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@ARTICLE{Krause:866555,
author = {Krause, Lars and Biesgen, Danh and Treder, Aaron and
Schweizer, Steffen A. and Klumpp, Erwin and Knief, Claudia
and Siebers, Nina},
title = {{I}nitial microaggregate formation: {A}ssociation of
microorganisms to montmorillonite-goethite aggregates under
wetting and drying cycles},
journal = {Geoderma},
volume = {351},
issn = {0016-7061},
address = {Amsterdam [u.a.]},
publisher = {Elsevier Science},
reportid = {FZJ-2019-05645},
pages = {250 - 260},
year = {2019},
abstract = {There is an intimate relationship between microorganisms
and the formation and stability of soil microaggregates,
realized by the immobilization and occlusion of
microorganisms. Little is known about the initial aggregate
formation phase and the role of microorganisms in this
process under the impact of environmental changes such as
wetting and drying. We investigated this initial aggregate
formation process of montmorillonite and goethite in
combination with two bacterial strains, Pseudomonas
protegens strain CHA0 and Gordonia alkanivorans strain MoAcy
2, in the presence or absence of stress conditions in form
of wetting and drying cycles for up to eight days.
Montmorillonite and goethite formed microaggregates
instantaneously, the size of these aggregates being enhanced
in the presence of microorganisms, resulting in up to
twofold larger aggregates. This increase in aggregate size
was strain-dependent. However, the aggregates that developed
during the first 48 h broke into smaller structures later
on. A microscopic analysis of the microaggregates revealed
that notably the larger microaggregates harbored bacteria
and that microaggregates had a sheltering effect on living
cells, especially when exposed to desiccation stress.
Additionally, aggregate formation was analyzed in the
presence of a Pseudomonas protegens mutant strain (CHA211)
with increased production capability of extracellular
polymeric substances (EPS). About fivefold higher survival
rates of culturable cells were observed after desiccation
for this EPS overproducing mutant strain in comparison to
the wild-type. Our results hint at an aggregate formation
process characterized by a rapid occlusion of mineral
compounds, and, after the addition of microorganisms, the
bacterial colonization of small microaggregates, leading to
an increase in aggregate size. The further development of
the aggregate size distribution varied depending on the
presence of microbial taxa and was modulated by
environmental conditions like desiccation events.},
cin = {IBG-3},
ddc = {910},
cid = {I:(DE-Juel1)IBG-3-20101118},
pnm = {255 - Terrestrial Systems: From Observation to Prediction
(POF3-255)},
pid = {G:(DE-HGF)POF3-255},
typ = {PUB:(DE-HGF)16},
UT = {WOS:000474495700024},
doi = {10.1016/j.geoderma.2019.05.001},
url = {https://juser.fz-juelich.de/record/866555},
}