A preliminary study on the phytoremediation of antibiotic contaminated sediment

Efficiency of phytoremediation and identification of biotransformation pathways of fluoroquinolones in the aquatic environment

Phytoremediation is a low-cost and sustainable green technology that uses plants to remove organic and inorganic pollutants from aquatic environments. The aim of this study was to investigate the phytoextraction, phytoaccumulation, and phytotransformation of three fluoroquinolones (FQs) (ciprofloxacin [CIP], enrofloxacin [ENF], and levofloxacin [LVF]) by Japanese radish (Raphanus sativus var. longipinnatus) and duckweed (Lemma minor). Determination of FQs and identification of their transformation products (TPs) were performed using ultra-high-performance liquid chromatography coupled with tandem mass spectrometry (UHPLC-MS/MS). Inter-tissue translocation of FQs in Japanese radish tissues depended on their initial concentration in the medium. CIP (IT = 14.4) and ENF (IT = 17.0) accumulated mainly in radish roots, while LVF in leaves (IT = 230.8) at an initial concentration of 10 µg g-1. CIP (2,104 ng g-1) was detected in the highest concentration, followed by ENF (426.3 ng g-1) and LVF (273.3 ng g-1) in the tissues of both plants. FQs' bioaccumulation factors were significantly higher for duckweed (1.490-18.240) than Japanese radish (0.027-0.103). The removal of FQs from water using duckweed was mainly due to their photolysis and hydrolysis than plant sorption. In the screening, analysis detected 29 FQ TPs. The biotransformation pathways of FQs are described in detail, and the factors that influence their formation are indicated.

Occurrence, distribution, and risk assessment of antibiotics in a typical aquaculture area around the Dongzhai Harbor mangrove forest on Hainan Island

The trees of the Dongzhai Harbor mangrove forest suffer from antibiotic contamination from surrounding aquaculture areas. Despite this being one of the largest mangrove forests in China, few studies have focused on the antibiotic pollution status in these aquaculture areas. In the present study, the occurrence, distribution, and risk assessment of 37 antibiotics in surface water and sediment samples from aquaculture areas around Dongzhai Harbor mangrove forests were analyzed. The concentration of total antibiotics (∑antibiotics) ranged from 78.4 ng/L to 225.6 ng/L in surface water (except S14-A2) and from 19.5 ng/g dry weight (dw) to 229 ng/g dw in sediment. In the sediment, the concentrations of ∑antibiotics were relatively low (19.5-52.3 ng/g dw) at 75 % of the sampling sites, while they were high (95.7-229.0 ng/g dw) at a few sampling sites (S13-A1, S13D, S8D). The correlation analysis results showed that the Kd values of the 9 antibiotics were significantly positively correlated with molecular weight (MW), Kow, and LogKow. Risk assessment revealed that sulfamethoxazole (SMX) in surface water and SMX, enoxacin (ENX), ciprofloxacin (CFX), enrofloxacin (EFX), ofloxacin (OFX), and norfloxacin (NFX) in sediment had medium/high risk quotients (RQs) at 62.5 % and 25-100 %, respectively, of the sampling sites. The antibiotic mixture in surface water (0.06-3.36) and sediment (0.43-309) posed a high risk at 37.5 % and 66.7 %, respectively, of the sampling sites. SMX was selected as an indicator of antibiotic pollution in surface water to assist regulatory authorities in monitoring and managing antibiotic pollution in the aquaculture zone of Dongzhai Harbor. Overall, the results of the present study provide a comprehensive and detailed analysis of the characteristics of antibiotics in the aquaculture environment around the Dongzhai Harbor mangrove system and provide a theoretical basis for the source control of antibiotics in mangrove systems.

A novel enrofloxacin-degrading fungus, Humicola sp. KC0924g, isolated from the rhizosphere sediment of the submerged macrophyte Vallisneria spiralis L

A novel enrofloxacin-degrading fungus was isolated from a rhizosphere sediment of the submerged macrophyte Vallisneria spiralis L.. The isolate, designated KC0924g, was identified as a member of the genus Humicola based on morphological characteristics and tandem conserved sequence analysis. The optimal temperature and pH for enrofloxacin degradation by strain KC0924g were 28 °C and 9.0, respectively. Under such condition, 98.2% of enrofloxacin with an initial concentration of 1 mg L-1 was degraded after 72 h of incubation, with nine possible degradation products identified. Four different metabolic pathways were proposed, which were initiated by cleavage of the piperazine moiety, hydroxylation of the aromatic ring, oxidative decarboxylation, or defluorination. In addition to enrofloxacin, strain KC0924g also degraded other fluoroquinolone antibiotics (ciprofloxacin, norfloxacin, and ofloxacin), malachite green (an illegal additive in aquaculture), and leucomalachite green. Pretreatment of cells of strain KC0924g with Cu2+ accelerated ENR degradation. Furthermore, it was speculated that a flavin-dependent monooxygenase was involved in ENR degradation, based on the increased transcriptional levels of these two genes after Cu2+ induction. This work enriches strain resources for enrofloxacin remediation and, more importantly, would facilitate studies on the molecular mechanism of ENR degradation with degradation-related transcriptome available.

