No abstract

We investigated the individual and combined contributions of two distinct heme proteins namely, ascorbate peroxidase (APX) and catalase (CAT) on the tolerance of Lemna minor plants to antibiotics. For our investigation, we used specific inhibitors of these two H2O2-scavenging enzymes (p-aminophenol, 3-amino,1,2,4-triazole, and salicylic acid). APX activity was central for the tolerance of this aquatic plant to amoxicillin (AMX), whereas CAT activity was important for avoiding oxidative damage when exposed to ciprofloxacin (CIP). Both monitored enzymes had important roles in the tolerance of Lemna minor to erythromycin (ERY). The use of molecular kinetic approaches to detect and increase APX and/or CAT scavenging activities could enhance tolerance, and, therefore, improve the use of L. minor plants to reclaim antibiotics from water bodies.

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).

trabalho licenciado sob licença Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License. RESUMOMacrófitas aquáticas do gênero Myriophyllum apresentam estratégias alelopáticas para o controle do fitoplâncton e, neste contexto, a utilização de extratos produzidos a partir destas espécies na inibição de cianobactérias têm sido investigadas. Neste estudo foi avaliado o efeito inibitório do extrato metanólico de M. aquaticum sobre o crescimento celular de Microcystis aeruginosa e a produção de microcistina-LR. Exemplares de M. aquaticum foram coletadas no reservatório do rio Verde (Araucária-PR, Brasil) e após a secagem foram pulverizadas. A extração hidrometanólica (50%) foi realizada por cavitação em ultrassom, os extratos brutos foram secos e liofilizados. Foram preparadas diferentes concentrações de soluções do extrato: 0 (Controle), 1, 10, 50, 100 e 250 mg.L -1 ). Posteriormente, foram realizados inóculos de M. aeruginosa (10 6 células mL -1 ). O crescimento celular foi analisado por contagem em câmaras de Neubauer. Após nove dias de exposição, alterações no potencial fotossintético foram avaliadas pela determinação de clorofila-a. Além disso, foi realizada a quantificação de microcistina-LR por cromatografia líquida de alta eficiência. O extrato metanólico de M. aquaticum apresentou potencial inibitório sobre o crescimento de M. aeruginosa, com valores inibitórios de até 71%. Houve redução do teor de clorofila-a nas concentrações de 10 a 250 mg.L -1 . Por fim, constatou-se redução de microcistina-LR de 90 a 99% para todas as concentrações de extratos testadas. Tais resultados indicam que o extrato metanólico de M. aquaticum foi eficiente para inibir M. aeruginosa, bem como reduziu a concentração de microcistina-LR, apresentando potencial para o uso como alternativa no controle de florações de cianobactérias. PALAVRAS-CHAVE: Cianobactérias. Microcistina-LR. Soluções Baseadas na Natureza ALLELOPATHIC BIOACTIVITY OF METHANOLIC EXTRACTS OF Myriophyllum aquaticum (Vell.) Verdc. ON Microcystis aeruginosa Kutzing.

No abstract

The current research aimed to investigate both the tolerance and the phytoremediation potential of Desmodium incanum DC. on petroleum-contaminated soil. There were analyzed D. incanum seeds germination, surviving, growth and development cultivated at different contaminants concentrations as well as the pollutant degradation rate by gas chromatography and rhizosphere community. The experiment was carried out on a greenhouse containing non-contaminated soil (NCS), vegetated contaminated soil (VCS) and non-vegetated contaminated soil (NVCS) at the following petroleum concentrations (petroleum per of dry soil): 50 g kg-1 and 100 g kg-1. The experiments were performed during 90 days. The germination was more evident as it was observed higher petroleum concentrations. After 90 days, the surviving rate of the both groups 100%, and the soil samples were extracted and analyzed by gas chromatography. The VCS (100 g kg-1) group growth was reduced when compared to the NVCS (100 g kg-1). The petroleum influenced the morph anatomy and development of the plant. Significant increases in the total area, cortical and central cylinder of the roots in the contamination presence. The plant provided the development of larger amounts of microorganisms in the rhizosphere zone, and higher petroleum compounds degradation, confirming their potential phytoremediation for soils contaminated by petroleum.

The intensive global use of glyphosate has led to the evolution of glyphosate resistant (GR) weed species, including the economically damaging horseweed (Conyza sumatrensis). We evaluated the glyphosate resistance mechanisms of C. sumatrensis. While 5-enolpyruvylshikimate-3-phosphate synthase activity was similar between the glyphosate resistant (GR) and nonresistant biotypes, plants from the GR population accumulated lower shikimate levels than susceptible ones, suggesting the absence of target-site resistance mechanisms. Decreases over time in glyphosate concentrations in GR leaves were not accompanied by increases in glyphosate concentrations in their stem and roots, indicating lower glyphosate distribution rates in GR plants. The early appearance of aminomethylphosphonic acid (the main glyphosate metabolite) in leaves, as well as its presence only in the stems and roots of GR plants, suggests faster glyphosate metabolism in GR plants than in susceptible ones. GR plants treated with glyphosate also showed greater antioxidant (ascorbate peroxidase [APX] and catalase [CAT]) and cytochrome P450-enzyme activities, indicating their great capacity to avoid glyphosate-induced oxidative stress. Three non-target mechanisms (reduced glyphosate translocation, increased metabolism, and increased antioxidant activity) therefore confer glyphosate resistance in C. sumatrensis plants. This is the first time that APX, CAT and P450-enzyme activities are related to GR in C. sumatrensis.

Harmful algal blooms are one of the greatest challenges when preserving water sources, especially when involving cyanobacteria such as Microcystis aeruginosa. Finding remediation possibilities is needed, and one of them has been the use of macrophytes such as the species Myriophyllum, which have presented allelopathic mechanisms of phytoplankton control. Thus, this work aimed to evaluate the inhibition of M. aeruginosa cell growth in a co-exposure with Myriophyllum aquaticum and the influence on microcystin-LR concentration. The experiments were carried out using a culture of M. aeruginosa (1x106 cells mL-1) in a co-exposure with M. aquaticum for seven days. The inhibitory effects were investigated by counting the cells; the effects on photosynthetic pigments were measured and microcystin-LR was quantified in the culture medium on the last experimental day. To evaluate the possible effects of competition for nutrients and space, the concentration of total orthophosphate was quantified and treatment with plastic plants was used. The experiments with Myriophyllum aquaticum achieved the total inhibition of M. aeruginosa growth and a significant reduction of the photosynthetic pigments (> 98%). Additionally, we observed a reduction of microcystin-LR concentration (79%) in the tests with macrophytes when compared to the control. Competition for space and nutrients was not observed, demonstrating that the effects on M. aeruginosa were caused by aquatic macrophyte presence. These results may indicate that M. aquaticum causes inhibitory effects on cyanobacteria growth by allelopathic effects and removes microcystin-LR.