Interactions between glyphosate and autochthonous soil fungi surviving in aqueous solution of glyphosate

doi:10.1016/j.chemosphere.2007.11.006

Chemosphere

Volume 71, Issue 7, April 2008, Pages 1386-1391

https://doi.org/10.1016/j.chemosphere.2007.11.006 Get rights and content

Abstract

The survival of autochthonous fungi in soil treated with 1 mM aqueous solution of glyphosate was investigated. Significant differences in the total number of fungi in the studied objects were observed, and additionally significant qualitative changes were encountered. The dominating group of fungi belonged to genus Fusarium: Fusarium solani H30, Fusarium solani H50 and Fusarium oxysporum H80. Interactions between the isolated strains of fungi and varying concentrations of glyphosate were determined. The studied strains possessed high tolerance against the applied doses of glyphosate (0.5–2.0 mM). In the presence of glyphosate (as a sole source of phosphorus) applied in concentrations of 1.0–1.5 mM the increase in dry mass of the tested fungi was highly significant. In the presence of glyphosate the phenotypic changes of studied strains were observed as was shown as the presence of colorants being indicators of such changes. Thus, their color and intensity depended on the age, pH and species present in the culture. The degradation of glyphosate by studied fungi was determined by means of TLC. Two types of compounds were formed. One of them (R_f = 0.21–0.35) contained free amino group but was not either glycine nor AMPA. Survival of Fusarium in soil environment is potentially dangerous.

Introduction

Increased consumption and high efficiency of herbicide Roundup stimulates studies not only on its activity and persistence in soil, but also on undesired interactions with soil microorganisms. Plants metabolize an active substance of Roundup–glyphosate only to low extent or do not metabolize it at all. Reactions catalyzed by microbial enzymes and adsorption on the surface of mineral components of soil play the mostly significant role in its persistence, bioavailability and mobility (Rueppel et al., 1997, Forlani et al., 1999, Busse et al., 2001, Araujo et al., 2003, Haney et al., 2003, Gimsing et al., 2004, Kools et al., 2005, Sorensen et al., 2006). Glyphosate is adsorbed by ferric and aluminum oxide (Gimsing et al., 2004) as well as by organic substances (Piccolo et al., 1996, Mamy and Barriuso, 2005).

The consequences of the application of glyphosate are changes in microbiological structure of soil, probably as the result of stimulation of growth of fungi. Araujo et al. (2003), pointed out on the increase of fungal counts in the presence of Roundup, which could be the effect of its direct or indirect interaction with other microorganisms.

Fungi can utilize glyphosate as nutriment and also as energetic substrate (Krzyśko-Łupicka and Orlik, 1997, Krzyśko-Łupicka et al., 1997). Significant for agricultural environment is the type of fungi arising after Roundup treatment, in particular the presence of phytopathogens in this group. Glyphosate inhibits growth of mycorrhizal fungi and consequently may stimulate the growth of Fusarium fungi (Levesque and Rahe, 1992). In spite of the persistence of C–P bond, glyphosate does not accumulate in soil, since microorganisms are capable to breakdown this bond, with the release of inorganic phosphorus.

Glyphosate degradation is performed co-metabolically and decomposition rate should depend on the general activity of soil microorganisms (Gimsing et al., 2004). Biodegradation products of glyphosate (N-phosphonomethylglycine) can be sarcosine – as the effect of direct activity of C–P lyase or aminomethylphosphonic acid (AMPA) formed as the result of the activity of glyphosate oxidoreductase (GOX) (Dick and Quinn, 1995, Dick and Quinn, 1995, Pipke and Amrhein, 1988, Obojska et al., 1999, Klimek-Ochab et al., 2004). Dick and Quinn, 1995, Dick and Quinn, 1995 suggest that sarcosine pathway is preferred by microorganisms. However, the presence of AMPA was also determined in some cases (Dick and Quinn, 1995, Dick and Quinn, 1995, Ternan et al., 1998, Araujo et al., 2003). The latter could be due to the presence of the enzyme oxidoreductase (GOX) in soil microorganisms. However, AMPA can further accumulate in soil and can be degraded with slower rate than glyphosate (Rueppel et al., 1997). Thus, Araujo et al. (2003) after 32 days of the experiments using various types of soil determined the presence of low quantities of glyphosate and significant level of the product of its degradation – AMPA.

