https://microbewiki.kenyon.edu/index.php?title=Nitrate/nitrite_methane_oxidation&feed=atom&action=historyNitrate/nitrite methane oxidation - Revision history2024-03-29T05:30:24ZRevision history for this page on the wikiMediaWiki 1.39.6https://microbewiki.kenyon.edu/index.php?title=Nitrate/nitrite_methane_oxidation&diff=65033&oldid=prevBarichD at 15:05, 13 July 20112011-07-13T15:05:22Z<p></p>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==Introduction==</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==Introduction==</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div><br>Methane (CH<sub>4</sub>) is a potent greenhouse gas. Marine and freshwater sources are important sources of methane. In oceans, methane seeps out of fissures along the ocean floor and from methane hydrates. The methane eventually bubbles out of the ocean and enters the atmosphere. It is estimated approximately 33 million tons of methane enters the atmosphere in this manner per year (Biello, 2006). Methane is also released from freshwater sediments (i.e. from lakes and wetlands) as a result of methanogenic activity.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div><br>Methane (CH<sub>4</sub>) is a potent greenhouse gas. Marine and freshwater sources are important sources of methane. In oceans, methane seeps out of fissures along the ocean floor and from methane hydrates. The methane eventually bubbles out of the ocean and enters the atmosphere. It is estimated approximately 33 million tons of methane enters the atmosphere in this manner per year (Biello, 2006). Methane is also released from freshwater sediments (i.e. from lakes and wetlands) as a result of methanogenic activity.</div></td></tr>
</table>BarichDhttps://microbewiki.kenyon.edu/index.php?title=Nitrate/nitrite_methane_oxidation&diff=64767&oldid=prevVenkateswaranK: /* References */2011-05-12T18:43:28Z<p><span dir="auto"><span class="autocomment">References</span></span></p>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1578726/ Holland, HD. 2006. The oxygenation of the atmosphere and oceans. Philosophical Transactions of the Royal Society B: Biological Sciences 361: 903-915.]</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1578726/ Holland, HD. 2006. The oxygenation of the atmosphere and oceans. Philosophical Transactions of the Royal Society B: Biological Sciences 361: 903-915.]</div></td></tr>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[http://www.ru.nl/publish/pages/567430/oremland2010naturenoconnectionwithmethane.pdf Oremland, RS. 2010. NO connection with methane. Nature 464: 500-501.]</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[http://www.ru.nl/publish/pages/567430/oremland2010naturenoconnectionwithmethane.pdf Oremland, RS. 2010. NO connection with methane. Nature 464: 500-501.]</div></td></tr>
</table>VenkateswaranKhttps://microbewiki.kenyon.edu/index.php?title=Nitrate/nitrite_methane_oxidation&diff=64765&oldid=prevVenkateswaranK at 18:42, 12 May 20112011-05-12T18:42:56Z<p></p>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>===Evolutionary Significance===</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>===Evolutionary Significance===</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div><br><del style="font-weight: bold; text-decoration: none;">The mechanism(s) of microbial </del>nitrate oxidation of methane <del style="font-weight: bold; text-decoration: none;">oxidation has </del>evolutionary <del style="font-weight: bold; text-decoration: none;">importance</del>. <del style="font-weight: bold; text-decoration: none;">It was</del>, for <del style="font-weight: bold; text-decoration: none;">example, </del>originally <del style="font-weight: bold; text-decoration: none;">thought that </del>the <del style="font-weight: bold; text-decoration: none;">three main oxygen-producing biological pathways were </del>photosynthesis, chlorate respiration and the detoxification of reactive oxygen species <del style="font-weight: bold; text-decoration: none;">and that these were the processes responsible for oxygenating the atmosphere </del>(Ettwig et al, 2010). <del style="font-weight: bold; text-decoration: none;">The </del>intra-aerobic pathway, discovered by Ettwig et al (2010), <del style="font-weight: bold; text-decoration: none;">may have also contributed to atmospheric oxygen levels because </del>it is <del style="font-weight: bold; text-decoration: none;">likely </del>that some of the oxygen <del style="font-weight: bold; text-decoration: none;">produced from NO </del>escaped before <del style="font-weight: bold; text-decoration: none;">it </del>could be used for methane oxidation.