Abstract

At present, gold extraction technology using microorganisms is increasingly interested in research and development with the aim of ensuring high gold recovery efficiency and reducing environmental pollution. This study aims to select indigenous iron-oxidizing bacteria from ore samples collected at gold ores in the Central Highlands (Vietnam) for the use in bioleaching ores. Fourteen strains were isolated from eight ore samples and TNG13.1 strain was selected with high iron-oxidizing ability (89.33%). The strain TNG13.1 is an aerobic, Gram-negative, and catalase positive bacteria; colonies areround, convex and dry, yellow; rod-shaped cells, incapable of forming spores, capable of tolerating acidic pH conditions, and heavy metals. The strainTNG13.1 strain belongs to the chemoautotropautotrophic chemical group, which uses energy from the oxidation of iron and sulfur compounds to grow; grows in the range of pH from 1.5 to 3.0, in temperature range 20 - 50°C. Results of 16S rRNA gene sequence analysis showed that strain TNG13.1 belonged to Acidithiobacillus ferrooxidans and named it A. ferrooxidans TNG13.1 (GenBank Accession numbers MW713141). Bioleaching on gold-bearing sulfide ore, gold-bearing tin-wolfram ore and gold-bearing antimony ore showed the best treatment efficiency at 1% (w/v) pulp density with efficiency of 100%; 48.44% and 63.13%, respectively. Initial positive results show the potential of the application of A. ferrooxidans TNG13.1 strain in the bioleaching of gold ores in Vietnam; contribute to improving the efficiency of gold mining and minimizing environmental pollution.