes (ARGs) pollution are urgently needed. Fermentation broth from fruit and vegetable waste (FFVW), an agricultural amendment, exhibits a remarkable capacity to reduce ARG pollution; however, the underlying mechanism of this effect remains unclear. We performed microcosm experiments to reappear the phenomenon of FFVW-driven reduction in ARGs. Moderate-level FFVW reduced gene resistance to sulfonamide (41.2 %), macrolide-lincosamide-streptogramin (MLS) (47.2 %), chloramphenicol (63.2 %), and tetracycline (61.4 %). Binning and network analyses revealed that Actinobacteria comprise the primary hosts of ARGs in arable soil, and FFVW substantially inhibited the growth and metabolic activity of these organisms. Moreover, tetracycline and MLS production was partially/completely inhibited by FFVW, further reducing the transfer frequency by 52.9-86.1 % and 46.6-66.6 % in the intragenic and intergenic mating systems, respectively. Furthermore, the expression of genes related to conjugation pairing and plasmid transfer was downregulated. Thus, FFVW effectively reduces ARG pollution by inhibiting Actinobacteria proliferation, thereby reducing selective pressure and restricting horizontal gene transfer. Our findings highlight the important underlying mechanisms of FFVW involved in ARG reduction, supporting its use in arable soil.

Rhizosphere effect on the relationship between dissolved organic matter and functional genes in contaminated soil

Arsenic contamination in a mining area is a potential threat to the local population. In the context of one-health, biological pollution in contaminated soil should be known and understandable. This study was conducted to clarify the effects of amendments on arsenic species and potential threat factors (e.g., arsenic-related genes (AMGs), antibiotic resistance genes (ARGs) and heavy-metal resistance genes (MRGs)). Ten groups (control (CK), T1, T2, T3, T4, T5, T6, T7, T8, and T9) were set up by adding different ratio of organic fertilizer, biochar, hydroxyapatite and plant ash. The maize crop was grown in each treatment. Compared with CK, the bioavailability of arsenic was reduced by 16.2%-71.8% in the rhizosphere soil treatments, and 22.4%-69.2% in the bulk soil treatments, except for T8. The component 2 (C2), component 3 (C3) and component 5 (C5) of dissolved organic matter (DOM) increased by 22.6%-72.6%, 16.8%-38.1%, 18.4%-37.1%, respectively, relative to CK in rhizosphere soil. A total of 17 AMGs, 713 AGRs and 492 MRGs were detected in remediated soil. The humidification of DOM might directly correlate with MRGs in both soils, while it was influenced directly on ARGs in bulk soil. This may be caused by the rhizosphere effect, which affects the interaction between microbial functional genes and DOM. These findings provide a theoretical basis for regulating soil ecosystem function from the perspective of arsenic contaminated soil.

Reforestation substantially changed the soil antibiotic resistome and its relationships with metal resistance genes, mobile genetic elements, and pathogens

Revealing the effects of reforestation on soil antibiotic resistome is essential for assessing ecosystem health, yet related studies remain scarce. Here, to determine the responses of the soil antibiotic resistome to reforestation, 30 pairs of cropland and forest soil samples were collected from southwestern China, a region with high environmental heterogeneity. All the forests had been derived from croplands more than one decade ago. The diversity and abundance of soil antibiotic resistance genes (ARGs), metal resistance genes (MRGs), mobile genetic elements (MGEs), and pathogens were determined by metagenomic sequencing and real-time PCR. The results showed that reforestation significantly increased soil microbial abundance and the contents of Cu, total carbon, total nitrogen, total organic carbon, and ammonium nitrogen. Nevertheless, it decreased the contents of soil Zn, Ba, nitrate nitrogen, and available phosphorus. The main soil ARGs identified in this region were vancomycin, multidrug, and bacitracin resistance genes. Reforestation significantly increased the soil ARG abundance by 62.58%, while it decreased the ARG richness by 16.50%. Reforestation exerted no significant effects on the abundance of heavy metal resistance genes and pathogens, but it doubled the abundance of MGEs. Additionally, reforestation substantially decreased the co-occurrence frequencies of ARGs with MRGs and pathogens. In contrast, the correlation between ARGs and MGEs was greatly enhanced by reforestation. Similarly, the correlations between soil ARG abundance and environmental factors were also strengthened by reforestation. These findings suggest that reforestation can substantially affect the soil antibiotic resistome and exerts overall positive effects on soil health by decreasing ARG richness, providing critical information for assessing the effects of "grain for green" project on soil health.

