title: Source of nitrous oxide emissions during the cow manure composting process as revealed by isotopomer analysis of and amoA abundance in betaproteobacterial ammonia-oxidizing bacteria.
abstract: A molecular analysis of betaproteobacterial ammonia oxidizers and a N(2)O isotopomer analysis were conducted to study the sources of N(2)O emissions during the cow manure composting process. Much NO(2)(-)-N and NO(3)(-)-N and the Nitrosomonas europaea-like amoA gene were detected at the surface, especially at the top of the composting pile, suggesting that these ammonia-oxidizing bacteria (AOB) significantly contribute to the nitrification which occurs at the surface layer of compost piles. However, the (15)N site preference within the asymmetric N(2)O molecule (SP = delta(15)N(alpha) - delta(15)N(beta), where (15)N(alpha) and (15)N(beta) represent the (15)N/(14)N ratios at the center and end sites of the nitrogen atoms, respectively) indicated that the source of N(2)O emissions just after the compost was turned originated mainly from the denitrification process. Based on these results, the reduction of accumulated NO(2)(-)-N or NO(3)(-)-N after turning was identified as the main source of N(2)O emissions. The site preference and bulk delta(15)N results also indicate that the rate of N(2)O reduction was relatively low, and an increased value for the site preference indicates that the nitrification which occurred mainly in the surface layer of the pile partially contributed to N(2)O emissions between the turnings.
authors.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. k_maeda@affrc.go.jp
authors.forename: Koki
authors.initials: K
authors.lastname: Maeda
authors.forename: Sakae
authors.initials: S
authors.lastname: Toyoda
authors.forename: Ryosuke
authors.initials: R
authors.lastname: Shimojima
authors.forename: Takashi
authors.initials: T
authors.lastname: Osada
authors.forename: Dai
authors.initials: D
authors.lastname: Hanajima
authors.forename: Riki
authors.initials: R
authors.lastname: Morioka
authors.forename: Naohiro
authors.initials: N
authors.lastname: Yoshida
mesh_terms: D000641:Ammonia / Q000378:metabolism*; D000818:Animals; D020562:Betaproteobacteria / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D002417:Cattle; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D008372:Manure / Q000382:microbiology*; D008969:Molecular Sequence Data; D009587:Nitrogen Isotopes / Q000378:metabolism; D009609:Nitrous Oxide / Q000378:metabolism*; D010084:Oxidation-Reduction; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA
chemical_list: D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D008372:Manure; D009587:Nitrogen Isotopes; D012336:RNA, Ribosomal, 16S; D000641:Ammonia; D009609:Nitrous Oxide