Isolation and characterization of<i>Ferroplasma thermophilum</i>sp. nov., a novel extremely acidophilic, moderately thermophilic archaeon and its role in bioleaching of chalcopyrite

Abstract

AIMS: To isolate Ferroplasma thermophilum L1(T) from a low pH environment and to understand its role in bioleaching of chalcopyrite. METHODS AND RESULTS: Using serial dilution method, a moderately thermophilic and acidophilic ferrous iron-oxidizing archaeon, named L1(T), was isolated from a chalcopyrite-leaching bioreactor. The morphological, biochemical and physiological characteristics of strain L1(T) and its role in bioleaching of chalcopyrite were studied. Strain L1(T) was a nonmotile coccus that lacked cell wall. Strain L1(T) had a temperature optimum of 45 degrees C and the optimum pH for growth was 1.0. Strain L1(T) was capable of chemomixotrophic growth on ferrous iron and yeast extract. Results of fatty acid analysis, DNA-DNA hybridization, G+C content, and analysis based on 16S rRNA gene sequence indicated that strain L1(T) should be grouped in the genus Ferroplasma, and represented a new species, Ferroplasma thermophilum. Ferroplasma thermophilum in combination with Acidithiobacillus caldus and Leptospirillum ferriphilum could improve the copper dissolution in bioleaching of chalcopyrite. CONCLUSIONS: A novel extremely acidophilic, moderately thermophilic archaeon isolated from a bioleaching reactor has been identified as F. thermophilum that played an important role in bioleaching of chalcopyrite at low pH. SIGNIFICANCE AND IMPACT OF THE STUDY: This study contributes to understand the characteristics of F. thermophilum L1(T) and its role in bioleaching of sulfide ores.