Gene expression levels of Acidithiobacillus ferrooxidans with varying intracellular c-di-GMP concentrations during bioleaching
Bioleaching, a sustainable and environmentally friendly emerging technology, relies on Acidithiobacillus ferrooxidans as a model microorganism for extracting metals from ores. This study investigated how intracellular cyclic diguanylate (c-di-GMP) concentrations regulate biofilm composition and bioleaching performance in A. ferrooxidans. By constructing strains with varying c-di-GMP levels, it was found that moderate c-di-GMP concentrations enhance bioleaching efficiency by upregulating genes associated with extracellular electron transfer (e.g., omcB and cyc2) in biofilms, a mechanism linked to optimized iron oxidation pathways. In contrast, high c-di-GMP levels improve arsenic resistance by promoting exopolysaccharide (EPS) synthesis in biofilms, likely through activation of pel-like operons (e.g., pelD), which strengthen biofilm structural integrity under toxic conditions. These findings reveal a dual regulatory role of c-di-GMP: prioritizing leaching efficiency via electron transport in low-arsenic environments and enhancing stress resistance through EPS production in high-arsenic scenarios. This study provides a theoretical foundation for tailoring A. ferrooxidans to diverse industrial bioleaching environments, leveraging its metabolic versatility and biofilm adaptability. The integration of synthetic biology approaches (e.g., genetic engineering of c-di-GMP pathways) further highlights potential applications for optimizing bioleaching strains. Overall design: Cell transcriptome data of Acidithiobacillus ferrooxidans strains with varying intracellular cyclic diguanylate (c-di-GMP) concentrations during bioleaching under arsenic stress.