TY  - JOUR
A1  - Cepakova, Zuzana
A1  - Hrouzek, Pavel
A1  - Ziskova, Eva
A1  - Nuyanzina-Boldareva, Ekaterina
A1  - Sorf, Michal
A1  - Kozlikova-Zapomelova, Eliska
A1  - Salka, Ivette
A1  - Grossart, Hans-Peter
A1  - Koblizek, Michal
T1  - High turnover rates of aerobic anoxygenic phototrophs in European freshwater lakes
JF  - Environmental microbiology
N2  - Aerobic Anoxygenic Phototrophic (AAP) bacteria are bacteriochlorophyll (BChl) a -containing organisms which use light energy to supplement their predominantly heterotrophic metabolism. Here, we investigated mortality and growth rates of AAP bacteria in three different freshwater lakes in Central Europe: the mountain lake Plesne, the oligo-mesotrophic Lake Stechlin and the forest pond Huntov. The mortality of AAP bacteria was estimated from diel changes of BChl a fluorescence. Net and gross growth rates were calculated from the increases in AAP cell numbers. The gross growth rates of AAP bacteria ranged from 0.38 to 5.6 d(-1), with the highest values observed during summer months. Simultaneously, the rapidly growing AAP cells have to cope with an intense grazing pressure by both zooplankton and protists. The presented results document that during the day, gross growth usually surpased mortality. Our results indicate that AAP bacteria utilize light energy under natural conditions to maintain rapid growth rates, which are balanced by a generally intense grazing pressure.
Y1  - 2016
U6  - https://doi.org/10.1111/1462-2920.13475
SN  - 1462-2912
SN  - 1462-2920
VL  - 18
SP  - 5063
EP  - 5071
PB  - Wiley-Blackwell
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Brentrup, Jennifer A.
A1  - Williamson, Craig E.
A1  - Colom-Montero, William
A1  - Eckert, Werner
A1  - de Eyto, Elvira
A1  - Grossart, Hans-Peter
A1  - Huot, Yannick
A1  - Isles, Peter D. F.
A1  - Knoll, Lesley B.
A1  - Leach, Taylor H.
A1  - McBride, Chris G.
A1  - Pierson, Don
A1  - Pomati, Francesco
A1  - Read, Jordan S.
A1  - Rose, Kevin C.
A1  - Samal, Nihar R.
A1  - Staehr, Peter A.
A1  - Winslow, Luke A.
T1  - The potential of high-frequency profiling to assess vertical and seasonal patterns of phytoplankton dynamics in lakes: an extension of the Plankton Ecology Group (PEG) model
JF  - Inland waters : journal of the International Society of Limnology
N2  - The use of high-frequency sensors on profiling buoys to investigate physical, chemical, and biological processes in lakes is 
increasing rapidly. Profiling buoys with automated winches and sensors that collect high-frequency chlorophyll fluorescence 
(ChlF) profiles in 11 lakes in the Global Lake Ecological Observatory Network (GLEON) allowed the study of the vertical 
and temporal distribution of ChlF, including the formation of subsurface chlorophyll maxima (SSCM). The effectiveness of 3 
methods for sampling phytoplankton distributions in lakes, including (1) manual profiles, (2) single-depth buoys, and (3) 
profiling buoys were assessed. High-frequency ChlF surface data and profiles were compared to predictions from the 
Plankton Ecology Group (PEG) model. The depth-integrated ChlF dynamics measured by the profiling buoy data revealed a 
greater complexity that neither conventional sampling nor the generalized PEG model captured. Conventional sampling 
techniques would have missed SSCM in 7 of 11 study lakes. Although surface-only ChlF data underestimated average water 
column ChlF, at times by nearly 2-fold in 4 of the lakes, overall there was a remarkable similarity between surface and mean 
water column data. Contrary to the PEG model’s proposed negligible role for physical control of phytoplankton during the 
growing season, thermal structure and light availability were closely associated with ChlF seasonal depth distribution. Thus, 
an extension of the PEG model is proposed, with a new conceptual framework that explicitly includes physical metrics to 
better predict SSCM formation in lakes and highlight when profiling buoys are especially informative.
