Glyphosate Pollution Treatment and Microbial Degradation Alternatives, a Review

In-situ formation of glyphosate and AMPA in activated sludge from phosphonates used as antiscalants and bleach stabilizers in households and industry

The herbicide glyphosate and aminomethyl phosphonic acid (AMPA), a transformation product of glyphosate and other aminopolyphosphonates are widespread pollutants in European rivers. We recently showed that besides rain-driven input after agricultural or urban herbicide application, municipal wastewater significantly contributes to glyphosate contamination in European rivers. The rather constant mass fluxes over the year, made an explanation by herbicide applications difficult. In our search for a new source of glyphosate and AMPA, we here provide experimental evidence that a certain aminopolyphosphonate, used as antiscalant and bleach stabilizer in household detergents and numerous industrial processes, is a precursor of both glyphosate and AMPA. During incubation experiments with diethylenetriamine penta(methylene phosphonic acid) (DTPMP) in fresh activated sludge, we observed the formation of glyphosate with yields ranging from 0.017 to 0.040 mol% and formation of AMPA in the range of 0.402 to 1.72 mol% after 72 h. Both compounds are formed from DTPMP and possible intermediates, but they are also further transformed themselves in consecutive reactions. Glyphosate formation from DTPMP was further proven by incubating 13C-labeled DTPMP, which transformed into 13C-glyphosate and 13C-AMPA. The addition of DTPMP to azide-treated activated sludge yielded similar or even higher glyphosate and AMPA concentrations indicating that abiotic processes dominate the transformation process. In order to judge the relevance of this in-situ formation of glyphosate and AMPA from the laundry additive DTPMP, we estimated the average concentrations in wastewater.

Degradation of Glyphosate to Benign N-Formyl Glycine Using MOF-808 Nanocrystals

Glyphosate (N-phosphonomethyl glycine, GPh) is an industrial herbicide used worldwide in modern agricultural practices. With the growing concerns regarding cumulative environmental and health effects, pathways for catalytic GPh degradation to benign products are becoming a pressing societal need. This report demonstrates that Zr-based metal-organic framework (MOF-808) with different crystal sizes and designed defect sites can be employed as an efficient heterogeneous catalyst for the complete degradation of GPh at room temperature. Importantly, the degradation mechanism produces N-formyl glycine and hydroxymethyl-phosphonate, which are largely innocuous chemicals, especially when compared to more common GPh degradation products. Nanocrystalline MOF-808 (nMOF-808) exhibits enhanced reactivity than larger MOF-808 crystals, attributed to the higher coordination of hydroxyl and water molecules to the secondary building units (SBU) as determined using a range of X-ray absorption spectroscopy (XAS) techniques. These studies indicate that the crystal size-dependency in GPh degradation is related to structural modifications on coordinative unsaturated Zr site that promote the fast exchange of weakly bonded ligands. Taken together, this study demonstrates that GPh degradation can be optimized through ligand field tuning in MOFs, which can help improve overall reactivity while also pushing the reaction toward desirable, nontoxic products.

Ability of mixed fungal cultures to remove glyphosate from soil microcosms under stressful conditions

Many herbicides used extensively to manage weeds and protect economically important crops contain glyphosate (GP) as their main ingredient, which contaminates ecosystems when it spreads from the soil into the surrounding environment. This study evaluated the ability of two fungal strains to remove GP at a microcosm scale. The strains, Aspergillus oryzae AM2 and Mucor circinelloides 166, were tested on their own and in mixed cultures. The microcosms were conditioned at 30 or 70% field capacity (FC), and contaminated with 5000 or 15,000 mg kg-1 GP. The native microbial communities played a crucial role in the dissipation of the herbicide. At the end of the incubation (60 days), they had achieved removal percentages above 95% in most treatments. The exceptions were the microcosms subjected to hydric stress (30% FC) and contaminated with 15,000 mg kg-1 GP, in which the co-cultures outperformed the native microbial species (≥ 80 vs 33% removal, respectively). An increase in AMPA (aminomethylphosphonic acid), the main metabolite of GP degradation, was usually detected after 60 days, which indicates that biodegradation may have been one of the main mechanisms involved in the removal of the herbicide. These results provide information about the potential of two mixed fungal cultures (containing species that are native to agricultural soils) to remove GP under stressful conditions.