</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><br> <ins style="font-weight: bold; text-decoration: none;">Microbial </ins>nitrate<ins style="font-weight: bold; text-decoration: none;">/nitrite </ins>oxidation of methane <ins style="font-weight: bold; text-decoration: none;">is likely to have </ins>evolutionary <ins style="font-weight: bold; text-decoration: none;">significance because it is an oxygen-producing process and therefore may have contributed to the oxygenation of the atmosphere 2</ins>.<ins style="font-weight: bold; text-decoration: none;">45-1.85 billion years ago (Holland</ins>, <ins style="font-weight: bold; text-decoration: none;">2006). The oxygenation of the atmosphere is important because it allowed </ins>for <ins style="font-weight: bold; text-decoration: none;">the evolution of aerobic organisms on Earth. The processes </ins>originally <ins style="font-weight: bold; text-decoration: none;">attributed to oxygenation of </ins>the <ins style="font-weight: bold; text-decoration: none;">atmosphere are </ins>photosynthesis, chlorate respiration and the detoxification of reactive oxygen species (Ettwig et al, 2010). <ins style="font-weight: bold; text-decoration: none;">Although oxygen produced from NO in the </ins>intra-aerobic pathway, discovered by Ettwig et al (2010), <ins style="font-weight: bold; text-decoration: none;">is used for methane oxidation, </ins>it is <ins style="font-weight: bold; text-decoration: none;">possible </ins>that some of the oxygen <ins style="font-weight: bold; text-decoration: none;">molecules </ins>escaped before <ins style="font-weight: bold; text-decoration: none;">they </ins>could be used for methane oxidation<ins style="font-weight: bold; text-decoration: none;">. The oxygen would have eventually dissolved out of the ocean and entered the atmosphere, thereby contributing to atmospheric oxygenation</ins>.</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div><del style="font-weight: bold; text-decoration: none;">Moreover</del>, the pathways proposed by Ettwig et al (2010) and Raghoebarsing et al (2006) may have evolved before photosynthesis and respiration. <del style="font-weight: bold; text-decoration: none;">In </del>the <del style="font-weight: bold; text-decoration: none;">Archaen </del>Eon<del style="font-weight: bold; text-decoration: none;">, </del>conditions were anaerobic and the atmosphere largely consisted of methane. In addition, Ducluzeau et al (2009) proposed that NO, nitrite and nitrate were widely available during the Archaen Eon as strong oxidants. Microorganisms using nitrate-dependent oxidation of methane could have thrived in such conditions. The pathways, therefore, also likely preceded aerobic respiration as aerobic respiration is thought to have evolved after photosynthesis (Ducluzeau et al, 2009). The intra-aerobic pathway, especially, may have actually allowed for the development of niches for the evolution of aerobic metabolism due to the local production of oxygen (Ettwig et al, 2010).</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">On what basis can we say that the intra-aerobic pathway is likely to be very old? M. oxyfera has the tetrahydromethanopterin-dependent C1 transfer module, a primordial metabolic molecule, suggesting that M. oxyfera is from a deep-branching lineage. Therefore</ins>, the pathways proposed by Ettwig et al (2010) and Raghoebarsing et al (2006) may have evolved before photosynthesis and respiration. <ins style="font-weight: bold; text-decoration: none;">M. oxyfera would have thrived in </ins>the <ins style="font-weight: bold; text-decoration: none;">Archaean </ins>Eon conditions were anaerobic and the atmosphere largely consisted of methane. In addition, Ducluzeau et al (2009) proposed that NO, nitrite and nitrate were widely available during the Archaen Eon as strong oxidants. Microorganisms using nitrate-dependent oxidation of methane could have thrived in such conditions. The pathways, therefore, also likely preceded aerobic respiration as aerobic respiration is thought to have evolved after photosynthesis (Ducluzeau et al, 2009). The intra-aerobic pathway, especially, may have actually allowed for the development of niches for the evolution of aerobic metabolism due to the local production of oxygen (Ettwig et al, 2010).</div></td></tr>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TCW-4F14YVK-2&_user=7774802&_coverDate=02%2F01%2F2005&_rdoc=1&_fmt=high&_orig=gateway&_origin=gateway&_sort=d&_docanchor=&view=c&_searchStrId=1730474886&_rerunOrigin=scholar.google&_acct=C000062877&_version=1&_urlVersion=0&_userid=7774802&md5=d26851c9a52852a73b7cef932dc3be39&searchtype=a Frey, AD and Kallio, PT. 2005. Nitric oxide detoxification – a new era for bacterial globins in biotechnology? Trends in Biotechnology 23(2): 69-73.]</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TCW-4F14YVK-2&_user=7774802&_coverDate=02%2F01%2F2005&_rdoc=1&_fmt=high&_orig=gateway&_origin=gateway&_sort=d&_docanchor=&view=c&_searchStrId=1730474886&_rerunOrigin=scholar.google&_acct=C000062877&_version=1&_urlVersion=0&_userid=7774802&md5=d26851c9a52852a73b7cef932dc3be39&searchtype=a Frey, AD and Kallio, PT. 2005. Nitric oxide detoxification – a new era for bacterial globins in biotechnology? Trends in Biotechnology 23(2): 69-73.]</div></td></tr>
