Identification and characterization of a metal-resistant Acidithiobacillus ferrooxidans as important potential application for bioleaching

Abstract

Bioleaching is a common and eco-friendly method for the metals mobilization from mines, contaminated soils and wastes and it can be used in metal extraction and bioremediation. Due to the fact that these processes are considered as metabolism-dependent processes, isolation and identifying of the strains with high resistance features in responsible bacteria are one of the most important steps to have. In present study, an Iranian new isolate of iron-oxidizing bacteria was characterized. The phylogenetic analysis and 16S rRNA gene sequence of strain ZT-94 indicated that this strain is related to Acidithiobacillus ferrooxidans. It is investigated that the ferrous iron oxidation was increased dramatically in the early hours of bacterial growth and the ferrous iron (Fe2+) was completely oxidized at 30 h. According to the results, strain ZT-94 had the high tolerance capability to U, Ba, Al and Se. Iron oxidation by strain ZT-94 was inhibited by the addition of 312.5 mg/L Se and 70 mg/L Te but concentrations above 5000 mg/L of Ba and 2000 mg/L Al had no inhibitory effect on bacterial growth. In addition, strain ZT-94 was able to grow in the pH range of 1–4, temperatures at 25–35 °C. Results showed no inhibitory effects on bacterial growth rate in presence of 0.1 w/v organic compounds like fructose and glucose but a delayed growth was detected in presence of yeast extract in comparison with the others. The results showed that strain ZT-94 had high environmental adaptability and can be introduced as a suitable and valuable candidate for research in the bioleaching and bioremediation processes.