Stress responses and biological residues of sulfanilamide antibiotics in Arabidopsis thaliana

Effects of water deficit on two cultivars of Hibiscus mutabilis: A comprehensive study on morphological, physiological, and metabolic responses

Hibiscus mutabilis, commonly known as the cotton rose, is a widely cultivated ornamental and has been acclaimed as the representative flower of the 2024 World Horticultural Exposition. The growth and ornamental characteristics of Hibiscus mutabilis can be affected by drought stress. Therefore, we investigated the physiological and metabolic responses of drought-sensitive Hibiscus mutabilis JRX-1 and drought-tolerant Hibiscus mutabilis CDS-4 under drought stress. The results of the physiological analyses revealed that, compared to JRX-1,CDS-4 maintained good growth and greater water use efficiency through stronger antioxidant defences, osmoregulatory capacity and stomatal regulation. A total of 3277 metabolites were identified in positive and negative ion modes, of which 663 metabolites presented changes in expression under drought conditions, including 306 upregulated metabolites and 357 downregulated metabolites. Secondary metabolites, such as flavonoids and diterpenoids, are crucial in the plant response to drought stress. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed that the differentially aboundant metabolites were significantly enriched in the pathways valine, leucine and isoleucine degradation; linoleic acid metabolism; one carbon pool by folate; and folate biosynthesis. The results of this study will not only help to elucidate and apply the physiological and metabolic regulatory strategies of Hibiscus mutabilis to improve its adaptation to water deficit conditions, but will also provide valuable guidance to breeders and molecular biologists in the screening and use of drought resistant genes in ornamental plants.

Dual-Mediated Roles of H+-ATPase in Alleviating the Phytotoxicity of Imazethapyr to Nontarget Wheat

The regulation solutions and mechanisms of reducing pesticide phytotoxicity to nontarget plants are not well-defined and detailed. Here, we have proposed a new detoxification strategy to control the toxic effects of herbicide imazethapyr (IM) induced in wheat seedlings from the perspective of the plasma membrane (PM) H+-ATPase. We found that the changes in PM H+-ATPase activity have a regulatory effect on the phytotoxic effects induced by IM in plants. Treatment with PM H+-ATPase activators restored the reduced auxin content and photosynthetic efficiency caused by IM, thereby promoting plant growth. Application of a PM H+-ATPase inhibitor further reduced phosphorus content and significantly increased 2,4-dihydroxy-7-methoxy-2H,1,4-benzoxazin-3(4H)one (DIMBOA) and jasmonic acid levels. These effects indicate that auxin and DIMBOA may regulate plant growth trends and detoxification effects mediated by PM H+-ATPase. This work opens a new strategy for regulating herbicide toxicity to nontarget plants from the PM H+-ATPase.

Phytoremediation of diclofenac and sulfamethoxazole in Arabidopsis thaliana cells and seedlings

Diclofenac (DLF), a widely recognized non-steroidal anti-inflammatory drug (NSAID), and sulfamethoxazole (SMX), a broad-spectrum sulfonamide antibiotic, are commonly prescribed medications that have raised concerns as significant contributors to pharmaceutical pollution in natural ecosystems despite their clinical effectiveness. This study investigates the potential phytoremediation pathways for these two drugs in plant systems by tracking and quantifying the fate of the parent compounds and their metabolites in Arabidopsis thaliana using cell and seedling cultures. Results indicated significant differences in the dissipation of DLF according to the treatment and time interaction within the cell cultures. Viable plant cells showed complete dissipation of DLF from an initial concentration of 2758 ng/mL in 96 h, whereas non-viable cells and blank solutions remained stable. The dissipation of SMX was comparable across viable, non-viable, and blanks, showing a minor decrease from 842 to 799 ng/mL over 120 h following the treatment of viable cells. DLF metabolites including 4'-hydroxy-diclofenac, 5-hydroxy-diclofenac, acyl-glutamatyl-diclofenac, 1-(2,6-dichlorophenyl)-5-hydroxy-2-indolinone, 5-sulfooxy-diclofenac, 5-glucopyranosyloxy-diclofenac, 1-(2,6-dichloro-4-hydroxyphenyl)-2-indolinone, and 4'-glucopyranosyloxy-diclofenac were recognized, likely formed through acylation, glutamyl conjugation, hydroxylation, dehydration, cyclization, sulfonation, and glucosidation. While for SMX, metabolites including sulfamethoxazole-glucuronide, nitroso-sulfamethoxazole, N4-acetylsulfamethoxazole, and N4-acetyl-5-OH-sulfamethoxazole were identified, potentially produced through glucuronidation, nitrosation, acetylation, and hydroxylation. Phase I metabolite concentrations of DLF and SMX peaked earlier than those of phase II metabolites. Hydroponic A. thaliana demonstrated comparable efficiencies in the phytoremediation of DLF and SMX, with concentrations varying from 1 mg/L to 10 mg/L. Detectable levels of both parent compounds and their metabolites confirmed successful absorption and metabolism within the plant system. This study provides valuable insights into the potential of phytoremediation as a sustainable approach for reducing the environmental toxicity of DLF and SMX and suggests comparable metabolic efficiency. These findings contribute to the growing body of knowledge on phytoremediation and its application in addressing pollution from pharmaceuticals and personal care products.