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<tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">[http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1578726/ Holland, HD. 2006. The oxygenation of the atmosphere and oceans. Philosophical Transactions of the Royal Society B: Biological Sciences 361: 903-915.]</ins></div></td></tr>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[http://www.ru.nl/publish/pages/567430/oremland2010naturenoconnectionwithmethane.pdf Oremland, RS. 2010. NO connection with methane. Nature 464: 500-501.]</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>[http://www.ru.nl/publish/pages/567430/oremland2010naturenoconnectionwithmethane.pdf Oremland, RS. 2010. NO connection with methane. Nature 464: 500-501.]</div></td></tr>
</table>VenkateswaranKhttps://microbewiki.kenyon.edu/index.php?title=Nitrate/nitrite_methane_oxidation&diff=64620&oldid=prevVenkateswaranK at 07:44, 12 May 20112011-05-12T07:44:22Z<p></p>
<a href="https://microbewiki.kenyon.edu/index.php?title=Nitrate/nitrite_methane_oxidation&diff=64620&oldid=64476">Show changes</a>VenkateswaranKhttps://microbewiki.kenyon.edu/index.php?title=Nitrate/nitrite_methane_oxidation&diff=64476&oldid=prevVenkateswaranK at 02:19, 12 May 20112011-05-12T02:19:07Z<p></p>
<a href="https://microbewiki.kenyon.edu/index.php?title=Nitrate/nitrite_methane_oxidation&diff=64476&oldid=63721">Show changes</a>VenkateswaranKhttps://microbewiki.kenyon.edu/index.php?title=Nitrate/nitrite_methane_oxidation&diff=63721&oldid=prevVenkateswaranK: /* Microbial Consortia Theory */2011-04-26T04:18:50Z<p><span dir="auto"><span class="autocomment">Microbial Consortia Theory</span></span></p>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div><br>[[Image:Kanmani_figure_1.jpg|thumb|300px|right|Figure 1. The coupling of anaerobic methane oxidation and nitrite denitrification after an enrichment period of 16 months. (a) and (b) show that CH<sub>4</sub> levels decrease as denitrification of nitrite/nitrate progresses. N<sub>2</sub> is produced as CH<sub>4</sub> is consumed by the microbial consortium (Raghoebarsing et al, 2006).]]</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div><br>[[Image:Kanmani_figure_1.jpg|thumb|300px|right|Figure 1. The coupling of anaerobic methane oxidation and nitrite denitrification after an enrichment period of 16 months. (a) and (b) show that CH<sub>4</sub> levels decrease as denitrification of nitrite/nitrate progresses. N<sub>2</sub> is produced as CH<sub>4</sub> is consumed by the microbial consortium (Raghoebarsing et al, 2006).]]</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>This theory hypothesizes that a microbial consortia consisting of an archaeon, <i>Methanosarcinales</i>, and bacteria, from the NC10 phylum, is required for the coupling of denitrification and anaerobic oxidation of methane (Raghoebarsing et al, 2006). Freshwater, anoxic sediment was collected from a canal in the Netherlands. The sediment was incubated and provided with carbon-13 labeled methane (electron donor), nitrite (electron acceptor), nitrate (electron acceptor), bicarbonate and essential trace elements. They found that nitrate, nitrite and methane were being consumed and that dinitrogen gas (N<sub>2</sub>) was being produced (Figure 1). Figure 1 shows that more nitrite was consumed by the culture than nitrate, indicating that nitrite is a better and therefore preferred electron acceptor. In addition, the denitrification rate was 290.1% faster with methane addition <del style="font-weight: bold; text-decoration: none;">suggesting </del>that denitrification and methane oxidation are coupled.</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>This theory hypothesizes that a microbial consortia consisting of an archaeon, <i>Methanosarcinales</i>, and bacteria, from the NC10 phylum, is required for the coupling of denitrification and anaerobic oxidation of methane (Raghoebarsing et al, 2006). Freshwater, anoxic sediment was collected from a canal in the Netherlands. The sediment was incubated and provided with carbon-13 labeled methane (electron donor), nitrite (electron acceptor), nitrate (electron acceptor), bicarbonate and essential trace elements. They found that nitrate, nitrite and methane were being consumed and that dinitrogen gas (N<sub>2</sub>) was being produced (Figure 1). Figure 1 shows that more nitrite was consumed by the culture than nitrate, indicating that nitrite is a better and therefore preferred electron acceptor. In addition, <ins style="font-weight: bold; text-decoration: none;">Raghoebarsing and colleagues found that </ins>the denitrification rate was 290.1% faster with methane addition<ins style="font-weight: bold; text-decoration: none;">. This suggests </ins>that denitrification and methane oxidation are coupled.