Influence of nine antibiotics on key secondary metabolites and physiological characteristics in Triticum aestivum: leaf volatiles as a promising new tool to assess toxicity

Toxic effects of tetracycline on non-target lichen Evernia prunastri

Tetracycline (TC) antibiotics are one of the class of drugs widely used in clinical practice but also constitute a significant environmental concern. However, the adverse effects of TC on non-target organisms have not been well studied. The aim of this study was to examine the influence of exposure to high levels of TC on thalli of lichens to determine the impact on (1) physiological parameters including integrity of cell membranes, photosynthetic efficiency and viability, (2) oxidative stress response such as membrane lipid peroxidation, and (3) enzymatic antioxidant activities as catalase (CAT), superoxide dismutase (SOD), ascorbate peroxidase (APX), and glutathione reductase (GR). Data demonstrated that exposure to tetracycline did not markedly affect the lichen membrane damage as indicated by no change in conductivity. This antibiotic diminished the potential photosystem II efficiency (FV/FM) indicating enhanced susceptibility as evidenced by lower chlorophyll fluorescence and chlorophyll content. The viability of lichens exposed to high concentrations of tetracycline was significantly reduced. The concentrations of thiobarbituric acid reactive substances were markedly elevated with increasing concentrations of antibiotics. At higher TC concentrations, 500 mg/L SOD activity was significantly elevated. In the case of CAT, APX and GR, TC at higher concentrations significantly decreased these enzymic activities. The findings of this study contribute to the knowledge that TC antibiotics exert adverse ecotoxicological effects on lichens at high concentrations and provided a better understanding of the mechanisms underlying toxicity. Data also indicates that lichens may serve as an effective biomonitoring species for TC antibiotic exposure.

Microplastics impacts the toxicity of antibiotics on Pinellia ternata: An exploration of their effects on photosynthesis, oxidative stress homeostasis, secondary metabolism, the AsA-GSH cycle, and metabolomics

Antibiotics and microplastics (MPs) are two new types of contaminants that are widely existent in agricultural systems. MPs could act as carriers of antibiotics, and affect the bioavailability and degradation of antibiotics, causing a combined effect on plant growth. The aim of the present experiment was to explore the effects of the treatments of oxytetracycline (OTC, 100 mg kg-1) alone and in combination with polyethylene microplastics (PE-MPs, 0.1 %, 1 %, 3 %) on P. ternata phenotypic parameters, photosynthetic system, reactive oxygen species (ROS), secondary metabolism, ascorbate-glutathione (AsA-GSH) cycle, and metabolomics. Results demonstrated that exposure to OTC alone reduced P. ternata fresh weight by causing oxidative damage, reducing photosynthetic pigment and secondary metabolite contents. OTC + MP0.1 group alleviated OTC stress to P. ternata by increasing photosynthetic pigment contents and antioxidant enzyme activities. OTC + MP3 group significantly reduced plant height of P. ternata. In addition, metabolomics analysis showed that OTC treatment interfered with pantothenate and CoA biosynthesis. The OTC + MP0.1 group activated pantothenate and CoA biosynthesis and glutathione metabolism. The significance of this study lies in clarifying the effects of OTC on medicinal plants and whether its influence mechanism is regulated by the concentration of MPs.

Biochar Nanoparticles Reduce Ciprofloxacin Accumulation and Restore Growth and Hormonal Balance in Rice Seedlings

Ciprofloxacin (CIP), a widely used fluoroquinolone antibiotic, poses a growing environmental concern due to its persistence in agricultural soils and potential adverse effects on crop production. While previous studies have documented CIP's negative impacts on plant growth, effective strategies to protect crops from antibiotic stress remain limited. Biochar-based approaches show promise, but their application at the nanoscale for antibiotic stress management is largely unexplored. This study demonstrates how biochar nanoparticles (BNPs) effectively mitigate CIP-induced stress in rice seedlings through adsorption mechanisms. Rice seedlings were treated with 5 and 10 mg L-1 CIP, with and without 0.2 g L-1 BNPs. Results showed that CIP significantly disrupted plant growth, decreasing shoot length by 20.5% and root length by 45.2%, along with reduced biomass. Application of BNPs effectively reduced CIP bioavailability by over 80%, leading to a decreased CIP accumulation of 49.7% in shoots and 33.1% in roots. The addition of BNPs mitigated these growth impacts by restoring shoot length to 98.2% of control levels at 5 mg L-1 CIP and improving root growth and biomass accumulation. BNPs also mitigated CIP-induced hormone imbalance, evidenced by a recovery in IAA levels by 8.9%, an increase in 6-BA by 152.6%, and an enhancement in SA levels by 12.7-13.6%. These findings demonstrate the significant potential of nanoscale biochar in reducing antibiotic stress in agricultural systems and provide insights into plant responses under these conditions. This research offers a promising strategy for enhancing crop resilience in areas affected by pharmaceutical pollutants.

Fate of emerging antibiotics in soil-plant systems: A case on fluoroquinolones

Fluoroquinolones (FQs), a class of broad-spectrum antibiotics widely used to treat human and animal diseases globally, have limited adsorption and are often excreted unchanged or as metabolites. These compounds enter the soil environment through feces, urban wastewater, or discharge of biological solids. The fluorine atoms in FQs impart high electronegativity, chemical stability, and resistance to microbial degradation, allowing them to potentially enter food chains. The persistence of FQs in soils raises questions about their impacts on plant growth, an aspect not yet conclusively determined. We reviewed whether, like other organic compounds, FQs are actively absorbed by plants, resulting in bioaccumulation and posing threats to human health. The influx of FQs has led to antibiotic resistance in soil microbes by exerting selective pressure and contributing to multidrug-resistant bacteria. Therefore, the environmental risks of FQs warrant further attention. This work provides a comprehensive review of the fate and behavior of FQs at the plant-environment interface, their migration and transport from the environment into plants, and associated toxicity. Current limitations in research are discussed and prospects for future investigations outlined. Thus, understanding antibiotic behavior in plants and translocation within tissues is not only crucial for ecosystem health (plant health), but also assessing potential human health risks. In addition, it can offer insights into the fate of emerging soil pollutants in plant-soil systems.

Exploring the ecotoxicological impact of meropenem on Lemna minor: Growth, photosynthetic activity, and oxidative stress

Meropenem is a potent carbapenem antibiotic frequently used in medical settings. Several studies have confirmed the pervasive presence of these antibiotics in wastewater treatment plants and aquatic environments. However, the effects of these substances on non-target organisms, such as plants, have not been adequately monitored. Thus, this study aimed to assess the short-term impact of meropenem on the growth, photosynthesis, chlorophyll content, and enzyme activity of the macrophyte plant Lemna minor. The methods involved exposing the plant to meropenem under controlled conditions and assessing physiological and biochemical parameters to determine the impact on photosynthetic activity and oxidative stress. These analyses included growth rate, antioxidant enzyme activity, and photosynthetic capacity. The findings suggest that the growth rate of Lemna minor remained unaffected by meropenem at concentrations <200000 μgL-1. However, plants exposed to concentrations >20 μgL-1showed physiological alterations, such as decreased net photosynthesis rate (17%) and chlorophyll concentration (57%), compared to the control group. For acute toxicity assays, the calculated EC50 7-day and EC20 7-day were 1135 μgL-1and 33 μgL-1, respectively. In addition, in most treatments tested, meropenem caused an increase in the superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) activity as a defense mechanism against oxidative stress. Our results suggest that meropenem affects photosynthetic processes and induces oxidative stress in the macrophyte plant Lemna minor. Further studies are needed to assess the physiological and metabolic interactions between antibiotics and primary producers at different long-term trophic levels.