Pharmaceutical-contaminated irrigation water: implications for ornamental plant production and phytoremediation using enrofloxacin-accumulating species

Enrofloxacin (Enro) has been widely encountered in natural water sources, and that water is often used for irrigation in crop production systems. Due to its phytotoxicity and accumulation in plant tissues, the presence of Enro in water used for crop irrigation may represent economical and toxicological concerns. Here, we irrigated two ornamental plant species (Zantedeschia rehmannii Engl. and Spathiphyllum wallisii Regel.) with water artificially contaminated with the antimicrobial enrofloxacin (Enro; 0, 5, 10, 100, and 1000 μg L-1) to evaluate its effects on ornamental plant production, as well as its accumulation and distribution among different plant organs (roots, leaves, bulbs, and flower stems), and examined the economic and environmental safety of commercializing plants produced under conditions of pharmaceutical contamination. The presence of Enro in irrigation water was not found to disrupt plant growth (biomass) or flower production. Both species accumulated Enro, with its internal concentrations distributed as the following: roots > leaves > bulbs > flower stems. In addition to plant tolerance, the content of Enro in plant organs indicated that both Z. rehmannii and S. wallisii could be safety produced under Enro-contaminated conditions and would not significantly contribute to contaminant transfer. The high capacity of those plants to accumulate Enro in their tissues, associated with their tolerance to it, indicates them for use in Enro-phytoremediation programs.

Field measures of strengthen plant-microbial remediation of PAHs-FQs compound pollution

In this study, five PAHs (benzo [b] fluoranthene (BbF), phenanthrene (Phe), fluoranthene (Flu), fluorene (Fl), benzo [A] pyrene (Bap)), and five FQs (ofloxacin (OFL), enrofloxacin (ENR), ciprofloxacin (CIP), norfloxacin (NOR), lomefloxacin (LOM)) were selected as ligands; peroxidase (1NML) was selected as receptor degrading protein. In the plant-microbial degradation, the factors with significant inhibitory effects are NOR, Bap, CIP, ENR, OFL, Flu, LOM, Phe, Fl, and BbF by the fractional factorial design experiment and molecular docking-assisted molecular dynamics methods. Using Taguchi experiment and molecular dynamics simulation methods, the main external field measures were designed and screened to effectively promote the degradation of PAHs-FQs under the combined pollution scenarios of Bap-CIP and BbF-NOR, respectively. The peroxidase mutation design plans with enhanced substrate affinity were then designed and screened using the DS software by predicting the virtual key amino acid of peroxidase. The novel biodegradable enzymes 2YCD-1, 2YCD-4, 2YCD-5, 2YCD-7, and 2YCD-9 had better structures and showed excellent degradability for PAHs and FQs. This study explored the degradation rules of the composite pollutants in the coexistence systems of multiple PAHs and FQs, providing the best external field measures for the control and treatment of the combined pollution effects of different PAHs and FQs. Overall, the current study has important practical significance for promoting the plant-microbial joint remediation of PAHs-FQs pollution and for reducing the combined pollution of PAHs and FQs in farmland systems.

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.

Characterizing bacterial communities in Phragmites australis rhizosphere and non-rhizosphere sediments under pressure of antibiotics in a shallow lake

Introduction

Antibiotics are ubiquitous pollutants and widely found in aquatic ecosystems, which of rhizosphere sediment and rhizosphere bacterial communities had certain correlation. However, the response of bacterial communities in Phragmites australis rhizosphere and non-rhizosphere sediments to antibiotics stress is still poorly understood.

Methods

To address this knowledge gap, the samples of rhizosphere (R) and non-rhizosphere (NR) sediments of P. australis were collected to investigate the differences of bacterial communities under the influence of antibiotics and key bacterial species and dominate environmental factors in Baiyangdian (BYD) Lake.

