Amazonian soil fungi are efficient degraders of glyphosate herbicide; novel isolates of Penicillium, Aspergillus, and Trichoderma

Pesticide residues that contaminate the environment circulate within the hydrological cycle can accumulate within the food chain and cause problems to both environmental and human health. Microbes, however, are well known for their metabolic versatility and the ability to degrade chemically stable substances, including recalcitrant xenobiotics. The current study focused on bio-prospecting within Amazonian rainforest soils to find novel strains fungi capable of efficiently degrading the agriculturally and environmentally ubiquitous herbicide, glyphosate. Of 50 fungal strains isolated (using culture media supplemented with glyphosate as the sole carbon-substrate), the majority were Penicillium strains (60%) and the others were Aspergillus and Trichoderma strains (26 and 8%, respectively). All 50 fungal isolates could use glyphosate as a phosphorous source. Eight of these isolates grew better on glyphosate-supplemented media than on regular Czapek Dox medium. LC-MS revealed that glyphosate degradation by Penicillium 4A21 resulted in sarcosine and aminomethylphosphonic acid.

Emerging Contaminants in Streams of Doce River Watershed, Minas Gerais, Brazil

This study investigated the occurrence and risk assessment of ten pharmaceutical products and two herbicides in the water of rivers from the Doce river watershed (Brazil). Of the 12 chemicals studied, ten (acyclovir, amoxicillin, azithromycin, ciprofloxacin, enrofloxacin, fluoxetine, erythromycin, sulfadiazine, sulfamethoxazole, glyphosate and aminomethylphosphonic acid) had a 100% detection rate. In general, total concentrations of all target drugs ranged from 4.6 to 14.5 μg L−1, with fluoroquinolones and sulfonamides being the most representative classes of pharmaceutical products. Herbicides were found at concentrations at least ten times higher than those of the individual pharmaceutical products and represented the major class of contaminants in the samples. Most of the contaminants studied were above concentrations that pose an ecotoxicological risk to aquatic biota. Urban wastewater must be the main source of contaminants in waterbodies. Our results show that, in addition to the study of metal in water (currently being conducted after the Fundão dam breach), there is an urgent need to monitor emerging contaminant in waters from Doce river watershed rivers, as some chemicals pose environmental risks to aquatic life and humans due to the use of surface water for drinking and domestic purposes by the local population. Special attention should be given to glyphosate, aminomethylphosaphonic acid, and to ciprofloxacin and enrofloxacin (whose concentrations are above predicted levels that induce resistance selection).

Morphospecies Abundance of Above-Ground Invertebrates in Agricultural Systems under Glyphosate and Microplastics in South-Eastern Mexico

Soil invertebrates are important for diverse soil ecosystem services, which are jeopardized by pesticides and microplastics. In the present study, we aimed to assess above-ground invertebrates’ morphospecies abundance in the presence of glyphosate (GLY), its main metabolite aminomethylphosphonic acid (AMPA), and microplastics (MPs). Three land-use systems were analyzed: agricultural systems with and without plastic mulch and pesticides (AwPM, AwoPM) and natural unmanaged farming systems (UF). Soil GLY, AMPA, MP concentrations and above-ground invertebrates were quantified. GLY concentrations were also assessed inside invertebrate tissues. GLY, AMPA and the highest concentration of GLY in invertebrates’ tissue were found only in AwoPM at 0.14–0.45 mg kg−1, 0.12–0.94 mg kg−1 and 0.03–0.26 mg kg−1, respectively. MPs were present as follows: AwPM system (100%, 400–2000 particles kg−1) > AwoPM (70.8%, 200–1000 particles kg−1) > UF (37.5%, 200–400 particles kg−1). No significant correlations were found between soil MPs, GLY and AMPA. There was a significant correlation between MPs and morphospecies from the order Entomobrymorpha (Collembola, R = 0.61, p < 0.05). Limnophila, Mesogastropoda (Gastropoda) and Siphonaptera morphospecies were only present in the UF system. GLY in invertebrate tissue was inversely correlated with soil GLY (R = −0.73, p < 0.05) and AMPA (R = −0.59, p < 0.05). Further investigations are required to understand these phenomena.

The Effect of Co-exposure to Glyphosate, Cadmium, and Arsenic on Chronic Kidney Disease

The usage of glyphosate is increasing worldwide. Glyphosate and its major metabolite, aminomethylphosphonic acid (AMPA), are of potential toxicological concern in unknown chronic kidney disease (CKDu). As with Cd and other elements, glyphosate exposure has been reported as risk factor for CKDu in farmers. This study aimed to evaluate the influence of co-exposure to glyphosate and heavy metals in chronic kidney disease. In this study, the urine samples from 55 patients with CKD and 100 participants without CKD were analyzed for glyphosate, As, Cd, and Pb concentrations, and eGFR. Negative associations between glyphosate, AMPA, As, and Cd concentrations in the urine and eGFR were found for study subjects (p < 0.05). With regard to the effect of co-exposure, the odds ratios (OR) for subjects with an eGFR of < 60 mL/min/1.73 m2 was significant because of the high Cd concentration (> 1 µg/g creatinine; OR = 7.57, 95% CI = 1.91–29.95). With regard to the effect of co-exposure, the OR for subjects with an of eGFR < 45 mL/min/1.73 m2 was significant at high glyphosate concentration (> 1 µg/g creatinine; OR = 1.57, 95% CI = 1.13–2.16) and As concentration (> 1 µg/g creatinine; OR = 1.01, 95% CI = 1.00–1.02). These results showed that glyphosate, AMPA, As, and Cd have an effect on CKD; notably, Cd, As, and glyphosate exposure can be important risk factors after stage 3a of CKD, and that there was a co-exposure effect of As and glyphosate in CKD after stage 3b. The potential health impacts of glyphosate should be considered, especial for patients with CKD and eGFR below 45 mL/min/1.73 m2.

