Responses of Acidithiobacillus thiooxidans A01 to Individual and Joint Nickel (Ni2+) and Ferric (Fe3+)

Accessing Metals from Low-Grade Ores and the Environmental Impact Considerations: A Review of the Perspectives of Conventional versus Bioleaching Strategies

Mining has advanced primarily through the use of two strategies: pyrometallurgy and hydrometallurgy. Both have been used successfully to extract valuable metals from ore deposits. These strategies, without a doubt, harm the environment. Furthermore, due to decades of excessive mining, there has been a global decline in high-grade ores. This has resulted in a decrease in valuable metal supply, which has prompted a reconsideration of these traditional strategies, as the industry faces the current challenge of accessing the highly sought-after valuable metals from low-grade ores. This review outlines these challenges in detail, provides insights into metal recovery issues, and describes technological advances being made to address the issues associated with dealing with low-grade metals. It also discusses the pragmatic paradigm shift that necessitates the use of biotechnological solutions provided by bioleaching, particularly its environmental friendliness. However, it goes on to criticize the shortcomings of bioleaching while highlighting the potential solutions provided by a bespoke approach that integrates research applications from omics technologies and their applications in the adaptation of bioleaching microorganisms and their interaction with the harsh environments associated with metal ore degradation.

Bioinformatics and Transcriptional Study of the Nramp Gene in the Extreme Acidophile Acidithiobacillus ferrooxidans Strain DC

The family of Nramp (natural resistance-associated macrophage protein) metal ion transporter functions in diverse organisms from bacteria to humans. Acidithiobacillus ferrooxidans (At. ferrooxidans) is a Gram-negative bacterium that lives at pH 2 in high concentrations of soluble ferrous ion (600 mM). The AFE_2126 protein of At. ferrooxidans of the Dachang Copper Mine (DC) was analyzed by bioinformatics software or online tools, showing that it was highly homologous to the Nramp family, and its subcellular localization was predicted to locate in the cytoplasmic membrane. Transcriptional study revealed that AFE_2126 was expressed by Fe2+-limiting conditions in At. ferrooxidans DC. It can be concluded that the AFE_2126 protein may function in ferrous ion transport into the cells. Based on the ΔpH of the cytoplasmic membrane between the periplasm (pH 3.5) and the cytoplasm (pH 6.5), it can be concluded that Fe2+ is transported in the direction identical to that of the H+ gradient. This study indirectly confirmed that the function of Nramp in At. ferrooxidans DC can transport divalent iron ions.