Characterization of Glyphosate Resistance and Degradation Profile of Caballeronia zhejiangensis CEIB S4-3 and Genes Involved in Its Degradation

Herbicides are the most employed pesticides in agriculture worldwide; among them, glyphosate is the most successful herbicide molecule in history. The extensive use of glyphosate has been related to environmental pollution and toxic effects on non-target organisms. Effective remediation and treatment alternatives must be developed to reduce the environmental presence of glyphosate and its adverse effects. Bioremediation using microorganisms has been proposed as a feasible alternative for treating glyphosate pollution; due to this, identifying and characterizing microorganisms capable of biodegrading glyphosate is a key environmental task for the bioremediation of polluted sites by this herbicide. This study characterized the glyphosate resistance profile and degradation capacity of the bacterial strain Caballeronia zhejiangensis CEIB S4-3. According to the results of the bacterial growth inhibition assays on agar plates, C. zhejiangensis CEIB S4-3 can resist exposure to high concentrations of glyphosate, up to 1600 mg/L in glyphosate-based herbicide (GBH) formulation, and 12,000 mg/L of the analytical-grade molecule. In the inhibition assay in liquid media, C. zhejiangensis CEIB S4-3 resisted glyphosate exposure to all concentrations evaluated (25-400 mg/L). After 48 h exposure, GBH caused important bacterial growth inhibition (>80%) at concentrations between 100 and 400 mg/L, while exposure to analytical-grade glyphosate caused bacterial growth inhibitions below 15% in all tested concentrations. Finally, this bacterial strain was capable of degrading 60% of the glyphosate supplemented to culture media (50 mg/L), when used as the sole carbon source, in twelve hours; moreover, C. zhejiangensis CEIB S4-3 can also degrade the primary glyphosate degradation metabolite aminomethylphosphonic acid (AMPA). Genomic analysis revealed the presence of genes associated with the two reported metabolic pathways for glyphosate degradation, the sarcosine and AMPA pathways. This is the first report on the glyphosate degradation capacity and the genes related to its metabolism in a Caballeronia genus strain. The results from this investigation demonstrate that C. zhejiangensis CEIB S4-3 exhibits significant potential for glyphosate biodegradation, suggesting its applicability in bioremediation strategies targeting this contaminant.

Mechanisms of interactions and the significance of different colloidal structures in the vertical transport of glyphosate in soils with contrasting mineralogies

Soil is regarded as a natural repository for strongly adsorbed pollutants since glyphosate (GLY) is preferentially adsorbed by the inorganic fraction of the soil, which may greatly limits its leaching. In this way, understanding how clay mineralogy influences the sorption and transport processes of glyphosate in soils with different mineralogical characteristics is highly relevant. In this work, two clay mineralogy contrasting soils were used to evaluate GLY retention: a Oxisol (OX) with high levels of iron oxides (amorphous and crystalline) and a Inceptisol (IN) with a predominance of kaolinite. According to results obtained, the sorption process is influenced by more than one mechanism, including intraparticle diffusion, which is particularly favored at pH 4.00, and mass transfer across the boundary layer, which is favored at pH 6.50. When evaluating the adsorption isotherms, some differences associated with pH were also observed. At pH 4.00, good fits were obtained with the Freundlich model, suggesting electrostatic interaction between the compound and the soil. At pH 6.50, the best modeling involves the Langmuir-Freundlich model, indicating the occurrence of chemical and physical interactions. Desorption studies suggest that GLY sorption at pH 4.00 mostly involves the formation of inner-sphere complexes, while at pH 6.50, much of the sorption involves outer-sphere complexes. In column studies, GLY leaching was observed in both soils at concentrations between 0.01 and 0.02 mg L-1. After pH correction by liming, differences were observed in the leached GLY concentration, especially in the second rain event in, which leached concentrations greater than 0.04 mg L-1. These results confirm the strong sorption of GLY in the soil, as well as its evident mobilization through the soil column, probably due to colloid-facilitated transport.

