Electric manipulation on deformation of ionic ferrofluid sessile droplets.

Active electric-driven droplet manipulation in digital microfluidics constitutes a promising domain owing to the unique and programmable wettability inherent in sessile ionic droplets. The coupling between the electric field and flow field enables precise control over wetting characteristics and droplet morphology. This study delves into the deformation phenomena of ionic sessile ferrofluid droplets in ambient air induced by uniform electric fields. Under the assumption of a pinned mode throughout the process, the deformation is characterized by variations in droplet height and contact angle in response to the applied electric field intensity. A numerical model is formulated to simulate the deformation dynamics of ferrofluid droplets, employing the phase field method for tracking droplet deformation. The fidelity of the numerical outcomes is assessed through the validation process, involving a comparison of droplet geometric deformations with corresponding experimental results. The impact of the electric field on the deformation of dielectric droplets is modulated by parameters such as electric field strength and droplet size. Through meticulously designed experiments, the substantial influence of both field strength and droplet size is empirically verified, elucidating the behavior of ionic sessile droplets. Considering the interplay of electric force, viscous force, and interfacial tension, the heightened field intensity is observed to effectively reduce the contact angle, augment droplet height, and intensify internal droplet flow. Under varying electric field conditions, droplets assume diverse shapes, presenting a versatile approach for microfluidic operations. The outcomes of this research hold significant guiding implications for microfluidic manipulation, droplet handling, and sensing applications.

Enhanced anaerobic digestion performance of food waste by zero-valent iron and iron oxides nanoparticles: Comparative analyses of microbial community and metabolism.

The effects of zero-valent iron (ZVI) and iron oxides nanoparticles on anaerobic digestion (AD) performance of food waste (FW) were comparably clarified in this study. Results indicated that the nanoparticles supplement effectively enhanced the methane yields. As observed, these nanoparticles accelerated organics transformation and alleviated acidification process. Also, the enriched total methanogens and functional bacteria (e.g., Proteiniphilum) were consistent with the promotion of oxidative phosphorylation, citrate cycle, coenzymes biosynthesis and the metabolisms of amino acid, carbohydrate, methane. Additionally, these nanoparticles stimulated electron transfer potential via enriching syntrophic genera (e.g., Geobacter, Syntrophomonas), primary acetate-dependent methanogens (Methanosaeta, Methanosarcina) and related functions (pilus assembly protein, ferredoxins). By comparison, ZVI nanoparticle presented the excellent performance on methanogenesis. This study provides comprehensive understanding of the methanogenesis facilitated by ZVI and iron oxides nanoparticles through the enhancement of key microbes and microbial metabolisms, while ZVI is an excellent option for promoting the methane production.

Size-dependent effects of polystyrene microplastics on anaerobic digestion performance of food waste: Focusing on oxidative stress, microbial community, key metabolic functions.

Polystyrene (PS) microplastics (MPs) are widely existed in food waste (FW) due to the usage of plastic food-packaging. However, the effects and mechanisms of PS MPs with different sizes on anaerobic digestion (AD) performance of FW have not been comprehensively studied yet. Herein, the impacts of different PS MPs sizes (1 mm, 100 µm and 1 µm) with 20, 200 particles/g-TS were investigated. Results showed that 20 particles/g-TS PS MPs decreased cumulative methane production by 1.46-18.11 %, while the higher levels (200 particles/g-TS) significantly inhibited by 9.14-33.08 % (p < 0.05) compared with control group. The inhibiting effects were enhanced as particle size smaller. Physicochemical analysis indicated that MPs prolonged organic matter hydrolysis, weakened the volatile fatty acids metabolism and inhibited methanogenesis-related microorganisms (Synergistetes, Proteiniphilum and Methanosarcina). Small-sized MPs could induce more reactive oxygen species causing cell toxicity and suppressed key enzymes (α-glucoside, protease, acetate kinases and F420) activities, thereby restraining methane production. The analyses of acetyl-CoA synthase and methyl-coenzyme M reductase functional genes illustrated that small-sized MPs negatively affected acetoclastic methanogenesis pathways. Overall, these results provide new insights into the size-dependent effects on AD performance induced by PS MPs.

