Metal Transformation by a Novel Isolate From a Subsurface Environment

The capability of microorganisms to alter metal speciation offers potential for the development of new strategies for immobilization of toxic metals in the environment. A metal-reducing microbe, "" strain UFO1, was isolated under strictly anaerobic conditions from an Fe(III)-reducing enrichment established with uncontaminated soil from the Department of Energy Oak Ridge Field Research Center, Tennessee. "" UFO1 is a rod-shaped, spore-forming, and Gram-variable anaerobe with a fermentative metabolism. It is capable of reducing the humic acid analog anthraquinone-2,6-disulfonate (AQDS) using a variety of fermentable substrates and H. Reduction of Fe(III)-nitrilotriacetic acid occurred in the presence of lactate as carbon and electron donor. Ferrihydrite was not reduced in the absence of AQDS. Nearly complete reduction of 1, 3, and 5 ppm Cr(VI) occurred within 24 h in suspensions containing 10 cells mL when provided with 10 mM lactate; when 1 mM AQDS was added, 3 and 5 ppm Cr(VI) were reduced to 0.1 ppm within 2 h. Strain UFO1 is a novel species within the bacterial genus , having 98.16% 16S rRNA gene sequence similarity with the most closely related described species, R7. The G+C content of the genomic DNA was 38 mol%, and DNA-DNA hybridization of "" UFO1 against R7 indicated an average 16.8% DNA-DNA similarity. The unique phylogenetic, physiologic, and metal-transforming characteristics of "" UFO1 reveal it is a novel isolate of the described genus .