Iron based catalysts from novel low-cost organic precursors for enhanced oxygen reduction reaction in neutral media microbial fuel cells

© 2016 The Royal Society of Chemistry. Two iron-based platinum group metal-free catalysts for the oxygen reduction reaction (ORR) were synthesized from novel and low cost organic precursors named niclosamide and ricobendazole. These catalysts have been characterized, incorporated in a gas diffusional electrode and tested in "clean" conditions as well as in operating microbial fuel cell (MFC) for 32 days. Both catalysts demonstrated unprecedented performance yielding a power density 25% higher than that of platinum (Pt) and roughly 100% higher than activated carbon (AC) used as a control. Durability tests were performed and showed that Pt-based cathodes lost their activity within the first week of operation, reaching the level of the supporting AC-based electrode. Fe-ricobendazole, however, demonstrated the highest performance during the long-term study with a power density of 195 ± 7 μW cm-2 (day 2) that slightly decreased to 186 ± 9 μW cm-2 at day 29. Fe-niclosamide also outperformed Pt and AC but the power density roughly decreased with 20% for the 32 days of the study. Accelerated poisoning test using S2- as pollutant showed high losses in activity for Pt. Fe-niclosamide suffered higher losses compared to Fe-ricobendazole. Importantly, Fe-ricobendazole represents a 55-fold cost reduction compared to platinum

A family of Fe-N-C oxygen reduction electrocatalysts for microbial fuel cell (MFC) application: Relationships between surface chemistry and performances

© 2016 The Author(s) Different iron-based cathode catalysts have been studied for oxygen reduction reaction (ORR) in neutral media and then applied into microbial fuel cells (MFC). The catalysts have been synthesized using sacrificial support method (SSM) using eight different organic precursors named Niclosamide, Ricobendazole, Guanosine, Succinylsulfathiazole, Sulfacetamide, Quinine, Sulfadiazine and Pyrazinamide. Linear Sweep Voltammetry (LSV) curves were obtained for the catalysts using a O2 saturated in 0.1M potassium phosphate buffer and 0.1M KCl solution and a Rotating Ring Disk Electrode (RRDE) setup in order to study the ORR characteristics. Additionally, we analyze the peroxide yield obtained for each catalyst which helps us determine the reaction kinetics. Those catalysts have been mixed with activated carbon (AC), carbon black (CB) and PTFE and pressed on a metallic mesh forming a pellet-like gas diffusion electrode (GDE). Results showed that Fe-Ricobendazole, Fe-Niclosamide and Fe-Pyrazinamide had the highest cathode polarization curves and highest power densities output that was above 200μWcm−2. Fe-Ricobendazole, Fe-Niclosamide, Fe-Pyrazinamide, Fe-Guanosine Fe-Succinylsulfathiazole and Fe-Sulfacetamide outperformed compared to Pt cathode. Fe-Sulfadiazene and Fe-Quinine performed better than AC used as control but less than Pt. Correlation of surface composition with performance showed that power density achieved is directly related to the total amount of nitrogen, and in particularly, N coordinated to metal and pyridinic and pyrrolic types while larger amounts of graphitic nitrogen result in worse performance

Discovery of the Class I Antimicrobial Lasso Peptide Arcumycin

Lasso peptides are a structurally diverse superfamily ofconformationally-constrained peptide natural products, of which asubset exhibits broad antimicrobial activity. Although advances inbioinformatics have increased our knowledge of strains harboringthe biosynthetic machinery for lasso peptide production, relatingpeptide sequence to bioactivity remains a continuous challenge.Towards this end, a structure-driven genome mining investigationof Actinobacteria-produced antimicrobial lasso peptides wasperformed to correlate predicted primary structure with antibioticactivity. Bioinformatic evaluation revealed eight putative novelclass I lasso peptide sequences. This subset is predicted topossess antibiotic activity as characterized members of this classhave both broad spectrum and potent activity against Gram positivestrains. Fermentation of one of these hits, StreptomycesNRRL F-5639, resulted in the production of a novel class I lassopeptide, arcumycin, named for the Latin word for bow or arch,arcum. Arcumycin exhibited antibiotic activity against Gram positivebacteria including Bacillus subtilis (4 μg/mL),Staphylococcus aureus (8 μg/mL), and Micrococcus luteus (8μg/mL). Arcumycin treatment of B. subtilis liaI-β-gal promoterfusion reporter strain resulted in upregulation of the system liaRSby the promoter liaI, indicating arcumycin interferes with lipid IIbiosynthesis. Cumulatively, the results illustrate the relationshipbetween phylogenetically related lasso peptides and theirbioactivity as validated through the isolation, structuraldetermination, and evaluation of bioactivity of the novel class Iantimicrobial lasso peptide arcumycin.</p