Potential of biogas residue biochar modified by ferric chloride for the enhancement of anaerobic digestion of food waste.

Biogas residue biochar (BRB) and BRB modified by ferric chloride (BRB-FeCl3) were applied to promote anaerobic digestion (AD) of food waste (FW), related mechanisms were also proposed in this study. Results indicated BRB-FeCl3 showed higher specific surface area, more abundant functional groups and impregnate iron than BRB, and they respectively increased 22.50% and 12.79% cumulative methane yields compared with control group because of accelerated volatile fatty acids (VFAs) transformation, which were confirmed by enhanced metabolism of glycolysis, fatty acid degradation and pyruvate. BRB, especially BRB-FeCl3 facilitated the growth of Syntrophomonas, Methanofollis, Methanoculleus and Methanosarcina, which further promoted the methanogenesis by enhancing the metabolic activities of methanol, dimethylamine and methylamine pathways, thereby causing more metabolically diverse methanogenic pathways. Metagenomics analysis revealed BRB, especially BRB-FeCl3 promoted the relative abundances of functional genes involved in direct interspecies electron transfer (DIET). Present study explored the enhancement mechanisms and feasibility of BRB-FeCl3 for AD process.

Inhibition of Metastatic Hepatocarcinoma by Combined Chemotherapy with Silencing VEGF/VEGFR2 Genes through a GalNAc-Modified Integrated Therapeutic System.

Hepatocellular carcinoma (HCC) is a highly malignant tumor related to high mortality and is still lacking a satisfactory cure. Tumor metastasis is currently a major challenge of cancer treatment, which is highly related to angiogenesis. The vascular endothelial growth factor (VEGF)/VEGFR signaling pathway is thus becoming an attractive therapeutic target. Moreover, chemotherapy combined with gene therapy shows great synergistic potential in cancer treatment with the promise of nanomaterials. In this work, a formulation containing 5-FU and siRNA against the VEGF/VEGFR signaling pathway into N-acetyl-galactosamine (GalNAc)-modified nanocarriers is established. The targeting ability, biocompatibility and pH-responsive degradation capacity ensure the efficient transport of therapeutics by the formulation of 5-FU/siRNA@GalNAc-pDMA to HCC cells. The nano-construct integrated with gene/chemotherapy exhibits significant anti-metastatic HCC activity against C5WN1 liver cancer cells with tumorigenicity and pulmonary metastasis in the C5WN1-induced tumor-bearing mouse model with a tumor inhibition rate of 96%, which is promising for future metastatic HCC treatment.

Joint Resource Allocation in Secure OFDM Two-Way Untrusted Relay System.

The security issue of wireless communication is a common concern because of its broadcast nature, especially when the relay becomes an eavesdropper. In the orthogonal frequency division multiplexing (OFDM) relay system, when the relay is untrusted, the security of the system faces serious threats. Although there exist some resource allocation schemes in a single-carrier system with untrusted relaying, it is difficult to apply them to the multi-carrier system. Hence, a resource allocation scheme for the multi-carrier system is needed. Compared to the one-way relay system, a two-way relay system can improve the data transmission efficiency. In this paper, we consider joint secure resource allocation for a two-way cooperative OFDM system with an untrusted relay. The joint resource allocation problem of power allocation and subcarrier pairing is formulated to maximize the sum secrecy rate of the system under individual power constraints. To solve the non-convex problem efficiently, we propose an algorithm based on the alternative optimization method. The proposed algorithm is evaluated by simulation results and compared with the benchmarks in the literature. According to the numerical results, in a high signal-to-noise ratio (SNR) scenario, the proposed algorithm improves the achievable sum secrecy rate of the system by more than 15% over conventional algorithms.