Immediate products of decomposition of glyphosate are further degraded microbiologically to NH₃, CO₂, C₂H₅OH, H₂O and phosphates (Dick and Quinn, 1995, Dick and Quinn, 1995, Obojska et al., 1999, Klimek-Ochab et al., 2004).

The time of decay of 90% of the initial dosage of the herbicide was 14–90 days, depending on the type of soil (Mensink and Janssen, 1994). In soils containing low levels of organic matter, nitrosoglyphosate was formed (Rueppel et al., 1997).

The aim of the present work was to isolate a group of autochthonous soil fungi that survive in 1 mM aqueous glyphosate solution as well as to investigate interactions between these fungal strains and glyphosate.

Section snippets

Glyphosate

N-Phosphonomethylglycine used in this study was obtained from commercial formulation by precipitation from its aqueous solution with concentrated hydrochloric acid.

Soil samples

The studied material consisted of samples of soil sampled in autumn period from the experimental field in which diversified content of organic carbon has been set up by fertilization with various dosage of sewage sludge (Table 1).

Ten grams soil samples were suspended in 90 ml of 1 mM glyphosate solution. After one and six months the

Results and discussion

Survival of autochthonous fungi in 1.0 mM glyphosate solution, depended on duration of its action and, in lower extent, on the content of total carbon in soil. Significant differences between total number of fungi in soil supplemented with different amounts of sludge were observed, as well as significant qualitative changes were encountered (Table 2).

As a result of 30 days of glyphosate action statistically significant change in fungal count was found in soils of high carbon content 1450 mg 100 g⁻¹

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Cited by (39)

