RESUMO
Simple and convenient innovative assays in vitro demonstrating Metschnikowia spp. competition with Saccharomyces cerevisiae for an essential nutrient iron are presented. The tested Metschnikowia strains possess a common genetically determined property of secreting a pulcherriminic acid which in the presence of iron (III) ions forms an insoluble red pigment pulcherrimin. Both initial accumulation in growing Metschnikowia cells and subsequent precipitation in the form of pulcherrimin in the media contribute to iron removal by functioning cells. The predominant way depends on the strain. Due to fast elimination of iron, the growth of S. cerevisiae can be inhibited by tested Metschnikowia strains at concentrations of elemental iron in the media not exceeding 12 mg kg-1. Inhibition can be regulated by additional supply of microquantities of iron onto the surface of the solid medium within 20-24 h. At relatively low concentrations of elemental iron (below 1 mg kg-1), additional supplements of iron onto the surface provide an advancement in understanding the inhibition possibilities and enable the assay control. Microscopy observations revealed that Metschnikowia chlamydospores are involved in iron removal at relatively high iron concentrations. The results may find application in development of new methodologies and strategies for biocontrol or inhibition of pathogenic microorganisms.
Assuntos
Antibiose , Meios de Cultura/química , Ferro/metabolismo , Metschnikowia/fisiologia , Saccharomyces cerevisiae/crescimento & desenvolvimento , Aminoácidos Sulfúricos/farmacologia , Antifúngicos/farmacologia , Agentes de Controle Biológico/metabolismo , Piperidinas/farmacologia , Pirazinas/metabolismoRESUMO
The Firmicutes bacteria participate extensively in virulence and pathological processes. Enterococcus faecalis is a commensal microorganism; however, it is also a pathogenic bacterium mainly associated with nosocomial infections in immunocompromised patients. Iron-sulfur [Fe-S] clusters are inorganic prosthetic groups involved in diverse biological processes, whose in vivo formation requires several specific protein machineries. Escherichia coli is one of the most frequently studied microorganisms regarding [Fe-S] cluster biogenesis and encodes the iron-sulfur cluster and sulfur assimilation systems. In Firmicutes species, a unique operon composed of the sufCDSUB genes is responsible for [Fe-S] cluster biogenesis. The aim of this study was to investigate the potential of the E. faecalis sufCDSUB system in the [Fe-S] cluster assembly using oxidative stress and iron depletion as adverse growth conditions. Quantitative real-time polymerase chain reaction demonstrated, for the first time, that Gram-positive bacteria possess an OxyR component responsive to oxidative stress conditions, as fully described for E. coli models. Likewise, strong expression of the sufCDSUB genes was observed in low concentrations of hydrogen peroxide, indicating that the lowest concentration of oxygen free radicals inside cells, known to be highly damaging to [Fe-S] clusters, is sufficient to trigger the transcriptional machinery for prompt replacement of [Fe-S] clusters.
Assuntos
Enterococcus faecalis/metabolismo , Proteínas Ferro-Enxofre/genética , Estresse Oxidativo , Vias Biossintéticas , Proteínas Ferro-Enxofre/biossíntese , Modelos Moleculares , Reação em Cadeia da Polimerase em Tempo Real , Especificidade por SubstratoRESUMO
The development of antibacterial and antifungal drugs has been the target of several pharmaceutical and chemical industries mainly due to the lack of effective drugs with low or no side effect. In this work, studies were conducted both in vitro and in vivo with 8-oxyquinolinepropoxycalix[4]arene (A) and 5-Cl-8-oxyquinolinepropoxycalix[4]arene (B) ligands, showing fairly good results. Cytotoxicity and fungicidal actions of compounds A and B were determined in Wistar male rats and peritoneal macrophages of mice. A slight change in the total of leukocytes and erythrocytes was observed on the hematologic assays, showing almost no inflammation after using both compounds in Wistar male rats. We have also noted some, but not significant, alteration in liver enzymes representing modest hepatotoxicity. Cytotoxicity of peritoneal macrophages, in the presence of compound A or B, showed 50% of survival of macrophages. On the other hand, macrophages previously infected with Candida albicans and treated with substance A or B exhibited an increased cytokine IL-10 at 24h incubation. By checking the effect of substance A or B on growing C. albicans, the results pointed that these substances revealed antifungal activity against C. albicans, in 24h culture with a reduction of yeast cells.