Environmental Implication of Herbicide Use

One of the guiding principles of the sustainable use of herbicides is their targeted action exclusively against weeds, consisting of blocking photosynthesis and synthesis of amino acids and growth regulators. Herbicides are major elements of plant production, indispensable to the functioning of modern agriculture. Nevertheless, their influence on all elements of the natural environment needs to be continuously controlled. This review article summarizes research addressing the effects of herbicides on the natural environment and the changes they trigger therein. Herbicides, applied to protect crops against weed infestation, are usually mixtures of various active substances; hence, it is generally difficult to analyze their impact on the environment and organisms. Nonetheless, an attempt was made in this review to discuss the effects of selected herbicides on individual elements of the natural environment (water, soil, and air) and organisms (humans, animals, plants, and microorganisms). In addition, the article presents examples of the biodegradation of selected herbicides and mechanisms of their degradation by bacteria and fungi. Based on this information, it can be concluded that the uncontrolled use of herbicides has led to adverse effects on non-target organisms, as documented in the scientific literature. However, further research on the environmental effects of these chemicals is needed address the missing knowledge on this subject.

Assessment of homogeneous electro-Fenton process coupled with microbial fuel cell utilizing Serratia sp. AC-11 for glyphosate degradation in aqueous phase

Glyphosate (GLY), a globally-used organophosphate herbicide, is frequently detected in various environmental matrices, including water, prompting significant attention due to its persistence and potential ecological impacts. In light of this environmental concern, innovative remediation strategies are warranted. This study utilized Serratia sp. AC-11 isolated from a tropical peatland as a biocatalyst in a microbial fuel cell (MFC) coupled with a homogeneous electron-Fenton (EF) process to degrade glyphosate in aqueous medium. After coupling the processes with a resistance of 100 Ω, an output voltage value of 0.64 V was obtained and maintained stable throughout the experiment. A bacterial biofilm of Serratia sp. AC-11 was formed on the carbon felt electrode, confirmed by attenuated total reflectance-Fourier transformed infrared (ATR-FTIR) and scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS). In the anodic chamber, the GLY biodegradation rate was 100% after 48 h of experimentation, with aminomethylphosphonic acid (AMPA) remaining in the solution. In the cathodic chamber, the GLY degradation rate for the EF process was 69.5% after 48 h experimentation, with almost all of the AMPA degraded by the in situ generated hydroxyl radicals. In conclusion, the results demonstrated that Serratia sp. AC-11 not only catalyzed the biodegradation of glyphosate but also facilitated the generation of electrons for subsequent transfer to initiate the EF reaction to degrade glyphosate. This dual functionality emphasizes the unique capabilities of Serratia sp. AC-11, it as an electrogenic microorganism with application in innovative bioelectrochemical processes, and highlighting its role in sustainable strategies for environmental remediation.

Disentangling the Regulatory Response of Agrobacterium tumefaciens CHLDO to Glyphosate for Engineering Whole-Cell Phosphonate Biosensors

Phosphonates (PHTs), organic compounds with a stable C-P bond, are widely distributed in nature. Glyphosate (GP), a synthetic PHT, is extensively used in agriculture and has been linked to various human health issues and environmental damage. Given the prevalence of GP, developing cost-effective, on-site methods for GP detection is key for assessing pollution and reducing exposure risks. We adopted Agrobacterium tumefaciens CHLDO, a natural GP degrader, as a host and the source of genetic parts for constructing PHT biosensors. In this bacterial species, the phn gene cluster, encoding the C-P lyase pathway, is regulated by the PhnF transcriptional repressor. We selected the phnG promoter, which displays a dose-dependent response to GP, to build a set of whole-cell biosensors. Through stepwise genetic optimization of the transcriptional cascade, we created a whole-cell biosensor capable of detecting GP in the 0.25-50 μM range in various samples, including soil and water.