Antibiotic Resistance in Plant Pathogenic Bacteria: Recent Data and Environmental Impact of Unchecked Use and the Potential of Biocontrol Agents as an Eco-Friendly Alternative

The economic impact of phytopathogenic bacteria on agriculture is staggering, costing billions of US dollars globally. Pseudomonas syringae is the top most phytopathogenic bacteria, having more than 60 pathovars, which cause bacteria speck in tomatoes, halo blight in beans, and so on. Although antibiotics or a combination of antibiotics are used to manage infectious diseases in plants, they are employed far less in agriculture compared to human and animal populations. Moreover, the majority of antibiotics used in plants are immediately washed away, leading to environmental damage to ecosystems and food chains. Due to the serious risk of antibiotic resistance (AR) and the potential for environmental contamination with antibiotic residues and resistance genes, the use of unchecked antibiotics against phytopathogenic bacteria is not advisable. Despite the significant concern regarding AR in the world today, there are inadequate and outdated data on the AR of phytopathogenic bacteria. This review presents recent AR data on plant pathogenic bacteria (PPB), along with their environmental impact. In light of these findings, we suggest the use of biocontrol agents as a sustainable, eco-friendly, and effective alternative to controlling phytopathogenic bacteria.

Urea promoted soil microbial community and reduced the residual ciprofloxacin in soil and its uptake by Chinese flowering cabbage

Antibiotics in agricultural soil can be accumulated in crops and might pose a potential risk to human health. Nevertheless, there is a lack of knowledge about the impact of nitrogen fertilizers on the dissipation and uptake of antibiotics in soils. Therefore, our aim in this study is to investigate the effects of urea fertilizer on the residues of ciprofloxacin and its uptake by Chinese flowering cabbage (Brassica parachinensis L.) as affected by the associated changes on the soil microbial community. A pot experiment has been conducted using spiked soil with 20 mg ciprofloxacin /kg soil and fertilized with urea at dosages equal to 0, 0.2, 0.4, 0.8 t/ha. Application urea especially at 0.4 t/ha decreased the residue of ciprofloxacin in the soil and its uptake by the roots and its translocation to the shoots of Chinese flowering cabbage. The translocation factors (TFs) for ciprofloxacin were significantly decreased (P < 0.05) only at the treatment of 0.4 t/ha, while no significant difference of bio-concentration factors (BCFs). The average well color development (AWCD) values, Shannon diversity, and richness index were higher in the fertilized than the un-fertilized soils, and all such indicators were greater at the treatment of 0.4 t/ha than at 0.2 and 0.8 t/ha. The carbon substrate utilization of phenolic acids at the treatments of 0.4 t/ha were greater than with other levels of urea fertilizer. In conclusion, moderate urea addition significantly increased soil microbial activity and abundance, which in turn promoted the ciprofloxacin dissipation in soil and plant tissue. The present study provides an economical and operational strategy for the remediation of ciprofloxacin contaminated soils.

A comprehensive review on the fate and impact of antibiotic residues in the environment and public health: A special focus on the developing countries

The widespread application of antibiotics in human and veterinary medicine has led to the pervasive presence of antibiotic residues in the environment, posing a potential hazard to public health. This comprehensive review aims to scrutinize the fate and impact of antibiotic residues, with a particular focus on the context of developing nations. The investigation delves into the diverse pathways facilitating the entry of antibiotics into the environment and meticulously examines their effects on human health. The review delineates the current state of antibiotic residues, evaluates their exposure in developing nations, and elucidates existing removal methodologies. Additionally, it probes into the factors contributing to the endurance and ecotoxicity of antibiotic residues, correlating these aspects with usage rates and associated mortalities in these nations. The study also investigates removal techniques for antibiotic residues, assessing their efficiency in environmental compartments. The concurrent emergence of antibiotic-resistant bacteria, engendered by antibiotic residues, and their adverse ecological threats underscore the necessity for enhanced regulations, vigilant surveillance programs, and the adoption of sustainable alternatives. The review underlines the pivotal role of public education and awareness campaigns in promoting responsible antibiotic use. The synthesis concludes with strategic recommendations, strengthening the imperative for further research encompassing comprehensive monitoring, ecotoxicological effects, alternative strategies, socio-economic considerations, and international collaborations, all aimed at mitigating the detrimental effects of antibiotic residues on human health and the environment. PRACTITIONER POINTS: Antibiotic residues are widely distributed in different environmental compartments. Developing countries use more antibiotics than developed countries. Human and veterinary wastes are one of the most responsible sources of antibiotic pollution. Antibiotics interact with biological systems and trigger pharmacological reactions at low doses. Antibiotics can be removed using modern biological, chemical, and physical-chemical techniques.

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.

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.

Antibiotic persistence and its impact on the environment

From boon molecules to molecules contributing to rising concern has been the sojourn of antibiotics. The problem of antibiotic contamination has gotten worse due to antibiotics' pervasive use in every aspect of the environment. One such consequence of pollution is the increase in infections with antibiotic resistance. All known antimicrobials being used for human benefit lead to their repetitive and routine release into the environment. The misuse of antibiotics has aggravated the situation to a level that we are short of antibiotics to treat infections as organisms have developed resistance against them. Overconsumption is not just limited to human health care, but also occurs in other areas such as aquaculture, livestock, and veterinary applications for the purpose of improving feed and meat products. Due to their harmful effects on non-target species, the trace level of antibiotics in the aquatic ecosystem presents a significant problem. Since the introduction of antibiotics into the environment is more than their removal, they have been given the status of persistent pollutants. The buildup of antibiotics in the environment threatens aquatic life and may lead to bacterial strains developing resistance. As newer organisms are becoming resistant, there exists a shortage of antibiotics to treat infections. This has presented a very critical problem for the health-care community. Another rising concern is that the development of newer drug molecules as antibiotics is minimal. This review article critically explains the cause and nature of the pollution and the effects of this emerging trend. Also, in the latter sections, why we need newer antibiotics is questioned and discussed.

The Impact of Increased CO2 and Drought Stress on the Secondary Metabolites of Cauliflower (Brassica oleracea var. botrytis) and Cabbage (Brassica oleracea var. capitata)

Elevated carbon dioxide and drought are significant stressors in light of climate change. This study explores the interplay between elevated atmospheric CO2, drought stress, and plant physiological responses. Two Brassica oleracea varieties (cauliflowers and cabbage) were utilized as model plants. Our findings indicate that elevated CO2 accelerates assimilation rate decline during drought. The integrity of photosynthetic components influenced electron transport, potentially due to drought-induced nitrate reductase activation changes. While CO2 positively influenced photosynthesis and water-use efficiency during drought, recovery saw decreased stomatal conductance in high-CO2-grown plants. Drought-induced monoterpene emissions varied, influenced by CO2 concentration and species-specific responses. Drought generally increased polyphenols, with an opposing effect under elevated CO2. Flavonoid concentrations fluctuated with drought and CO2 levels, while chlorophyll responses were complex, with high CO2 amplifying drought's effects on chlorophyll content. These findings contribute to a nuanced understanding of CO2-drought interactions and their intricate effects on plant physiology.

Antimicrobial and Apoptotic Efficacy of Plant-Mediated Silver Nanoparticles

Phytogenically synthesised nanoparticle (NP)-based drug delivery systems have promising potential in the field of biopharmaceuticals. From the point of view of biomedical applications, such systems offer the small size, high surface area, and possible synergistic effects of NPs with embedded biomolecules. This article describes the synthesis of silver nanoparticles (Ag-NPs) using extracts from the flowers and leaves of tansy (Tanacetum vulgare L.), which is known as a remedy for many health problems, including cancer. The reducing power of the extracts was confirmed by total phenolic and flavonoid content and antioxidant tests. The Ag-NPs were characterised by various analytical techniques including UV-vis spectroscopy, scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS), Fourier transform infrared (FT-IR) spectroscopy, and a dynamic light scattering (DLS) system. The obtained Ag-NPs showed higher cytotoxic activity than the initial extracts against both human cervical cancer cell lines HeLa (ATCC CCL-2) and human melanoma cell lines A375 and SK-MEL-3 by MTT assay. However, the high toxicity to Vero cell culture (ATCC CCL-81) and human fibroblast cell line WS-1 rules out the possibility of their use as anticancer agents. The plant-mediated Ag-NPs were mostly bactericidal against tested strains with MBC/MIC index ≤4. Antifungal bioactivity (C. albicans, C. glabrata, and C. parapsilosis) was not observed for aqueous extracts (MIC > 8000 mg L^-1), but Ag-NPs synthesised using both the flowers and leaves of tansy were very potent against Candida spp., with MIC 15.6 and 7.8 µg mL^-1, respectively.