Effects of environmentally relevant concentrations of oxytetracycline and sulfadiazine on the bacterial communities, antibiotic resistance genes, and functional genes are different between maize rhizosphere and bulk soil

Antibiotic contamination in soil has become a major concern worldwide. At present, it is not clear how two co-existed antibiotics with environmentally relevant concentrations would affect soil bacterial community structure, the abundances of antibiotic resistance genes (ARGs) and functional genes, and whether the effects of antibiotics would differ between rhizosphere and bulk soil. We conducted a greenhouse pot experiment to grow maize in a loess soil treated with oxytetracycline (OTC) or sulfadiazine (SDZ) or both at an environmentally relevant concentration (1 mg kg-1) to investigate the effects of OTC and SDZ on the rhizosphere and bulk soil bacterial communities, abundances of ARGs and carbon (C)-, nitrogen (N)-, and phosphorus (P)-cycling functional genes, and on plant growth and plant N and P nutrition. The results show that the effects of environmentally relevant concentrations of OTC and SDZ on bacterial communities and abundances of ARGs and functional genes differ between maize rhizosphere and bulk soil. The effects of two antibiotics resulted in a higher absolute abundances of accA, tet(34), tnpA-04, and sul2 in the rhizosphere soil than in the bulk soil and different bacterial community compositions and biomarkers in the rhizosphere soil and the bulk soil. However, OTC had a stronger inhibitory effect on the abundances of a few functional genes in the bulk soil than SDZ did, and their combination had no synergistic effect on plant growth, ARGs, and functional genes. The role of co-existed OTC and SDZ decreased shoot height and increased root N concentration. The results demonstrate that environmentally relevant concentrations of antibiotics shift soil microbial community structure, increase the abundances of ARGs, and reduce the abundances of functional genes. Furthermore, soil contamination with antibiotics can diminish agricultural production via phytotoxic effects on crops, and combined effects of antibiotics on plant growth and nutrient uptake should be considered.

Simple, fast and eco-friendly micro-solid phase extraction based on thiol and ionic liquid bi-functional nanofibers membrane for the determination of sulfonamides in environmental water

BACKGROUND

Sulfonamides (SAs) are a class of synthetic antibacterial agents that are diffusely used in the medical industry and animal husbandry. Their prevalence in the influents and effluents of water treatment plants, as well as in rivers and groundwater, has provoked worldwide concern. Monitoring SAs in environmental water is of great significance for public health. However, most of the available detection techniques for SAs are cumbersome and time-consuming. With the increasing number of actual samples, simple, fast and environmentally friendly analytical methods are always in demand.

RESULTS

Herein, we describe a highly efficient micro-solid phase extraction (μ-SPE) sample preparation technique based on a novel thiol and ionic liquid bi-functional nanofibers membrane (IL-SH-PAN NFsM) for multi-residue detection of sulfonamides (SAs) in water samples. By the synergistic effect of -SH and -IL, the as-prepared IL-SH-PAN NFsM demonstrated high adsorption capacity and excellent selectivity for SAs. The water samples can be directly used for μ-SPE without pH and ionic strength adjustment, and the eluent can be directly collected for HPLC-MS/MS analysis. Compared with other methods reported in the literature, this method required much shorter extraction time (2 min for a batch), much less amount of adsorbent (4.0 mg) and organic solvent (0.5 mL), while providing much higher sensitivity (1.4-3.9 ng L-1), and fine recoveries (88.8%-117.7%) with relative standard deviations less than 4.26%.