Adsorption of antibiotic, heavy metal and antibiotic plasmid by a wet-state silicon-rich biochar/ferrihydrite composite to inhibit antibiotic resistance gene proliferation/transformation

Decreasing bioaccessible antibiotics, heavy metals, and antibiotic resistance genes (ARGs) in soil by adsorption is an attractive, but unrealized, approach for ARG risk reduction. This approach has the potential to reduce the (co)selection pressure from antibiotics and heavy metals on bacteria and ARG horizontal gene transformation to pathogens. Here, a wet-state silicon-rich biochar/ferrihydrite composite (SiC-Fe(W)) synthesized by loading ferrihydrite onto rice straw-derived biochar was examined for i) adsorption of oxytetracycline and Cu²⁺ to reduce (co)selection pressure and ii) adsorption of extracellular antibiotic resistance plasmid pBR322 (containing tetA and bla_TEM-1) to inhibit ARG transformation. SiC-Fe(W) gained the adsorption priority of biochar (for Cu²⁺) and wet-state ferrihydrite (for oxytetracycline and pBR322) and showed adsorptive enhancement (for Cu²⁺ and oxytetracycline) from a more wrinkled and exposed surface from biochar silica-dispersed ferrihydrite and a more negatively charged biochar, and the adsorption capacity for SiC-Fe(W) was 17-135 times that of soil. Correspondingly, 10 g/kg SiC-Fe(W) amendment increased the soil adsorption coefficient K_d by 31%-1417% and reduced the selection pressure from dissolved oxytetracycline, co-selection pressure from dissolved Cu²⁺, and transformation frequency of pBR322 (assessed with Escherichia coli). The development of Fe-O-Si bonds on silicon-rich biochar in alkaline enhanced ferrihydrite stability and adsorption capacity (for oxytetracycline), presenting a new potential strategy of biochar/ferrihydrite composite synthesis for adsorptive inhibition of ARG proliferation and transformation in ARG pollution control.

Antibiotic resistance in soil-plant systems: A review of the source, dissemination, influence factors, and potential exposure risks

As an emerging environmental contaminant, the widespread of antibiotic resistance has caused a series of environmental issues and human health concerns. A load of antibiotic residues induced by agricultural practices have exerted selective pressure to bacterial communities in the soil-plant system, which facilitated the occurrence and dissemination of antibiotic resistance genes (ARGs) through horizontal gene transfer. As a result, the enrichment of ARGs within crops at harvest under the influence of food ingestion could lead to critical concerns of public health. In this review, the prevalence and dissemination of antibiotic resistance in the soil-plant system are highlighted. Moreover, different underlying mechanisms and detection methods for ARGs transfer between the soil environment and plant compartments are summarized and discussed. On the other hand, a wide range of influencing factors for the transfer and distribution of antibiotic resistance within the soil-plant system are also presented and discussed. In response to exposure of antibiotic residues and resistomes, corresponding hazard identification assessments have been summarized, which could provide beneficial guides of the toxicological tolerance for the general population. Finally, further research priorities for detection and management ARGs spread are also suggested.

Does increasing the organic fertilizer application rate always boost the antibiotic resistance level in agricultural soils?

The amendment of organic fertilizer derived from livestock manure or biosolids is a significant driver of increasing antibiotic resistance in agricultural soils; however, it remains unclear whether increasing organic fertilizer application rates consistently enhances soil antibiotic resistance levels. Herein, we collected soils with long-term amendment with three types of organic fertilizers at four application rates (15, 30, 45, and 60 t/ha/y) and found that the higher the fertilization rate, the higher the antibiotic resistance gene (ARG) abundance. However, when the fertilization rate exceeded 45 t/ha/y, the ARG abundance ceased to significantly increase. Moreover, the soil ARG abundance was positively correlated with total nitrogen (TN) content and bacterial abundance, especially Firmicutes, and negatively affected by pH and bacterial diversity. Soil TN/bacterial abundance and pH/bacterial diversity reached maximum and minimum values at the 45 t/ha/y fertilization rate, respectively. Meanwhile, at this fertilization rate, Firmicutes enrichment peaked. Therefore, an organic fertilization rate of 45 t/ha/y appeared to represent the threshold for soil antibiotic resistance in this study. The underlying mechanism for this threshold was closely related to soil TN, pH, bacterial abundance, and diversity. Taken together, the findings of this study advance the current understanding regarding the soil resistome under different fertilization rates, while also providing novel insights into organic fertilizer management in agricultural practices.