The Research Status, Potential Hazards and Toxicological Mechanisms of Fluoroquinolone Antibiotics in the Environment

Fluoroquinolone antibiotics are widely used in human and veterinary medicine and are ubiquitous in the environment worldwide. This paper recapitulates the occurrence, fate, and ecotoxicity of fluoroquinolone antibiotics in various environmental media. The toxicity effect is reviewed based on in vitro and in vivo experiments referring to many organisms, such as microorganisms, cells, higher plants, and land and aquatic animals. Furthermore, a comparison of the various toxicology mechanisms of fluoroquinolone antibiotic residues on environmental organisms is made. This study identifies gaps in the investigation of the toxic effects of fluoroquinolone antibiotics and mixtures of multiple fluoroquinolone antibiotics on target and nontarget organisms. The study of the process of natural transformation toward drug-resistant bacteria is also recognized as a knowledge gap. This review also details the combined toxicity effect of fluoroquinolone antibiotics and other chemicals on organisms and the adsorption capacity in various environmental matrices, and the scarcity of data on the ecological toxicology evaluation system of fluoroquinolone antibiotics is identified. The present study entails a critical review of the literature providing guidelines for the government to control the discharge of pollutants into the environment and formulate policy coordination. Future study work should focus on developing a standardized research methodology for fluoroquinolone antibiotics to guide enterprises in the design and production of drugs with high environmental biocompatibility.

Fluoroquinolone antibiotics: Occurrence, mode of action, resistance, environmental detection, and remediation - A comprehensive review

Antibiotics play an essential role in the medical healthcare world, but their widespread usage and high prevalence have posed negative environmental consequences. During the past few decades, various antibiotic drugs have been detected in aquatic and terrestrial ecosystems. Among them, the Fluoroquinolones (FQ) group is ubiquitous in the environment and has emerged as a major environmental pollutant. FQs are very significant, broad-spectrum antibiotics used in treating various pathogenic diseases of humans and animals. The most known and used FQs are ciprofloxacin, norfloxacin, ofloxacin, levofloxacin, enrofloxacin, danofloxacin, and moxifloxacin. After human and animal administration, about 70% of these drugs are excreted out in unaltered form into the environment. Besides, wastewater discharge from pharmaceutical industries, hospitals, and agriculture runoff is the major contributor to the accumulation of FQs into the ecosystem. Their long-term presence in the environment creates selection pressure on microorganisms and contributes to the emergence of multi-drug-resistant bacteria. In addition to the resistance, these antibiotics also impose ecotoxicological effects on various animals and plant species. The presence of the fluorine atom in Fluoroquinolones makes them highly electronegative, strong, recalcitrant, and less compatible with microbial degradation. Many biological and chemical processes have been invented and successfully implemented during the past few decades for the elimination of these pollutants from the environment. This review provides a detailed overview of the classification, occurrence, distribution, and ecotoxicological effects of Fluoroquinolones. Their modes of action, resistance mechanism, detection and analysis methods, and remediation strategies have also been discussed in detail.

Responses of cherry radish to different types of microplastics in the presence of oxytetracycline

Croplands have become a hotspot for antibiotic and microplastic (MP) pollution. However, little is known regarding their combined effects on crops. In this study, the individual and combined effects of oxytetracycline (OTC) and three MPs (i.e., polypropylene (PP), polyamide (PA), and polyvinylchloride (PVC)) on cherry radish were investigated using pot experiments. Individually, OTC (50 mg kg^-1), PA (2%, w/w), and PP (2%, w/w) induced negligible effects on cherry radish biomass and the root/shoot ratio. However, PVC (2%, w/w) significantly inhibited cherry radish growth; that is, its shoot and root fresh weight decreased by 46.2% and 81.1%, respectively. In the combined exposure groups, OTC alleviated the adverse effects of PVC on the cherry radish leaf number and shoot fresh weight. This was linked to that OTC increased the content of photosynthetic pigments. Superoxide dismutase activity in cherry radish roots was inhibited to different extents in all treatment groups except for the PA and PVC treatments. Malondialdehyde (MDA) content in cherry radish roots increased in all treatment groups, suggesting that both OTC and MPs caused oxidative damage to cherry radish root cells, therefore inhibiting cherry radish root growth. However, the presence of OTC non-significantly changed the effects of MPs on cherry radish roots. Irrespective of OTC presence, MPs induced a reduction in the root/shoot ratio of cherry radish, suggesting that the inhibitory effect of MPs on cherry radish roots was stronger than that on shoots. These findings contribute to the evaluation of the phytotoxicity of antibiotics and MPs in soil-vegetable systems.

Effects of tetracycline on the secondary metabolites and nutritional value of oilseed rape (Brassica napus L.)

Secondary metabolism, which helps a plant cope with external stress, is sensitive to environmental changes and plays a prominent role in maintaining plant health. However, few studies of the effects of tetracycline on the relationships between secondary metabolism and plant stress responses have been performed. Here, secondary metabolism, nutritional value, and oxidative stress responses in oilseed rape (Brassica napus L.) exposed to tetracycline for 14 days were investigated. Tetracycline inhibited growth and biomass accumulation and decreased the chlorophyll content. The sinapine, phenol, and flavonoid contents were 118.46%, 99.67%, and 93.07% higher, respectively, but the carotenoid content was 76.47% lower in plants exposed to 8 mg/L tetracycline than the control plants. Tetracycline affected the nutritional value of oilseed rape. Tetracycline decreased the dietary fiber, soluble sugar contents, and microelement (Fe, Mn, and Zn) contents. The antioxidant system also responded strongly to tetracycline. The catalase and peroxidase activities were increased and the superoxide dismutase activity was decreased by tetracycline. Tetracycline caused oxidative damage and secondary metabolite disturbances and adversely affected oilseed rape growth and quality. The results provide a new perspective on the effects of tetracycline on plants in relation to secondary metabolites and improve our understanding involved in the toxicity of tetracycline.

Antagonist Temperature Variation Affects the Photosynthetic Parameters and Secondary Metabolites of Ocimum basilicum L. and Salvia officinalis L

Climate change is one of the main challenges for actual and future generations. Global warming affects plants and animals and is responsible for considerable crop loss. This study studied the influence of antagonist successive stresses, cold-heat and heat-cold, on two medicinal plants Ocimum basilicum L. and Salvia officinalis L. The photosynthetic parameters decreased for plants under the variation of subsequent stress. Net assimilation rates and stomatal conductance to water vapor are more affected in the case of plants under cold-heat consecutive stress than heat-cold successive stress. Emissions of volatile organic compounds have been enhanced for plants under successive stress when compared with control plants. Chlorophyll concentrations for plants under successive stress decreased for basil and sage plants. The total phenolic and flavonoid contents were not affected by the successive stresses when compared with the plants under only one type of treatment.

Influence of Nonsteroidal Anti-Inflammatory Drugs (NSAIDs) on Photosynthetic Parameters and Secondary Metabolites of Plants from Fabaceae Family

Nonsteroidal anti-inflammatory medications (NSAIDs) are commonly used painkillers, anti-inflammatory agents, and fever reducers. They arrive in the environment from municipal wastewater and/or agriculture waste, affecting growing plants. In our study, the impact of NSAIDs, namely, diclofenac, indomethacin, naproxen, and paracetamol, on four plant species from the Fabaceae family (Cicer arietinum, Pisum sativum, Lens culinaris, and Vicia faba) was tested. The assimilation rate and stomatal conductance decreased for all plants treated with NSAIDs. Chlorophyll and carotenoid contents in the leaves of plants under stress declined by more than 15% compared with the control plants, while the flavonoids and total phenols decreased to a lesser extent. In contrast, the plants treated with NSAIDs emit terpenes and green leaf were volatile, at a level of some nmol m−2 s−1, which could influence the atmospheric reaction and ozone formation.