Results

The results showed that the contents of norfloxacin (NOR), ciprofloxacin (CIP) and total antibiotics in rhizosphere sediments were significantly higher than that in non-rhizosphere sediments, meanwhile, bacterial communities in non-rhizosphere sediments had significantly higher diversity (Sobs, Shannon, Simpsoneven and PD) than those in rhizosphere sediments. Furthermore, total antibiotics and CIP were found to be the most important factors in bacterial diversity. The majority of the phyla in rhizosphere sediments were Firmicutes, Proteobacteria and Campilobacterota, while Proteobacteria, Chloroflexi was the most abundant phyla followed by Bacteroidota, Actinobacteriota in non-rhizosphere sediments. The dominate factors of shaping the bacterial communities in rhizosphere were total antibiotics, pH, sediment organic matter (SOM), and NH₄-N, while dissolved organic carbon (DOC), NO₃-N, pH, and water contents (WC) in non-rhizosphere sediments.

Discussion

It is suggested that antibiotics may have a substantial effect on bacterial communities in P. australis rhizosphere sediment, which showed potential risk for ARGs selection pressure and dissemination in shallow lake ecosystems.

Current Progress in Natural Degradation and Enhanced Removal Techniques of Antibiotics in the Environment: A Review

Antibiotics are used extensively throughout the world and their presence in the environment has caused serious pollution. This review summarizes natural methods and enhanced technologies that have been developed for antibiotic degradation. In the natural environment, antibiotics can be degraded by photolysis, hydrolysis, and biodegradation, but the rate and extent of degradation are limited. Recently, developed enhanced techniques utilize biological, chemical, or physicochemical principles for antibiotic removal. These techniques include traditional biological methods, adsorption methods, membrane treatment, advanced oxidation processes (AOPs), constructed wetlands (CWs), microalgae treatment, and microbial electrochemical systems (such as microbial fuel cells, MFCs). These techniques have both advantages and disadvantages and, to overcome disadvantages associated with individual techniques, hybrid techniques have been developed and have shown significant potential for antibiotic removal. Hybrids include combinations of the electrochemical method with AOPs, CWs with MFCs, microalgal treatment with activated sludge, and AOPs with MFCs. Considering the complexity of antibiotic pollution and the characteristics of currently used removal technologies, it is apparent that hybrid methods are better choices for dealing with antibiotic contaminants.

Phytoremediation as an effective tool to handle emerging contaminants

Phytoremediation is a process which effectively uses plants as a tool to remove, detoxify or immobilize contaminants. It has been an eco-friendly and cost-effective technique to clean contaminated environments. The contaminants from various sources have caused an irreversible damage to all the biotic factors in the biosphere. Bioremediation has become an indispensable strategy in reclaiming or rehabilitating the environment that was damaged by the contaminants. The process of bioremediation has been extensively used for the past few decades to neutralize toxic contaminants, but the results have not been satisfactory due to the lack of cost-effectiveness, production of byproducts that are toxic and requirement of large landscape. Phytoremediation helps in treating chemical pollutants on two broad categories namely, emerging organic pollutants (EOPs) and emerging inorganic pollutants (EIOPs) under in situ conditions. The EOPs are produced from pharmaceutical, chemical and synthetic polymer industries, which have potential to pollute water and soil environments. Similarly, EIOPs are generated during mining operations, transportations and industries involved in urban development. Among the EIOPs, it has been noticed that there is pollution due to heavy metals, radioactive waste production and electronic waste in urban centers. Moreover, in recent times phytoremediation has been recognized as a feasible method to treat biological contaminants. Since remediation of soil and water is very important to preserve natural habitats and ecosystems, it is necessary to devise new strategies in using plants as a tool for remediation. In this review, we focus on recent advancements in phytoremediation strategies that could be utilized to mitigate the adverse effects of emerging contaminants without affecting the environment.

Phytoremediation of antibiotic-contaminated wastewater: Insight into the comparison of ciprofloxacin absorption, migration, and transformation process at different growth stages of E. crassipes

The selection of aquatic plants at different growth stages and their absorption, migration, and transformation mechanisms has yet to be clarified. In this study, Eichhornia crassipes at the seedling and mature stages were selected to uptake antibiotics under hydroponic conditions. The results showed that the enrichment of ciprofloxacin (CIP) in roots at the seedling and mature stages were 7.72～2114.39 μg g^-1 and 0.07～3711.33 μg g^-1, respectively. The enrichment of CIP in aerial parts at the seedling and mature stages were 16.38～24.24 μg g^-1 and 9.55～20.13 μg g^-1, respectively. The translocation from roots to aerial parts at the seedling stage was high, as evidenced by the relatively higher transfer factor (TF). In addition, eight and ten major metabolic products were observed in the tissues of seeding and mature stage of E. crassipes, respectively. The metabolic pathway of CIP was short at the maturity stage, and CIP had a strong upward migration ability at the seedling stage, facilitating long-time photodegradation. However, E. crassipes exhibited a poor CIP tolerance at the mature stage and decayed relatively early. Therefore, the seedling stage of E. crassipes was proposed to be applied for phytoremediation, and these findings might improve the ability to phytoremediation of antibiotic-contaminated water.

