Glyphosate and fungi in agricultural environments

CARINA ELIZABETH MAGNOLI; BARBERIS CARLA; CHIACCHIERA, S.M.; MARÍA DEL PILAR MONGE; CARRANZA CECILIA; BENITO NICOLÁS; MELISA EGLÉ ALUFFI

Glyphosate: Chemistry, Uses and Safety Concerns

Nova Science Publishers, Inc.

Lugar: New York; Año: 2018; p. 1 - 18

Chemical herbicides are widely used throughout the world in food production. At the present time, they represent approximately 40% of chemical products sales, followed by insecticides, fungicides, and other types of pesticides. Among these products, commercial formulations based on N-phosphonomethyl-glycine (PMG), commonly known as glyphosate, are the most used worldwide. Such herbicidal formulations play a key role in promoting crop yields. PMG is a broad-spectrumcompound that kills weeds that compete with crops in agricultural soils environments (such as green spaces and gardens). In the last decade, some annual broadleaf weeds have developed resistance to PMG. For this reason, it has become necessary to apply higher and repeated doses ofPMG, which may lead to contamination of the environment. Some works have reported a relatively fast biodegradation of PMG in contaminated soils, with a half-life period of nearly 20 days. However, after 30-years of application of glyphosate-based herbicides (GBH), this herbicide and itsprimary degradation product, aminomethylphosphonic acid (AMPA), stillare the most frequently detected compounds in water bodies, mainly inagricultural areas. In addition to environmental pollution and humanhealth risks, these residual compounds can have a phytotoxic effect on thenext crop and become a threat to food production. Several processes actin the dissipation of organophosphorus compounds on soil, being themicrobial activity one of the most relevant. Since the 1980s, appliedresearchers have become increasingly interested in the study of the effectsof GBH on microbial communities. Although considerable research hasbeen done on biodegradation of PMG by bacteria, much less is knownregarding this capacity in fungi. Fungal species belonging to genera suchas Phanerochaete, Trametes, Aspergillus, Fusarium, Penicillium andTrichoderma are able to metabolize important environmental pollutantssuch as herbicides. They possess a number of advantages that can beexploited in bioremediation systems. They can degrade a diverse range ofpersistent toxic environmental pollutants and carry out a relevant role inco-metabolic degradation processes. The persistence of PMG and AMPAin soils and aquatic sediments depends on the type of soil, tillage, andclimatic conditions, among other factors. Both are polar compounds thatstrongly bind to Fe and Al oxides, clays and organic matter (humic acids)of the soil, decreasing the availability of free herbicide. The purpose ofthis chapter is to review information on the presence of GBH in theenvironment, their potentially harmful effects, their influence on soilmicrobial communities and their capacity to adsorb to clay particles(which affects their environmental availability).