SIGNIFICANCE AND NOVELTY

A bi-functional nanofibers membrane was prepared for efficient extraction of SAs. The adsorbent exhibited superior adsorption performance and excellent selectivity. The underlying interaction mechanisms derived from -SH and -IL were proposed, which provide a new idea for preparing versatile adsorbents. Rapid, efficient and sensitive detection of SAs in water was achieved. The novel sample preparation technique can be expected as an efficient method for routine trace SAs residue monitoring in various water samples.

Biodegradation of sulfadiazine by ryegrass (Lolium perenne L.) in a soil system: Analysis of detoxification mechanisms, transcriptome, and bacterial communities

The indiscriminate use of sulfadiazine has caused severe harm to the environment, and biodegradation is a viable method for the removal of sulfadiazine. However, there are few studies that consider sulfadiazine biodegradation mechanisms. To comprehensively investigate the process of sulfadiazine biodegradation by plants in a soil system, a potted system that included ryegrass and soil was constructed in this study. The removal of sulfadiazine from the system was found to be greater than 95% by determining the sulfadiazine residue. During the sulfadiazine removal process, a significant decrease in ryegrass growth and a significant increase in antioxidant enzyme activity were observed, which indicates the toxic response and detoxification mechanism of sulfadiazine on ryegrass. The ryegrass transcriptome and soil bacterial communities were further investigated. These results revealed that most of the differentially expressed genes (DEGs) were enriched in the CYP450 enzyme family and phenylpropanoid biosynthesis pathway after sulfadiazine exposure. The expression of these genes was significantly upregulated. Sulfadiazine significantly increased the abundance of Vicinamibacteraceae, RB41, Ramlibacter, and Microvirga in the soil. These key genes and bacteria play an important role in sulfadiazine biodegradation. Through network analysis of the relationship between the DEGs and soil bacteria, it was found that many soil bacteria promote the expression of plant metabolic genes. This mutual promotion enhanced the sulfadiazine biodegradation in the soil system. This study demonstrated that this pot system could substantially remove sulfadiazine and elucidated the biodegradation mechanism through changes in plants and soil bacteria.

Source, transport, and toxicity of emerging contaminants in aquatic environments: A review on recent studies

Emerging contaminants (ECs) are gaining global attention owing to their widespread presence and adverse effects on human health. ECs comprise numerous composite types and pose a potential threat to the growth and functional traits of species and ecosystems. Although the occurrence and fate of ECs has been extensively studied, little is known about their long-term biological effects. This review attempts to gain insights into the unhindered connections and overlaps in aquatic ecosystems. Microplastics (MPs), one of the most representative ECs, are carriers of other pollutants because of their strong adsorption capacity. They form a complex of pollutants that can be transmitted to aquatic organisms and humans through the extended food chain, increasing the concentration of pollutants by tens of thousands of times. Adsorption, interaction and transport effects of emerging contaminants in the aquatic environment are also discussed. Furthermore, the current state of knowledge on the ecotoxicity of single- and two-pollutant models is presented. Herein, we discuss how aquatic organisms within complex food networks may be particularly vulnerable to harm from ECs in the presence of perturbations. This review provides an advanced understanding of the interactions and potential toxic effects of ECs on aquatic organisms.

Analysis of the effects of sulfamethoxazole on the secondary metabolites and antioxidants in oilseed rape (Brassica napus L.) and the underlying mechanisms