The fate of sulfonamides in the process of phytoremediation in hydroponics

Phytoremediation has been proven to be an alternative in-situ treatment technique for sulfonamide polluted wastewater. However, the fate of sulfonamides in the phytoremediation process of multiple sulfonamides coexistence is unclear. Therefore, the possibility and mechanism of phytoremediation of ten sulfonamides by different wetland plants through hydroponics were investigated in this study. The phytoremediation rates of Σsulfonamides by different wetland plants were from 44.5% to 56.9%. Mass balance analysis showed that rhizosphere biodegradation (90.2% - 92.2%) dominated the phytoremediation of Σsulfonamides, while hydrolysis (7.63% - 8.95%) and plant uptake (0.05% - 0.17%) accounted for a small proportion. It is worth mentioning that the dissipation of the target sulfonamides in the hydroponic system followed the first-order reaction kinetic model, with half-lives of 13.3 d to 53.3 d, which are close to or even lower than that of aerobic biodegradation in river water, sediment, and piggery wastewater. Six of the ten spiked sulfonamides were detected in plant samples demonstrated that the selective uptake of plants under the coexistence of multiple sulfonamides. The distribution of sulfonamides (concentrations and uptake amounts) in plant tissues followed the sequence of root > stem > leaf in this study, but the distribution in stems and leaves needs further study. The uptake and rhizosphere biodegradation of Cyperus papyrus to sulfonamides are optimally resulting that its phytoremediation rate is significantly higher than other plants (p < 0.05), which indicates that plant species is one of the key factors affecting the phytoremediation efficiency of sulfonamides. These findings verify the feasibility of phytoremediation of sulfonamides, and provide new insights into the fate of sulfonamides in the process of phytoremediation.

Recent advancement in remediation of synthetic organic antibiotics from environmental matrices: Challenges and perspective

Continuous discharge and persistence of antibiotics in aquatic ecosystem is identified as emerging environment health hazard. Partial degradation and inappropriate disposal induce appearance of diverse antibiotic resistant genes (ARGs) and bacteria, hence their execution is imperative. Conventional methods including waste water treatment plants (WWTPs) are found ineffective for the removal of recalcitrant antibiotics. Therefore, constructive removal of antibiotics from environmental matrices and other alternatives have been discussed. This review summarizes present scenario and removal of micro-pollutants, antibiotics from environment. Various strategies including physicochemical, bioremediation, use of bioreactor, and biocatalysts are recognized as potent antibiotic removal strategies. Microbial Fuel Cells (MFCs) and biochar have emerged as promising biodegradation processes due to low cost, energy efficient and environmental benignity. With higher removal rate (20-50%) combined/ hybrid processes seems to be more efficient for permanent and sustainable elimination of reluctant antibiotics.

Trace analysis of 28 antibiotics in plant tissues (root, stem, leaf and seed) by optimized QuEChERS pretreatment with UHPLC-MS/MS detection

Phytoremediation has proven to be an effective in-situ treatment technique for antibiotic contamination. Due to the immature methods of extracting multi-antibiotics in different plant tissues, the antibiotic absorption and transportation mechanism in the phytoremediation process has yet to be resolved. Therefore, an improved Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) pretreatment with ultra-high-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) detection method for 28 antibiotics in different plant tissues (root, stem, leaf and seed) was developed in this study. The optimized method showed satisfactory performance with recoveries for most antibiotics ranging from 70% to 130% (except sulfadoxine with 138 ± 8.84% in root, sulfameter with 68.9 ± 1.87% and sulfadoxine with 141 ± 10.0% in seed). The limits of detection (LODs) of the target compounds in root, stem, leaf and seed were 0.04 ± 0.02 ~ 2.50 ± 1.14 ng/g, 0.05 ± 0.02 ~ 1.78 ± 0.42 ng/g, 0.06 ± 0.01 ~ 2.50 ± 0.14 ng/g and 0.13 ± 0.10 ~ 3.64 ± 0.74 ng/g, respectively. This developed method was successfully applied to the determination of antibiotics in different tissues of hydroponic wetland plants exposed to antibiotics-spiked water for one-month. Sixteen of 28 spiked antibiotics were detected in plant tissue samples. Overall, of these 16 antibiotics, all were detected in root samples (from < LOQ to 1478 ± 353 ng/g), eleven in stem samples (from < LOQ to 425 ± 47.0 ng/g), and nine in leaf samples (from < LOQ to 429 ± 84.5 ng/g). This developed analytical method provided a robust tool for the simultaneous screening and determination of antibiotics in different plant tissues.

