Douglas E. Rawlings

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Microorganisms are used in large-scale heap or tank aeration processes for the commercial extraction of a variety of metals from their ores or concentrates. These include copper, cobalt, gold and, in the past, uranium. The metal solubilization processes are considered to be largely chemical with the microorganisms providing the chemicals and the space(More)
Biomining is the use of microorganisms to extract metals from sulfide and/or iron-containing ores and mineral concentrates. The iron and sulfide is microbially oxidized to produce ferric iron and sulfuric acid, and these chemicals convert the insoluble sulfides of metals such as copper, nickel and zinc to soluble metal sulfates that can be readily recovered(More)
The pasABC genes of the proteic plasmid addiction system of broad-host-range plasmid pTF-FC2 were autoregulated. The PasA antidote was able to repress the operon 25-fold on its own, and repression was increased to 100-fold when the PasB toxin was also present. Autoregulation appears to be an essential requirement for pas-mediated plasmid stabilization(More)
BACKGROUND Acidithiobacillus caldus is a sulfur oxidizing extreme acidophile and the only known mesothermophile within the Acidithiobacillales. As such, it is one of the preferred microbes for mineral bioprocessing at moderately high temperatures. In this study, we explore the genomic diversity of A. caldus strains using a combination of bioinformatic and(More)
Acidithiobacillus caldus is a moderately thermophilic, acidophilic bacterium that has been reported to be the dominant sulfur oxidizer in stirred-tank processes used to treat gold-bearing arsenopyrite ores. It is also widely distributed in heap reactors used for the extraction of metals from ores. Not only are these bacteria commercially important, they(More)
An understanding of biofilm formation is relevant to the design of biological strategies to improve the efficiency of the bioleaching process and to prevent environmental damages caused by acid mine/rock drainage. For this reason, our laboratory is focused on the characterization of the molecular mechanisms involved in biofilm formation in different(More)
During a search for genes encoding electron transport proteins from a Thiobacillus ferroxidans ATCC 33020 gene bank, a 19.8 kb plasmid, pTF5, which conferred increased sensitivity to the antimicrobial agent metronidazole upon an Escherichia coli mutant, was isolated and cloned in E. coli. The plasmid had an identical restriction enzyme map to a plasmid(More)
The gene for gamma-glutamylcysteine synthetase (gshA) from Thiobacillus ferrooxidans was isolated from a family of cosmids by its ability to complement an Escherichia coli gshA trxA double mutant which was unable to grow on minimal medium lacking glutathione. The predicted sequence of the gamma-glutamylcysteine synthetase was found to have only 18% amino(More)
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