The Influence of Elevated CO2 on Volatile Emissions, Photosynthetic Characteristics, and Pigment Content in Brassicaceae Plants Species and Varieties

Climate change will determine a sharp increase in carbon dioxide in the following years. To study the influence of elevated carbon dioxide on plants, we grew 13 different species and varieties from the Brassicaceae family at three carbon dioxide concentrations: 400, 800, and 1200 ppmv. The photosynthetic parameters (assimilation rate and stomatal conductance to water vapor) increase for all species. The emission of monoterpenes increases for plants grown at elevated carbon dioxide while the total polyphenols and flavonoids content decrease. The chlorophyll content is affected only for some species (such as Lipidium sativum), while the β-carotene concentrations in the leaves were not affected by carbon dioxide.

The Effect of Antagonist Abiotic Stress on Bioactive Compounds from Basil (Ocimum basilicum)

Drought and flooding are some of the most common stressful conditions for plants. Due to the recent climate changes, they can occur one after another. This study is focused on the effect of antagonistic abiotic stress such as drought and flooding on the different metabolites from Ocimum basilicum leaves. Six-week-old plants of Ocimum basilicum were exposed to drought or flooding stress for 15 days, followed by antagonist stress for 14 days. The assimilation rates decrease drastically for plants under consecutive stresses from 18.9 to 0.25 µmol m−2 s−1 starting at day 3 of treatment. The stomatal conductance to water vapor gs was also reduced from 86 to 29 mmol m−2 s−1. The emission of green leaf volatiles compounds increases from 0.14 to 2.48 nmol m−2 s−1, and the emission of monoterpenes increased from 2.00 to 7.37 nmol m−2 s−1. The photosynthetic pigment concentration (chlorophyll a and b, and β-carotene), the flavonoid content, and total phenolic content decrease for all stressed plants. The results obtained in this study could indicate that the water status (drought and/or flooding) directly impacts basil plants’ physiological parameters and secondary metabolites.

Effect of soil sulfamethoxazole on strawberry (Fragaria ananassa): Growth, health risks and silicon mitigation

The negative impact of antibiotic pollution on the agricultural system and human health is a hot issue in the world. However, little information is available on the antibiotics toxicity mechanism and the role of silicon (Si) to alleviate the antibiotics toxicity. In this study, strawberry (Fragaria ananassa) showed excitatory response to low-dose SMZ (1 mg L^-1), but strawberry root and photosynthetic efficiency were damaged under high level. When SMZ level exceeded 10 mg L^-1, H₂0₂, O₂^-, MDA and relative conductivity increased, while SOD and CAT activities first increased and then decreased. SMZ accumulated more in roots and fruits, but less in stems, and the accumulation increased with the increase of SMZ-dose. Under 1 mg L^-1 SMZ, the SMZ accumulation in fruits was 110.54 μg kg^-1, which exceeded the maximum residue limit. SMZ can induce the expression of sul1, sul2 and intI1, and intI1 had the highest abundance. Exogenous application of Si alleviated the toxicity of SMZ, which is mainly related to the degradation of SMZ in soil and the reduction of SMZ absorption by strawberry. In addition, Si relieved root damage, promoted the increase of photosynthetic efficiency, and improved the antioxidant system to resist SMZ toxicity.

Content of Carotenoids, Violaxanthin and Neoxanthin in Leaves of Triticum aestivum Exposed to Persistent Environmental Pollutants

Persistent pollutants such as pharmaceuticals, pesticides, musk fragrances, and dyes are frequently detected in different environmental compartments and negatively impact the environment and humans. Understanding the impacts of diffuse environmental pollutants on plants is still limited, especially at realistic environmental concentrations of contaminants. We studied the effects of key representatives of two major classes of environmental pollutants (nine different antibiotics and six different textile dyes) on the leaf carotenoid (violaxanthin and neoxanthin) content in wheat (Triticum aestivum L.) using different pollutant concentrations and application times. The wheat plants were watered with solutions of selected environmental pollutants in two different concentrations of 0.5 mg L⁻¹ and 1.5 mg L⁻¹ for one week (0.5 L) and two weeks (1 L). Both categories of pollutants selected for this study negatively influenced the content of violaxanthin and neoxanthin, whereas the textile dyes represented more severe stress to the wheat plants. The results demonstrate that chronic exposure to common diffusively spread environmental contaminants constitutes significant stress to the plants.

Veterinary antibiotics and plant physiology: An overview

Antibiotics are considered one of the greatest advances of medicine and, in addition to their use in treating a wide spectrum of illnesses, they have been widely employed to promote animal growth. As many of those pharmaceuticals are only partially absorbed by the digestive system, a considerable fraction is excreted in its original active form or only partially metabolized. Therefore, the use of animal excrement in agriculture represents one of the principal routes of insertion of antibiotics into the environment. Within that context, plants, principally those of agricultural interest, will be exposed to those compounds when present in the soil or when irrigated with contaminated water. Although not yet fully understood, there are reports of phytotoxic effects of antibiotics that can diminish agricultural production. This review is designed to provide a general and integrative overview of physiological alterations observed in plants caused by environmental exposures to veterinary-use antibiotics. This text principally focuses on the processes involved in antibody absorption and accumulation, and their effects on the primary (photosynthesis, respiration, nitrogen assimilation) and oxidative metabolisms of plants. We also bring attention to germinative and plant establishment processes under conditions of antibiotic contamination. The different effects of different antibiotics on plant physiology are listed here to provide a better understanding of their phytotoxicities.

Crop irrigation (soybean, bean, and corn) with enrofloxacin-contaminated water leads to yield reductions and antibiotic accumulation

The increasing use of antibiotics in animal production has become an emergent environmental problem. The large percentages of applied antibiotic doses eliminated in animal excrement often end up contaminating water resources, which are then used for irrigation - compromising agricultural production and/or food security. Here, we evaluated the effects of crop irrigation with water artificially contaminated by enrofloxacin (10 μg l-1) and its accumulation in soybean, bean, and corn tissues. Grain production was evaluated on the basis of grain dry weight plant-1, while enrofloxacin and ciprofloxacin (its breakdown metabolite) concentrations in plant tissues were evaluated by HPLC after harvesting. Diminished production was observed only in soybean plants irrigated with antibiotic-contaminated water. Enrofloxacin [1.68 ng g fresh weight (FW)-1 to 26.17 µg g FW-1] and ciprofloxacin (8.23 ng g FW-1 to 51.05 ng g FW-1), were found in all of the plant tissues (roots, leaves, and seeds) of the three species. Regardless of the species, the highest enrofloxacin concentrations were observed in their roots, followed by the leaves and seeds, while ciprofloxacin concentrations varied among the different plant tissues of the different species. The presence of enrofloxacin in the water used for irrigating soybeans can result in productivity losses and, as that antibiotic was encountered in plant tissues (leaves and seeds) of all of the three species analyzed that are consumed in the diets of both humans and animals, it can interfere with food security.

