N20 emission by earthworms
Earthworms emit
the greenhouse gas nitrous oxide (N2O) under in vivo
conditions due
to microbial activity in their gut. In soils that are inhabited by
earthworms,
gut-associated N2O emission by earthworms may account for up
to 30%
of the total N2O emission from those soils. Three microbial
processes,
denitrification, nitrate reduction to ammonium or nitrite, and
nitrification,
can result in significant N2O production. In earthworms,
denitrification is involved in the emission of N2O, and
denitrifiers
are enriched in the earthworm gut. Other N2O-producing
microorganisms, i.e., nitrate reducing bacteria, are also abundant in
high
numbers. The current project is focused on (i) microbiological and
molecular
identification of N2O-producing bacteria in the earthworm
gut, (ii)
analysis of the physical-chemical conditions inside the earthworm gut,
(iii)
regulation and ecological significance of the earthworm-associated N2O-production.
left:
earthworms emit the greenhouse gas N2O;
middle/right: microsensor measurements of O2 and N2O
in
earthworms