Pseudo wastewater treatment by combining adsorption and phytoaccumulation on the Acrostichum aureum Linn. plant/activated carbon system

In this study, the pseudo wastewater containing Zn, Fe, Cu ions was clean-up by a combination of physical adsorption onto activated carbon medium and phytoaccumulation using Acrostichum aureum Linn. plants. The adsorption capability of the activated carbon for the Fe, Cu, and Zn ions was 3.05, 3.72, and 2.85 mg·g - 1, respectively, at the saturation. The phytoaccumulation performance was proved by analyzing the individual residual ash collected after pyrolysis up to 1000 °C of the leaf, stem, and root of the plants. Thermal analyses of thermogravimetry data showed that the weight of the residual ash of the phytoremediated leaf, stem, and root of the plants was 37.0, 19.0, and 65.7 wt.%, respectively. Energy-dispersive X - ray spectroscopy determined the amount of Fe element in the residual ash of phytoremediated root is 7.05 wt.%, while that of the initial root is 1.18 wt.%. Conclusively, it can be proved that combining physical and biological processes is feasible to treat wastewater containing metal ions.

Phytoremediation—From Environment Cleaning to Energy Generation—Current Status and Future Perspectives

Phytoremediation is a technology based on the use of green plants to remove, relocate, deactivate, or destroy harmful environmental pollutants such as heavy metals, radionuclides, hydrocarbons, and pharmaceuticals. Under the general term of phytoremediation, several processes with distinctively different mechanisms of action are hidden. In this paper, the most popular modes of phytoremediation are described and discussed. A broad but concise review of available literature research with respect to the dominant process mechanism is provided. Moreover, methods of plant biomass utilization after harvesting, with particular regard to possibilities of “bio-ore” processing for metal recovery, or using energy crops as a valuable source for bio-energy production (bio-gas, bio-ethanol, bio-oil) are analyzed. Additionally, obstacles hindering the commercialization of phytoremediation are presented and discussed together with an indication of future research trends.

Migration of antibiotic ciprofloxacin during phytoremediation of contaminated water and identification of transformation products

Phytoremediation is an effective and environmentally friendly approach to treat antibiotic contaminated water, however, the mechanisms of migration and transformation of antibiotics in plant tissues are still far from clear. In this study, the floating macrophyte Eichhornia crassipes was exposed to a series of antibiotic ciprofloxacin (CIP) concentrations. The results showed that the CIP was taken up and accumulated in the roots, which were the major accumulative tissue. CIP content increased with lipid content. During cultivation, the root bioconcentration factor (RCF) gradually increased. The average CIP content detected in aerial parts was 12.80 μg g^-1, an order of magnitude lower than in the roots. At low CIP concentrations, the highest leaf bioconcentration factor (LCF) and transfer factor (TF) indicated highly efficient translocation from roots to aerial parts. The soluble protein growth rate of leaves, which is associated with metabolic activity, increased following CIP exposure. Overall, eight major transformation products in E. crassipes tissues were identified, and three possible transformation pathways were proposed involving the processes of desethylation, dehydroxylation, oxidation, hydroxylation and cleavage of the piperazine and quinoline rings. These findings could prove beneficial for improving the management or amelioration methods used for treating water contaminated with antibiotics.

Removal of antibiotics and nutrients by Vetiver grass (Chrysopogon zizanioides) from secondary wastewater effluent

Persistence of antibiotics in soil and aquatic ecosystem is the primary reason for the emergence of antimicrobial resistant microorganisms. After consumption, antibiotics are poorly retained in our body, and a major fraction is excreted out. These bioactive compounds end up in wastewater. The routine treatment practiced by the conventional wastewater treatment plants does not remove the entire load of antibiotics. Cost-effective and environment-friendly treatment technologies need to be developed to address this issue. Vetiver system is being adapted throughout the world due to its removal capacity and high tolerance toward several toxic organic and inorganic pollutants. In this study, we investigated the potential of vetiver (Chrysopogon zizanioides), a fast-growing, perennial grass capable of growing in a hydroponic setup, to remove two widely prescribed antibiotics, ciprofloxacin (CIP) and tetracycline (TTC) from secondary wastewater effluent. Significant (p < 0.05) removal of antibiotics and nutrients (N & P) by vetiver grass from secondary wastewater effluent was observed within 30 days. Vetiver grass removed more than 90% antibiotics from secondary wastewater matrix. In addition to antibiotics, vetiver grass also removed nitrate (>40%), phosphate (>60%), total organic carbon (>50%), and chemical oxygen demand (>40%) from secondary wastewater effluent.