Distinguishing removal and regrowth potential of antibiotic resistance genes and antibiotic resistant bacteria on microplastics and in leachate after chlorination or Fenton oxidation.

The prevalence of antibiotic resistance, as well as microplastics (MPs) as vectors for antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) has attracting growing attention. However, the fate of ARB/ARGs on MPs treated by chlorination and Fenton oxidation were poorly understood. Herein, the removal and regrowth of ARGs/ARB on MPs and in MPs-surrounding landfill leachate (an important reservoir of MPs and ARGs) after chlorination and Fenton oxidation were comparatively analyzed. Target ARGs on MPs were reduced obviously less than that in leachate, with the largest percentages reduction of 34.0-46.3% vs. 54.3-77.6% after chlorination and 92.1-97.3% vs. > 99.9% after Fenton oxidation, and similar removal patterns were observed for ARB. Moreover, a considerable regrowth of ARGs/ARB in leachate were found after 48 h of storage at the end of chlorination (5, 10, 20 and 50 mg/L), and a greater regrowth of ARGs and ARB occurred on MPs with up to 17 and 139 fold, respectively. In contrast, Fenton oxidation achieved a reduced regrowth of target ARGs/ARB. These findings indicated that the removal of ARGs/ARB on MPs were more difficult than that in leachate, and ARGs/ARB in leachate and especially on MPs exhibited a considerable potential for rapid regrowth after chlorination.

Insight into how fertilization strategies increase quality of grape (Kyoho) and shift microbial community.

Organic and bioorganic fertilizers were increasingly used for agricultural soil. However, little is known on what kind of organic fertilizer application strategies can promote grape production well and how appropriate fertilization strategies improve soil properties and shift microbial community. This study investigated the improvement in soil physicochemical properties as well as their relations with microbial community structure and grape quality under different fertilization strategies. Our results found that (bio)organic fertilizer (CF1, CF2, and BF) especially combined application of organic and bioorganic fertilization (CBF) had smaller effects on electrical conductivity (EC) and pH, while it improved soil nutrients including N, P, K, and organic matter (OM) well, thereby promoting the grape quality comparing to the group without any fertilizer (CK) and with chemical fertilizer (NPK). Especially, the concentrations of Cr, Hg, Zn, and Cu were reduced by 13.63%, 12.50%, 12.52%, and 11.75% in CBF, respectively. Additionally, CF1, CF2, and BF, especially CBF, optimized the communities' composition and increased the abundance of some plant probiotics such as Solirubrobacter and Lysobacter. Nevertheless, excessive application of organic fertilizer derived from livestock manure could cause the accumulation of heavy metals such as Zn and Cu in soil and leaves, which could further influence the grape quality. Additionally, the structure of microbial communities was also changed possibly because some bacterial genera showed distinct adaptability to the stress of heavy metals or the utilization capacity of N, P, K, and OM. Our results demonstrated that combined application of organic and bioorganic fertilization showed a great influence on soil physicochemical properties, whose positive changes could further optimize microbial communities and facilitate the promotion of grape quality.

Short-term biodrying achieves compost maturity and significantly reduces antibiotic resistance genes during semi-continuous food waste composting inoculated with mature compost.

Food waste (FW) is important object of resource utilization and source of antibiotic resistance genes (ARGs). This study investigated the effects of biodrying combined with inoculating mature compost (B&M) on the composting efficiency, succession of bacterial communities and their links with metabolism functions as well as the fate of ARGs during FW composting. The results showed that B&M could rapidly raise and maintain high relative abundance of Bacillaceae (66.59-94.44%) as well as composting temperature (45.86-65.86 â„ƒ), so as to achieve the final maturity of FW composting in a short time by regulating microbial carbohydrate (14.02-15.31%) and amino acid metabolism (10.33-12.47%). Network analysis demonstrated that high temperature could effectively inhibit the proliferation and spread of potential bacterial hosts of ARGs and integrons including Lactobacillaceae, Enterobacteriaceae, Leuconostocaceae and Corynebacteriaceae during the first two days of composting. As a result, B&M significantly reduced the absolute (72.09-99.47%) and relative abundances (0.31-2.44 logs) of nearly all ARGs especially ermB, tetM, blaCTX-M and blaOXA. Present study deepened the knowledge of ARGs variation, succession and metabolism functions of bacterial communities when B&M processes were used for FW composting, suggesting a promising technology for reducing the transmission risk of ARGs and reaching maturity of FW composting.

