RESUMEN
Glyphosate is a herbicide commonly used in agriculture for weed control. Current agricultural production demands vast amounts of this product, which are applied by ground or aerial spraying. The concomitant aerial currents promote glyphosate drift to vegetated or urban areas. In this context, we hypothesized that the lichens, Parmotrema tinctorum and Usnea barbata, could be sensitive to the action of glyphosate and therefore be used to bio-indicate the presence of this herbicide in areas affected by drift. Since living organisms respond in different ways to the action of herbicides, our interest was also to indicate biological markers responsive to the action of glyphosate, through concentrations and exposure times of the thallus, besides identifying the most sensitive species. We evaluated the effect of different concentrations (0.0, 4.8, 9.6, and 19.2 mg L-1) and exposure times (24, 48, and 72 hours) to glyphosate on the morphoanatomy, photobiont vitality, photosynthetic efficiency, and oxidative metabolism of the thalli. We found that the lichens, P. tinctorum and U. barbata, respond to glyphosate stress, with prospects for use in the biomonitoring of pollutant dispersal from plantation areas. When using P. tinctorum as a bioindicator, lichen morphoanatomy, photobiont vitality, and photosynthetic pigment concentration were efficient biomarkers for the effect of concentration and exposure time. For U. barbata, the lichenic morphoanatomy and the activity of SOD and APX enzymes were essential tools to indicate the herbicide action. Parmotrema tinctotum, however, was characterized as more sensitive in bio-indicating the presence of this herbicide to diagnose the air quality in urban areas or vegetation sectors adjacent to agricultural environments.
Asunto(s)
Herbicidas , Líquenes , Usnea , Biomarcadores , Herbicidas/toxicidad , GlifosatoRESUMEN
Das sementes da mamona extrai-se o óleo de rícino, utilizado in natura ou em sua forma modificada nas áreas médica, farmacêutica e industrial. Um de seus derivados químicos - o Poliquilgerm® - evidencia propriedades antifúngicas sobre Candida albicans e bacteriostática/ bactericida sobre Escherichia coli no nível de 99,9%. Considerando-se essas propriedades, aplicouse o Poliquilgerm® em culturas de Leuconostoc mesenteroides, uma das espécies de bactéria contaminante dos mostos em indústrias sucroalcooleiras. Esta bactéria quando presente em mostos produz além do ácido láctico, a dextrana, que é um polímero da glicose que aumenta a viscosidade dos fluidos dos processos. No presente trabalho avaliou-se o efeito de diferentes concentrações do Poliquilgerm® sobre a viscosidade produzida por L. mesenteroides em diferentes meios de cultivo, condições de pH, e temperatura. Verificou-se 20,56% de diminuição da viscosidade quando se utilizou 1,0% do produto, além da inibição do crescimento da bactéria após 20 horas em contato com 1,0 e 0,2% de Poliquilgerm®. L. mesenteroides apresentou melhor crescimento em valores de pH 6,0, tanto a 28 como a 33º C, evidenciado pela maior produção de biomassa. Além disso, em meio de cultura neste pH verificou-se maior porcentagem de diminuição da viscosidade em ambas as concentrações utilizadas. Estas mesmas concentrações alcançaram até 100% de diminuição das UFC/mL após 24 horas em contato com o produto, evidenciado por quantificação da biomassa e confirmado mediante plaqueamento pela técnica "Pour Plate".
Castor-oil, extracted from seeds of Ricinus communis L., is normally used in natura or in its modified form in the medical, pharmaceutical and industrial areas. One of its chemical derivates Poliquilgerm® has shown antifungal properties on Candida albicans, and bacteriostatic/bactericide effects on Escherichia coli reaching 99.9%. Considering these features, in the present study Poliquilgerm® was applied in cultures of Leuconostoc mesenteroides, a frequent contaminant bacterium of musts in the sugar and alcohol industries. This bacterium, when a contaminant of must, produces lactic acid as well as dextran, a polymer of glucose which may increase the viscosity of fluids in the operation. The present study evaluated the effect of different concentrations of Poliquilgerm® on viscosity produced by L. mesenteroides cultures under different conditions of various culture media, pH and temperature. A 20.56% decrease in viscosity was verified when 1.0% of the product was used, and bacterium growth inhibition after 20 hours in media with 1.0 and 0.2% of Poliquilgerm®. L. mesenteroides showed a higher growth rate in pH 6.0, at both 28 and 33º C, evidenced by greater biomass production. Also, in the culture media at this pH a greater decrease in viscosity percentages was verified at both concentrations used. The media with these same concentrations reached up to 100% decrease of UFC/mL after 24 hours in the presence of the product, observed by biomass quantification and confirmed by the Pour Plate technique.