Microbiology of nitrogen cycle in animal manure compost.
Bottom Line: Composting is the major technology in the treatment of animal manure and is a source of nitrous oxide, a greenhouse gas.Although the microbiological processes of both nitrification and denitrification are involved in composting, the key players in these pathways have not been well identified.This review article discusses these potential microbial players in nitrification-denitrification within the composting pile and highlights the relevant unknowns through recent activities that focus on the nitrogen cycle within the animal manure composting process.
Affiliation: Hokkaido Research Subteam for Waste Recycling System, National Agricultural Research Center for Hokkaido Region, National Agricultural and Food Research Organization, 1 Hitsujigaoka, Sapporo 062-8555, Japan. email@example.comShow MeSH
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Mentions: A study about denitrifier communities in the composting process revealed an initial variation of nirK diversity and stability after that (Maeda etāal., 2010a). Hallin and colleagues (2006) also reported that the addition of methanol or ethanol to activated sludge significantly affected the diversity of nirS but not that of nirK. On the other hand, the addition of mature compost that contains NO2 or NO3āN did not affect nirK diversity but significantly affected nosZ diversity, suggesting that denitrifiers possessing the nosZ gene in the compost would be more sensitive to environmental conditions. It is necessary to isolate the major denitrifier revealed by molecular methods in order to understand the actual denitrification occurring in the environment. In a denitrifier community study of rice paddy soil, Ashida and colleagues (2010) successfully isolated a major denitrifier through the enhancement of denitrification activity with succinate amendment and molecular methods such as the 16S rRNA gene clone library approach (Ishii etāal., 2009) or the stable isotope probing approach (Saito etāal., 2008). Moreover, Ishii and colleagues (2011) proved that denitrifiers with different 16S rRNA gene phylogeny possess same nirS or nirK gene in the same environment (Fig.ā2). Their data show previously unknown complex relationship between 16S rRNA gene and functional gene possession. To understand the denitrifier community completely, it is necessary to combine independent approaches such as molecular and conventional cultivation approaches. The molecular methods used to characterize the unknown and uncultivated denitrifier communities, and the subsequent singleācell isolation strategy would be effective for the denitrifiers that are truly functioning for actual denitrification in the environment (Ishii etāal., 2010).
Affiliation: Hokkaido Research Subteam for Waste Recycling System, National Agricultural Research Center for Hokkaido Region, National Agricultural and Food Research Organization, 1 Hitsujigaoka, Sapporo 062-8555, Japan. firstname.lastname@example.org