Challenges and opportunities in the selective degradation of organophosphorus herbicide glyphosate

The wide and continuous usage of glyphosate in the environment poses a serious threat to biological systems. Besides the accumulation of glyphosate in vivo, a growing body of research has revealed that aminomethylphosphonic acid (AMPA), the main degradation intermediate of glyphosate, has significant environmental and biological influences by inducing chromosome aberration of fish and canceration of human erythrocyte. Therefore, the development of new strategies avoiding the generation of the toxic AMPA intermediate during the full degradation of glyphosate is becoming of high importance. Herein, we provide a mini-review that includes the most recent advances in the selective degradation of glyphosate avoiding the generation of AMPA in the last several years from 2018. The developments of the selective degradation of glyphosate, highlighting its synthesis and selective degradation mechanism, are summarized here. This review intends to attract more attention from researchers toward this area and to emphasize the recent developments of selective degradation of glyphosate in highlighting future challenges.

Current status of advancement in remediation technologies for the toxic metal mercury in the environment: A critical review

Currently, pollution due to heavy metals, in particular dissolved mercury, is a major concern for society and the environment. This work aims to evaluate the current scenario regarding the removal/elimination of mercury. Mercury removal through adsorption is mainly done through artificial resins and metallic-organic frameworks. In the case of the zinc organic framework, it was able to adsorb Hg2+, reaching an adsorption capacity of 802 mg g-1. As for the Hg(0) the coconut husk was found to have the lowest equilibrium time, 30 min, and the highest adsorption capacity of 956.2 mg g-1. Experimental reports and molecular simulation indicate that the adsorption of mercury and other chemical forms occurs due to electrostatic interactions, ion exchange, precipitation, complexation, chelation, and covalent bonds, according to the material nature. The reported thermodynamic results show that, in most cases, the mercury adsorption has an endothermic nature with enthalpy levels below 40 kJ mol-1. Thermal and chemical regeneration methods lead to a similar number of 5 cycles for different materials. The presence of other ions, in particular cadmium, lead, and copper, generates an antagonistic effect for mercury adsorption. Regarding the other current technologies, it was found that mercury removal is feasible through precipitation, phytoremediation, and marine microalgae; all these methods require constant chemicals or a slow rate of removal according to the conditions. Advanced oxidative processes have noteworthy removal of Hg(0); however, Fenton processes lead to mineralization, which leads to Fe2+ and Fe3+ in solution; sonochemical processes are impossible to scale up at the current technology level; and electrochemical processes consume more energy and require constant changes of the anode and cathode. Overall, it is possible to conclude that the adsorption process remains a more friendly, economical, and greener process in comparison with other processes.

In vitro effects of two environmental toxicants, beauvericin and glyphosate in Roundup, on cell numbers and steroidogenesis of bovine ovarian cells

Beauvericin is an emerging Fusariotoxin naturally occurring in cereal grains throughout the world whereas glyphosate (N-phosphonomethyl-glycine) is a non-selective systemic herbicide used worldwide. The purpose of this study is to evaluate a newly developed ovarian cell culture system (that includes both granulosa and theca cells) as an in vitro model for toxicological studies. Specifically, the effects of beauvericin and glyphosate in formulation with Roundup on ovarian cell numbers and steroid production were evaluated. Ovaries collected from cattle without luteal structures were sliced into 30-70 pieces each, and granulosa and theca cells were collected. Harvested cells were cultured for 48 h in 10% fetal bovine serum-containing medium followed by 48 h in serum-free medium containing testosterone (500 ng/mL; as an estrogen precursor) with the following eight treatments: (1) controls, (2) FSH (30 ng/mL) alone, (3) FSH plus insulin-like growth factor-1 (IGF1; 30 ng/mL), (4) FSH plus IGF1 plus beauvericin (3 µM), (5) FSH plus IGF1 plus glyphosate in Roundup (10 µg/mL), (6) FSH plus IGF1 plus fibroblast growth factor 9 (FGF9, 30 ng/mL), (7) a negative control without added testosterone, and (8) IGF1 plus LH (30 ng/mL) with basal medium without added testosterone. In the presence of FSH, IGF1 significantly increased cell numbers, estradiol and progesterone production by severalfold. Glyphosate in Roundup formulation significantly inhibited IGF1-induced cell numbers and estradiol and progesterone production by 89-94%. Beauvericin inhibited IGF1-induced cell numbers and estradiol and progesterone by 50-97% production. LH plus IGF1 significantly increased androstenedione secretion compared with controls without added testosterone indicating the presence of theca cells. In conclusion, the present study demonstrates that toxicological effects of beauvericin and glyphosate in Roundup formulation are observed in a newly developed ovarian cell model system and further confirms that both glyphosate and beauvericin may have the potential to impair reproductive function in cattle.