The effect of bio/organic fertilizers on the phytotoxicity of sulfadiazine to Echium amoenum in a calcareous soil

The fate of antibiotics and their effects on plant growth may be changed by the application of fertilizers. The present study was carried out to investigate the effect of sulfadiazine (SDZ), rice husk compost (RHC), rice husk biochar (RHB), and mycorrhiza (MR) on the growth attributes of Iranian Echium amoenum Fisch & C.A. Mey. A greenhouse experiment as a completely randomized design with six treatments of bio/organic-fertilizers (no bio-fertilizer (NF), RHB, RHC, MR, RHB+MR, and RHC+MR) and three levels of SDZ application (0, 100, and 200 mg kg^-1) was performed for 7months with three replicates. Shoot and root SDZ concentrations were determined using high-pressure liquid chromatography-diode array detection (HPLC-DAD) instrumentation. The results revealed that the application of RHC, RHB, and MR had a significant impact on the reduction of the toxicity effects of SDZ on plant properties. The lowest values of growth parameters belonged to the 200 mg kg^-1 of SDZ with no bio-fertilizers, while the highest growth parameters were observed in the treatments of RHB+MR, and RHC+MR with no SDZ application. Also, chlorophyll pigments content was affected by used treatments and the lowest rates of chlorophyll a (4.24), chlorophyll b (2.99), and carotenoids (2.88) were related to the 200 mg kg^-1 of SDZ with no biofertilizers application. The co-application of bio-fertilizers and SDZ (at both levels of 100 and 200 mg kg^-1) decreased SDZ uptake by both shoot and root in comparison with the control. The same results were obtained with macro (NPK) and micro (Fe, Zn, Cu, and Mn) nutrients uptake by the shoot in which the lowest values of nutrients uptake were observed in treatment of 200 mg kg^-1 of SDZ with no bio-fertilizers. Furthermore, in the case of the effect of the used treatments on root colonization, the results showed that the lowest value (7.26%) belonged to the 200 mg kg^-1 application of SDZ with no bio-fertilizers. Generally, this study demonstrated that bio-fertilizers could be considered as an effective strategy in controlling the negative effects of antibiotics on the growth properties and nutrients status of the plants grown in such contaminated soils.

Erythromycin Treatment of Brassica campestris Seedlings Impacts the Photosynthetic and Protein Synthesis Pathways

Erythromycin (Ery) is a commonly used veterinary drug that prevents infections and promotes the growth of farm animals. Ery is often detected in agricultural fields due to the effects of manure application in the ecosystem. However, there is a lack of information on Ery toxicity in crops. In this study, we performed a comparative proteomic analysis to identify the molecular mechanisms of Ery toxicity during seedling growth based on our observation of a decrease in chlorophyll (Chl) contents using Brassica campestris. A total of 452 differentially abundant proteins (DAPs) were identified including a ribulose-1,5-bisphosphate carboxylase (RuBisCO). The proteomic analysis according to gene ontology (GO) classification revealed that many of these DAPs responding to Ery treatment functioned in a cellular process and a metabolic process. The molecular function analysis showed that DAPs classified within catalytic activity were predominantly changed by Ery, including metabolite interconversion enzyme and protein modifying enzyme. An analysis of functional pathways using MapMan revealed that many photosynthesis components were downregulated, whereas many protein biosynthesis components were upregulated. A good relationship was observed between protein and transcript abundance in a photosynthetic pathway, as determined by qPCR analysis. These combined results suggest that Ery affects plant physiological activity by downregulating protein abundance in the photosynthetic pathway.

Tetracycline and Sulfonamide Antibiotics in Soils: Presence, Fate and Environmental Risks

Veterinary antibiotics are widely used worldwide to treat and prevent infectious diseases, as well as (in countries where allowed) to promote growth and improve feeding efficiency of food-producing animals in livestock activities. Among the different antibiotic classes, tetracyclines and sulfonamides are two of the most used for veterinary proposals. Due to the fact that these compounds are poorly absorbed in the gut of animals, a significant proportion (up to ~90%) of them are excreted unchanged, thus reaching the environment mainly through the application of manures and slurries as fertilizers in agricultural fields. Once in the soil, antibiotics are subjected to a series of physicochemical and biological processes, which depend both on the antibiotic nature and soil characteristics. Adsorption/desorption to soil particles and degradation are the main processes that will affect the persistence, bioavailability, and environmental fate of these pollutants, thus determining their potential impacts and risks on human and ecological health. Taking all this into account, a literature review was conducted in order to shed light on the current knowledge about the occurrence of tetracycline and sulfonamide antibiotics in manures/slurries and agricultural soils, as well as on their fate in the environment. For that, the adsorption/desorption and the degradation (both abiotic and biotic) processes of these pollutants in soils were deeply discussed. Finally, the potential risks of deleterious effects on human and ecological health associated with the presence of these antibiotic residues were assessed. This review contributes to a deeper understanding of the lifecycle of tetracycline and sulfonamide antibiotics in the environment, thus facilitating decision-making for the application of preventive and mitigation measures to reduce its negative impacts and risks to public health.

Phytotoxicity of different antibiotics to rice and stress alleviation upon application of organic amendments

Extensive use of antibiotic results in significant antibiotics pollution in the environment. Main objective of this study was to gain insight into potential impacts of antibiotics on plant physiological growth and nutritional composition, and stress alleviation through application of different organic amendments. Effects of five antibiotics (ciprofloxacin, levofloxacin, ofloxacin, amoxicillin and ampicillin) were observed in the presence of three organic amendments (rice husk, farmyard manure and poultry litter) with rice (Oryza sativa L.) as a model plant. Organic amendments were mixed with soil (@ 5 g kg^-1) and after three weeks, antibiotics were applied (@10 mg kg^-1) and plants were allowed to grow for four months. After which plants were harvested and physical growth parameters (root/shoot length, biomass) and nutritional composition (grain protein content, carbohydrates, phosphorous and iron) were monitored. It was observed that germination rate, seedling root/shoot length, seedling biomass and vigor index were negatively impacted. The application of organic amendments alleviated antibiotic stress on seedling dry biomass, length and vigor index by 1.8-, 3.1- and 2.5-folds, respectively as compared to the antibiotic controls. Concentrations of phosphorous, iron, carbohydrates and proteins were decreased by 5.3-, 1.3-, 1.4- and 1.6-folds upon application of antibiotics. Rice husk was the most effective treatment in case of physical growth parameters and alleviating antibiotics' induced genotoxicity. Whereas, poultry litter had the highest positive effect on nutritional composition of plants. In general, the application of organic amendments alleviated the phytotoxicity as well as genotoxicity in plants under antibiotics stress.

Reclaimed wastewater as a viable water source for agricultural irrigation: A review of food crop growth inhibition and promotion in the context of environmental change

The geographical and temporal distribution of precipitation has and is continuing to change with changing climate. Shifting precipitation will likely require adaptations to irrigation strategies, and because 35% of rainfed and 60% of irrigated agriculture is within 20 km of a wastewater treatment plant, we expect that the use of treated wastewater (e.g., reclaimed wastewater) for irrigation will increase. Treated wastewater contains various organic and inorganic substances that may have beneficial (e.g., nitrate) or deleterious (e.g., salt) effects on plants, which may cause a change in global food productivity should a large change to treated wastewater irrigation occur. We reviewed literature focused on food crop growth inhibition or promotion resulting from exposure to xenobiotics, engineered nanoparticles, nitrogen, and phosphorus, metals, and salts. Xenobiotics and engineered nanoparticles, in nearly all instances, were detrimental to crop growth, but only at concentrations much greater than would be currently expected in treated wastewater. However, future changes in wastewater flow and use of these compounds and particles may result in phytotoxicity, particularly for xenobiotics, as some are present in wastewater at concentrations within approximately an order of magnitude of concentrations which caused growth inhibition. The availability of nutrients present in treated wastewater provided the greatest overall benefit, but may be surpassed by the detrimental impact of salt in scenarios where either high concentrations of salt are directly deleterious to plant development (rare) or in scenarios where soils are poorly managed, resulting in soil salt accumulation.