</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>To ensure that both archaea and bacteria were participating in the coupling of denitrification and methane oxidation, Raghoebarsing et al (2006) measured the absorption of methane into the membrane lipids of the bacteria and archaea. To do this, they measured depletion of 13C in the membrane and compared it to that of methane before and after exposure to methane. They found that bacterial biomarkers were labeled more quickly and were more depleted in <sup>13</sup>C than archaeal biomarkers; in fact only one archaeal biomarker showed signs of significant <sup>13</sup>C depletion. The slow incorporation of methane into biomass by the archaeon suggests slow growth. Fluorescence in situ hybridization (FISH) analysis of culture biomass showed the presence of bacteria and archaea in the consortium. Archaea only comprised of 10% of the consortium, also indicating slow growth.</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>To ensure that both archaea and bacteria were participating in the coupling of denitrification and methane oxidation, Raghoebarsing et al (2006) measured the absorption of methane into the membrane lipids of the bacteria and archaea. To do this, they measured depletion of 13C in the membrane and compared it to that of methane before and after exposure to methane. They found that bacterial biomarkers were labeled more quickly and were more depleted in <sup>13</sup>C than archaeal biomarkers; in fact only one archaeal biomarker showed signs of significant <sup>13</sup>C depletion. The slow incorporation of methane into biomass by the archaeon suggests slow growth. Fluorescence in situ hybridization (FISH) analysis of culture biomass showed the presence of bacteria and archaea in the consortium. Archaea only comprised of 10% of the consortium, also indicating slow growth.</div></td></tr>
</table>VenkateswaranKhttps://microbewiki.kenyon.edu/index.php?title=Nitrate/nitrite_methane_oxidation&diff=63715&oldid=prevVenkateswaranK: /* Global Climate Change */2011-04-26T04:16:33Z<p><span dir="auto"><span class="autocomment">Global Climate Change</span></span></p>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Climate warming has a positive feedback loop. In the case of wetlands, for example, warming has accelerated the metabolism of soil methanogens, thereby increasing the release of methane from the soil. Since methane is a potent greenhouse gas, the increase in methane levels will only increase warming. This, in turn will further increase methane release from the soil provided that soil moisture levels remain high (Cao et al, 1998). This is also the case for methane fluxes from methane hydrates, as discussed earlier. Rising ocean temperatures are causing the release of methane from the hydrates, and a positive feedback loop ensues. </div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Climate warming has a positive feedback loop. In the case of wetlands, for example, warming has accelerated the metabolism of soil methanogens, thereby increasing the release of methane from the soil. Since methane is a potent greenhouse gas, the increase in methane levels will only increase warming. This, in turn will further increase methane release from the soil provided that soil moisture levels remain high (Cao et al, 1998). This is also the case for methane fluxes from methane hydrates, as discussed earlier. Rising ocean temperatures are causing the release of methane from the hydrates, and a positive feedback loop ensues. </div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>Methane-oxidizing bacteria, as mentioned earlier, can mediate methane fluxes and nitrate levels. It may, therefore, be possible to use them for bioremediation. Nitrate/ nitrite-dependent methane-oxidizing microbes can be used to offset increases in methane production (Raghoebarsing et al, 2006). In the case of agricultural run-off, the same microbes can be used to consume the nitrate/ nitrite in soils and aquatic and marine sediments. These microbes can also be used to restore eutrophic marine and freshwater ecosystems as they thrive in anoxic conditions where there is a lot of nitrite and methane available. The use of the intra-aerobic pathway may help re-oxygenate the ecosystem, allowing the ecosystem to sustain life once again. </div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>Methane-oxidizing bacteria, as mentioned earlier, can mediate methane fluxes and nitrate