The secondary metabolism of plants is key for mediating responses to environmental stress, but few studies have examined how the relationship between secondary metabolism and the stress response of plants is affected by exposure to antibiotics. Here, we studied the effects of sulfamethoxazole (SMZ) on the secondary metabolism and antioxidant activity of oilseed rape (Brassica napus L.). SMZ significantly affected the growth of rape seedlings. Low and high concentrations of SMZ induced the production of a large number of reactive oxygen species (ROS) in rape seedlings, which damaged cells. SMZ stress altered the activity of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), as well as the content of malondialdehyde (MDA). SMZ promoted the activities of phenylalanine ammonia lyase (PAL), tyrosine ammonia lyase (TAL), cinnamic acid-4-hydroxylase (C4H), and 4-coumaric acid: coenzyme A ligase (4CL) by activating the phenylpropanoid pathway. The content of secondary metabolites changed. The content of phenolic acids and flavonoids increased, and the content of sinapine and anthocyanins was altered to cope with the oxidative damage induced by antibiotics. Transcriptomic and metabolomic analysis showed that differentially expressed genes and differentially expressed metabolites were mainly involved in Phenylpropanoid biosynthesis. SMZ alters the secondary metabolites of rapeseed, which mitigates the deleterious effects of stress, by modulating upstream secondary metabolism pathways and the production of plant hormones involved in signal transduction. In sum, these results provide a new perspective on the effects of SMZ on plants relative to secondary metabolites and improve our understanding of the toxicity of SMZ.

Hydrogen Peroxide Activated by Biochar-Supported Sulfidated Nano Zerovalent Iron for Removal of Sulfamethazine: Response Surface Method Approach

Biochar (BC)-supported sulfide-modified nanoscale zerovalent iron (S-nZVI/BC) was prepared using the liquid-phase reduction method for the application of the removal of sulfamethazine (SMZ) from water. The reaction conditions were optimized by the Box−Behnken response surface method (RSM). A model was constructed based on the influence factors of the removal rate, i.e., the carbon-to-iron ratio (C/Fe), iron-sulfur ratio (Fe/S), pH, and hydrogen peroxide (H2O2) concentration, and the influence of each factor on the removal efficiency was investigated. The optimal removal process parameters were determined based on theoretical and experimental results. The results showed that the removal efficiency was significantly affected by the C/Fe ratio and pH (p < 0.0001) but relatively weakly affected by the Fe/S ratio (p = 0.0973) and H2O2 concentration (p = 0.022). The optimal removal process parameters were as follows: 0.1 mol/L H2O2, a pH of 3.18, a C/Fe ratio of 0.411, and a Fe/S ratio of 59.75. The removal rate of SMZ by S-nZVI/BC was 100% under these conditions. Therefore, it is feasible to use the Box−Behnken RSM to optimize the removal of emerging pollutants in water bodies by S-nZVI/BC.

Research on advanced methods of electrochemiluminescence detection combined with optical imaging analysis for the detection of sulfonamides

In this study, a novel method that combines electrochemiluminescence (ECL) analysis and digital image processing was developed for the detection of sulfonamides. This method is based on the ECL system of ruthenium terpyridine, with 1 mM tripropylamine as a co-reactant to enhance the performance. Under the optimal conditions comprising a solution of pH 7 and a scanning rate of 0.08 V s^-1, the Pt electrode has an excellent linear detection range from 5 μM to 5 mM, with a detection limit of 0.85 μM (S/N = 3). A wireless camera is used to record the light-emitting process. The recordings are processed, and the digital images are extracted using image-processing algorithms implemented in Python to calculate the brightness value of the image, which has a linear relationship with the logarithm of the sulfonamide concentration. Image analysis simplifies and improves the stability of the ECL analysis process, while also increasing the speed of analysis. The results indicate that the method can successfully detect a sulfonamide concentration of 5 μM. Thus, the analysis method of ECL combined with image processing is feasible for the detection of sulfonamides, thereby displaying its potential applicability as a novel method in drug and food safety, for instance, for sulfonamide detection in antibiotics.

Antibiotic Resistance Gene Transformation and Ultrastructural Alterations of Lettuce (Lactuca sativa L.) Resulting from Sulfadiazine Accumulation in Culture Solution