D-amino Acids in Plants: Sources, Metabolism, and Functions

Although plants are permanently exposed to d-amino acids (d-AAs) in the rhizosphere, these compounds were for a long time regarded as generally detrimental, due to their inhibitory effects on plant growth. Recent studies showed that this statement needs a critical revision. There were several reports of active uptake by and transport of d-AAs in plants, leading to the question whether these processes happened just as side reactions or even on purpose. The identification and characterization of various transporter proteins and enzymes in plants with considerable affinities or specificities for d-AAs also pointed in the direction of their targeted uptake and utilization. This attracted more interest, as d-AAs were shown to be involved in different physiological processes in plants. Especially, the recent characterization of d-AA stimulated ethylene production in Arabidopsis thaliana revealed for the first time a physiological function for a specific d-AA and its metabolizing enzyme in plants. This finding opened the question regarding the physiological or developmental contexts in which d-AA stimulated ethylene synthesis are involved in. This question and the ones about the transport characteristics of d-AAs, their metabolism, and their different physiological effects, are the focus of this review.

Antibiotics in the environment: causes and consequences

Antibiotics represent one of the main discoveries of the last century that changed the treatment of a large array of infections in a significant way. However, increased consumption has led to an exposure of bacterial communities and ecosystems to a large amount of antibiotic residues.

This paper aims to provide a brief overview of the primary drivers associated with antibiotic occurrence in the environment. Furthermore, we attempted to summarize the behavior of antibiotic residues in the environment and the necessity of their detection and quantification. Also, we provide updated scientific and regulatory facts about environmental antibiotic discharge and environmental and human antibiotics risk assessment.

We propose that environmental antibiotic contamination should be diminished beginning from regulating the causes of occurrence in the environment (such as antibiotic consumption) and ending with regulating antibiotic discharge and risk assessment. Some important intermediate steps are represented by the detection and quantification of the antibiotics and the characterization of their behavior in the environment, which could come to support future regulatory decisions.

Investigating the effects of non-steroidal anti-inflammatory drugs (NSAIDs) on the composition and ultrastructure of green leafy vegetables with important nutritional values

The global presence of pharmaceuticals in the environment has been particularly considered a concerning problem with unknown consequences. Non-steroidal anti-inflammatory drugs (NSAIDs) are among the most frequently prescribed drugs in the world, and as a result, they are commonly found in different environmental compartments. In the present work, we studied the effects of NSAIDs (diclofenac, ibuprofen, and naproxen) on the composition and ultrastructure of Atriplex patula L., S. oleracea, and Lactuca sativa L., three green leafy vegetables with significant nutritional value. Contaminant solutions of NSAIDs were applied every two days using concentrations of 0.1 mg L^-1, 0.5 mg L^-1, and 1 mg L^-1. After eight weeks of exposure of the green leafy vegetables to the selected NSAIDs, the chlorophylls (a + b), carotenoids (zeaxanthin, lutein, and ß-carotene), total polyphenol and total flavonoid contents, antioxidant capacity, and the ultrastructural modifications were determined. The obtained results indicated a moderate reduction in the assimilating pigments, total polyphenol and flavonoid contents. In addition, ultrastructural damages of the chloroplasts and cell walls were observed in the leaves of the selected vegetables, which were exposed to abiotic stress-induced by NSAIDs. All data collectively suggest that this group of drugs induced harmful effects on plants, and implicitly they may also negatively affected human health on the long term.

Investigation of chlorophyll degradation by tetracycline

Antibiotics represent a novel type of environment pollutants which modify chlorophyll content in plants. Spectroscopic methods were employed to investigate the effect of tetracycline on chlorophyll degradation. Changes in absorbance and fluorescence demonstrated that tetracycline reaction with chlorophyll results in the formation of pheophytin, which was confirmed by new bands typical of pheophytin which appeared in the absorbance spectrum. The rate of pheophytin formation depended on ratio tetracycline to chlorophyll concentration in solution. In solutions with chlorophyll concentration of C = 1 × 10^-5 M and tetracycline concentrations of C = 1 × 10^-3 M and C = 1 × 10^-2 M, pheophytin was formed after 28 h and 25 min, respectively. The obtained lifetime for pheophytin formed during chlorophyll reaction - with tetracycline hydrochloride was τ = 5.71 ± 0.02 ns and its value coincides, within the error limits, with the value obtained for pure pheophytin purchased from ChromaDex. The experiment demonstrated two mechanisms of chlorophyll degradation to pheophytin by tetracycline hydrochloride, i.e. 1) loss of Mg²⁺ ions from the chlorophyll molecule as a result of the presence of H⁺ ions in solution (i.e. as a result of medium acidification), and 2) removal of Mg²⁺ ions directly from chlorophyll by tetracycline which binds Mg²⁺ ions from the chlorophyll. We demonstrated that magnesium occurring in low concentrations attached to a tetracycline molecule in the BCD ring, and that the second ion of Mg2+ may attach to the A ring of tetracycline at higher Mg2+ concentrations. Two fluorescence bands appeared which indicated such magnesium attachments indeed occurred.

Evaluation of the photosynthetic parameters, emission of volatile organic compounds and ultrastructure of common green leafy vegetables after exposure to non-steroidal anti-inflammatory drugs (NSAIDs)

Understanding the effects of many essential non-steroidal anti-inflammatory drugs (NSAIDs) on plants is still limited, especially at environmentally realistic concentrations. This paper presents the influence of three of the most frequently used NSAIDs (diclofenac, ibuprofen, and naproxen) at environmentally realistic concentrations on the autochthonous green leafy vegetables: orache (Atriplex patula L.), spinach (Spinacia oleracea L.) and lettuce (Lactuca sativa L.). Our research was focused on the determination of the photosynthetic parameters, the emission rate of volatile organic compounds, and the evaluation of the ultrastructure of leaves of studied vegetables after exposure to abiotic stress induced by environmental pollutants, namely NSAIDs. The data obtained indicate a moderate reduction of foliage physiological activity as a response to the stress induced by NSAIDs to the selected green leafy vegetables. The increase of the 3-hexenal and monoterpene emission rates with increasing NSAIDs concentration could be used as a sensitive and a rapid indicator to assess the toxicity of the NSAIDs. Microscopic analysis showed that the green leafy vegetables were affected by the selected NSAIDs. In comparison to the controls, the green leafy vegetables treated with NSAIDs presented irregular growth of glandular trichomes on the surface of the adaxial side of the leaves, less stomata, cells with less cytoplasm, irregular cell walls and randomly distributed chloroplasts. Of the three NSAIDs investigated in this study, ibuprofen presented the highest influence. The results obtained in this study can be used to better estimate the impact of drugs on the environment and to improve awareness on the importance of the responsible use of drugs.

Individual and mixture toxicity evaluation of three pharmaceuticals to the germination and growth of Lactuca sativa seeds

This work aims to assess, individually and in mixtures, possible phytotoxic effects of three pharmaceuticals (paracetamol, ibuprofen and amoxicillin) on germination and early growth of Lactuca sativa seeds. Pharmaceuticals are an important group of emerging contaminants, whose presence has been described in several environmental compartments, including soils. However, knowledge on their possible impact in terrestrial organisms is still sparse and even more when mixtures are considered. Germination tests are important to evaluate the quality of soil and the toxic effects that contaminants can pose to plants. The acute effects of individual pharmaceuticals as well as binary and ternary mixtures were assessed using different endpoints, namely: percentage of seed germination, root elongation, shoot and leaf length, after an exposure time of five days. Overall, in the exposure of L. sativa seeds to individual pharmaceuticals there are indications of acute toxicity in the early plant growth. However, this inhibitory effect tends to be cancelled in the acute exposure to mixtures. This study shows the importance of evaluating the toxicity of mixtures of pharmaceuticals, since they might have distinct toxic effects when compared to the single compounds, and also because, probably, it is the closest scenario to the reality that can be found in the environment.