Effects of glyphosate on soil fungal communities: A field study
2021, Revista Argentina de Microbiologia
Citation Excerpt :
In agricultural systems, the non-target effects that glyphosate could have on soil microbial communities are now of concern since they negatively affect soil functions, plant health, and crop productivity34. There are numerous reports on the harmful effects of glyphosate on microorganisms under laboratory conditions2,5,8,13,23,26,34 and extensive research has been done on the short-term response of soil microorganisms to glyphosate; however, relatively little information is available on the effects under field conditions11,12,41. The field experiments are more complex, but they are important to validate the studies performed in vitro at a laboratory scale.
The driving forces behind many soil processes are microorganisms and they are able to respond immediately to environmental changes. The soil microbial community impacts on many soil properties. More than one-third of the terrestrial ecosystems are semiarid. However, a limited number of studies have been conducted to characterize soil fungal communities in semiarid grasslands, in particular those of agricultural fields. The aim of this study was to explore changes in the diversity and structure of soil fungal communities in semiarid grasslands, after different doses of glyphosate were applied under field conditions. Changes in soil fungal communities were examined using different approaches including culturing, calcofluor white stain and denaturing gradient gel electrophoresis (DGGE). The different approaches complement each other, revealing different aspects of the effect of glyphosate on soil fungal communities. We demonstrated a negative effect of glyphosate on soil fungal biomass at high doses and an early and transitory stimulatory effect on soil fungal biomass. We also found a negative effect of glyphosate on the species richness of cultivable fungi and changes in the molecular structure of soil fungal communities after double doses or long-term glyphosate application. In summary, our findings demonstrate an overall negative effect of glyphosate on soil fungal communities.
Los microorganismos del suelo son los responsables de llevar a cabo la mayoría de los procesos biológicos que ocurren en el suelo, y son capaces de reaccionar ante el estrés ambiental. Más de un tercio de los ecosistemas terrestres son semiáridos. Sin embargo, son escasos los estudios realizados para caracterizar las comunidades fúngicas en suelos agrícolas en ecosistemas semiáridos. El objetivo del presente trabajo fue estudiar los cambios que se producen en la biomasa, la diversidad y la estructura de las comunidades fúngicas del suelo, luego de la aplicación de distintas dosis de glifosato en condiciones de campo. Se emplearon diferentes técnicas incluidas el cultivo, la tinción directa con blanco de calcoflúor y PCR acoplada a electroforesis en geles de gradiente desnaturalizante (DGGE). Las distintas metodologías empleadas se complementan entre sí al detectar cada una distintos aspectos del efecto del glifosato en las comunidades fúngicas del suelo. Se encontró que el glifosato produce un efecto negativo sobre la biomasa fúngica, también se encontró un efecto transitorio estimulante inmediatamente posterior a la aplicación del herbicida. Además, se vio un efecto negativo sobre la riqueza de hongos cultivables, así como también cambios en la estructura molecular de las comunidades luego de aplicaciones repetidas. En conclusión, se demostró un efecto negativo generalizado sobre las comunidades fúngicas del suelo.
Isolation of culturable mycota from Argentinean soils exposed or not-exposed to pesticides and determination of glyphosate tolerance of fungal species in media supplied with the herbicide
2020, Revista Argentina de Microbiologia
Citation Excerpt :
Ten grams of each soil sample were added in Erlenmeyer flasks containing 50 ml of sterile modified Czapeck-Dox medium (CZD), with the following composition (l); 10 g glucose, 0.5 g MgSO4·7H2O, 0.5 g KCl, 2 g NaNO3, 0.01 g FeSO4, 1 g KH2PO4, 0.5 g yeast extract, gentamicin and chloramphenicol (100 mg/l each) to inhibit bacterial growth. CZD without glucose, NaNO3 or KH2PO4; and supplied with GP at a final concentration of 10 mM (CZDC); 1.5 mM (CZDN) and 1.0 mM (CZDP), respectively were prepared to evaluate the use of GP as sole source of carbon, nitrogen and phosphorus33. The CZD media were autoclaved at 121 °C for 15 min and the appropriate aliquot of GP was added to the sterilized culture media template at 45–50 °C to obtain the final concentrations mentioned above.
The current agricultural system has led to the development of glyphosate (GP)-resistant weeds, causing an increase in GP doses and applications. Native mycota of pesticide-contaminated sites are the major source of pesticide-degrading microorganisms. The aims of the present study were to isolate the GP-tolerant culturable mycota in two soils with different pesticide exposure from Córdoba, Argentina, and to evaluate the growth parameters in native fungal isolates in the presence of GP and the effective dose that caused 50% growth reduction. The results showed that the genera Fusarium, Aspergillus, Mucor, Penicillium and Sterilia were the prevalent fungi isolated from soils both exposed and not-exposed to pesticides. The highest value (>100 mM) of effective concentration of herbicide that caused 50% growth inhibition (EC50), was found for Trichoderma isolates. Sterilia spp. had EC50 values of 100 mM, while Aspergillus spp. and Mucor had EC50 values between 50 and 100 mM. The growth rate evaluation varied according to the isolates and GP concentrations. The data showed that all Aspergillus spp., Trichoderma spp., Mucor and three Sterilia spp. had the best growth performance in media supplied with GP after a variable acclimation period. This study provides valuable data for further studies that would allow to know the metabolic capacity of these fungal species that can be potential candidates for GP removal from contaminated environments.
El sistema agrícola actual condujo al desarrollo de malezas resistentes a glifosato (GP), lo que deriva en el aumento de las dosis y el número de aplicaciones requeridas. La microbiota nativa de sitios contaminados con plaguicidas constituye la fuente principal de microorganismos capaces de degradar este herbicida. Los objetivos del presente estudio fueron aislar la microbiota cultivable tolerante a GP a partir de dos suelos agrícolas con diferente grado de exposición a plaguicidas, ambos de la provincia de Córdoba, Argentina, y evaluar en los hongos nativos aislados los parámetros de crecimiento en presencia de GP y la dosis efectiva que produce un 50% de reducción del crecimiento (EC50). Los géneros Fusarium, Aspergillus, Mucor, Penicillium y Sterilia fueron los de mayor prevalencia, tanto en suelos expuestos como no expuestos a plaguicidas. La mayor EC50 hallada (> 100 mM) correspondió a dos aislamientos de Trichoderma. En dos aislamientos de Sterilia, los valores de EC50 fueron de 100 mM, mientras que en los dos de Aspergillus y en uno de Mucor fueron de entre 50 y 100 mM. La velocidad de crecimiento varió según la concentración de GP empleada y el aislamiento considerado. Todos los aislamientos de Aspergillus, Trichoderma y Mucor, y tres aislamientos de Sterilia mostraron el mejor rendimiento en cuanto al crecimiento en los medios con GP después de un período de aclimatación variable. Este trabajo proporciona datos preliminares valiosos referidos a la capacidad metabólica de estos aislados y su potencial para remover GP en ambientes contaminados.
