Análise de degradação do herbicida glifosato por fungos isolados da Bacia do Tarumã Açu

Abstract

Fungi are eukaryotic microorganisms, heterotrophic, and feed by absorption, excreting enzymes onto the substrate and absorbing the released nutrients. This characteristic makes them allies of bioremediation, as the metabolites they produce can degrade various substances depending on the conditions and physiological traits of the microorganism. Bioremediation is the process of using living organisms to reduce or eliminate pollutants, serving as an ecologically viable and cost-effective alternative, ideal for the recovery of degraded areas. Sewage discharges, industrial activities, and the intensive use of pesticides in agriculture are sources of soil and water contamination. This raises concerns for human health and biodiversity because these pollutants, often toxic, affect water springs and can cause health problems and reduce quality of life. Pesticides, such as fungicides, herbicides, and insecticides, have environmental and health impacts when used indiscriminately. Glyphosate, the most widely used herbicide in the world, is harmful to human health and the environment, being genotoxic, cytotoxic, and potentially causing neurological disorders and other health issues. The Tarumã-Açu Watershed, located in Manaus, is a periurban basin that integrates a complex water system. Its black, acidic waters, rich in organic compounds, are decomposed by aquatic microorganisms, forming the base of the local food chain. Although there have been studies on the recovery of areas affected by pesticides, there is limited research on the bioremediation and biodegradation of herbicides by aquatic fungi. To examine the bioremediation potential of fungi isolated from the Tarumã Basin, three fungal isolates (Aspergillus F2P3, Penicillium F3P2, and Trichoderma F4P3) from the Tarumã-Açu River Basin were selected. To evaluate the degradation of glyphosate and its possible use as a source of carbon and phosphorus, the isolates were cultured in media I) Czapek with a low concentration of sucrose (2.35 g/L), II) medium containing low concentration of sucrose with the addition of KH2PO4, and III) medium containing low concentration of sucrose with the addition of glyphosate (2.35 g/L) for 14 days at 28°C with agitation at 150 rpm. The isolates showed negative results when cultured in the Czapek medium with low sucrose concentration and supplemented with 2.35 g/L of glyphosate, showing no growth. Chromatography confirmed the presence of the herbicide, proving its non-degradation. It was concluded that the analyzed fungi do not have the potential to biodegrade glyphosate. Keywords: Biodegradation; Herbicide; Environmental impact; Isolation; River Negro