Human and veterinary antibiotics induce hormesis in plants: Scientific and regulatory issues and an environmental perspective

Veterinary and human pharmaceuticals have been widely used in the developed world, thus increasing their accumulation in the environment and thereby posing ecological risks. Earlier studies report that active pharmaceutical ingredients induce hormesis in plants, i.e. at low doses may enhance plant health whereas at high doses may suppress plant vigor. There is hitherto no study critically reviewing the effects of antibiotics on plants within a hormetic context despite effects of low doses on plants can have implications to animals, including humans, and to ecological processes. This study critically reviews for first time antibiotic-induced hormesis in plants, both quantitatively and qualitatively. Hormesis was induced by several antibiotics in a variety of species and endpoints. The maximum stimulatory response (MAX) was commonly <1.5-fold the control response and the distance from MAX to no-observed-adverse-effect level (NOAEL) was commonly up to 10-fold. Further quantitative and qualitative evaluations are provided and discussed in relation to scientific and regulatory aspects. Low doses of antibiotics are equally important as high doses as they can negatively affect plants, depending on plant tissues and the time tissues are subject to exposure. Antibiotic-induced hormesis in plants provides a significant environmental perspective and should be incorporated into the hazard and risk assessment process.

CAPSULE

Common antibiotics released in the environment induce hormesis in plants, urging for re-examination of the risk assessment practices by worldwide regulatory agencies.

Cephalosporin antibiotics in the aquatic environment: A critical review of occurrence, fate, ecotoxicity and removal technologies

Due to their widespread occurrence in the aquatic environment, human and veterinary cephalosporin antibiotics have been studied as water pollutants. In order to characterize environmental risks of this compound class, this review evaluates relevant data about physicochemical properties, occurrence, ecotoxicity and degradation of cephalosporins. Although application of cephalosporins is rather low compared to other antibiotics and their environmental life-time is believed to be short (i.e. days), the available data is insufficient to draw conclusions on their environmental relevance. Few studies concerning the fate of cephalosporins in soil are available, while hydrolysis and photo-degradation are suggested as the main attenuation processes in the aquatic environment. Cephalosporins have been detected in different aqueous matrices in concentrations ranging from 0.30 ng L^-1 to 0.03 mg L^-1, with sewage and wastewater being the main matrices with positive findings. For wastewater treatment purposes, several technologies have been tested for the abatement of cephalosporins, including photolysis and adsorption. In most cases, the technology employed led to complete or significant removal (>95%) of parental drugs but few authors reported on cephalosporins' metabolites and transformation products. Furthermore, the present ecotoxicological data are insufficient for comprehensive ecological risk quotient calculations. Considering the total of 53 cephalosporins, effective values (EC, LC, NOAEC, NOAEL, etc.) are only available for around 30% of parental drugs and are very scarce for cyanobacteria, which is considered to be the most sensitive group of organisms to antibiotics. Furthermore, it has been demonstrated that cephalosporins' transformation products can be more toxic and more persistent than the parental drugs. Few investigations considering this possibility are available. Consequently, more effort on ecotoxicological data generation and verification of biological inactivation of cephalosporins-related products is needed. Likewise, the lack of natural depletion rates and knowledge gaps on mixture effects for cephalosporins' degradation and toxicity have to be overcome.

Comparative study of binding interactions between porphyrin systems and aromatic compounds of biological importance by multiple spectroscopic techniques: A review

The specific spectroscopic and redox properties of porphyrins predestine them to fulfill the role of sensors during interacting with different biologically active substances. Monitoring of binding interactions in the systems porphyrin-biologically active compound is a key question not only in the field of physiological functions of living organisms, but also in environmental protection, notably in the light of the rapidly growing drug consumption and concurrently the production of drug effluents. Not always beneficial action of drugs on natural porphyrin systems induces to further studies, with commercially available porphyrins as the model systems. Therefore the binding process between several water-soluble porphyrins and a series of biologically active compounds (e.g. caffeine, guanine, theophylline, theobromine, xanthine, uric acid) has been studied in different aqueous solutions analyzing their absorption and steady-state fluorescence spectra, the porphyrin fluorescence lifetimes and their quantum yields. The magnitude of the binding and fluorescence quenching constants values for particular quenchers decreases in a series: uric acid > guanine > caffeine > theophylline > theobromine > xanthine. In all the systems studied there are characters of static quenching, as a consequence of the π-π-stacked non-covalent and non-fluorescent complexes formation between porphyrins and interacting compounds, accompanied simultaneously by the additional specific binding interactions. The porphyrin fluorescence quenching can be explain by the photoinduced intermolecular electron transfer from aromatic compound to the center of the porphyrin molecule, playing the role of the binding site. Presented results can be valuable for designing of new fluorescent porphyrin chemosensors or monitoring of drug traces in aqueous solutions. The obtained outcomes have also the toxicological and medical importance, providing insight into the interactions of the water-soluble porphyrins with biologically active substances.

Fluoroquinolones (FQs) in the environment: A review on their abundance, sorption and toxicity in soil

The use of fluoroquinolones (FQs) antibiotics as therapeutic agents and growth promoters is increasing worldwide; however their extensive uses are also resulting in antibiotic resistance among world communities. FQs have also become one of the major contaminants in the waste water bodies, which are not even completely removed during the treatment processes. Furthermore, their abundance in agricultural resources, such as the irrigation water, the bio-solids and the livestock manure can also affect the soil micro-environment. These antibiotics in soil tend to interact in several different ways to affect soil flora and fauna. The current review endeavors to highlight the some critical aspects of FQs prevalence in the environment. The review presents a detailed discussion on the pathways and abundance of FQs in soil. The discussion further spans the issue of sorption and FQs transformation into the soil better understand of their behavior and their toxicity to soil flora and fauna.

Disproportionate photosynthetic decline and inverse relationship between constitutive and induced volatile emissions upon feeding of Quercus robur leaves by large larvae of gypsy moth (Lymantria dispar)

Gypsy moth (Lymantria dispar L., Lymantriinae) is a major pest of pedunculate oak (Quercus robur) forests in Europe, but how its infections scale with foliage physiological characteristics, in particular with photosynthesis rates and emissions of volatile organic compounds has not been studied. Differently from the majority of insect herbivores, large larvae of L. dispar rapidly consume leaf area, and can also bite through tough tissues, including secondary and primary leaf veins. Given the rapid and devastating feeding responses, we hypothesized that infection of Q. robur leaves by L. dispar leads to disproportionate scaling of leaf photosynthesis and constitutive isoprene emissions with damaged leaf area, and to less prominent enhancements of induced volatile release. Leaves with 0% (control) to 50% of leaf area removed by larvae were studied. Across this range of infection severity, all physiological characteristics were quantitatively correlated with the degree of damage, but all these traits changed disproportionately with the degree of damage. The net assimilation rate was reduced by almost 10-fold and constitutive isoprene emissions by more than 7-fold, whereas the emissions of green leaf volatiles, monoterpenes, methyl salicylate and the homoterpene (3E)-4,8-dimethy-1,3,7-nonatriene scaled negatively and almost linearly with net assimilation rate through damage treatments. This study demonstrates that feeding by large insect herbivores disproportionately alters photosynthetic rate and constitutive isoprene emissions. Furthermore, the leaves have a surprisingly large capacity for enhancement of induced emissions even when foliage photosynthetic function is severely impaired.

Synergism between macrolide antibiotics and the azole fungicide ketoconazole in growth inhibition testing of the green alga Pseudokirchneriella subcapitata

Macrolide antibiotics and azole fungicides are detected widely in the aquatic environment as a result of their increased use in humans and animal livestock disease and their incomplete removal by wastewater treatment plants. In most cases, ecotoxicological tests are performed by using individual chemical substances, but because of the coexistence of a number of chemicals in the environment, organisms are exposed to many chemicals simultaneously. Therefore, it is important to evaluate effects of chemical interactions, adding to potential hazards of individual chemical. Here, we investigated the synergetic effects of combined chemicals (the azole fungicide ketoconazole and either of two macrolide antibiotics, erythromycin and clarithromycin) in growth inhibition testing using Pseudokirchneriella subcapitata according to OECD Test guideline 201. Combination index plots, isobolograms, and curve-shift analyses revealed that the combination of macrolide antibiotic and ketoconazole at various ratios resulted in strong synergism that enhanced growth inhibition of P. subcapitata, suggesting the necessity of investigating potential hazard of combined chemicals for regulatory purposes.