Decreases mycorrhizal colonization and affects plant-soil feedback
2018, Science of the Total Environment
Citation Excerpt :
High microbial activity in the soil enhances the degradation rate of glyphosate. On the other hand, glyphosate may also affect microbiota and enzymatic activities in the soil (Carlisle and Trevors, 1988; Cherni et al., 2015; Imfeld and Vuilleumier, 2012; Krzysko-Lupicka and Sudol, 2008). Thus, for example soil management practices modulating soil biotic and abiotic characteristics may alter glyphosate degradation in soil (Alvarez and Steinbach, 2009; Doran, 1980).
Our aim was to study the effects of glyphosate, tilling practice and cultivation history on mycorrhizal colonization and growth of target (weeds) and non-target (crops) plants. Glyphosate, the world's most widely used pesticide, inhibits an enzyme found in plants but also in microbes. We examined the effects of glyphosate treatment applied in the preceding fall on growth of a perennial weed, Elymus repens (target plant) and a forage grass, Festuca pratensis (non-target plant) and their arbuscular mycorrhizal fungal (AMF) root colonization in a field pot experiment. Non-target plants were sown in the following spring. Furthermore, we tested if glyphosate effects depend on tillage or soil properties modulated by long cultivation history of endophyte symbiotic grass (E+ grass). AMF root colonization, plant establishment and growth, glyphosate residues in plants, and soil chemistry were measured. Glyphosate reduced the mycorrhizal colonization and growth of both target and non-target grasses. The magnitude of reduction depended on tillage and soil properties due to cultivation history of E+ grass. We detected glyphosate residues in weeds and crop plants in the growing season following the glyphosate treatment. Residues were higher in plants growing in no-till pots compared to conspecifics in tilled pots. These results demonstrate negative effects of glyphosate on non-target organisms in agricultural environments and grassland ecosystems.
Assessment of growth of Aspergillus spp. from agricultural soils in the presence of glyphosate
2017, Revista Argentina de Microbiologia
Citation Excerpt :
In addition, sucrose was replaced by glyphosate at a final concentration of 10 mM as sole carbon source. When glyphosate was used as sole source of phosphorus or nitrogen, K2HPO4 and NaNO3 were replaced by glyphosate at final concentrations of 1.0 and 1.5 mM, respectively22. The control Czapek Dox agar is referred to as CZ.
Agriculture is one of the bases of the Argentine economy. Glyphosate is undoubtedly one of the most important herbicides used. The increasing consumption and the efficiency of glyphosate-based herbicides have encouraged several studies on their persistence in soils, their effects on soil microbiota and their degradation processes. Fungi have been reported as being the main herbicide-degrading microorganisms as well as the most tolerant to environmental stress conditions. This study evaluated the growth performance of Aspergillus section Flavi and Aspergillus niger aggregate strains on Czapek Dox media supplied with a commercial glyphosate formulation as sole source of carbon (CZC), phosphorus (CZP) or nitrogen (CZN). Six Aspergillus spp. strains were evaluated. Each medium was stab-inoculated with fungal spores from 7-day old cultures. Two measures of colony radii were taken daily. All of the Aspergillus section Flavi strains showed a significant increase (from 24 to 44%) in growth rate on the CZN medium, as compared to controls. The A. niger aggregate strains exhibited the same behavioral pattern under all the conditions tested, except on the CZN medium. Velutinous or slightly floccose colonies with abundant sporulation were observed on CZP. Moreover, the colonies produced sparse sporulation on CZC or CZN media, being their appearances completely different from those on the CZP medium. This study establishes that A. section Flavi and A. niger aggregate strains can grow in vitro in the presence of glyphosate, especially when it is used as a sole source of phosphorus or nitrogen.
La agricultura es una de las bases de la economía argentina. El glifosato es, indudablemente, uno de los herbicidas más utilizados. El incremento en el consumo y la eficiencia de estos herbicidas han estimulado investigaciones sobre su persistencia en el suelo, sus efectos sobre la microbiota edáfica y su proceso de degradación. Los hongos son conocidos por su importancia como degradadores de herbicidas y por su tolerancia a condiciones de estrés ambiental. El objetivo del presente estudio fue evaluar el crecimiento de cepas de Aspergillus sección Flavi y del agregado Aspergillus niger en el medio Czapeck Dox suplementado con una solución comercial de glifosato como única fuente de carbono (CZC), de fósforo (CZP) o de nitrógeno (CZN). Seis cepas de Aspergillus fueron evaluadas. Cada medio fue inoculado con esporas fúngicas provenientes de cultivos de 7 días. Diariamente se tomaron 2 medidas del radio de las colonias. Todas las cepas de Aspergillus sección Flavi mostraron un incremento significativo (del 24 al 44%) en la velocidad de crecimiento en el medio CZN comparado con los controles. Las cepas del agregado A. niger mostraron el mismo comportamiento bajo todas las condiciones ensayadas, excepto en el medio CZN. Se observaron colonias velutinosas o ligeramente flocosas con abundante esporulación en los medios CZP. En los medios CZC o CZN, las colonias produjeron una esporulación escasa. Este estudio establece que cepas de Aspergillus sección Flavi y del agregado A. niger pueden desarrollar in vitro en presencia de glifosato, especialmente cuando es usado como única fuente de fósforo o nitrógeno.
Amino polyphosphonates - chemical features and practical uses, environmental durability and biodegradation
2015, New Biotechnology
Citation Excerpt :
Both cyanobacteria and fungi are known to adapt easily to contaminated environments [54]. Additionally, a few species have been found to exhibit tolerance to glyphosate and are able to grow in media containing phosphonates as the only sources of phosphorus [55,56]. Furthermore, as phylogenetically the oldest autotrophs and inhabiting all natural water reservoirs, cyanobacteria seem to possess a special position in relation to organophosphonates.
Growing concerns about the quality of the environment led to the introduction of complex system of safety assessment of synthetically manufactured and commonly applied chemicals. Sometimes, however, our knowledge of consequences that result from the usage of these substances, appears far later, than at the beginning of their application. Such situation is observed in the case of aminopolyphosphonates being an important subgroup of organophosphorus compounds. The increasing industrial and household applications, led to introduce thousand tons of polyphosphonates every year into the environment. These substances are difficult to determine in environmental samples because of lack of appropriate analytical procedures. On the other hand they are suspected to influence the ecological equilibrium in aquatic ecosystems. Thus, studies on their fate in the environment, especially on the routes of their degradation seem to be of interest to both industrial and environmental chemistry. Wherefore this review contains recent available data on the impact of aminophosphonates on environment, microbial degradation methods and evaluation of the possibility for using microorganisms to remove aminophosphonates from wastewater.
Effects of the herbicide glyphosate [n-(phosphonomethyl) glycine] on biodiversity and organisms in the soil-A review
2023, European Journal of Environmental Sciences

