The removal of iron and phosphate from culture medium by Rhodococcus ruber SiAl

The microbial accumulation of heavy metals and phosphate is of interest for the bioremediation of polluted waters. In this work, we showed that at cultivation of the bacterium Rhodococcus ruber SiAl in the medium with 2.0 mM Fe³⁺ for stationary growth stage, up to 99% of the iron was associated with the biomass. Magnesium ion accumulation from the medium with 2 mM Mg²⁺ did not exceed 5% of the initial content. The cells did not remove manganese ions from the medium; moreover, the presence of MnSO₄ inhibited growth. The cells of Rhodococcus ruber SiAl removed phosphate from the medium: 75, 20, and 10% of the initial phosphate content was removed during cultivation in the presence of 6 mM phosphate and 2 mM Fe³⁺, 2 mM Mg²⁺, or 2 mM Mn²⁺, respectively. In the genome of R. ruber SiAl, genes encoding proteins of the siderophore synthesis systems and phosphate transport systems were identified. The strain was the most efficient for iron accumulation, which suggests a promising application for the removal of phosphate and iron from polluted waters.