Exposure to cadmium induced gut antibiotic resistance genes (ARGs) and microbiota alternations of Babylonia areolata

Cadmium (Cd) is widely distributed in aquatic environments and has multiple adverse effects on aquatic organisms such as the ivory shell (Babylonia areolata). However, its effects on antibiotic resistance genes (ARGs) and gut microbiota of B. areolata remain unclear. In this study, we explored the effects of different concentrations (0, 0.03, 0.18 and 1.08 mg/L) of Cd on intestinal microbial communities and ARGs in B. areolata through 16S rRNA gene sequencing and high-throughput quantitative PCR. The results showed that the structure and diversity of ARGs and microbiota in B. areolata gut were altered upon Cd exposure. Tetracycline, Vancomycin and Macrolide-Lincosamide-Streptogramin B (MLSB) resistance genes were identified as the major ARGs in B. areolata gut. The absolute abundance and alpha diversity of ARGs in B. areolata gut increased with the rise of cadmium concentration. The microbial communities at genus level were enriched in the low and medium Cd concentration groups, while decreased in the high Cd concentration group compared to the control groups. In addition, the influence of microbiota on the ARG profile was more significant than that of Cd concentration and MGEs in B. areolata gut. Null model analysis demonstrated that stochastic processes dominated ARG assembly in the Cd-exposed groups and were enhanced with the increasing Cd concentrations. Four opportunistic bacterial pathogens (Bacteroides, Legionella, Acinetobacter and Escherichia) detected in B. areolata gut maybe the potential hosts of ARGs. Our findings provide references for the hazards assessment of environmental Cd exposure of gut microbiome in aquatic animals.

Hormetic Effect of Pyroligneous Acids on Conjugative Transfer of Plasmid-mediated Multi-antibiotic Resistance Genes within Bacterial Genus

Spread of antibiotic resistance genes (ARGs) by conjugation poses great challenges to public health. Application of pyroligneous acids (PA) as soil amendments has been evidenced as a practical strategy to remediate pollution of ARGs in soils. However, little is known about PA effects on horizontal gene transfer (HGT) of ARGs by conjugation. This study investigated the effects of a woody waste-derived PA prepared at 450°C and its three distillation components (F1, F2, and F3) at different temperatures (98, 130, and 220°C) on conjugative transfer of plasmid RP4 within Escherichia coli. PA at relatively high amount (40-100 μL) in a 30-mL mating system inhibited conjugation by 74-85%, following an order of PA > F3 ≈ F2 ≈ F1, proving the hypothesis that PA amendments may mitigate soil ARG pollution by inhibiting HGT. The bacteriostasis caused by antibacterial components of PA, including acids, phenols, and alcohols, as well as its acidity (pH 2.81) contributed to the inhibited conjugation. However, a relatively low amount (10-20 μL) of PA in the same mating system enhanced ARG transfer by 26-47%, following an order of PA > F3 ≈ F2 > F1. The opposite effect at low amount is mainly attributed to the increased intracellular reactive oxygen species production, enhanced cell membrane permeability, increased extracellular polymeric substance contents, and reduced cell surface charge. Our findings highlight the hormesis (low-amount promotion and high-amount inhibition) of PA amendments on ARG conjugation and provide evidence for selecting an appropriate amount of PA amendment to control the dissemination of soil ARGs. Moreover, the promoted conjugation also triggers questions regarding the potential risks of soil amendments (e.g., PA) in the spread of ARGs via HGT.

