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<oai_dc:dc xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:oai_dc="http://www.openarchives.org/OAI/2.0/oai_dc/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/oai_dc/ http://www.openarchives.org/OAI/2.0/oai_dc.xsd">
  <dc:contributor>Kelly P. Nevin</dc:contributor>
  <dc:contributor>Derek R. Lovely</dc:contributor>
  <dc:creator>Dawn E. Holmes</dc:creator>
  <dc:date>2004</dc:date>
  <dc:description>&lt;p&gt;&lt;span&gt;In order to determine whether the metabolic state of &lt;/span&gt;&lt;i&gt;Geobacteraceae&lt;/i&gt;&lt;span&gt; involved in bioremediation of subsurface sediments might be inferred from levels of mRNA for key genes, in situ expression of &lt;/span&gt;&lt;i&gt;nifD&lt;/i&gt;&lt;span&gt;, a highly conserved gene involved in nitrogen fixation, was investigated. When &lt;/span&gt;&lt;i&gt;Geobacter sulfurreducens&lt;/i&gt;&lt;span&gt; was grown without a source of fixed nitrogen in chemostats with acetate provided as the limiting electron donor and Fe(III) as the electron acceptor, levels of &lt;/span&gt;&lt;i&gt;nifD&lt;/i&gt;&lt;span&gt; transcripts were 4 to 5 orders of magnitude higher than in chemostat cultures provided with ammonium. In contrast, the number of transcripts of &lt;/span&gt;&lt;i&gt;recA&lt;/i&gt;&lt;span&gt; and the 16S rRNA gene were slightly lower in the absence of ammonium. The addition of acetate to organic- and nitrogen-poor subsurface sediments stimulated the growth of &lt;/span&gt;&lt;i&gt;Geobacteraceae&lt;/i&gt;&lt;span&gt; and Fe(III) reduction, as well as the expression of &lt;/span&gt;&lt;i&gt;nifD&lt;/i&gt;&lt;span&gt; in &lt;/span&gt;&lt;i&gt;Geobacteraceae&lt;/i&gt;&lt;span&gt;. Levels of &lt;/span&gt;&lt;i&gt;nifD&lt;/i&gt;&lt;span&gt; transcripts in &lt;/span&gt;&lt;i&gt;Geobacteraceae&lt;/i&gt;&lt;span&gt; decreased more than 100-fold within 2 days after the addition of 100 μM ammonium, while levels of &lt;/span&gt;&lt;i&gt;recA&lt;/i&gt;&lt;span&gt; and total bacterial 16S rRNA in &lt;/span&gt;&lt;i&gt;Geobacteraceae&lt;/i&gt;&lt;span&gt; remained relatively constant. Ammonium amendments had no effect on rates of Fe(III) reduction in acetate-amended sediments or toluene degradation in petroleum-contaminated sediments, suggesting that other factors, such as the rate that &lt;/span&gt;&lt;i&gt;Geobacteraceae&lt;/i&gt;&lt;span&gt; could access Fe(III) oxides, limited Fe(III) reduction. These results demonstrate that it is possible to monitor one aspect of the in situ metabolic state of &lt;/span&gt;&lt;i&gt;Geobacteraceae&lt;/i&gt;&lt;span&gt; species in subsurface sediments via analysis of mRNA levels, which is the first step toward a more global analysis of in situ gene expression related to nutrient status and stress response during bioremediation by &lt;/span&gt;&lt;i&gt;Geobacteraceae&lt;/i&gt;&lt;span&gt;.&lt;/span&gt;&lt;/p&gt;</dc:description>
  <dc:format>application/pdf</dc:format>
  <dc:identifier>10.1128/AEM.70.12.7251-7259.2004</dc:identifier>
  <dc:language>en</dc:language>
  <dc:publisher>American Society for Microbiology</dc:publisher>
  <dc:title>In situ expression of nifD in Geobacteraceae in subsurface sediments</dc:title>
  <dc:type>article</dc:type>
</oai_dc:dc>