Glyphosate resistance and biodegradation by Burkholderia cenocepacia CEIB S5-2

Glyphosate is a broad spectrum and non-selective herbicide employed to control different weeds in agricultural and urban zones and to facilitate the harvest of various crops. Currently, glyphosate-based formulations are the most employed herbicides in agriculture worldwide. Extensive use of glyphosate has been related to environmental pollution events and adverse effects on non-target organisms, including humans. Reducing the presence of glyphosate in the environment and its potential adverse effects requires the development of remediation and treatment alternatives. Bioremediation with microorganisms has been proposed as a feasible alternative for treating glyphosate pollution. The present study reports the glyphosate resistance profile and degradation capacity of the bacterial strain Burkholderia cenocepacia CEIB S5-2, isolated from an agricultural field in Morelos-México. According to the agar plates and the liquid media inhibition assays, the bacterial strain can resist glyphosate exposure at high concentrations, 2000 mg·L-1. In the degradation assays, the bacterial strain was capable of fast degrading glyphosate (50 mg·L-1) and the primary degradation metabolite aminomethylphosphonic acid (AMPA) in just eight hours. The analysis of the genomic data of B. cenocepacia CEIB S5-2 revealed the presence of genes that encode enzymes implicated in glyphosate biodegradation through the two metabolic pathways reported, sarcosine and AMPA. This investigation provides novel information about the potential of species of the genus Burkholderia in the degradation of the herbicide glyphosate and its main degradation metabolite (AMPA). Furthermore, the analysis of genomic information allowed us to propose for the first time a metabolic route related to the degradation of glyphosate in this bacterial group. According to the findings of this study, B. cenocepacia CEIB S5-2 displays a great glyphosate biodegradation capability and has the potential to be implemented in glyphosate bioremediation approaches.

Toxicity of glyphosate to animals: A meta-analytical approach

Glyphosate (GLY)-based herbicides (GBHs) are the most commonly applied pesticide worldwide, and non-target organisms (e.g., animals) are now regularly exposed to GLY and GBHs due to the accumulation of these chemicals in many environments. Although GLY/GBH was previously considered to be non-toxic, growing evidence indicates that GLY/GBH negatively affects some animal taxa. However, there has been no systematic analysis quantifying its toxicity to animals. Therefore, we used a meta-analytical approach to determine whether there is a demonstrable effect of GLY/GBH toxicity across animals. We further addressed whether the effects of GLY/GBH vary due to (1) taxon (invertebrate vs. vertebrate), (2) habitat (aquatic vs. terrestrial), (3) type of biological response (behavior vs. physiology vs. survival), and (4) dosage or concentration of GLY/GBH. Using this approach, we also determined whether adjuvants (e.g., surfactants) in commercial formulations of GBHs increased toxicity for animals relative to exposure to GLY alone. We analyzed 1282 observations from 121 articles. We conclude that GLY is generally sub-lethally toxic for animals, particularly for animals in aquatic or marine habitats, and that toxicity did not exhibit dose-dependency. Yet, our analyses detected evidence for widespread publication bias so we encourage continued experimental investigations to better understand factors influencing GLY/GBH toxicity to animals.

Enhanced Power Generation Using a Dual-Surface-Modified Hematite Photoanode in a Direct Glyphosate Photo Fuel Cell