Metatranscriptomic insight into the effects of antibiotic exposure on performance during anaerobic co-digestion of food waste and sludge.

Antibiotics are inevitably entered into anaerobic co-digestion (AcoD) system of food waste (FW) and sludge along with the addition of abundant antibiotic-containing activated sludge. However, the in-depth insights into antibiotics affecting AcoD performance have not comprehensively studied. In present study, the results showed that tetracycline (TC), sulfamethoxazole (SMZ) and erythromycin (ERY) inhibited and delayed methane production except for 5 mg/L ERY. By comparison, TC and SMZ significantly inhibited the cumulative methane yields (one-way ANOVA, p < 0.01), and the inhibition effects were magnified as the antibiotic level increased. Physicochemical and methane yield analysis indicated antibiotics inhibited hydrolysis process and delayed methanogenesis process, which was in line with the declined abundance of acetogenic Proteiniphilum and hydrogenotrophic Methanobacterium during AcoD. Furthermore, metatranscriptomic analysis demonstrated the microbial activities of major organic and energy metabolism were down-regulated under antibiotics exposure, thereby down-regulating the expressions of key coenzymes (coenzymes M, F420, methanofuran) biosynthesis for methanogenesis and methane metabolism. The declined methanogenesis activity was completely consistent with the inhibited activity of dominant Methanosarcina and methane production, proving the importance of Methanosarcina on methane production. This study provides new metatranscriptomic evidence into the effects of antibiotics on methanogenesis during AcoD.

Dissemination of antibiotic resistance under antibiotics pressure during anaerobic co-digestion of food waste and sludge: Insights of driving factors, genetic expression, and regulation mechanism.

This study revealed the effects and regulation mechanisms on antibiotic resistance genes (ARGs) dissemination during anaerobic co-digestion (AcoD) of food waste and sludge under the exposure of tetracycline, sulfamethoxazole (SMZ) and erythromycin (ERY). Results indicated antibiotics significantly increased the abundance of ARGs, and selectively enriched integron gene, suggesting antibiotics promoted the dissemination of ARGs. Procrustes analysis indicated that bacterial community, integrons and physicochemical properties displayed significant correlations with ARGs, and they respectively contributed 10.61%, 6.94% and 2.97% of explanations on ARGs variation. Especially, the maximum combined contribution (48.6%) of bacterial community and integrons, implying their significances on ARGs alteration. Metatranscriptomic analysis further demonstrated antibiotics upregulated the expressions of total ARGs and virulence factors, raising potential risks. The proposed mechanisms for ARGs dissemination facilitated by antibiotics might be attributed to the changes of ARGs-regulated functions for inducing DNA/cell damage and DNA conjugation during AcoD.

The variation of antibiotic resistance genes and their links with microbial communities during full-scale food waste leachate biotreatment processes.