KW  - chlorophyll fluorescence
KW  - Global Lake Ecological Observatory Network (GLEON)
KW  - high-frequency sensors
KW  - PEG model
KW  - phytoplankton
KW  - profiling buoys
KW  - subsurface chlorophyll maximum
Y1  - 2016
U6  - https://doi.org/10.5268/IW-6.4.890
SN  - 2044-2041
SN  - 2044-205X
VL  - 6
SP  - 565
EP  - 580
PB  - Freshwater Biological Association
CY  - Ambleside
ER  - 
TY  - JOUR
A1  - Cuadrat, Rafael R. C.
A1  - Ferrera, Isabel
A1  - Grossart, Hans-Peter
A1  - Davila, Alberto M. R.
T1  - Picoplankton Bloom in Global South? A High Fraction of Aerobic Anoxygenic Phototrophic Bacteria in Metagenomes from a Coastal Bay (Arraial do Cabo-Brazil)
JF  - OMICS : a journal of integrative biology
N2  - Marine habitats harbor a great diversity of microorganism from the three domains of life, only a small fraction of which can be cultivated. Metagenomic approaches are increasingly popular for addressing microbial diversity without culture, serving as sensitive and relatively unbiased methods for identifying and cataloging the diversity of nucleic acid sequences derived from organisms in environmental samples. Aerobic anoxygenic phototrophic bacteria (AAP) play important roles in carbon and energy cycling in aquatic systems. In oceans, those bacteria are widely distributed; however, their abundance and importance are still poorly understood. The aim of this study was to estimate abundance and diversity of AAPs in metagenomes from an upwelling affected coastal bay in Arraial do Cabo, Brazil, using in silico screening for the anoxygenic photosynthesis core genes. Metagenomes from the Global Ocean Sample Expedition (GOS) were screened for comparative purposes. AAPs were highly abundant in the free-living bacterial fraction from Arraial do Cabo: 23.88% of total bacterial cells, compared with 15% in the GOS dataset. Of the ten most AAP abundant samples from GOS, eight were collected close to the Equator where solar irradiation is high year-round. We were able to assign most retrieved sequences to phylo-groups, with a particularly high abundance of Roseobacter in Arraial do Cabo samples. The high abundance of AAP in this tropical bay may be related to the upwelling phenomenon and subsequent picoplankton bloom. These results suggest a link between upwelling and light abundance and demonstrate AAP even in oligotrophic tropical and subtropical environments. Longitudinal studies in the Arraial do Cabo region are warranted to understand the dynamics of AAP at different locations and seasons, and the ecological role of these unique bacteria for biogeochemical and energy cycling in the ocean.
Y1  - 2016
U6  - https://doi.org/10.1089/omi.2015.0142
SN  - 1536-2310
SN  - 1557-8100
VL  - 20
SP  - 76
EP  - 87
PB  - Liebert
CY  - New Rochelle
ER  - 
TY  - JOUR
A1  - Lischke, Betty
A1  - Weithoff, Guntram
A1  - Wickham, Stephen A.
A1  - Attermeyer, Katrin
A1  - Grossart, Hans-Peter
A1  - Scharnweber, Inga Kristin
A1  - Hilt, Sabine
A1  - Gaedke, Ursula
T1  - Large biomass of small feeders: ciliates may dominate herbivory in eutrophic lakes
JF  - Journal of plankton research
N2  - The importance of ciliates as herbivores and in biogeochemical cycles is increasingly recognized. An opportunity to observe the potential consequences of zooplankton dominated by ciliates arose when winter fish kills resulted in strong suppression of crustaceans by young planktivorous fish in two shallow lakes. On an annual average, ciliates made up 38-76% of the total zooplankton biomass in both lakes during two subsequent years. Consequently, ciliate biomass and their estimated grazing potential were extremely high compared with other lakes of various trophic states and depths. Grazing estimates based on abundance and size suggest that ciliates should have cleared the water column of small (<5 mu m) and intermediate (5-50 mu m) sized phytoplankton more than once a day. Especially, small feeders within the ciliates were important, likely exerting a strong top-down control on small phytoplankton. Particle-attached bacteria were presumably strongly suppressed by intermediate-sized ciliate feeders. In contrast to other lakes, large phytoplankton was proportionately very abundant. The phytoplankton community had a high evenness, which may be attributed to the feeding by numerous fast growing and selective ciliate species. Our study highlights ciliates as an important trophic link and adds to the growing awareness of the role of winter processes for plankton dynamics.