Antagonistic impact on cadmium stress in alfalfa supplemented with nano-zinc oxide and biochar via upregulating metal detoxification

Eco-toxicological estimation of cadmium induced damages by morpho-physiological and cellular response could be an insightful strategy to alleviate negative impact of Cd in agricultural crops. The current study revealed novel patterns of Cd-bioaccumulation and cellular mechanism opted by alfalfa to acquire Cd tolerance under various soil applied zinc oxide nanoparticles (nZnO) doses (0, 30, 60, 90 mg kg^-1), combined with 2% biochar (BC). Herein, the potential impact of these soil amendments was justified by decreased Cd and increased Zn-bioaccumulation into roots by 38 % and 48 % and shoots by 51 % and 72 % respectively, with co-exposure of nZnO with BC. As, the transmission electron microscopy (TEM) and scanning electron microscopy and energy dispersive spectroscopy (SEM-EDS) ultrastructural observations confirmed that Cd-exposure induced stomatal closure, and caused damage to roots and leaves ultrastructure as compared to the control group. On the contrary, the damages to the above-mentioned traits were reversed by a higher nZnO dose, and the impact was further aggravated by adding BC along nZnO. Furthermore, higher nZnO and BC levels efficiently alleviated the Cd-mediated reductions in alfalfa biomass, antioxidant enzymatic response, and gaseous exchange traits than control. Overall, soil application of 90 mg kg^-1 nZnO with BC (2 %) was impactful in averting Cd stress damages and ensuring better plant performance. Thereby, applying soil nZnO and BC emerge as promising green remediation techniques to enhance crop tolerance in Cd-polluted soil.

Effect of graphene and graphene oxide on antibiotic resistance genes during copper-contained swine manure anaerobic digestion

Copper is an important selectors for antibiotic resistance genes (ARGs) transfer because of metal-antibiotic cross-resistance and/or coresistance. Due to carbon-based materials' good adsorption capacity for heavy metals, graphene and graphene oxide have great potential to reduce ARGs abundance in the environment with copper pollution. To figure out the mechanics, this study investigated the effects of graphene and graphene oxide on the succession of ARGs, mobile genetic elements (MGEs), heavy metal resistance genes (HMRGs), and bacterial communities during copper-contained swine manure anaerobic digestion. Results showed that graphene and graphene oxide could reduce ARGs abundance in varying degrees with the anaerobic reactors that contained a higher concentration of copper. Nevertheless, graphene decreased the abundance of ARGs more effectively than graphene oxide. Phylum-level bacteria such as Firmicutes, Bacteroidetes, Spirochaetes, and Verrucomicrobiaat were significantly positively correlated with most ARGs. Network and redundancy analyses demonstrated that alterations in the bacterial community are one of the main factors leading to the changes in ARGs. Firmicutes, Bacteroidetes, and Spirochaetes were enriched lower in graphene reactor than graphene oxide in anaerobic digestion products, which may be the main reason that graphene is superior to graphene oxide in reduced ARGs abundance. Additionally, ARGs were close to HMRGs than MGEs in the treatments with graphene, the opposite in graphene oxide reactors. Therefore, we speculate that the reduction of HMRGs in graphene may contribute to the result that graphene is superior to graphene oxide in reduced ARGs abundance in anaerobic digestion.

Manure application facilitated electrokinetic remediation of antibiotic-arsenic co-contaminated paddy soil

The co-existence of antibiotics and heavy metals in soil with manure application poses high risk to both environment and human health, and thus effective remediation methods are in urgent need. This study investigated the synergistic effects of electrokinetic remediation (EKR) on antibiotic resistance and arsenic (As) in co-contaminated paddy soils. EKR treatments in soil amended with pig manure (EKR-PD) showed better remediation efficiency compared with that without pig manure. In detail, the content of available As and the abundance of antibiotic-resistant bacteria (ARB) decreased by 25.2 %-41.4 % and 9.5 %-21.1 % after 7-d remediation, respectively, due to a relatively higher current density for EKR-PD. The role of the electric field contributed to 33.9 % of antibiotic degradation. Antibiotic resistance genes (ARGs) with ribosomal-protection and enzymatic-deactivation types were easier to remove, with the removal ratio of 37.8 %-41.6 % in EKR-PD. Brevundimonas was the most significantly different species during remediation. Bacillus and Clostridium_ sensu_stricto_1 were potential host bacteria of ARGs in the electric field. Membrane transport might be an effective strategy for microorganisms to respond to the stress of both electric field and co-contaminated environments. This study supports the potential role of EKR in the co-contamination of heavy metals and antibiotic resistance under manure application.