Impact of Veterinary Pharmaceuticals on the Agricultural Environment: A Re-inspection

The use of veterinary pharmaceuticals (VPs) is a result of growing animal production. Manure, a great crop fertilizer, contains a significant amount of VPs. The investigation of VPs in manure is prevalent, because of the potential risk for environmental organisms, as well as human health. A re-evaluation of the impact of veterinary pharmaceuticals on the agricultural environment is needed, even though several publications appear every year. The aim of this review was to collate the data from fields investigated for the presence of VPs as an inevitable component of manure. Data on VP concentrations in manure, soils, groundwater and plants were collected from the literature. All of this was connected with biotic and abiotic degradation, leaching and plant uptake. The data showed that the sorption of VPs into soil particles is a process which decreases the negative impact of VPs on the microbial community, the pollution of groundwater, and plant uptake. What was evident was that most of the data came from experiments conducted under conditions different from those in the environment, resulting in an overestimation of data (especially in the case of leaching). The general conclusion is that the application of manure on crop fields leads to a negligible risk for plants, bacteria, and finally humans, but in future every group of compounds needs to be investigated separately, because of the high divergence of properties.

Fading of wound-induced volatile release during Populus tremula leaf expansion

The release of stress-driven volatiles throughout leaf development has been little studied. Therefore, we subjected poplar leaves during their developmental stage (from 2 days to 2 weeks old) to wounding by a single punch hole, and measured online the wound-induced volatile organic compound emissions. Our study shows that the emission of certain volatile compounds fades with increasing leaf age. Among these compounds we found lipoxygenase products (LOX products), acetaldehyde, methyl benzoate, methyl salicylate, and mono- and sesquiterpenes. In parallel, we studied the fading of constitutive emissions of methanol during leaf maturation, as well as the rise in isoprene constitutive emission during leaf maturation and its relationship to leaf photosynthetic capacity. We found highly significant relationships between leaf chlorophyll content, photosynthetic capacity, and leaf size during leaf ageing. As the level of constitutive defences increases with increasing leaf age, the strength of the volatile signal is expected to be gradually reduced. The higher elicitation of volatile organic compound emissions (especially LOX products) in younger leaves could be an evolutionary defence against herbivory, given that younger leaves are usually more subjected to infestation and herbivory.

Induction of stress volatiles and changes in essential oil content and composition upon microwave exposure in the aromatic plant Ocimum basilicum

Exposure to sustained low intensity microwaves can constitute a stress for the plants, but its effects on plant secondary chemistry are poorly known. We studied the influence of GSM and WLAN-frequency microwaves on emissions of volatile organic compounds and content of essential oil in the aromatic plant Ocimum basilicum L. hypothesizing that microwave exposure leads to enhanced emissions of stress volatiles and overall greater investment in secondary compounds. Compared to the control plants, microwave irradiation led to decreased emissions of β-pinene, α-phellandrene, bornyl acetate, β-myrcene, α-caryophyllene and benzaldehyde, but increased emissions of eucalyptol, estragole, caryophyllene oxide, and α-bergamotene. The highest increase in emission, 21 times greater compared to control, was observed for caryophyllene oxide. The irradiation resulted in increases in the essential oil content, except for the content of phytol which decreased by 41% in the case of GSM-frequency, and 82% in the case of WLAN-frequency microwave irradiation. The strongest increase in response to WLAN irradiation, >17 times greater, was observed for hexadecane and octane contents. Comparisons of volatile compositions by multivariate analyses demonstrated a clear separation of different irradiance treatments, and according to the changes in the volatile emissions, the WLAN-frequency irradiation represented a more severe stress than the GSM-frequency irradiation. Overall, these results demonstrating important modifications in the emission rates, essential oil content and composition indicate that microwave irradiation influences the quality of herbage of this economically important spice plant.

Morpho-physiological response of Populus alba to erythromycin: A timeline of the health status of the plant

Populus alba Villafranca clone was chosen for a proof of concept study to determine the potential uptake and accumulation of antibiotics by trees. Plants were grown hydroponically and irrigated with a recirculating Hoagland's nutrient solution (control) and Hoagland's nutrient solution fortified with erythromycin at 0.01, 0.1 and 1mgL(-1). After 3 and 28days of treatment, poplar plants were separated into roots, stem, and leaves. Plants showed good health all over the period of treatment, and no differences in poplar growth for all the concentrations of erythromycin tested were observed. Quantification of erythromycin was performed using liquid chromatography electrospray ionization tandem mass spectrometry (LC-MS/MS) in positive ion mode using multiple reaction ion monitoring. Erythromycin was detected in all organs analyzed. Roots showed an erythromycin concentration tenfold higher than leaves. The photochemical efficiency of photosystem II did not show a dose-dependant trend. From the quenching analysis of chlorophyll fluorescence, low nonphotochemical quenching (NPQ) and high photochemical quenching (qP) for the first week of erythromycin exposure was observed, depending on leaves position along the stem. Results suggest a short term adaptation of the photosynthetic apparatus of Populus alba in response to environmental realistic erythromycin concentrations.

Results of extended plant tests using more realistic exposure scenarios for improving environmental risk assessment of veterinary pharmaceuticals

BACKGROUND

Residues of veterinary medicinal products (VMPs) enter the environment via application of manure onto agricultural areas where in particular antibiotics can cause phytotoxicity. Terrestrial plant tests according to OECD guideline 208 are part of the environmental risk assessment of VMPs. However, this standard approach might not be appropriate for VMPs which form non-extractable residues or transformation products in manure and manure-amended soil. Therefore, a new test design with a more realistic exposure scenario via manure application is needed. This paper presents an extended plant test and its experimental verification with the veterinary antibiotics florfenicol and tylosin tartrate. With each substance, plant tests with four different types of application were conducted: standard tests according to OECD 208 and three tests with application of test substance via spiked manure either without storage, aerobically incubated, or anaerobically incubated for different time periods.

RESULTS

In standard tests, the lowest NOEC was <0.06 mg/kg dry soil for florfenicol and 16.0 mg/kg dry soil for tylosin tartrate. Pre-tests showed that plant growth was not impaired at 22-g fresh manure/kg dry soil, which therefore was used for the final tests. The application of the test substances via freshly spiked as well as via aerobically incubated manure had no significant influence on the test results. Application of florfenicol via anaerobically incubated manure increased the EC10 by a factor up to 282 and 540 for half-maximum and for maximum incubation period, respectively. For tylosin tartrate, this factor amounted to 64 at half-maximum and 61 at maximum incubation period. The reduction of phytotoxicity was generally stronger when using cattle manure than pig manure and particularly in tests with cattle manure phytotoxicity decreased over the incubation period.

CONCLUSIONS

The verification of the extended plant test showed that seedling emergence and growth are comparable to a standard OECD 208 test and reliable effect concentrations could be established. As demonstrated in the present study, phytotoxicity of veterinary antibiotics can be significantly reduced by application via incubated manure compared to the standard plant test. Overall, the presented test design proved suitable for inclusion into the plant test strategy for VMPs.

Toxic influence of key organic soil pollutants on the total flavonoid content in wheat leaves

Textile dyes and antibiotics are two main classes of environmental pollutants which could be found in soil and water. Those persistent pollutants can have a negative influence on plant growth and development and affect the level of secondary metabolites. In the present work we studied the effect of textile dyes and antibiotics on total leaf flavonoid contents in wheat (Triticum aestivum L.). Contaminant solutions were applied daily using concentrations of 0.5 mg L^-1 (lower) and 1.5 mg L^-1 (higher dose) for either one or two weeks. We observed that exposure to the higher concentration of textile dyes resulted in a reduction in flavonoid content while antibiotics enhanced flavonoid contents at lower doses of exposure, and reduced at higher doses of exposure. These results suggest that diffuse chronic pollution by artificial organic contaminants can importantly alter antioxidative capacity of plants.