Attempts to Stimulate Leaching Activity of Acidithiobacillus ferrooxidans Strain TFBk

Autotrophic acidophilic bacteria Acidithiobacillus ferrooxidans is a model species for studying metal bioleaching from low-grade sulfide ores and concentrates. Arsenopyrite gold-bearing concentrates are refractory and often processed using biohydrometallurgical approaches; therefore, it is important to develop methods to improve arsenopyrite bioleaching. In the present work, we have studied the possibility of improving arsenopyrite concentrate bioleaching by the strain of A. ferrooxidans. For this purpose, we have analyzed the genome of the strain A. ferrooxidans TFBk to reveal the genes potentially important in the bioleaching process. Genes determining resistance to arsenic, as well genes involved in the utilization of C-1-compounds and resistance to oxidative stress, were revealed. Therefore, the possibility of increasing the rate of arsenopyrite concentrate bioleaching using C-1-compounds (methanol and formate) was studied. Formate was able to increase both the biomass yield of the strain A. ferrooxidans TFBk as well as the bioleaching rate. In addition, the effect of redox potential increase by means of the addition of sodium persulfate in the medium on arsenopyrite concentrate bioleaching was studied. It was shown that the addition of 0.1% sodium persulfate stimulated strain growth, while a higher concentration inhibited it. Despite this, the rate of concentrate bioleaching increased in the presence of 0.5-1.0% of persulfate, which may be explained by the interactions of added oxidizer with concentrate components.

Automated summary

In this study, the genome of Acidithiobacillus ferrooxidans strain TFBk was analyzed to identify genes potentially important in the bioleaching process of arsenopyrite concentrate. The study found genes related to arsenic resistance, utilization of C-1 compounds, and oxidative stress resistance. The results showed that the addition of formate increased both the biomass yield and the bioleaching rate of the strain. Furthermore, the effect of increasing redox potential by adding sodium persulfate on arsenopyrite concentrate bioleaching was investigated. The addition of 0.1% sodium persulfate stimulated strain growth and increased the rate of concentrate bioleaching.