Effects of Glyphosate and Its Metabolite AMPA on Aquatic Organisms

Glyphosate (N-(phosphonomethyl)glycine) was developed in the early 1970s and at present is used as a herbicide to kill broadleaf weeds and grass. The widely occurring degradation product aminomethylphosphonic acid (AMPA) is a result of glyphosate and amino-polyphosphonate degradation. The massive use of the parent compound leads to the ubiquity of AMPA in the environment, and particularly in water. Considering this, it can be assumed that glyphosate and its major metabolites could pose a potential risk to aquatic organisms. This review summarizes current knowledge about residual glyphosate and its major metabolite AMPA in the aquatic environment, including its status and toxic effects in aquatic organisms, mainly fish. Based on the above, we identify major gaps in the current knowledge and some directions for future research knowledge about the effects of worldwide use of herbicide glyphosate and its major metabolite AMPA. The toxic effect of glyphosate and its major metabolite AMPA has mainly influenced growth, early development, oxidative stress biomarkers, antioxidant enzymes, haematological, and biochemical plasma indices and also caused histopathological changes in aquatic organisms.

Dynamics of Glyphosate and Aminomethylphosphonic Acid in Soil Under Conventional and Conservation Tillage

This study investigates the adsorption and dissipation of glyphosate and the formation/dissipation of AMPA in non-tilled (NT) and conventionally tilled (CT) soil at 0–5 and 5–20 cm depth. Glyphosate adsorption was mainly related to the different NT and CT soil properties (clay and amorphous Al oxides), whereas an effect of the soil management could not be identified. Glyphosate dissipation was initially fast, and it slowed down later. The initial glyphosate concentration in NT soil at 0–5 cm was significantly lower than the dose applied due to the interception by the weeds and crop residues. AMPA began to form early after treatment and persisted longer than glyphosate. The DT50 range was 8–18 days for glyphosate and 99–250 days for AMPA. Longer glyphosate and AMPA DT50 were observed in NT soil compared to CT soil but, for glyphosate, the difference was significant only at 5–20 cm. Higher glyphosate and AMPA concentrations were detected in NT than in CT soil at the end of the study at 0–5 cm. The differences in glyphosate and AMPA DT50 and persistence were mainly attributable to the influence of different NT and CT soil characteristics. However, other factors could have contributed to the different glyphosate and AMPA dynamics between the soils, like glyphosate wash-off from crop residues on NT soil with the rainfall, the delayed glyphosate return to the soil by weed root exudation or weeds decomposition, and the NT soil compaction which may have reduced the microbial degradation of glyphosate at low concentrations. Graphic abstract

Response of broadleaf and grass cover crop species to soil residues of glyphosate and aminomethylphosphonic acid (AMPA)

Glyphosate is the most widely used herbicide in the United States; however, concern about increasing residues of glyphosate and its metabolite aminomethylphosphonic acid (AMPA) in soil is escalating. There is a lack of scientific literature examining the response of cover crops to soil residues of glyphosate or AMPA. The objectives of this study were to evaluate the impact of glyphosate or AMPA residues in silty clay loam soil on emergence, growth, and biomass of cover crops, including cereal rye, crimson clover, field pea, hairy vetch, and winter wheat, as well as their germination in a 0.07% (0.7 g/L) solution of AMPA or glyphosate. Greenhouse studies were conducted at the University of Nebraska-Lincoln to determine the dose response of broadleaf and grass cover crops to soil-applied glyphosate or AMPA. The results indicated that soil treated with glyphosate or AMPA up to 105 mg ae kg–1 of soil had no effect on the emergence, growth, above-ground biomass, and root biomass of any of the cover crop species tested. To evaluate the impact of AMPA or glyphosate on the seed germination of cover crop species, seeds were soaked in petri plates filled with a 0.7 g L−1 solution of AMPA or glyphosate. There was no effect of AMPA on seed germination of any of the cover crop species tested. Seed germination of crimson clover and field pea in a 0.7 g L−1 solution of glyphosate was comparable to the nontreated control; however, the germination of cereal rye, hairy vetch, and winter wheat was reduced by 48%, 75%, and 66%, respectively, compared to the nontreated control. The results suggested that glyphosate or AMPA up to 105 mg ae kg–1 in silt clay loam soil is unlikely to cause any negative effect on the evaluated cover crop species.