The prevalence of antibiotic resistance genes (ARGs) has been widely reported in various environments. However, little is known of them in food waste (FW) leachate with high organic content and how their distribution is influenced by biotreatment processes. Here, twelve ARGs, two integrase genes and bacterial communities were investigated during two full-scale FW biotreatment processes. High ARGs abundances (absolute: 1.03 × 107-2.82 × 109copies/mL; relative: 0.076-2.778copies/16S rRNA) were observed across all samples. Although biotreatment effectively reduced absolute abundance of ARGs, additional bacteria acquiring ARGs caused an increase in their relative abundance, which further increased the transmission risk of ARGs. mexF, blaCTX-M, sul1 played crucial roles and sul1 might be considered as an indicator for the prediction of total ARGs. It is worrying that the discharge (effluent and sludge) included highly abundant ARGs (5.09 × 1014-4.83 × 1015copies/d), integrons (1.11 × 1014-6.04 × 1014copies/d) and potential pathogens (such as Pseudomonas and Streptococcus), which should be given more attentions. blaCTX-M and tetQ possessed most potential hosts, Proteobacteria-L and Firmicutes-W were predominant contributors of ARGs-hosts at genus level. This study suggested FW leachate biotreatment systems could be reservoirs of ARGs and facilitated the proliferation of them. The exploration of effective removal methods and formulation of emission standard are necessary for future ARGs mitigation.

Fate of integrons, antibiotic resistance genes and associated microbial community in food waste and its large-scale biotreatment systems.

The prevalence and dissemination of antibiotic resistance genes (ARGs) have been globally gained increasing concerns. However, the fate and spread of ARGs in food waste (FW) and its large-scale biotreatment systems are seldomly understood. Here, we investigated the initial and biologically treated FW in two major FW treatment systems of aerobic fermentation (AF) and anaerobic co-digestion (AcoD) processes. The total relative abundances of integrons and ARGs significantly increased from initial FW to treated FW. Among targeted ARGs, ermB and strB were predominant ARGs, which accounted for 52.58-95.28% of total abundance across all samples. Mantel test indicated that integrons (intl1 and intl2) were positively and significantly correlated with detected ARGs (Mantel test, r = 0.24, p < 0.05), suggesting integrons display significant contributions on driving ARG alteration during FW treatment processes. RDA results indicated that blaOXA, strB and blaTEM were more likely to be proliferated by potential host of Firmicutes (96.55-99.77%) in initial FW, while blaCTX-M and mefA were potentially enriched by Proteobacteria (17.12-49.82%) in AF system and ermB, sul1, aadA and tetQ were possibly enhanced by Bacteroidetes (27.43-43.71%) in AcoD system. Consideration of the higher enriched abundance of total ARGs (66.88 ± 87.34 times) and the used inoculum sludge in AcoD-treated system, the resource utilization of anaerobically digested products should draw our more attentions. These findings would deepen our understanding of prevalence and proliferation of ARGs in FW treatment systems and serve as a foundation for guiding the application of biologically treated FW.

Functional characteristic of microbial communities in large-scale biotreatment systems of food waste.

In order to evaluate microbial community structure dominated metabolic function profiles in large-scale food waste (FW) biotreatment systems, bacterial, archaeal and fungal community associated with metabolic function in high-temperature aerobic fermentation (AF) and anaerobic co-digestion (AcoD) processes were comprehensively investigated in this study. The qPCR results showed the higher gene copies of bacteria and fungi in initial and AF-treated FW compared with AcoD-treated FW, as well as bacteria and archaea in AcoD-treated FW were highly abundant among detected samples. Furthermore, the total abundances of archaea ((1.18-4.88) × 106 copies/ng DNA) in AcoD system were 2-3 orders of magnitude higher than that in other samples (P < 0.01), indicating active archaeal activity in AcoD system. Correlation analysis of microbial community and metabolic function indicated that the higher abundances of Kazachstania, Pyrobaculum, Sulfophobococcus, Lactobacillus and Candida in initial FW had close linkages with lipid metabolism (P < 0.05). Abundant Aspergillus, Staphylococcus, Pelomonas, Corynebacterium, Faecalibacterium, Methanobacterium and Xeromyces in AF system were positively and significantly correlated with high metabolic activities of energy metabolism, carbohydrate metabolism, amino acid metabolism, fatty acid metabolism, glycosaminoglycan degradation, sulfur metabolism and nitrogen metabolism. As for AcoD system, dominant genera Methanosaeta, Methanoculleus, Methanobacterium, Fastidiosipila, Rikenellaceae RC9, Bifidobacterium and Xeromyces had close relationships with metabolism of cofactors and vitamins, energy metabolism, methane metabolism, carbohydrate metabolism and glycosaminoglycan degradation (P < 0.05). These results are expected to improve the metabolic efficiency by functional microorganism in different large-scale FW treatment systems.