Given the current and escalating global energy and environmental concerns, this work explores an innovative approach to mitigate a widely employed commercial herbicide using a direct glyphosate (Gly) photocatalytic fuel cell (PFC). The device generates power continuously by converting solar radiation, degrading and mineralizing commercial glyphosate-based fuel, and reducing sodium persulfate at the cathode. Pristine and modified hematite photoanodes were coupled to Pt/C nanoparticles dispersed in a carbon paper (CP) support (Pt/C/CP) dark cathode by using an H-type cell. The Gly/persulfate PFC shows a remarkable current and power generation enhancement after dual-surface modification of pristine hematite with segregated Hf and FeNiOx cocatalysts. The optimized photoanode elevates maximum current density (Jmax) from 0.35 to 0.71 mA cm-2 and maximum power generation (Pmax) from 0.04 to 0.065 mW cm-2, representing 102.85 and 62.50% increase in Jmax and Pmax, respectively, as compared to pristine hematite. The system demonstrated stability over a studied period of 4 h; remarkably, the photodegradation of Gly proved substantial, achieving ∼98% degradation and ∼6% mineralization. Our findings may significantly contribute to reducing Gly's environmental impact in agribusiness since it may convert the pollutant into energy at zero bias. The proposed device offers a sustainable solution to counteract Gly pollution while concurrently harnessing solar energy for power generation.

Systemic Analysis of Glyphosate Impact on Environment and Human Health

With a growing global population, agricultural scientists are focusing on crop production management and the creation of new strategies for a higher agricultural output. However, the growth of undesirable plants besides the primary crop poses a significant challenge in agriculture, necessitating the massive application of herbicides to eradicate this problem. Several synthetic herbicides are widely utilized, with glyphosate emerging as a potential molecule for solving this emerging issue; however, it has several environmental and health consequences. Several weed species have evolved resistance to this herbicide, therefore lowering agricultural yield. The persistence of glyphosate residue in the environment, such as in water and soil systems, is due to the misuse of glyphosate in agricultural regions, which causes its percolation into groundwater via the vertical soil profile. As a result, it endangers many nontarget organisms existing in the natural environment, which comprises both soil and water. The current Review aims to provide a systemic analysis of glyphosate, its various effects on the environment, its subsequent impact on human health and animals, which will lead us toward a better understanding of the issues about herbicide usage and aid in managing it wisely, as in the near the future glyphosate market is aiming for a positive forecast until 2035.

Efficient treatment of actual glyphosate wastewater via non-radical Fenton-like oxidation

Compared to radical oxidative pathway, recent research revealed that non-radical oxidative pathway has higher selectivity, higher adaptability and lower oxidant requirement. In this work, we have designed and synthesized Cu2O/Cu nanowires (CuNWs), by pyrolysis of copper chloride and urea, to selectively generate high-valent copper (CuIII) upon H2O2 activation for the efficient treatment of actual glyphosate wastewater. The detailed characterizations confirmed that CuNWs nanocomposite was comprised of Cu0 and Cu2O, which possessed a nanowire-shaped structure. The electron paramagnetic resonance (EPR) analysis, in situ Raman spectra, chronoamperometry and liner sweep voltammetry (LSV) verified CuIII, which mainly contributed to glyphosate degradation, was selectively generated from CuNWs/H2O2 system. In particular, CuI is mainly oxidized by H2O2 into CuIIIvia dual-electron transfer, rather than simultaneously releasing OH• via single electron transfer. More importantly, CuNWs/H2O2 system exhibited the excellent potential in the efficient treatment of actual glyphosate wastewater, with 96.6% degradation efficiency and chemical oxygen demand (COD) dropped by 30%. This novel knowledge gained in the work helps to apply CuNWs into heterogeneous Fenton-like reaction for environmental remediation and gives new insights into non-radical pathway in H2O2 activation.

Assessment of chitosan-based adsorbents for glyphosate removal

Exposure to glyphosate produces various toxic effects, due to this, different methods have been evaluated for its elimination. The objective of this work was to formulate chitosan-based adsorbents and evaluate their efficiency in the removal of glyphosate in vitro. Four films were made by varying the weight ratio of silica/chitosan particles, and four sponges were made by varying the chitosan/chitosan ratio in a reticulated manner. Both adsorbents were characterized based on their porosity, water absorption, glyphosate removal, and reusability. It was found that increasing the porosity in both films and sponges resulted in an increase in the adsorption efficiency of glyphosate. The adsorption process exhibited a better fit in both adsorbents to the pseudo-second-order model. The adsorption of glyphosate to the films fit better with the Langmuir model, demonstrating that the process occurs in the form of a monolayer. In the case of sponges, the adsorption of glyphosate fit better with the Freundlich model, indicating that the process takes place in a multilayer form. Finally, when the reusability was evaluated, the adsorbents showed a loss of effectiveness. However, they still proved to be an efficient alternative for the removal of glyphosate in water, providing a cost-effective and environmentally friendly solution.

