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Journal of Environmental Quality Abstract - Waste Management

Real-Time Quantification of mcrA, pmoA for Methanogen, Methanotroph Estimations during Composting


This article in JEQ

  1. Vol. 40 No. 1, p. 199-205
    Received: Feb 25, 2010

    * Corresponding author(s): sharmar@agr.gc.ca
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  1. Ranjana Sharma *a,
  2. Kelly Ryana,
  3. Xiying Haoa,
  4. Francis J. Larneya,
  5. Tim A. McAllistera and
  6. Edward Toppb
  1. a Agriculture and Agri-Food Research Centre, 5403 1st Ave. S., Lethbridge, AB, Canada T1J 4B1
    b Southern Crop Protection and Food Research Centre, Agriculture and Agri-Food Canada, 1391 Sandford St., London, ON, Canada N5V 4T3. Assigned to Associate Editor Soren O. Petersen


Composting is the controlled biological decomposition of organic matter by microorganisms during predominantly aerobic conditions. It is being increasingly adopted due to its benefits in nutrient recycling, soil reclamation, and urban land use. However, it poses an environmental concern related to its contribution to greenhouse gas production. During composting, activities of methanogenic and methanotrophic communities influence the net methane (CH4) release into the atmosphere. Using quantitative polymerase chain reaction (qPCR), this study was aimed at assessing the changes in the methyl–coenzyme M reductase (mcrA) and particulate methane monooxygenase (pmoA) copy numbers for estimation of methanogenic and methanotrophic communities, respectively. Open-windrow composting of beef cattle (Bos Taurus L.) manure with temperatures reaching >55°C was effective in degrading commensal Escherichia coli within the first week. Quantification of community DNA revealed significant differences in mcrA and pmoA copy numbers between top and middle sections. Consistent mcrA copy numbers (7.07 to 8.69 log copy number g−1) were detected throughout the 15-wk composting period. However, pmoA copy number varied significantly over time, with higher values during Week 0 and 1 (6.31 and 5.41 log copy number g−1, respectively) and the lowest at Week 11 (1.6 log copy number g−1). Net surface CH4 emissions over the 15-wk period were correlated with higher mcrA copy number. Higher net ratio of mcrA: pmoA copy numbers was observed when surface CH4 flux was high. Our results indicate that mcrA and pmoA copy numbers vary during composting and that methanogen and methanotroph populations need to be examined in conjunction with net CH4 emissions from open-windrow composting of cattle feedlot manure.

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