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Co3O4 was synthesized on carbon paper (CP) using a facile method to improve electrochemical nitrate-toammonia conversion efficiency. The resulting Co3O4-CP electrode demonstrated an exceptional Faradaic efficiency of almost 100% across a broad range of application conditions, with a peak NH3 yield of 3.43 mmol h-1 cm-2 (2.25 mol gCo-1 h-1). [ABSTRACT FROM AUTHOR]

Arabidopsis halleri ssp. gemmifera is classified as Cd and Zn hyperaccumulator plant; however, the disparity accumulation preferences in organs (root, stem and leaves) between cadmium and zinc seems less understandable. Therefore, this study aimed to portray accumulation behaviour toward the presence of Cd and Zn in the hydroponic method employing A. halleri ssp. gemmifera. The experiment was conducted by applying this plant using 2 and 300 µM of Cd, and 2 and 200 µM Zn, together with 20% Hoagland solution for 7 days, separately. The results showed that Zn in the medium was uptake faster than Cd. Furthermore, increasing Cd/Zn supply at the medium resulted in an increasing accumulation of Cd/Zn in the organs of the plant. In both Cd treatments, the accumulation followed the order of stem>root>leaves, indicating Cd transportation to the upper part has occurred during this period. The same accumulation preference pattern was also reported in the 200 µM Zn supply. However, at 2 µM Zn supply, Zn accumulation was mainly found in the leaves, followed by the root and stem. A. halleri ssp. gemmifera uptake Zn faster from the medium and translocate rapidly to the leaves at low-level Zn supply. Increasing Zn supply concentration might inhibit the translocation of Zn from stem to leaves. Meanwhile, regardless of Cd supply concentrations, this plant could only translocate Cd to the stem mostly within a short-time exposure period. Therefore, this study concluded that A. halleri ssp. gemmifera exhibited different accumulation responses when exposed to different Cd and Zn supply concentrations. [ABSTRACT FROM AUTHOR]

This study focuses on how to solve cadmium (Cd) contamination in soil because this contaminant decreases soil quality. Soil remediation using the hyperaccumulator plants is an optional process to solve soil contamination. Arabidopsis halleri ssp. gemmifera (hereinafter referred to as A. halleri), is one of the candidate plants expected to be used for phytoremediation of Cd contaminated soil. The A. halleri promote solubilization of Cd in the soil directly or indirectly using its secreted root exudate. However, the effect of the metabolites profile of this plant to Cd uptake from contaminated soil is still unclear. The purpose of this study was to examine the contribution of root exudates of A. halleri to extract Cd in the soil. Cd-contaminated soil used in this study was a farmland soil containing 5.8 mg kg-1 of Cd and 648 mg kg-1 of Zn taken from Tome City, Miyagi Prefecture, Japan. Soil leaching tests were conducted using the solution containing the root exudates from A. halleri plant. The accelerating effect of root exudates of A. halleri on solubilization of Cd is fundamental information to construct the benefit of phytoremediation. [ABSTRACT FROM AUTHOR]

A total of 65 spore-forming mercury-resistant bacteria were isolated from natural environments worldwide in order to understand the acquisition of additional genes by and dissemination of mercury resistance transposons across related Bacilli genera by horizontal gene movement. PCR amplification using a single primer complementary to the inverted repeat sequence of TnMERI1-like transposons showed that 12 of 65 isolates had a transposon-like structure. There were four types of amplified fragments: Tn5084, Tn5085, TndMER3 (a newly identified deleted transposon-like fragment) and Tn6294 (a newly identified transposon). TndMER3 is a 3.5-kb sequence that carries a merRETPA operon with no merB or transposase genes. It is related to the mer operon of Bacillus licheniformis strain FA6-12 from Russia. DNA homology analysis shows that Tn6294 is an 8.5-kb sequence that is possibly derived from TndMER3 by integration of a TnMERI1-type transposase and resolvase genes and in addition the merR2 and merB1 genes. Bacteria harboring Tn6294 exhibited broad-spectrum mercury resistance to organomercurial compounds, although Tn6294 had only merB1 and did not have the merB2 and merB3 sequences for organomercurial lyases found in Tn5084 of B. cereus strain RC607. Strains with Tn6294 encode mercuric reductase (MerA) of less than 600 amino acids in length with a single N-terminal mercury-binding domain, whereas MerA encoded by strains MB1 and RC607 has two tandem domains. Thus, TndMER3 and Tn6294 are shorter prototypes for TnMERI1-like transposons. Identification of Tn6294 in Bacillus sp. from Taiwan and in Paenibacillus sp. from Antarctica indicates the wide horizontal dissemination of TnMERI1-like transposons across bacterial species and geographical barriers. [ABSTRACT FROM AUTHOR]

Recombinant tilapia ( Oreochromis mossambicus) fish metallothionein (MT) was used as a surface biosorbent for mercury removal in Escherichia coli. Fish MT conferred better resistance than did mouse or human MT. When tilapia MT (tMT) was fused with an outer-membrane protein, outer membrane protein C (OmpC), the membrane-targeted fusion protein, OmpC–tMT, gave enhanced resistance compared with cytoplasmic tMT expressed in the same host cell. The cytoplasmically expressed tMT showed high mercury adsorption (4.3 ± 0.4 mg/g cell dry weight). The cell surface that expressed E. coli showed about 25% higher adsorption ability (5.6 ± 0.4 mg/g) than the cells expressing cytoplasmic MT, attaining almost twice the level of adsorption of the control plasmid (3.0 ± 0.4 mg/g). As MTs are also known for their ability to scavenge hydroxyl-free radicals, it was also shown that tMT exhibited better radical-scavenging activities than glutathione. These results suggest that fish MT has potential for the development of a bioremediation system for mercury removal that protects the harboring E. coli host by free-radical scavenging. [ABSTRACT FROM AUTHOR]