Antioxidant Vitamins Attenuate Glyphosate-Induced Development of Type-2 Diabetes Through the Activation of Glycogen Synthase Kinase-3 β and Forkhead Box Protein O-1 in the Liver of Adult Male Rats

INTRODUCTION

 Glyphosate is a well-known broad-spectrum desiccant and herbicide. It is an active component used widely in popular weed control products like Roundup (BigHaat Agro Pvt Ltd, Bangalore, Karnataka, India), Rodeo (Corteva, Inc., Indianapolis, Indiana, United States), and PondMaster (PBI-Gordon Corporation, Shawnee, Kansas, United States). However, due to sustained presence, they tend to get deposited in the environmental resources and leach into the living system. It has been shown to develop various cancers and diabetes. However, its impact on GSK-3β (glycogen synthase kinase-3 beta) and FOXO-1 (forkhead box protein O1), both critical proteins involved in the regulation of glucose metabolism and insulin signaling, is unknown.  Objective: The primary objective of this study was to check whether antioxidant vitamins (C and E) can reduce hyperglycemia and hyperinsulinemia in response to glyphosate exposure and the secondary objective was to investigate whether antioxidant vitamins have the capacity to downregulate GSK-3β and FOXO-1-mediated oxidative stress in the liver of glyphosate induced rats.  Methods: We divided the experimental animals into three groups. Group 1 - control rats (animals were injected with olive oil (0.8ml) intraperitoneally), Group 2 - glyphosate-treated rats orally for ten weeks, Group 3 - glyphosate-treated rats received vitamin C and vitamin E. After 30 days of treatment, the animals were anesthetized, sera were separated and used for the biochemical analysis. Liver tissues from control and treated animals were dissected and stored at -20°C for further gene expression analysis. Fasting blood glucose (FBG) was assessed by calorimetric analysis, while serum insulin was measured by enzyme-linked immunosorbent assay (ELISA). Gene expression studies of specific genes (FOXO1 and GSK3) were analyzed by real-time reverse transcriptase-polymerase chain reaction (RT-PCR) analysis.

RESULTS

The expression level of FOX01 and GSK3β genes was higher in glyphosate-induced animals compared with the control group but was reduced significantly (p＜0.05) upon treatment with antioxidant vitamins (C and E). Other biochemical parameters, including FBG, serum insulin, and antioxidant enzyme assays, also showed that antioxidant vitamins reduce glyphosate-induced insulin resistance and type-2 diabetes.  Conclusion: The current study provides in vivo experimental evidence that antioxidant vitamins (C and E) reduce the glyphosate-mediated development of type-2 diabetes risk via the downregulation of FOX01 and GS-3β mRNA expression in the liver. Hence, vitamins C and E may be considered as therapeutics for the treatment of diabetes.

Bioremediation of the herbicide glyphosate in polluted soils by plant-associated microbes

Most productive lands worldwide base their crop production on the use of glyphosate (GLY)-resistant plants, and consequently, widespread use of this herbicide has led to environmental issues that need to be solved. Soil bioremediation technologies based on degradation of GLY by microorganisms are strategies that have been considered useful to solve this environmental problem. Recently, a further step has been taken considering the use of bacteria that interact with plants, either alone or both bacteria and plant together, for the removal of GLY herbicide. Plant-interacting microorganisms with plant growth-promoting traits can also enhance plant growth and contribute to successful bioremediation strategies.

