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Real‐Time Quantification of mcr A, pmo A for Methanogen, Methanotroph Estimations during Composting
Author(s) -
Sharma Ranjana,
Ryan Kelly,
Hao Xiying,
Larney Francis J.,
McAllister Tim A.,
Topp Edward
Publication year - 2011
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2010.0088
Subject(s) - methanotroph , methanogen , methane monooxygenase , biology , manure , methane , environmental chemistry , chemistry , anaerobic oxidation of methane , agronomy , ecology
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 (CH 4 ) release into the atmosphere. Using quantitative polymerase chain reaction (qPCR), this study was aimed at assessing the changes in the methyl–coenzyme M reductase ( mcr A) and particulate methane monooxygenase ( pmo A) 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 mcr A and pmo A copy numbers between top and middle sections. Consistent mcr A copy numbers (7.07 to 8.69 log copy number g −1 ) were detected throughout the 15‐wk composting period. However, pmo A 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 CH 4 emissions over the 15‐wk period were correlated with higher mcr A copy number. Higher net ratio of mcr A: pmo A copy numbers was observed when surface CH 4 flux was high. Our results indicate that mcr A and pmo A copy numbers vary during composting and that methanogen and methanotroph populations need to be examined in conjunction with net CH 4 emissions from open‐windrow composting of cattle feedlot manure.