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N2O-producing microorganisms in the gut of the earthworm Aporrectodea caliginosa are indicative of ingested soil bacteria

Title data

Ihssen, Julian ; Horn, Marcus A. ; Gößner, Anita S. ; Matthies, Carola ; Schramm, Andreas ; Drake, Harold L.:
N2O-producing microorganisms in the gut of the earthworm Aporrectodea caliginosa are indicative of ingested soil bacteria.
In: Applied and Environmental Microbiology. Vol. 69 (2003) Issue 3 . - pp. 1655-1661.
ISSN 1098-5336
DOI: https://doi.org/10.1128/AEM.69.3.1655-1661.2003

Abstract in another language

The main objectives of this study were to (i) determine if gut-wall associated microorganisms are responsible for the capacity of earthworms to emit nitrous oxide (N2O) and (ii) characterize the N2O-producing bacteria of the earthworm gut. The production of N2O in the gut of garden soil earthworms (Aporrectodea caliginosa) was mostly associated with the gut contents rather than the gut wall. Under anoxic conditions, nitrite and N2O were transient products when supplemental nitrate was reduced to N2 by gut content homogenates. In contrast, nitrite and N2O were essentially not produced by nitrate-supplemented soil homogenates. Most probable numbers (MPN) of fermentative anaerobes and microbes that used nitrate as a terminal electron acceptor were approximately 2 orders of magnitude higher in the earthworm gut than in the soil from which the earthworms originated. The fermentative anaerobes in the gut and soil displayed similar physiological functionalities. 136 N2O-producing isolates that reduced either nitrate or nitrite were obtained from high serial dilutions of gut homogenates. Of the 25 representative N2O-producing isolates that were chosen for characterization, (i) 22 isolates shared >99 % 16S rRNA gene sequence similarity with their closest cultured relative, which in most cases was a soil bacterium, (ii) most isolates were affiliated with the gamma proteobacteria or the Gram-positive bacteria with low DNA G+C content, and (iii) 5 isolates were denitrifiers and reduced nitrate to N2O or N2. The initial N2O-production rates of denitrifiers were 1-to-2 orders of magnitude greater than those of the non-denitrifying isolates. However, most non-denitrifying nitrate dissimilators produced nitrite and might therefore indirectly stimulate the production of N2O via nitrite-utilizing denitrifiers in the gut. The results of this study suggest that most of the N2O emitted by earthworms is due to the activation of ingested denitrifiers and other nitrate-dissimilating bacteria in the gut lumen.

Further data

Item Type: Article in a journal
Refereed: Yes
Additional notes: BAYCEER14121
Institutions of the University: Research Institutions > Research Centres > Bayreuth Center of Ecology and Environmental Research- BayCEER
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Biology > Chair Ecological Microbiology
Faculties
Faculties > Faculty of Biology, Chemistry and Earth Sciences
Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Biology
Research Institutions
Research Institutions > Research Centres
Result of work at the UBT: Yes
DDC Subjects: 500 Science
Date Deposited: 24 Sep 2015 09:38
Last Modified: 24 Sep 2015 09:38
URI: https://eref.uni-bayreuth.de/id/eprint/19573