Open AccessMetabolically active microbial communities in uranium‐contaminated subsurface sediments
Author(s) -
Akob Denise M.,
Mills Heath J.,
Kostka Joel E.
Publication year - 2007
Publication title -
fems microbiology ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.377
H-Index - 155
eISSN - 1574-6941
pISSN - 0168-6496
DOI - 10.1111/j.1574-6941.2006.00203.x
Subject(s) - gammaproteobacteria , biology , bioremediation , microbial population biology , bacteroidetes , firmicutes , environmental chemistry , actinobacteria , proteobacteria , sediment , microbial mat , stable isotope probing , nitrate , ecology , contamination , microorganism , bacteria , 16s ribosomal rna , cyanobacteria , chemistry , paleontology , genetics
In order to develop effective bioremediation strategies for radionuclide contaminants, the composition and metabolic potential of microbial communities need to be better understood, especially in highly contaminated subsurface sediments for which little cultivation‐independent information is available. In this study, we characterized metabolically active and total microbial communities associated with uranium‐contaminated subsurface sediments along geochemical gradients. DNA and RNA were extracted and amplified from four sediment‐depth intervals representing moderately acidic (pH 3.7) to near‐neutral (pH 6.7) conditions. Phylotypes related to Proteobacteria ( Alpha‐, Beta‐, Delta‐ and Gammaproteobacteria ), Bacteroidetes , Actinobacteria, Firmicutes and Planctomycetes were detected in DNA‐ and RNA‐derived clone libraries. Diversity and numerical dominance of phylotypes were observed to correspond to changes in sediment geochemistry and rates of microbial activity, suggesting that geochemical conditions have selected for well‐adapted taxa. Sequences closely related to nitrate‐reducing bacteria represented 28% and 43% of clones from the total and metabolically active fractions of the microbial community, respectively. This study provides the first detailed analysis of total and metabolically active microbial communities in radionuclide‐contaminated subsurface sediments. Our microbial community analysis, in conjunction with rates of microbial activity, points to several groups of nitrate‐reducers that appear to be well adapted to environmental conditions common to radionuclide‐contaminated sites.