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.

Ciprofloxacin induces oxidative stress in duckweed (Lemna minor L.): Implications for energy metabolism and antibiotic-uptake ability

We investigate the physiological responses and antibiotic-uptake capacity of Lemna minor exposed to ciprofloxacin. Ciprofloxacin (Cipro) induced toxic effects and hormesis in plants by significantly modifying photosynthesis and respiration pathways. A toxic effect was induced by a concentration ≥1.05mg ciprofloxacin l^-1 while hormesis occurs at the lowest concentration studied (0.75mg ciprofloxacin l^-1). By impairing normal electron flow in the respiratory electron transport chain, ciprofloxacin induces hydrogen peroxide (H₂O₂) production. The ability of plants to cope with H₂O₂ accumulation using antioxidant systems resulted in stimulation/deleterious effects to photosynthesis by Cipro. Cipro-induced oxidative stress was also associated with the ability of L. minor plants to uptake the antibiotic and, therefore, with plant-uptake capacity. Our results indicate that instead of being a photosystem II binding molecule, Cipro induces oxidative stress by targeting the mitochondrial ETC, which would explain the observed effects of the antibiotic on non-target eukaryotic organisms. The selection of plants species with a high capacity to tolerate oxidative stress may constitute a strategy to be used in Cipro-remediation programs.

Tracking aquaculture-derived fluoroquinolones in a mangrove wetland, South China

Aquaculture in mangrove wetlands has been developed rapidly, causing various environmental problems (e.g., antibiotic residue). In the present study, the levels and distributions of a well-known class of antibiotics (fluoroquinolones; FQs), including norfloxacin (NOR), ciprofloxacin (CIP), and enrofloxacin (ENR), were examined in sediment and mangrove plant (Aegiceras corniculatum) from a mangrove wetland in the Zhanjiang Mangrove National Nature Reserve, South China. NOR and CIP were detected in all sediment samples, with concentrations ranging from 4.3 to 64.2 ng/g and from 7.62 to 68.5 ng/g on a basis of dry weight (dw), respectively, whereas ENR was found with relatively lower frequency (<78%) and lower concentrations (<19.3 ng/g). Sediments in mangrove rhizosphere area contained considerably higher concentrations of all FQs (except for ENR). FQs were largely varied in mangrove plant tissues; NOR and ENR were not detected in leaf and root samples, respectively. CIP featured an increasing tendency from the root to the upper parts of plants, whereas a decreasing trend was found for NOR. Three bioconcentration factors (BCF_s) of FQs, including BCFs for roots (BCF_r), branches (BCF_b), and leaves (BCF_l) were calculated, and most of them exceeded 1. Especially for NOR, its BCF_r can reach up to 9.9, indicating that Aegiceras corniculatum has a strong ability to accumulate FQs from sediment and/or surrounding environment. For NOR and CIP, strong positive relationships were observed between BCF_r and concentrations in root, but no significant correlations were observed between BCF_r and root lipid of mangrove plant. More studies are needed to investigate the uptake mechanism of antibiotics in mangrove plants.

Phytoremediation of aspirin and tetracycline by Brassica juncea

With the increasing release of pharmaceutical drugs in the environment, research is in progress for investigating alternative methods for their remediation. Various studies have shown the phytoremediation potential of Brassica juncea for metals. The current study was aimed at evaluating the phytoremediation potential of B. juncea for two different pharmaceutical drugs i.e. aspirin and tetracycline in in-vitro conditions. The seeds of B. juncea were germinated and grown for a period of 28 and 24 days for aspirin and tetracycline, respectively. The study analyzed the remediation rate of B. juncea for the selected drugs in three different sets of varying concentration along with any phytotoxic effects exerted by the drugs on the seeds. Preliminary results showed that the average remediation rate of aspirin and tetracycline at the end of experiment was approximately 90% and 71%, respectively. As initial drug concentrations were increased in the media, the remediation rate also improved. However, at higher concentrations, the plants showed phytotoxicity as depicted by the decrease in shoot length of the germinated seeds. These preliminary results indicated that B. juncea could tolerate and remediate pharmaceutical drugs such as analgesics and antibiotics.