Potential of industrial composting and anaerobic digestion for the removal of antibiotics, antibiotic resistance genes and heavy metals from chicken manure.

Composting and anaerobic digestion techniques are widely used for manure recycling, but these methods have shown conflicting results in the removal of antibiotics, antibiotic resistance genes (ARGs), and heavy metals. In the present study, anaerobically digested chicken manure and various types of composted chicken manure were investigated on an industrial scale. Antibiotics, ARGs, and heavy metals had shown inconsistent results for anaerobic digestion and composting. The different composting processes either declined or completely removed the blaCTX-M, intl1 and oqxB genes. In addition, composting processes decreased the absolute abundance of aac6'-Ib and aadA genes, while increased the absolute abundance of qnrD, sul1, and tet(A) genes. On the other hand, anaerobic digestion of chicken manure increased the absolute abundance of ere(A) and tet(A). High throughput sequencing showed that Firmicutes, Proteobacteria, Bacteroidetes, and Actinobacteria dominated the total bacterial composition of composted and anaerobically digested samples. Network analysis revealed the co-occurrence of ARGs and intl1. The redundancy analysis showed a significant correlation between some heavy metals and ARGs. Similarly, the bacterial composition showed a positive correlation with the prevalence of ARGs in treated manure. These findings suggest that bacterial community, heavy metals, and mobile genetic elements can play a significant role in the abundance and variation of ARGs during composting and anaerobic digestion. In conclusion, anaerobic digestion and composting methods at industrial scale need to be improved for the effective removal of antibiotics, ARGs and heavy metals from chicken manure.

l-arginine alleviates doxorubicin-induced endothelium-dependent dysfunction by promoting nitric oxide generation and inhibiting apoptosis.

BACKGROUND/AIMS: Patients with doxorubicin (Dox) treatment have a high risk of developing vascular toxicity with an unknown mechanism. l-arginine is a substrate for nitric oxide (NO). The decreased level of arginine-NO metabolite in Dox-treated cancer patients was associated with increased level of vascular damage, which promoted us to investigate the mechanism of Dox-induced vascular dysfunction and verify whether l-arginine supplement could alleviate this vasculotoxic effect. METHOD: Within a mouse model of Dox injection (5 mg/kg i.p., 2 or 4 weeks), we measured vascular relaxation, blood pressure, vascular NO generation, apoptosis, and oxidative stress. We tested the efficacy of l-arginine (1.5 mg/g/day, 4 weeks) on Dox-induced vascular relaxation, blood pressure, vascular NO generation, apoptosis, as well as oxidative stress. RESULTS: Dox induced endothelium-dependent vascular dysfunction, which was associated with increased reactive oxidative stress (ROS) production and reduced NO generation in the vessel. ROS was required for Dox-induced apoptosis of both smooth muscle cells and endothelial cells. Dox treatment in mice increased blood pressure, but had no effect on vascular inflammation and fibrosis. L-aringine restored Dox-induced vascular dysfunction via enhancing vascular NO production and alleviating ROS-mediated apoptosis. CONCLUSION: We for the first time demonstrated l-arginine was effectively in suppressing Dox-induced vascular dysfunction, by attenuating vascular NO release and apoptosis. Our results provide a therapeutic target or a circulating marker for assessing vascular dysfunction which response to Dox treatment, and advance our understanding of the mechanisms of Dox-induced vascular dysfunction.

