ABSTRACT
Solar-to-fuel conversion is a novel clean energy approach that has gained the interest of many researchers. Solar-driven photocatalysts have become essential to providing valuable fuel gases such as methane and hydrogen. Solar energy has emerged as a renewable, abundant energy source that can efficiently drive photochemical reactions through plasmonic photocatalysis. As a capping agent, orange peel extract was used in this study in a microwave-assisted green method to incorporate titanium dioxide with distinct amounts (3, 5, and 7 wt%) from Pd-plasmonic nanoparticles (2-5 nm). The leading role for plasmonic nanoparticles made from Pd-metal is enhancing the photocatalyst's ability to capture visible light, improving its performance. X-Ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), Brunauer, Emmett, and Teller (BET) surface area analysis, and UV-vis DRS analyses have investigated the obtained plasmonic photocatalysts' crystallographic, morphological, and optical characteristics. The UV-vis absorption spectra demonstrated the visible light absorption capacity attributed to the localized surface plasmonic resonance (LSPR) behavior of the newly formed nanoplasmonic photocatalysts. The generated Pd-TiO2 nanomaterials' photocatalytic activity has been examined and evaluated for combustible gas production, including the formation of CH4 and H2 from the photocatalytic degradation of Reactive Yellow 15 (RY) during a deoxygenated photoreaction in a homemade solar photobiogas reactor.
ABSTRACT
Promoters of genes encoding superoxide dismutase (sodA) and peptide methionine sulfoxide reductase (msrA) from Cory-nebacterium glutamicum were cloned and sequenced. Promoter region analysis of sodA-msrA was unable to identify putative sites of fixed eventual regulators except for possible sites of fixed OxyR and integra-tion host factor. A study of the regulation of these genes was performed using the lacZ gene of Escherichia coli as a reporter placed under the control of sequences downstream of sodA and msrA. In silico analysis was used to identify regulators in the genome of C. glutamicum, which revealed the absence of homologs of soxRS and arcA and the presence of inactive oxyR and putative candidates of the homologs of ahpC, ohrR, integration host factor, furA, IdeR, diphtheria toxin repressor, and mntR.
Subject(s)
Corynebacterium glutamicum/genetics , Gene Expression Regulation, Bacterial , Gene Expression Regulation, Enzymologic , Methionine Sulfoxide Reductases/genetics , Oxidative Stress/physiology , Superoxide Dismutase/genetics , Bacterial Proteins/biosynthesis , Bacterial Proteins/genetics , Corynebacterium glutamicum/metabolism , Corynebacterium glutamicum/radiation effects , Methionine Sulfoxide Reductases/biosynthesis , Oxidative Stress/genetics , Promoter Regions, Genetic , Stress, Physiological , Superoxide Dismutase/biosynthesisABSTRACT
Superoxide dismutase (SOD) of Corynebacterium glutamicum was purified and characterized. The enzyme had a native molecular weight of about 80kDa, whereas a monomer with molecular weight of 24kDa was found on SDS-PAGE suggesting it to be homotetramer. The native SOD activity stained gel revealed a unique cytosolic enzyme. Supplementing growth media with manganese increased the specific activity significantly, while adding iron did not result in significant difference. No growth perturbation was observed with the supplemented media. In vitro metal removal and replacement studies revealed conservation of about 85% of the specific activity by substitution with manganese, while substitution with copper, iron, nickel or zinc did not restore any significant specific activity. Manganese was identified by atomic absorption spectrometer, while no signals corresponding to fixing other metallic elements were detected. Thus, C. glutamicum SOD could be considered a strict (non-cambialistic) manganese superoxide dismutase (MnSOD).