The research herein explored the possible mechanism of toxicity of the antibiotic sulfadiazine (SD) and the related antibiotic resistance gene transformation in lettuce by systematically investigating its growth responses, ultrastructural changes, and antibiotic resistance gene transformation via solution culture experiments. The results showed that SD mainly accumulated in the roots of lettuce at concentrations ranging from 6.48 to 120.87 μg/kg, which were significantly higher than those in leaves (3.90 to 16.74 μg/kg). Lower concentrations of SD (0.5 and 2.0 mg/L) in the culture nutrient solution exerted little effect on lettuce growth, while at SD concentrations higher than 10 mg/L, the growth of lettuce was significantly inhibited, manifesting as shorter root length and lower dry matter yield of whole lettuce plants. Compared with that for the control group, the absolute abundance of bacteria in the root endophyte, rhizosphere, and phyllosphere communities under different concentrations of SD treatment decreased significantly. sul1 and sul2 mainly accumulated in the root endophyte community, at levels significantly higher than those in the leaf endophyte community. Studies of electrolyte leakage and ultrastructural characteristics of root and leaf cells indicated that lettuce grown in culture solutions with high SD concentrations suffered severe damage and disintegration of the cell walls of organs, especially chloroplasts, in leaves. Furthermore, the possible mechanism of SD toxicity in lettuce was confirmed to start with the roots, followed by a free flow of SD into the leaves to destroy the chloroplasts in the leaf cells, which ultimately reduced photosynthesis and decreased plant growth. Studies have shown that antibiotic residues have negative effects on the growth of lettuce and highlight a potential risk of the development and spread of antibiotic resistance in vegetable endophyte systems.

Macleaya cordata extract, an antibiotic alternative, does not contribute to antibiotic resistance gene dissemination

The abuse of antibiotics and their associated health risks are receiving global attention. The use of antibiotic additives in fodder has been banned in the European Union since 2006 and in China since 2020. Antibiotic alternatives are being developed, but their risks to the soil ecosystem remain poorly understood. Here, we compared the effects of the antibiotic oxytetracycline (OTC10, 10 mg/kg) with those of a Macleaya cordata extract (MCE, 10 and 100 mg/kg), the major antibiotic substitute. All tested concentrations of MCE and OTC10 exerted slight effects on the soil microbiome, but OTC10 and MCE100 could interfere with the structures and functions of the gut microbiome and might thus affect the soil ecological functions of Enchytraeus crypticus. Furthermore, OTC10 exposure inevitably increased the antibiotic resistance gene (ARG) abundance by 213%, whereas MCE did not induce ARG dissemination, which explains why MCE is considered to be associated with a low ecological risk. Our research provides the first demonstration of the risks posed by antibiotic alternatives to soil animals from the perspective of environmental toxicology and explores the potential development of antibiotic alternatives associated with a low ecological risk from a new perspective.

Impacts of Simulated Acid Rain on the Growth and the Yield of Soybean (Glycine max (L.) Merr.) in the Mountains of Northern Vietnam

In the mountains of Northern Vietnam, frequent and intense acid rain affects the crops. This paper assesses the impacts of simulated acid rain (SAR) on the growth and the yield of soybeans (Glycine max (L.) Merr.) in Hoa Binh province. A field study in the summer–autumn seasons in 2017 (from May to August) in an area of 189 square meters was arranged according to a Randomized Complete Block Design (RCBD) with three repetitions including six treatments and a control. The experimental area was protected from ambient rain. Soybean plants were exposed three times a week to SAR at pH 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, and 6.0 (control). The results show that the growth parameters such as germination rate, stem length, and the number of main branches of the plants dramatically decreased in a dose–effect experiment. Gradual declines in the chlorophyll content (indirectly determined by SPAD) and the leaf area index (LAI) were observed as the acidity increased. The actual yield and yield components also tended to decrease when the pH of the rainwater fell, especially in the experimental plots treated at pH 3.0. The growth and yield of soybean were adversely affected when the plants were exposed to simulated acid rain, especially from a pH value of 3.5 and lower. This is the first study to evaluate the effects of acid rain on the growth and the yield of soybean grown in the mountains of Northern Vietnam.

Enhanced Degradation of Sulfonamide Antibiotics by UV Irradiation Combined with Persulfate

In this study, the degradation of sulfonamide antibiotics was investigated through persulfate-enhanced UV advanced oxidation process. Factors that may affect the degradation efficiency were analyzed. Results showed that the persulfate imposed a significant enhancement on the UV oxidation process during the sulfathiazole degradation. The combined process of UV/persulfate can effectively remove about 96% of sulfathiazole within 60 min. With the increase in the dosage of persulfate, the removal efficiency increased as well. Different water matrix almost had no effect on the removal efficiency. Two intermediates were found during the sulfathiazole degradation. It can be predicted that the combined process of UV/persulfate has a broad application prospect for removing sulfonamide antibiotics in water treatment.