Impacts of long-term exposure to tetracycline and sulfamethoxazole on the sludge granules in an anoxic-aerobic wastewater treatment system.

Occurrence and effects of antibiotics and antibiotic resistance in various wastewater treatment systems have been widely investigated. However, few reports address the impacts of antibiotic exposure on wastewater treatment system operating characteristics, especially the characteristics of sludge granules under long-term operation. In this study, two laboratory scale anoxic-aerobic systems were established to investigate the combined effects of tetracycline and sulfamethoxazole. The results indicated that under long-term exposure to 5 mg·L-1 tetracycline and 1 mg·L-1 sulfamethoxazole, removals of chemical oxygen demand and total nitrogen were inhibited, the tendency of sludge bulking was increased, more filamentous bacteria were observed and more extracellular polymeric substance was secreted. This tendency was stronger than that from exposure to tetracycline alone. Molecular biological analysis indicated that the microbial community changed significantly especially with Thiothrix (instead of Sphaerotilus under tetracycline alone) becoming the dominant population under combined antibiotics. The results are relevant for operation of WTS receiving wastewater with high antibiotic concentrations.

Evolution of microbial community and drug resistance during enrichment of tetracycline-degrading bacteria.

Recently, the microbial degradation of tetracycline has been widely reported. However, its potential risks in treating wastewater containing high concentrations of tetracycline have not been fully evaluated. In this study, the evolution of the microbial community and drug resistance was traced during the enrichment of tetracycline-degrading bacteria. The results showed that some minor compositions such as Shewanella, Bacillus, and Pseudomonas in the seed sludge became the predominant genera in the enrichment cultures when continuously using tetracycline as the sole carbon source, especially some possible pathogenic bacteria increased significantly in this process. The abundances of most TRGs/16S rDNA were increased after enrichment, although the relative abundance of tetA and tetL genes decreased to some extent. From the enrichment culture, 7 predominant tetracycline-degrading strains were isolated, of which TD-1 (Bacillus) and TD-5 (Shewanella) presented high degradation efficiencies (6-day degradation rate > 95%, half-life period of tetracycline ≈ 24 h). In addition, multiple TRGs, mobile genetic elements (MGEs) and even gene cassettes were found in each tetracycline-degrading isolate. The findings suggested that some risks such as the pathogenicity of isolates and the spread of ARGs should be considered when the biodegradation method is used to treat wastewater polluted with high concentrations of tetracycline.

Plant Growth, Antibiotic Uptake, and Prevalence of Antibiotic Resistance in an Endophytic System of Pakchoi under Antibiotic Exposure.

Antibiotic contamination in agroecosystems may cause serious problems, such as the proliferation of various antibiotic resistant bacteria and the spreading of antibiotic resistance genes (ARGs) in the environment or even to human beings. However, it is unclear whether environmental antibiotics, antibiotic resistant bacteria, and ARGs can directly enter into, or occur in, the endophytic systems of plants exposed to pollutants. In this study, a hydroponic experiment exposing pakchoi (Brassica chinensis L.) to tetracycline, cephalexin, and sulfamethoxazole at 50% minimum inhibitory concentration (MIC) levels and MIC levels, respectively, was conducted to explore plant growth, antibiotic uptake, and the development of antibiotic resistance in endophytic systems. The three antibiotics promoted pakchoi growth at 50% MIC values. Target antibiotics at concentrations ranging from 6.9 to 48.1 µg·kg-1 were detected in the treated vegetables. Additionally, the rates of antibiotic-resistant endophytic bacteria to total cultivable endophytic bacteria significantly increased as the antibiotics accumulated in the plants. The detection and quantification of ARGs indicated that four types, tetX, blaCTX-M, and sul1 and sul2, which correspond to tetracycline, cephalexin, and sulfamethoxazole resistance, respectively, were present in the pakchoi endophytic system and increased with the antibiotic concentrations. The results highlight a potential risk of the development and spread of antibiotic resistance in vegetable endophytic systems.