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Chemosphere

Abstract

Introduction

Section snippets

Glyphosate

Soil samples

Results and discussion

References (28)

Effect of glyphosate the microbial activity of two Brazilian soils

Chemosphere

Glyphosate toxicity and the effects of long term vegetation control on soil microbial communities

Soil. Biol. Biochem.

Control of Glyphosate uptake and metabolism in Pseudomonas sp. 4 ASW

FEMS Microbiol. Lett.

The colorimetric determination of phosphorus

J. Biol. Chem.

Degradation of the phosphonate herbicide glyphosate in soil: evidence for possible involvement of unculturable microorganisms

Soil Biol. Biochem.

Chemical and microbiological soil characteristics controlling glyphosate mineralisation in Danish surface soils

Appl. Soil Ecol.

Glyphosate degradation as a soil health indicator for heavy metal polluted soils

Soil Biol. Biochem.

The use of glyphosate as the sole source of phosphorus or carbon for the selection of soil-borne fungal strains capable to degrade this herbicide

Chemosphere

Glyphosate adsorption in soil compared to herbicides replaced with the introduction of glyphosate resistant crops

Chemosphere

Carbon–phosphorus lyase activity in permeabilized cells of Arthrobacter sp

GLP-1. Febs Lett.

Sorption, desorption and mineralisation of the herbicides glyphosate and MCPA in samples from two Danish soil and subsurface profiles

Environ. Pollut.

Fungicidal effect of disinfectants against 25 fungal contaminants commonly found in bread and cheese manufacturing

J. Food Protect.

Cited by (39)

Effects of glyphosate on soil fungal communities: A field study

Isolation of culturable mycota from Argentinean soils exposed or not-exposed to pesticides and determination of glyphosate tolerance of fungal species in media supplied with the herbicide

Decreases mycorrhizal colonization and affects plant-soil feedback

Assessment of growth of Aspergillus spp. from agricultural soils in the presence of glyphosate

Amino polyphosphonates - chemical features and practical uses, environmental durability and biodegradation

Effects of the herbicide glyphosate [n-(phosphonomethyl) glycine] on biodiversity and organisms in the soil-A review