%0 Journal Article
%9 ACL : Articles dans des revues avec comité de lecture répertoriées par l'AERES
%A Majeed, M. Z.
%A Miambi, E.
%A Barois, I.
%A Blanchart, Eric
%A Brauman, Alain
%T Emissions of nitrous oxide from casts of tropical earthworms belonging to different ecological categories
%D 2013
%L fdi:010060709
%G ENG
%J Pedobiologia
%@ 0031-4056
%K N2O emissions ; Earthworm feeding behavior ; Functional genes ; Denitrification ; Nitrification
%K ZONE TROPICALE
%M ISI:000315547500007
%N 1
%P 49-58
%R 10.1016/j.pedobi.2012.10.003
%U https://www.documentation.ird.fr/hor/fdi:010060709
%> https://www.documentation.ird.fr/intranet/publi/2013/04/010060709.pdf
%V 56
%W Horizon (IRD)
%X While earthworms' feeding behavior has been shown to be a key driver of greenhouse gas like nitrous oxide (N2O) emissions for temperate species, this assessment remains to be demonstrated for tropical ones. This study constitutes a comparative assessment of the impact of different feeding strategies of tropical earthworms on their cast emissions of N2O and the characterization of microbial communities associated with these emission dynamics. N2O flux was determined in vitro from casts of 2 epigeic (Dichogaster annae and Eisenia andrei) and 4 endogeic/epiendogeic (Metaphire houlleti, Octolasion tyrtaeum, Pontoscolex corethrurus and Amynthas corticis) earthworm species in the presence or absence of acetylene. Casts of epigeic earthworms, fed on fresh coffee pulp, emitted about 392-fold higher amounts of N2O than those of endogeic ones, fed on a tropical soil. Acetylene exposure significantly increased the cast emission rates indicating that (i) apart from N2O, dinitrogen (N-2) is also emitted by earthworm casts, particularly by the epigeic guild (45%) and (ii) denitrification is the major microbial process responsible for these N-gas emissions from casts. Total bacteria were 10-fold higher in epigeic casts than endogeic but the relative abundance of nitrifier (AOB) and denitrifiers (nirK and nirS) was many times higher in endogeic casts than epigeic ones. The relative gene density of nosZ to (nirK + nirS) was 4-fold higher in epigeic casts than endogeic ones. Moreover, bacterial amoA gene abundance was higher in casts of all species than for their archaeal counterparts. Cast N2O emission was positively correlated with nitrifier as well as denitrifier gene abundance, while it was positively correlated with epigeic nitrate and negatively with endogeic nitrate contents. Ammonium contents did not show any relationship with cast emissions. Mean ammonium and nitrate contents were many times higher in casts than food substrates except nitrate in endogeic casts which was 4-fold less than parent food substrate.
%$ 074