Effect of biogenic siderophores produced by Bacillus thuringiensis on gold and other element bioleaching from silicate ore

Abstract

This comprehensive study delves into the role of silicate ore pretreatment and the biogenic siderophores produced by Bacillus thuringiensis in the bioleaching process of gold (Au) and various other elements. The results revealed that an effective pretreatment method involved subjecting silicate ore to ball milling (BM) at 200 rpm for 1 h, followed by ozonation (O3) for 10 min before initiating the bioleaching process. Subsequently, in the leaching of Au and other elements, the highest leachability was achieved through a two-step conditioning approach, involving the first and second stages of bioleaching with B. thuringiensis. The results strongly suggest that the mechanism of elements leaching is closely linked to the release of biogenic siderophores by B. thuringiensis, which possess remarkable potential as chelators and metal-binding agents, facilitating the formation of metal-siderophore complexes. Furthermore, the finding confirmed that commercial siderophores can effectively facilitate the leaching of Au and elements from silicate ore. Additionally, the presence of amino acids in nutrient broth (NB) medium provides the ability to bind with Au, forming Au-amino acids complexes. This finding underscores the effectiveness of the two-step conditioning approach with B. thuringiensis, particularly under mild alkaline pH conditions. This innovative technology offers numerous advantages, including its environmentally friendly and sustainable nature, safety, and cost-effectiveness. It presents a promising method for the efficient recovery of Au and other elements from pretreated silicate ore, especially those with low concentrations of valuable minerals, all through the remarkable capabilities of biogenic siderophores.