Veterinary antibiotics in animal waste, its distribution in soil and uptake by plants: A review

Therapeutic and sub-therapeutic use of antibiotics in livestock farming is and has been, a common practice worldwide. These bioactive organic compounds have short retention period and partial uptake into the animal system. The uptake effects of this pharmaceutics, with plants as the primary focus, has not been reviewed so far. This review addresses three main concerns 1) the extensive use of veterinary antibiotics in livestock farming, 2) disposal of animal waste containing active biosolids and 3) effects of veterinary antibiotics in plants. Depending upon the plant species and the antibiotic used, the response can be phytotoxic, hormetic as well as mutational. Additionally, the physiological interactions that make the uptake of these compounds relatively easy have also been discussed. High water solubility, longer half-lives, and continued introduction make them relatively persistent in the environment. Lastly, some prevention measures that can help limit their impact on the environment have been reviewed. There are three methods of control: treatment of animal manure before field application, an alternative bio-agent for disease treatment and a well targeted legalized use of antibiotics. Limiting the movement of these biosolids in the environment can be a challenge because of their varying physiological interactions. Electron irradiation and supervised inoculation of beneficial microorganisms can be effective remediation strategies. Thus, extensive future research should be focused in this area.

Interspecific differences in growth response and tolerance to the antibiotic sulfadiazine in ten clonal wetland plants in South China

Pollution caused by residual antibiotics is a worldwide environmental issue. Antibiotic residues often occur in aquatic ecosystems, posing threats to the health of aquatic organisms. The effects of antibiotic residues on the growth of crop plants and on human health are reasonably well known. However, less is known about antibiotic effects on wetland plants. Therefore, we studied the response and tolerance of ten clonal wetland plants grown in soil spiked with sulfadiazine at 10 mg kg(-1) (an environmentally relevant concentration) and 100 mg kg(-1). At 10 mg kg(-1), ramet number was the least affected trait, while root number was the most affected among plant species. Plant shoot and total biomass were reduced in all species except in Cyperus malaccensis var. brevifolius and Panicum repens. Chlorophyll content was reduced in Alocasia macrorrhiza, Saururus chinensis, and Commelina diffusa. In general, Panicum paludosum and C. malaccensis var. brevifolius showed the least reduction of growth parameters, whereas growth of both A. macrorrhiza and S. chinensis was severely reduced. At 100 mg kg(-1), negative responses occurred in all species. Comprehensive tolerance analysis revealed that P. paludosum and C. malaccensis var. brevifolius were the species most resistant to sulfadiazine. These species are potential candidates for sulfadiazine polluted wetland restoration. A. macrorrhiza and S. chinensis were the most susceptible species and they should be protected from sulfadiazine pollution. Relative plant shoot biomass and height were the most useful indicators for evaluating plant tolerance to sulfadiazine. Plant tolerance to sulfadiazine was associated with the differences of plants in height and shoot biomass.

Antibiotics in typical marine aquaculture farms surrounding Hailing Island, South China: occurrence, bioaccumulation and human dietary exposure

The occurrence, bioaccumulation, and human dietary exposure via seafood consumption of 37 antibiotics in six typical marine aquaculture farms surrounding Hailing Island, South China were investigated in this study. Sulfamethoxazole, salinomycin and trimethoprim were widely detected in the water samples (0.4-36.9 ng/L), while oxytetracycline was the predominant antibiotic in the water samples of shrimp larvae pond. Enrofloxacin was widely detected in the feed samples (16.6-31.8 ng/g) and erythromycin-H2O was the most frequently detected antibiotic in the sediment samples (0.8-4.8 ng/g). Erythromycin-H2O was the dominant antibiotic in the adult Fenneropenaeus penicillatus with concentrations ranging from 2498 to 15,090 ng/g. In addition, trimethoprim was found to be bioaccumulative in young Lutjanus russelli with a median bioaccumulation factor of 6488 L/kg. Based on daily intake estimation, the erythromycin-H2O in adult F. penicillatus presented a potential risk to human safety.

A review of plant-pharmaceutical interactions: from uptake and effects in crop plants to phytoremediation in constructed wetlands

Pharmaceuticals are commonly found both in the aquatic and the agricultural environments as a consequence of the human activities and associated discharge of wastewater effluents to the environment. The utilization of treated effluent for crop irrigation, along with land application of manure and biosolids, accelerates the introduction of these compounds into arable lands and crops. Despite the low concentrations of pharmaceuticals usually found, the continuous introduction into the environment from different pathways makes them 'pseudo-persistent'. Several reviews have been published regarding the potential impact of veterinary and human pharmaceuticals on arable land. However, plant uptake as well as phytotoxicity data are scarcely studied. Simultaneously, phytoremediation as a tool for pharmaceutical removal from soils, sediments and water is starting to be researched, with promising results. This review gives an in-depth overview of the phytotoxicity of pharmaceuticals, their uptake and their removal by plants. The aim of the current work was to map the present knowledge concerning pharmaceutical interactions with plants in terms of uptake and the use of plant-based systems for phytoremediation purposes.

