Heavy metal resistance by two bacteria strains isolated from a copper mine tailing in China

Abstract

Two highly heavy metal resistant indigenous bacterial strains, DX-T3-01 and DX-T3-03, were isolated from the biggest tailing in Asia-Dexing copper mine 4# tailing. The strain DX-T3-01 exhibited high tolerance to cadmium: 10 mM Cd2+ with yeast tryptophan peptone glucose (YTPG) agar plates and 18 mM in liquid medium. The strain DX-T3-03 was highly resistant to zinc and could endure 35 mM Zn2+ with YTPG agar plates and 40 mM in liquid medium. They also showed tolerance to other heavy metals, such as copper, lead and nickel. The morphology, physiological and biochemical characteristics of the two strains were examined by scanning electron microscope (SEM) and BIOLOG. The strains showed different metabolic patterns of carbon sources. The strain DX-T3-03 had a larger range of antibiotic resistance than DX-T3-01. On the basis of 16S rDNA sequencing, the two strains were identified as Ralstonia pickettii strain DX-T3-01 and Sphingomonas sp. strain DX-T3-03, respectively. This study supplied potential bacterial materials for tailing bioremediation in the future.   Key words: Heavy metals, tolerant bacteria, isolation, mine tailing.