RESUMEN

BACKGROUND: Several two-component systems of Streptomyces coelicolor, a model organism used for studying antibiotic production in Streptomyces, affect the expression of the bfr (SCO2113) gene that encodes a bacterioferritin, a protein involved in iron storage. In this work, we have studied the effect of the deletion mutant ∆bfr in S. coelicolor. RESULTS: The ∆bfr mutant exhibits a delay in morphological differentiation and produces a lesser amount of the two pigmented antibiotics (actinorhodin and undecylprodigiosin) compared to the wild type on complex media. The effect of iron in minimal medium was tested in the wild type and ∆bfr mutant. Consequently, we also observed different levels of production of the two pigmented antibiotics between the two strains, depending on the iron concentration and the medium (solid or liquid) used. Contrary to expectations, no differences in intracellular iron concentration were detected between the wild type and ∆bfr mutant. However, a higher level of reactive oxygen species in the ∆bfr mutant and a higher tolerance to oxidative stress were observed. Proteomic analysis showed no variation in iron response proteins, but there was a lower abundance of proteins related to actinorhodin and ribosomal proteins, as well as others related to secondary metabolite production and differentiation. Additionally, a higher abundance of proteins related to various types of stress, such as respiration and hypoxia among others, was also revealed. Data are available via ProteomeXchange with identifier PXD050869. CONCLUSION: This bacterioferritin in S. coelicolor (Bfr) is a new element in the complex regulation of secondary metabolism in S. coelicolor and, additionally, iron acts as a signal to modulate the biosynthesis of active molecules. Our model proposes an interaction between Bfr and iron-containing regulatory proteins. Thus, identifying these interactions would provide new information for improving antibiotic production in Streptomyces.

Asunto(s)

Antraquinonas , Antibacterianos , Proteínas Bacterianas , Ferritinas , Hierro , Streptomyces coelicolor , Streptomyces coelicolor/metabolismo , Streptomyces coelicolor/genética , Streptomyces coelicolor/crecimiento & desarrollo , Antibacterianos/biosíntesis , Antibacterianos/metabolismo , Ferritinas/metabolismo , Ferritinas/genética , Proteínas Bacterianas/metabolismo , Proteínas Bacterianas/genética , Hierro/metabolismo , Antraquinonas/metabolismo , Grupo Citocromo b/metabolismo , Grupo Citocromo b/genética , Regulación Bacteriana de la Expresión Génica , Prodigiosina/metabolismo , Prodigiosina/análogos & derivados , Prodigiosina/biosíntesis , Especies Reactivas de Oxígeno/metabolismo , Proteómica , Benzoisocromanquinonas

RESUMEN

Non-destructive techniques are used widely in the metal industry in order to control the quality of materials. Eddy current testing is one of the most extensively used non-destructive techniques for inspecting electrically conductive materials at very high speeds that does not require any contact between the test piece and the sensor. This paper includes an overview of the fundamentals and main variables of eddy current testing. It also describes the state-of-the-art sensors and modern techniques such as multi-frequency and pulsed systems. Recent advances in complex models towards solving crack-sensor interaction, developments in instrumentation due to advances in electronic devices, and the evolution of data processing suggest that eddy current testing systems will be increasingly used in the future.

Asunto(s)

Electricidad , Metalurgia/métodos , Magnetismo , Metalurgia/instrumentación

RESUMEN

The adsorption of five Nalpha-substituted amino acids with a 5-nitroso-6-oxo pyrimidine as substituent on a commercial activated carbon (AC) has been studied in aqueous solution at several pH values. The adsorption processes of these organic compounds have been analyzed on the basis of the electrolytic behavior of the adsorbates. In all cases, the adsorption process is highly irreversible due to strong pi-pi interactions between the arene centers of the AC and the pyrimidine residue of the adsorbates. This interaction is consistent with XPS data and HOMO-LUMO theoretical calculations. The adsorption of these organic compounds provides a new route for the functionalization of the AC surface with carboxyl groups. In addition, the adsorption capacity of the AC/organic compound systems for Cu(II) ions in aqueous solution has been studied at different pH values. These systems show an increase of the adsorption capacity for Cu(II) compared to the AC, which is related to the AC functionalization with carboxyl groups due to the adsorbed organic compounds.