Leptospirillum forms a minor portion of the population in Zijinshan commercial non-aeration copper bioleaching heap identified by 16S rRNA clone libraries and real-time PCR

Abstract

The distribution and diversity of acidophilic microbe at the ore surface of Zijinshan commercial non-aeration low-grade copper bioleaching heap operated at pH 0.8 were investigated. Samples taken from − 1 m, − 2 m, − 3 m from the top of heap surface were investigated by 16S rRNA gene clone library. Phylogenetic analyses of 16S rRNA fragments revealed that the retrieved bacterial sequences mainly related to genus Acidithiobacillus (66.78%), genus Leptospirillum (28.29%), genus Sulfobacillus (3.29%) and genus Ferrimicrobium (1.64%). For archaea, only Ferroplasma acidiphilum was detected. Bacterial diversity in the heap was increased from surface layer to underground. The proportion of genus Leptospirillum was sharply reduced (from 48.5% to 5%) from higher depth to lower depth and reverse correlation of increased A. ferrooxidans (from 0.95% to 15.00%) and S. thermotolerans (from undetectable to 7.00%) were found in the heap. Sulfur oxidizers including A. albertensis and A. caldus also vertically increased from higher depth to lower depth (from 50.47% to 70.00%). Samples taken from − 2 m, − 3 m from the top of heap surface were further investigated by real-time PCR, the results were consistent with clone libraries that the growth of genus Leptospirillum was decreased from higher depth to lower depth. Our finding indicated that growth inhibition of genus Leptospirillum could be achieved in the non-aeration heap and genus Acidithiobacillus especially sulfur oxidizers A. albertensis and A. caldus were dominant at the ore surface inside the non-aeration heap.