TY  - JOUR
A1  - Wanner, Manfred
A1  - Seidl-Lampa, Barbara
A1  - Höhn, Axel
A1  - Puppe, Daniel
A1  - Meisterfeld, Ralf
A1  - Sommer, Michael
T1  - Culture growth of testate amoebae under different silicon concentrations
JF  - European journal of protistology
N2  - Testate amoebae with self-secreted siliceous shell platelets ("idiosomes") play an important role in terrestrial silicon (Si) cycles. In this context, Si-dependent culture growth dynamics of idiosomic testate amoebae are of interest. Clonal cultures of idiosomic testate amoebae were analyzed under three different Si concentrations: low (50 mu mol L-1), moderate/site-specific (150 mu mol L-1) and high Si supply (500 mu mol L-1). Food (Saccharomyces cerevisiae) was provided in surplus. (i) Shell size of four different clones of idiosomic testate amoebae either decreased (Trinema galeata, Euglypha filifera cf.), increased (E. rotunda cf.), or did not change (E. rotunda) under the lowest Si concentration (50 mu mol Si L-1). (ii) Culture growth of idiosomic Euglypha rotunda was dependent on Si concentration. The more Si available in the culture medium, the earlier the entry into exponential growth phase. (iii) Culture growth of idiosomic Euglypha rotunda was dependent on origin of inoculum. Amoebae previously cultured under a moderate Si concentration revealed highest sustainability in consecutive cultures. Amoebae derived from cultures with high Si concentrations showed rapid culture growth which finished early in consecutive cultures. (iv) Si (diluted in the culture medium) was absorbed by amoebae and fixed in the amoeba shells resulting in decreased Si concentrations. (C) 2016 Elsevier GmbH. All rights reserved.
KW  - Amoebal silicon
KW  - Sommer et al. 2006
KW  - Biosilicification
KW  - Consumption
KW  - Culture growth dynamics
KW  - Euglyphida
KW  - Terrestrial Si cycle
Y1  - 2016
U6  - https://doi.org/10.1016/j.ejop.2016.08.008
SN  - 0932-4739
SN  - 1618-0429
VL  - 56
SP  - 171
EP  - 179
PB  - Royal Society of Chemistry
CY  - Jena
ER  - 
TY  - JOUR
A1  - Puppe, Daniel
A1  - Ehrmann, Otto
A1  - Kaczorek, Danuta
A1  - Wanner, Manfred
A1  - Sommer, Michael
T1  - The protozoic Si pool in temperate forest ecosystems - Quantification, abiotic controls and interactions with earthworms
JF  - Geoderma : an international journal of soil science
N2  - Biogenic silicon (BSI) pools influence Si cycling in terrestrial ecosystems. As research has been focused mainly on phytogenic BSi pools until now, there is only little information available on quantities of other BSi pools. There are no systematic studies on protozoic Si pools - here represented by idiosomic testate amoebae (TA) - and abiotic and biotic influences in temperate forest ecosystems. We selected ten old forests along a strong gradient in soil forming factors (especially parent material and climate), soil properties and humus forms. We quantified idiosomic Si pools, corresponding annual biosilicification, plant-available and amorphous Si fractions of topsoil horizons. Furthermore, we analyzed the potential influences of abiotic factors (e.g. soil pH) and earthworms on idiosomic Si pools.
 While idiosomic Si pools were relatively small (up to 5 kg Si ha(-1)), annual biosilicification rates of living TA (17-80 kg Si ha(-1)) were comparable to or even exceeded reported data of annual Si uptake by trees. Soil pH exerted a strong, non-linear control on plant-available Si. Surprisingly, no relationship between Si supply and idiosomic Si pools could be found (no Si limitation). Instead, idiosomic Si pools showed a strong, negative relationship to earthworm biomasses, which corresponded to humus forms. We concluded that earthworms control idiosomic Si pools in forest soils by direct (feeding, competition) and/or indirect mechanisms (e.g. change of habitat structure). Earthworms themselves were strongly influenced by soil pH: Below a threshold of pH 3.8 no endogeic or anecic earthworms existed. As soil pH is a result of weathering and acidification idiosomic Si pools are indirectly, but ultimately controlled by soil forming factors, mainly parent material and climate. (C) 2014 Elsevier B.V. All rights reserved.
KW  - Biogenic silica
KW  - Testate amoebae
KW  - Biosilicification
KW  - Terrestrial Si cycle
KW  - Si fractions
KW  - Humus forms
Y1  - 2015
U6  - https://doi.org/10.1016/j.geoderma.2014.12.018
SN  - 0016-7061
SN  - 1872-6259
VL  - 243
SP  - 196
EP  - 204
PB  - Elsevier
CY  - Amsterdam
ER  -