Characterization of a New Pseudomonas Putida Strain Ch2, a Degrader of Toxic Anthropogenic Compounds Epsilon-Caprolactam and Glyphosate

In this work, a new Ch2 strain was isolated from soils polluted by agrochemical production wastes. This strain has a unique ability to utilize toxic synthetic compounds such as epsilon-caprolactam (CAP) as a sole carbon and energy source and the herbicide glyphosate (GP) as a sole source of phosphorus. Analysis of the nucleotide sequence of the 16S rRNA gene of Ch2 revealed that the strain belongs to the species Pseudomonas putida. This strain grew in the mineral medium containing CAP in a concentration range of 0.5 to 5.0 g/L and utilized 6-aminohexanoic acid and adipic acid, which are the intermediate products of CAP catabolism. The ability of strain Ch2 to degrade CAP is determined by a conjugative megaplasmid that is 550 kb in size. When strain Ch2 is cultured in a mineral medium containing GP (500 mg/L), more intensive utilization of the herbicide occurs in the phase of active growth. In the phase of declining growth, there is an accumulation of aminomethylphosphonic acid, which indicates that the C-N bond is the first site cleaved during GP degradation (glyphosate oxidoreductase pathway). Culture growth in the presence of GP during the early step of its degradation is accompanied by unique substrate-dependent changes in the cytoplasm, including the formation of vesicles of cytoplasmic membrane consisting of specific electron-dense content. There is a debate about whether these membrane formations are analogous to metabolosomes, where the primary degradation of the herbicide can take place. The studied strain is notable for its ability to produce polyhydroxyalkanoates (PHAs) when grown in mineral medium containing GP. At the beginning of the stationary growth phase, it was shown that, the amount and size of PHA inclusions in the cells drastically increased; they filled almost the entire volume of cell cytoplasm. The obtained results show that the strain P. putida Ch2 can be successfully used for the PHAs’ production. Moreover, the ability of P. putida Ch2 to degrade CAP and GP determines the prospects of its application for the biological cleanup of CAP production wastes and in situ bioremediation of soil polluted with GP.

Effects of Free or Immobilized Bacterium Stenotrophomonas acidaminiphila Y4B on Glyphosate Degradation Performance and Indigenous Microbial Community Structure

The overuse of glyphosate has resulted in serious environmental contamination. Thus, effective techniques to remove glyphosate from the environment are required. Herein, we isolated a novel strain Stenotrophomonas acidaminiphila Y4B, which completely degraded glyphosate and its major metabolite aminomethylphosphonic acid (AMPA). Y4B degraded glyphosate over a broad concentration range (50-800 mg L^-1), with a degradation efficiency of over 98% within 72 h (50 mg L^-1). Y4B degraded glyphosate via the AMPA pathway by cleaving the C-N bond, followed by degradation of AMPA and subsequent metabolism. Y4B demonstrated strong competitiveness and substantially accelerated the degradation of glyphosate in different soils, degrading 71.93 and 89.81% of glyphosate (400 mg kg^-1) within 5 days in sterile and nonsterile soils, respectively. The immobilized cells of Y4B were more efficient than their free cells and they displayed excellent biodegradation efficiency in a sediment-water system. Taken together, Y4B is an ideal degrader for the bioremediation of glyphosate-contaminated sites.

Characterization of a novel glyphosate-degrading bacterial species, Chryseobacterium sp. Y16C, and evaluation of its effects on microbial communities in glyphosate-contaminated soil

Widespread use of the herbicide glyphosate in agriculture has resulted in serious environmental problems. Thus, environment-friendly technological solutions are urgently needed for the removal of residual glyphosate from soil. Here, we successfully isolated a novel bacterial strain, Chryseobacterium sp. Y16C, which efficiently degrades glyphosate and its main metabolite aminomethylphosphonic acid (AMPA). Strain Y16C was found to completely degrade glyphosate at 400 mg·L-1 concentration within four days. Kinetics analysis indicated that glyphosate biodegradation was concentration-dependent, with a maximum specific degradation rate, half-saturation constant, and inhibition constant of 0.91459 d-1, 15.79796 mg·L-1, and 290.28133 mg·L-1, respectively. AMPA was identified as the major degradation product of glyphosate degradation, suggesting that glyphosate was first degraded via cleavage of its C-N bond prior to subsequent metabolic degradation. Strain Y16C was also found to tolerate and degrade AMPA at concentrations up to 800 mg·L-1. Moreover, strain Y16C accelerated glyphosate degradation in soil indirectly by inducing a slight alteration in the diversity and composition of soil microbial community. Taken together, our results suggest that strain Y16C may be a potential microbial agent for bioremediation of glyphosate-contaminated soil.