KW  - phytoplankton
KW  - crustaceans
KW  - rotifers
KW  - filtration rate
KW  - winter fish kill
Y1  - 2016
U6  - https://doi.org/10.1093/plankt/fbv102
SN  - 0142-7873
SN  - 1464-3774
VL  - 38
SP  - 2
EP  - 15
PB  - Oxford Univ. Press
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Grossart, Hans-Peter
A1  - Wurzbacher, Christian
A1  - James, Timothy Y.
A1  - Kagami, Maiko
T1  - Discovery of dark matter fungi in aquatic ecosystems demands a reappraisal of the phylogeny and ecology of zoosporic fungi
JF  - Fungal ecology
N2  - Our knowledge of zoosporic fungal phylogeny, physiology, and ecological functions, in particular their role in aquatic food web dynamics and biogeochemistry, is limited. The recent discovery of numerous dark matter fungi (DMF), i.e., uncultured and poorly known taxa belonging to early diverging branches of the fungal tree (namely the Rozellomycota and Chytridiomycota) calls for reconsideration of the phylogeny and ecology of zoosporic fungi. In this opinion paper, we summarize the exploration of new, recently discovered lineages of DMF and their implications for the ecology, evolution, and biogeography of the rapidly growing fungal tree. We also discuss possible ecological roles of zoosporic fungi in relation to recent methodological developments including single cell genomics and cultivation efforts. Finally, we suggest linking explorative with experimental research to gain deeper insights into the physiology and ecological functioning of zoosporic fungi DMF in aquatic habitats. (C) 2015 Elsevier Ltd and The British Mycological Society. All rights reserved.
KW  - Dark matter fungi
KW  - Zoosporic fungi
KW  - Fungal tree
KW  - Chytridiomycota
KW  - Rozellomycota
KW  - Fungal physiology and ecology
KW  - Aquatic habitats
Y1  - 2016
U6  - https://doi.org/10.1016/j.funeco.2015.06.004
SN  - 1754-5048
SN  - 1878-0083
VL  - 19
SP  - 28
EP  - 38
PB  - Elsevier
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Izhitskiy, A. S.
A1  - Zavialov, P. O.
A1  - Sapozhnikov, P. V.
A1  - Kirillin, G. B.
A1  - Grossart, Hans-Peter
A1  - Kalinina, O. Y.
A1  - Zalota, A. K.
A1  - Goncharenko, I. V.
A1  - Kurbaniyazov, A. K.
T1  - Present state of the Aral Sea: diverging physical and biological characteristics of the residual basins
JF  - Scientific reports
N2  - Latest data on the hydrophysical and biological state of the residual basins of the Aral Sea are presented and compared. Direct, quasi-simultaneous observations were carried out in the central part of the Western Large Aral Sea, the northern extremity of the Large Aral known as Chernyshev Bay, Lake Tshchebas, and the Small Aral Sea in October 2014. The Large Aral Sea and Lake Tshchebas transformed into hyperhaline water bodies with highly special taxocene structure. The Small Aral Sea was a relatively diverse brackish ecosystem, which was rather similar to the pre-desiccation environment. The Small Aral Sea and Lake Tshchebas exhibited a fully-mixed vertical structure, whereas the Western Large Aral Sea was strongly stratified. Our data show that during desiccation, different parts of the Aral Sea experienced different environmental conditions, resulting in qualitative and quantitative differences in the physical and biological regimes among the different residual basins.
Y1  - 2016
U6  - https://doi.org/10.1038/srep23906
SN  - 2045-2322
VL  - 6
SP  - 1435
EP  - 1442
PB  - Nature Publ. Group
CY  - London
ER  - 
TY  - JOUR
A1  - Svanys, Algirdas
A1  - Eigemann, Falk
A1  - Grossart, Hans-Peter
A1  - Hilt, Sabine
T1  - Microcystins do not necessarily lower the sensitivity of Microcystis aeruginosa to tannic acid
JF  - FEMS microbiology letters
N2  - Different phytoplankton strains have been shown to possess varying sensitivities towards macrophyte allelochemicals, yet the reasons for this are largely unknown. To test whether microcystin (MC) is responsible for strain-specific sensitivities of Microcystis aeruginosa to macrophyte allelochemicals, we compared the sensitivity of 12 MC- and non-MC-producing M. aeruginosa strains, including an MC-deficient mutant and its wild type, to the polyphenolic allelochemical tannic acid (TA). Non-MC-producing strains showed a significantly higher sensitivity to TA than MC-producing strains, both in Chlorophyll a concentrations and quantum yields of photosystem II. In contrast, an MC-deficient mutant displayed a higher fitness against TA compared to its wild type. These results suggest that the resistance of M. aeruginosa to polyphenolic allelochemicals is not primarily related to MCs per se, but to other yet unknown protective mechanisms related to MCs.
