Integrated physiological and metabolomic analysis reveals the cytochrome c oxidase gene ccoQ-mediated biotite dissolution by Pseudomonas pergaminensis F77

Abstract

To date, the cytochrome c oxidase-synthesizing gene ccoQ-mediated mineral solubilization by bacteria was poorly characterized. Here, the impact of mineral-dissolving Pseudomonas pergaminensis F77 on iron (Fe) and aluminium (Al) release from biotite was evaluated and the relative expression of ccoQ in F77 was analyzed by real-time reverse transcription-quantitative PCR (RT–qPCR) during mineral dissolution process. Then, F77 and the F77∆ccoQ mutant constructed from F77 using homologous recombination were compared for ccoQ-mediated Fe and Al release from biotite and the underlying molecular mechanisms. The F77∆ccoQ decreased the Fe and Al concentrations in the medium by 11 %–49 % between 8 h and 12 h compared to F77. The F77∆ccoQ mutant significantly reduced the Fe²⁺ concentrations by 67 %–80 % between 6 h and 8 h and Fe³⁺ concentrations by 19 %–50 % between 10 h and 12 h compared with F77. Furthermore, significantly enhanced pH values and no significant change in the cell numbers were found in the presence of F77∆ccoQ compared to those in the presence of F77 between 4 h and 12 h. Comparative metabolomic analysis demonstrated downregulated extracellular metabolites (biotin, D-Altro-D-Manno-Heptose, and a variety of acidic metabolites involved in carbohydrate and amino acid metabolisms, cofactor and vitamin synthesis, and glycan biosynthesis) associated with biotite dissolution in the F77∆ccoQ. Furthermore, the expression levels of the metabolite-synthesizing related genes were downregulated in the F77∆ccoQ compared with those in F77. Our findings suggested that ccoQ in F77 facilitated mineral dissolution by upregulating the production of extracellular metabolites associated with mineral dissolution by F77.