The bioleaching of metal sulfide has developed into a very important industrial process and understanding the microbial dynamic is key to advancing commercial bioleaching operations. Here we report the first quantitative description of the dynamic of active communities in an industrial bioleaching heap. Acidithiobacillus ferrooxidans was the most abundant during the first part of the leaching c...

The composition of bacterial populations in copper bioleaching systems was investigated by analysis of DNA obtained either directly from ores or leaching solutions or after laboratory cultures. This analysis consisted of the characterization of the spacer regions between the 16 and 23S genes in the bacterial rRNA genetic loci after PCR amplification. The sizes of the spacer regions, amplified f...

In mixed-culture microbial fuel cells (MFCs), exoelectrogens and other microorganisms compete for substrate. It has previously been assumed that substrate losses to other terminal electron acceptors over a fed-batch cycle, such as dissolved oxygen, are constant. However, a constant rate of substrate loss would only explain small increases in coulombic efficiencies (CEs, the fraction of substrat...

In the absence of iron, dissolution of zinc sulfide was enhanced by the action of Acidithiobacillus caldus at 40 o C. The bioleaching mechanism was similar to that observed for mesophilic species of Acidithiobacillus at 30 o C, although the final metal recovery was lower. When iron was added to the cultures, the solubilization of zinc and copper from the sulfides was higher than that in sterile...

Bioleaching is the extraction of specific metals from ores by using bacteria. The typical bioleaching strain Acidithiobacillus ferrooxidans utilizes energy from the oxidation of ironand sulfur-containing minerals (Baker & Banfield, 2003) and grows around pH 2.0. As bacteria grow optimally within a specific narrow range of pH, the fluctuation of environmental acidity can bring certain disadvanta...

The aim of this investigation was to determine the efficacy of chalcopyrite bioleaching using pure cultures of Acidithiobacillus ferrooxidans or Acidithiobacillus thiooxidans and a mixed culture composed of Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans. The experiments were carried out in shake flasks with [Fe] 4 gL 1 and S 1 gL 1 at pH 1.80, 130 rpm and 30 C. Inocula of both...

The recovery of metal values and safe disposal of spent catalyst is gaining interest due to both its hazardous nature and increased regulation associated with disposal methods. Prior to the recovery of the valuable metals, removal of entrained deposits limit the diffusion of lixiviate resulting in low recovery of metals must be taken into consideration. Therefore, petroleum refinery spent catal...

Expression of aminoacyl-tRNA synthetases is regulated by a variety of mechanisms at the level of transcription or translation. A T-box dependent transcription termination / antitermination riboswitch system that responds to charged / uncharged tRNA regulates expression of aminoacyl tRNA synthetase genes in Gram-positive bacteria. TyrZ, the gene encoding tyrosyl-tRNA synthetase from Acidithiobac...

GeoBiotics, LLC and Kumba Resources (Pty) Ltd are jointly developing the GEOCOAT heap bioleaching technology and downstream processing technology for recovery of zinc from tailings at the Rosh Pinah Mine in Namibia. This paper outlines the development of a computer simulation for the bioleaching of sphalerite and the downstream processing. Computer modeling has shortened the product development...

Leptospirillum ferriphilum Sp-Cl is a Gram negative, thermotolerant, curved, rod-shaped bacterium, isolated from an industrial bioleaching operation in northern Chile, where chalcocite is the major copper mineral and copper hydroxychloride atacamite is present in variable proportions in the ore. This strain has unique features as compared to the other members of the species, namely resistance t...