Magnesium-sulfur batteries are one of the most promising next-generation battery systems due to their high energy density, low cost, and high level of safety. However, the reaction mechanisms are not well understood, and in particular, the discharge reaction products have not yet been identified. Here we show that zinc blende magnesium sulfide is observed as a reaction product after discharging in magnesium-sulfur batteries. When magnesium reacts electrochemically with sulfur in a sulfone-based magnesium electrolyte, sulfur becomes amorphous consisting of magnesium and sulfur in the cathode. In this study, it has been found that the amorphous material has an unusual local structure, which is not related to the most stable rock salt phase of magnesium sulfide but rather the metastable zinc blende phase. It was indicated that this material realizes the reversibility of magnesium-sulfur batteries.
The development of as a non-model host organism for synthetic biology is hampered by a lack of genetic tools and techniques. New plating and liquid-based selection methods were developed to improve the identification of transformed cell lines. Enabled by these methods, a hyperactive transposase was used to generate mutants with integrated genes for the expression of the superfolder green fluorescent protein (sfGFP) gene or a 2-keto decarboxylase (KDC) gene, which enabled the production and secretion of isobutyric acid (IBA). An inverse PCR method was used to identify the insertion sites of the KDC gene in several mutants, leading to the identification of a region on the chromosome that may be suitable for future genetic insertions. These results demonstrate that functional exogenous metabolic genes have been chromosomally integrated into, and this advance will facilitate the future development of these cells for new biotechnology applications. is an iron- and sulfur-oxidizing chemolithoautotroph and is a key member of the microbial consortia used in industrial biomining applications. There is interest in exploiting these cells for other metal recovery applications as well as in developing them as unique nonmodel microbial cell factories. Plasmid-driven expression of exogenous genes has been reported, and homologous recombination has been used to knock out some gene expression. Here, new selection protocols facilitated the development of a transposition method for chromosomal integration of exogenous genes into This greatly expands the available genetic toolbox, which will open the door to greater metabolic engineering efforts for these cells.
Acidithiobacillus ferrooxidans cells can oxidize iron and sulfur and are key members of the microbial biomining communities that are exploited in the large-scale bioleaching of metal sulfide ores. Some minerals are recalcitrant to bioleaching due to the presence of other inhibitory materials in the ore bodies. Additives are intentionally included in processed metals to reduce environmental impacts and microbially influenced corrosion. We have previously reported a new aerobic corrosion
Microbially influenced corrosion (MIC) results in significant damage to metallic materials in many industries. Anaerobic sulfate-reducing bacteria (SRB) have been well studied for their involvement in these processes. Highly corrosive environments are also found in pulp and paper processing, where chloride and thiosulfate lead to the corrosion of stainless steels. Acidithiobacillus ferrooxidans is a critically important chemolithotrophic acidophile exploited in metal biomining operations, and there is interest in using A. ferrooxidans cells for emerging processes such as electronic waste recycling. We explored conditions under which A. ferrooxidans could enable the corrosion of stainless steel. Acidic medium with iron, chloride, low sulfate, and pyrite supplementation created an environment where unstable thiosulfate was continuously generated. When combined with the chloride, acid, and iron, the thiosulfate enabled substantial corrosion of stainless steel (SS304) coupons (mass loss, 5.4 ± 1.1 mg/cm2 over 13 days), which is an order of magnitude higher than what has been reported for SRB. There results were verified in an abiotic flow reactor, and the importance of mixing was also demonstrated. Overall, these results indicate that A. ferrooxidans and related pyrite-oxidizing bacteria could produce aggressive MIC conditions in certain environmental milieus.
IMPORTANCE MIC of industrial equipment, gas pipelines, and military material leads to billions of dollars in damage annually. Thus, there is a clear need to better understand MIC processes and chemistries as efforts are made to ameliorate these effects. Additionally, A. ferrooxidans is a valuable acidophile with high metal tolerance which can continuously generate ferric iron, making it critical to copper and other biomining operations as well as a potential biocatalyst for electronic waste recycling. New MIC mechanisms may expand the utility of these cells in future metal resource recovery operations.
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