Potential and whole-genome sequence-based mechanism of elongated-prismatic magnetite magnetosome formation in Acidithiobacillus ferrooxidans BYM.

A magnetosome-producing bacterium Acidithiobacillus ferrooxidans BYM (At. ferrooxidans BYM) was isolated and magnetically screened. The magnetosome yield from 0.5896 to 13.1291 mg/g was achieved under different aeration rates, ferrous sulfate, ammonium sulfate, and gluconic acid concentrations at 30 ℃. TEM observed 6-9 magnetosomes in size of 20-80 nm irregularly dispersed in a cell. STEM-EDXS and HRTEM-FFT implied that the elongated-prismatic magnetite magnetosomes with {110} crystal faces grown along the [111] direction. Whole-genome sequencing and annotation of BYM showed that 3.2 Mb chromosome and 47.11 kb plasmid coexisted, and 322 genes associated with iron metabolism were discovered. Ten genes shared high similarity with magnetosome genes were predicted, providing sufficient evidence for the magnetosome-producing potential of BYM. Accordingly, we first proposed a hypothetic model of magnetosome formation including vesicle formation, iron uptake and mineralization, and magnetite crystal maturation in At. ferrooxidans. These indicated that At. ferrooxidans BYM would be used as a commercial magnetosome-producing microorganism.