Integrated Ecogenomics Study for Bioremediation of Cr(VI) at Hanford 100H Area

Conference · Tue Aug 12 00:00:00 EDT 2008

OSTI ID:936749

Chakraborty, Romy; Chakraborty, Romy

Hexavalent chromium is a widespread contaminant found in groundwater. In order to stimulate microbially mediated Cr(VI)-reduction, a poly-lactate compound was injected into Cr(VI)-contaminated aquifers at site 100H at Hanford. Investigation of bacterial community composition using high-density DNA microarray analysis of 16S rRNA gene products revealed a stimulation of Pseudomonas, Desulfovibrio and Geobacter species amongst others. Enrichment of these organisms coincided with continued Cr(VI) depletion. Functional gene-array analysis of DNA from monitoring well indicated high abundance of genes involved in nitrate-reduction, sulfate-reduction, iron-reduction, methanogenesis, chromium tolerance/reduction. Clone-library data revealed Psedomonas was the dominant genus in these samples. Based on above results, we conducted lab investigations to study the dominant anaerobic culturable microbial populations present at this site and their role in Cr(VI)-reduction. Enrichments using defined anaerobic media resulted in isolation of an iron-reducing, a sulfate-reducing and a nitrate-reducing isolate among several others. Preliminary 16S rDNA sequence analysis identified the isolates as Geobacter metallireducens, Pseudomonas stutzeri and Desulfovibrio vulgaris species respectively. The Pseudomonas isolate utilized acetate, lactate, glycerol and pyruvate as alternative carbon sources, and reduced Cr(VI). Anaerobic washed cell suspension of strain HLN reduced almost 95?M Cr(VI) within 4 hr. Further, with 100?M Cr(VI) as sole electron-acceptor, cells grew to 4.05 x 107 /ml over 24 h after an initial lag, demonstrating direct enzymatic Cr(VI) reduction coupled to growth. These results demonstrate that Cr(VI)-immobilization at Hanford 100H site could be mediated by direct microbial metabolism in addition to indirect chemical reduction of Cr(VI) by end-products of microbial activity.

• Research Organization: Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: Earth Sciences Division; Physical Biosciences Division
• DOE Contract Number: DE-AC02-05CH11231
• OSTI ID: 936749
• Report Number(s): LBNL-890E; TRN: US200818%%1180
• Resource Relation: Conference: Society for Industrial Microbiology 2008 Annual Meeting, San Diego, CA, 08/10-14/2008
• Country of Publication: United States
• Language: English

Related Subjects

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ABUNDANCE
AQUIFERS
BINDING ENERGY
BIOREMEDIATION
CARBON SOURCES
CHROMIUM
DESULFOVIBRIO
DNA
ELECTRONS
FUNCTIONALS
GENES
GLYCEROL
METABOLISM
PSEUDOMONAS
STIMULATION
STRAINS
STRUCTURAL CHEMICAL ANALYSIS
VALENCE
Biogeochemistry
Bioremediation
Environmental Genomics
Field Studies
Phenomics
Sulfate Reducers