Biorefining waste into nanobiotechnologies can revolutionize sustainable agriculture

Modern agriculture has evolved technological innovations to sustain crop productivity. Recent advances in biorefinery technology use crop residue as feedstock, but this raises carbon sequestration concerns as biorefining utilizes carbon that would otherwise be returned to the soil, thus causing a decline in crop productivity. Furthermore, biorefining generates abundant lignin waste that significantly impedes the efficiency of biorefineries. Valorizing lignin into advanced nanobiotechnologies for agriculture provides a unique opportunity to balance bioeconomy and soil carbon sequestration. Integration of agricultural practices such as utilization of agrochemicals, fertilizers, soil modifiers, and mulching with lignin nanobiotechnologies promotes crop productivity and also enables advanced manufacturing of high-value bioproducts from lignin. Lignin nanobiotechnologies thus represent state-of-the-art innovations to transform both the bioeconomy and sustainable agriculture.

Reduction of antibiotic resistance genes (ARGs) in swine manure-fertilized soil via fermentation broth from fruit and vegetable waste

The issue of growing increase of antibiotic resistance genes (ARGs) in manure-fertilized soil needs urgently addressing. In this study, fermentation broth from fruit and vegetable waste was prepared to reduce ARG abundance in swine manure-fertilized soils. With a six-month field experiment, we found that swine manure-fertilized soil had significantly higher ARG abundance than soil applied with chemical fertilizer. As expected, the homemade fermentation broth significantly reduced ARG abundance in swine manure-fertilized soil, possibly through the decrease of abundance of Actinomyces, in which there was a 48.0%, 51.9%, and 66.7% decrease in the abundance of Nocardioides, Streptomyces, and Nonomuraea, respectively. With the bacteriostatic experiment, we observed that fermentation broth (5 mL/L) significantly inhibited the growth and metabolism in Actinomycetes spp. and Nocardioides sp., in terms of ATPase and PDH activity. These findings confirmed that the inhibition of Actinobacteria, some of the most dominant ARG hosts, was one of the main mechanisms responsible for the decrease in ARG abundance in fermentation broth-treated soil. This study provides field-scale evidence of a feasible strategy for controlling farmland ARG pollution, which is of utmost importance for soil health in the context of sustainable agriculture.

The effects of biochar on antibiotic resistance genes (ARGs) removal during different environmental governance processes: A review

Antibiotic resistance genes (ARGs) pollution has been considered as one of the most significant emerging environmental and health challenges in the 21st century, many efforts have been paid to control the proliferation and dissemination of ARGs in the environment. Among them, the biochar performs a positive effect in reducing the abundance of ARGs during different environmental governance processes and has shown great application prospects in controlling the ARGs. Although there are increasing studies on employing biochar to control ARGs, there is still a lack of review paper on this hotspot. In this review, firstly, the applications of biochar to control ARGs in different environmental governance processes were summarized. Secondly, the processes and mechanisms of ARGs removal promoted by biochar were proposed and discussed. Then, the effects of biochar properties on ARGs removal were highlighted. Finally, the future prospects and challenges of using biochar to control ARGs were proposed. It is hoped that this review could provide some new guidance for the further research of this field.

Integrated metagenomic and metatranscriptomic analysis reveals actively expressed antibiotic resistomes in the plastisphere

The plastisphere is viewed as a reservoir for the antibiotic resistome in water environments and may pose health concerns. However, the expression profiles of the resistome in the plastisphere are largely unknown. Here, we profiled the occurrence, abundance, and transcriptional level of antibiotic resistance genes (ARGs), plasmid associated ARGs, microbial composition and ARG bacterial hosts in the plastisphere and urban river water using 16S rRNA gene sequencing, metagenomic sequencing, and metatranscriptomic sequencing methods. A total of 173 ARGs conferring resistance to 24 major classes of antibiotics commonly prescribed to humans and animals were detected in the plastisphere. Of these, 75 genes were observed with transcriptional activity, indicating that the antibiotic resistome in the plastisphere was not only present, but also actively expressed. Human pathogens belonging to family Enterobacteriaceae were identified as bacterial hosts of ARGs in the plastisphere. The opportunistic and multidrug resistant human pathogen Enterobacter cloacae was found to actively express tetG and confer tetracycline resistance to the plastisphere. Furthermore, 39 genes were identified as "plasmid associated ARGs" in the plastisphere, displaying a higher proportion of transcript abundance compared with water. The above results suggest that the plastisphere is a hotspot for antibiotic resistome acquisition, expression, and dissemination.