levels. It may, therefore, be possible to use them for bioremediation. Nitrate/ nitrite-dependent methane-oxidizing microbes can be used to offset increases in methane production (Raghoebarsing et al, 2006). In the case of agricultural run-off, the same microbes can be used to consume the nitrate/ nitrite in soils and aquatic and marine sediments. These microbes can also be used to restore eutrophic marine and freshwater ecosystems as they thrive in anoxic conditions where there is a lot of nitrite and methane available. The use of the intra-aerobic pathway may help re-oxygenate the ecosystem, allowing the ecosystem to sustain life once again<ins style="font-weight: bold; text-decoration: none;">. This is, however, difficult to say given that relatively little oxygen escapes the intra-aerobic pathway (Ettwig et al, 2010)</ins>. </div></td></tr>
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</table>VenkateswaranKhttps://microbewiki.kenyon.edu/index.php?title=Nitrate/nitrite_methane_oxidation&diff=63702&oldid=prevVenkateswaranK: /* Conclusion */2011-04-26T04:12:45Z<p><span dir="auto"><span class="autocomment">Conclusion</span></span></p>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div><br>It is evident that microbial nitrate/ nitrite oxidation of methane has important implications for methane fluxes, making it an important area of research. Firstly, it needs to be determined whether both theories, the microbial consortium theory and the intra-aerobic denitrification pathway theory, or just one theory serves as a viable pathway for the coupling of anaerobic methane oxidation and nitrate/ nitrite reduction. To a large extent, the existence of the intra-aerobic denitrification pathway can be proven by the isolation and identification of the enzyme, or enzymes, responsible for the conversion of NO to N<sub>2</sub> and O<sub>2</sub>. The microbial consortium theory, on the other hand, can be tested by removing either the bacteria or the archaea from the enrichment culture and evaluating how the remaining species survives. Does anaerobic oxidation of methane continue? Does denitrification continue? </div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div><br>It is evident that microbial nitrate/ nitrite oxidation of methane has important implications for methane fluxes, making it an important area of research. Firstly, it needs to be determined whether both theories, the microbial consortium theory and the intra-aerobic denitrification pathway theory, or just one theory serves as a viable pathway for the coupling of anaerobic methane oxidation and nitrate/ nitrite reduction. To a large extent, the existence of the intra-aerobic denitrification pathway can be proven by the isolation and identification of the enzyme, or enzymes, responsible for the conversion of NO to N<sub>2</sub> and O<sub>2</sub>. The microbial consortium theory, on the other hand, can be tested by removing either the bacteria or the archaea from the enrichment culture and evaluating how the remaining species survives. Does anaerobic oxidation of methane continue? Does denitrification continue? </div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div>Scientists also need to determine what conditions anaerobic methane-oxidizing species such as <i>M. oxyfera</i> require for their survival. The enrichment cultures obtained by Raghoebarsing et al (2006) and Ettwig et al (2008, 2010) were from shallow freshwater sediments; pH and temperature conditions were both mesophilic meaning that pH was close to neutral and temperatures were moderate. Can these microbial species involved in nitrate/ nitrite oxidation of methane survive in high pressure and high salinity environments? What about thermophilic or psychrophilic environments? <del style="font-weight: bold; text-decoration: none;">It </del>is only with holistic understanding that <del style="font-weight: bold; text-decoration: none;">the </del>species <del style="font-weight: bold; text-decoration: none;">in question </del>can be used for bioremediation purposes. <del style="font-weight: bold; text-decoration: none;"> </del></div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div>Scientists also need to determine what conditions anaerobic methane-oxidizing species such as <i>M. oxyfera</i> require for their survival. The enrichment cultures obtained by Raghoebarsing et al (2006) and Ettwig et al (2008, 2010) were from shallow freshwater sediments; pH and temperature conditions were both mesophilic meaning that pH was close to neutral and temperatures were moderate. Can these microbial species involved in nitrate/ nitrite oxidation of methane survive in high pressure and high salinity environments? What about thermophilic or psychrophilic environments? </div></td></tr>
<tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div> </div></td></tr>
<tr><td colspan="2" class="diff-side-deleted"></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><ins style="font-weight: bold; text-decoration: none;">Another important question is whether or not these species can be cultured in enormous quantities for the purposes of bioremediation. This requires knowledge of nutrient requirements (macro- and micro-nutrients, inorganic ions) and optimal environmental conditions (temperature, pH and levels of oxygen). Once cultured, the effect of the species on the biodiversity of environments needing to be restored in terms of methane and nitrate/ nitrite flux needs to be determined. Adding non-native species to environments or drastically increasing their population in environments that they already exist in can result in food web and ecosystem collapse. Therefore, it </ins>is only with <ins style="font-weight: bold; text-decoration: none;">such </ins>holistic understanding that species <ins style="font-weight: bold; text-decoration: none;">such as <i>M. oxyfera</i> </ins>can be used for bioremediation purposes<ins style="font-weight: bold; text-decoration: none;">; such understanding requires the collaboration of microbiologists, biochemists and ecologists. Despite this, microbes specializing in anaerobic nitrate/ nitrite oxidation of methane hold a lot of purpose as a means of offsetting climate change resulting from large outward fluxes of methane</ins>.</div></td></tr>
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</table>VenkateswaranKhttps://microbewiki.kenyon.edu/index.php?title=Nitrate/nitrite_methane_oxidation&diff=63622&oldid=prevVenkateswaranK at 03:54, 26 April 20112011-04-26T03:54:02Z<p></p>
<a href="https://microbewiki.kenyon.edu/index.php?title=Nitrate/nitrite_methane_oxidation&diff=63622&oldid=63462">Show changes</a>VenkateswaranKhttps://microbewiki.kenyon.edu/index.php?title=Nitrate/nitrite_methane_oxidation&diff=63462&oldid=prevVenkateswaranK: /* Intra-aerobic Denitrification Pathway Theory */2011-04-26T02:50:47Z<p><span dir="auto"><span class="autocomment">Intra-aerobic Denitrification Pathway Theory</span></span></p>
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<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==Intra-aerobic Denitrification Pathway Theory==</div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>==Intra-aerobic Denitrification Pathway Theory==</div></td></tr>
<tr><td class="diff-marker" data-marker="−"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;"><div><br>[[Image:Kanmani_figure_2.jpg|thumb|600px|right|<del style="font-weight: bold; text-decoration: none;">legend</del>]]</div></td><td class="diff-marker" data-marker="+"></td><td style="color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;"><div><br>[[Image:Kanmani_figure_2.jpg|thumb|600px|right|<ins style="font-weight: bold; text-decoration: none;">Figure 2. FISH analysis of microbial biomass in enrichment showing that denitrifying bacteria can anaerobically oxidize methane without archaea. Bacterial biomass is purple and archaeal biomass is green. (a) after 7 months archaea make up approximately 10% of cells in enrichment, (b) after 13 months, <1% of cells are archaeal, and (c)after 19 months, archaeal cells are undetectable. Scale bar= 5µm (Ettwig et al, 2008).</ins>]]</div></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><br/></td></tr>
<tr><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Ettwig et al (2008) found that methane could be anaerobically oxidized in the absence of archaea. The researchers experimented with the same enriched culture, in anoxic conditions, used by Raghoebarsing and colleagues (2006) over a 22 month period. The culture was also provided with the same nutrients, electron donors and electron acceptors. They found that archaeal composition reduced over the time period and could not be detected by the fifteenth month using FISH analysis of biomass (Figure 2). Despite this decrease, the bacteria continued to oxidize methane. This suggests one of two things: </div></td><td class="diff-marker"></td><td style="background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;"><div>Ettwig et al (2008) found that methane could be anaerobically oxidized in the absence of archaea. The researchers experimented with the same enriched culture, in anoxic conditions, used by Raghoebarsing and colleagues (2006) over a 22 month period. The culture was also provided with the same nutrients, electron donors and electron acceptors. They found that archaeal composition reduced over the time period and could not be detected by the fifteenth month using FISH analysis of biomass (Figure 2). Despite this decrease, the bacteria continued to oxidize methane. This suggests one of two things: </div></td></tr>
</table>VenkateswaranK