The increasing emergence of multidrug-resistant (MDR) organisms in hospital infections is causing a global public health crisis. The development of drugs with effective antibiotic action against such agents is of the highest priority. In the present study, the action of Fluopsin C against MDR clinical isolates was evaluated under in vitro and in vivo conditions. Fluopsin C was produced in cell suspension culture of Pseudomonas aeruginosa LV strain, purified by liquid adsorption chromatography and identified by mass spectrometric analysis. Bioactivity, bacterial resistance development risk against clinically important pathogenic strains and toxicity in mammalian cell were initially determined by in vitro models. In vivo toxicity was evaluated in Tenebrio molitor larvae and mice. The therapeutic efficacy of intravenous Fluopsin C administration was evaluated in a murine model of Klebsiella pneumoniae (KPC) acute sepsis, using six different treatments. The in vitro results indicated MIC and MBC below 2 μg/mL and low bacterial resistance development frequency. Electron microscopy showed that Fluopsin C may have altered the exopolysaccharide matrix and caused disruption of the cell wall of MDR bacteria. Best therapeutic results were achieved in mice treated with a single dose of 2 mg/kg and in mice treated with two doses of 1 mg/kg, 8 h apart. Furthermore, acute and chronic histopathological studies demonstrated absent nephrotoxicity and moderate hepatotoxicity. The results demonstrated the efficacy of Fluopsin C against MDR organisms in in vitro and in vivo models, and hence it can be a novel therapeutic agent for the control of severe MDR infections.

No abstract

The no-tillage system requires a higher use of herbicides to control weeds before sowing, increasing the concern over the effect that such products might have on the environment. However, few studies reporting the influence of glyphosate on soil microorganisms are available in the literature. The aim of this work was to evaluate the effect of two formulations of glyphosate on functional groups of microorganisms in soybean rhizosphere. The experiment was performed in a greenhouse, and the treatments were the isopropylamine salt and the ammonium salt of glyphosate at the maximum and twice the maximum allowed dose. The control treatment had no application. The populations of soil bacteria, fungi, actinomycetes, fluorescent pseudomonas, cellulolytics, amylolytics, proteolytics and free-living N-fixing were determined by plate counts on selective media. Plant root dry weight, shoot dry weight and the number and dry weight of nodules were determined. The application of herbicides had little effect on the populations of microorganisms, as well as on plant growth. Nevertheless, the interactions among some populations of microorganisms and between these and the plant were influenced by the formulation of the glyphosate applied.

No abstract

Neglected Glyphosate-resistant (GR) crops are common in agro-ecosystems mainly due to its benefits of weed management. However, the effect of GR crops on soil ecosystem and on non-target soil organisms need to be monitored. The effect of two transgenic soybeans GR on soil microorganisms, soil enzymes, microbial biomass and plant growth were evaluated. The experimental design was conducted as factorial arrangement with two GR soybean varieties, the Londrina (RR 59) and its near isogenic non-GM 59 Londrina called VAR 1; the second was Valiosa soybean (RR Conquista) and its near isogenic non-GM Conquista - Uberaba soybean called VAR 2. The plants were inoculated with arbuscular mycorrhiza fungi and rhizobia. The results showed that significant differences were observed among GM plants and their parental non-GM only for N biomass, AM colonization and cellulase activity. The presence of AM fungi had great influence on the functional groups of microorganisms while some enzymes activity decreased.