Phytoremediation of levonorgestrel in aquatic environment by hydrophytes

Adsorption and degradation of levonorgestrel (LNG) by two hydrophytes, Cyperus alternifolius (CA) and Eichhornia crassipes (EC), were investigated under light-shielding conditions in the water column. Variations of LNG concentrations in water, plant root epidermis, root, stem and leaf of the plants were analyzed. The results indicated that the removal efficiency of LNG by hydrophytes over the period of 50days was significantly greater than the blank control (p<0.05), with the removal rates of 79.80%±3.10% and 78.86%±2.55% for CA and EC, respectively. Compared with bio-adsorption, bio-conversion of LNG was found to be the dominant elimination pathway, evidenced by relatively high conversion rates (77.31%±2.68% for CA and 77.82%±2.95% for EC), while the adsorption rates were lower (1.77%±0.90% for CA and 1.05%±0.40% for EC). The bio-adsorption and conversion of LNG showed no significant differences between the two hydrophytes. Additionally, the mineralization on root epidermis played an important role in the reduction of LNG in water.

Accumulation and response of willow plants exposed to environmental relevant sulfonamide concentrations

As a result of manure application to arable lands, agricultural ecosystems are often contaminated by veterinary antibiotics. In this study the aptitude of Salix fragilis L. to accumulate and tolerate sulfadimethoxine (SDM) was evaluated, together with the antibiotic effects on the plant development, with particular attention focused on roots. Results showed an antibiotic presence in root tissues, but not in leaves, after one month of SDM exposure to 0.01, 0.1, 1 and 10 mg l(-1). A hormetic growth of the hypogeal system was observed, however stress symptoms on the root development were only noticed after treatment to the highest dose. Results obtained from a second test, where new cuttings were exposed to 10 mg SDM l(-1) for different periods, suggested that willow tolerance to SDM increased with the exposure duration, probably because of the onset of particular acclimation mechanisms. Therefore, the present work indicates that this woody species could be utilized in the phytoremediation of sulfonamide antibiotics at doses comparable to that found in agricultural ecosystems once obtained appropriate confirmations through future studies at a laboratory and field scale.

Uptake of zwitterionic antibiotics by rice (Oryza sativa L.) in contaminated soil

Antibiotics, including members of the tetracycline and fluoroquinolone families, are emerging organic environmental contaminants. Uptake from soil by plants is a means for antibiotics to enter terrestrial food chains. Chemical exchange between plant and the soil/water matrix occurs simultaneously with degradation in the soil/water matrix. In this study, the comparative temporal behaviour of rice (Oryza sativa L.) towards the zwitterionic antibiotics oxytetracycline, chlortetracycline and norfloxacin at initial soil/water concentrations of 10, 20 and 30 μg g(-1) (dry weight) is investigated. This is accomplished within the framework of an activity-based mass-conserving dynamic model. Plant antibiotic concentrations are observed to increase to a maximum then decline. Maximum concentrations in rice are compound-dependent linear functions of initial soil/water concentrations, but the relationships are not related to the compound octan-1-ol/water distribution ratio (DOW). The times required to attain maximal concentrations are independent of initial soil/water levels for a given antibiotic, but again vary between antibiotics and are not related to DOW values. Translocation from root to other tissues is not observed. The magnitudes of Root Concentration Factors (RCFs), the ratio of root and soil/water concentrations, are consistent with significant sorption to soil and consequent relatively low concentrations in interstitial water.

Biotransformation of benzimidazole anthelmintics in reed (Phragmites australis) as a potential tool for their detoxification in environment

Benzimidazole anthelmintics, the drugs against parasitic worms, are widely used in human as well as veterinary medicine. Following excretion, these substances may persist in the environment and impact non-target organisms. In order to test phytoremediation as a possible tool for detoxification of anthelmintics in environment, the biotransformation pathways of albendazole (ABZ) and flubendazole (FLU) were studied in reed (Phragmites australis) in vitro. Reed cells were able to uptake and biotransform both anthelmintics. Ten ABZ metabolites and five FLU metabolites were found. Some atypical biotransformation reactions (formation of glucosylglucosides, acetylglucosides and xylosylglucosides), which have not been described previously, were identified. Based on the obtained results, the schemes of metabolic pathways of ABZ and FLU in reed were proposed. Most of ABZ and FLU metabolites can be considered as anthelmintically less active; therefore uptake and biotransformation of these anthelmintics by reed could be useful for decrease of their toxicity in environment.