KW  - allelopathy
KW  - Delta mcyB mutant
KW  - microcystin
KW  - Microcystis aeruginosa
KW  - tannic acid
Y1  - 2016
U6  - https://doi.org/10.1093/femsle/fnv227
SN  - 0378-1097
SN  - 1574-6968
VL  - 363
SP  - 53
EP  - 77
PB  - Oxford Univ. Press
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Vorburger, Thomas
A1  - Nedielkov, Ruslan
A1  - Brosig, Alexander
A1  - Bok, Eva
A1  - Schunke, Emina
A1  - Steffen, Wojtek
A1  - Mayer, Sonja
A1  - Goetz, Friedrich
A1  - Möller, Heiko Michael
A1  - Steuber, Julia
T1  - Role of the Na+-translocating NADH:quinone oxidoreductase in voltage generation and Na+ extrusion in Vibrio cholerae
JF  - Biochimica et biophysica acta : Bioenergetics
N2  - For Vibrio cholerae, the coordinated import and export of Na+ is crucial for adaptation to habitats with different osmolarities. We investigated the Na+-extruding branch of the sodium cycle in this human pathogen by in vivo Na-23-NMR spectroscopy. The Na+ extrusion activity of cells was monitored after adding glucose which stimulated respiration via the Na+-translocating NADH:quinone oxidoreductase (Na+-NQR). In a V. cholerae deletion mutant devoid of the Na+-NQR encoding genes (nqrA-F), rates of respiratory Na+ extrusion were decreased by a factor of four, but the cytoplasmic Na+ concentration was essentially unchanged. Furthermore, the mutant was impaired in formation of transmembrane voltage (Delta psi, inside negative) and did not grow under hypoosmotic conditions at pH 8.2 or above. This growth defect could be complemented by transformation with the plasmid encoded nqr operon. In an alkaline environment, Na+/H+ antiporters acidify the cytoplasm at the expense of the transmembrane voltage. It is proposed that, at alkaline pH and limiting Na+ concentrations, the Na+-NQR is crucial for generation of a transmembrane voltage to drive the import of H+ by electrogenic Na+/H+ antiporters. Our study provides the basis to understand the role of the Na+-NQR in pathogenicity of V. cholerae and other pathogens relying on this primary Na+ pump for respiration. (C) 2015 Elsevier B.V. All rights reserved.
KW  - Nuclear magnetic resonance (NMR)
KW  - Sodium transport
KW  - Vibrio cholerae
KW  - Respiration
KW  - Na+ homeostasis
KW  - Hypoosmotic stress
Y1  - 2016
U6  - https://doi.org/10.1016/j.bbabio.2015.12.010
SN  - 0005-2728
SN  - 0006-3002
VL  - 1857
SP  - 473
EP  - 482
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Kohler, Ulrich
ED  - König, Christian
ED  - Stahl, Matthias Matthias Stahl
ED  - Wiegand, Erich
T1  - Anforderungen an Hochschulabsolventen
BT  - oder: was Projektmitarbeiter in einem empirisch ausgerichteten Forschungsprojekt können sollten?
JF  - Human Resources : Qualitätsaspekte der Ausbildung in der empirischen Forschung
N2  - Was sollten Mitarbeiter in einem empirisch ausgerichteten Forschungsprojekt können, und welche Kernkompetenzen sollte die Ausbildung an den Universitäten daher vermitteln? Die Antworten auf diese Fragen hängen – wie sollte es anders sein – von der inhaltlichen Fragestellung und methodischen Ausrichtung des jeweiligen Forschungsprojektes ab. Natürlich sollten Projektmitarbeiter über Vorkenntnisse zum Forschungsthema verfügen. Natürlich sollten Kenntnisse des projektspezifischen (statistischen) Methodenarsenals vorliegen.
Y1  - 2016
SN  - 978-3-658-12567-7
SN  - 978-3-658-12568-4
U6  - https://doi.org/10.1007/978-3-658-12568-4_4
SP  - 43
EP  - 77
PB  - Springer
CY  - Wiesbaden
ER  -