TY  - JOUR
A1  - Lundgreen, Regitze B. C.
A1  - Jaspers, Cornelia
A1  - Traving, Sachia J.
A1  - Ayala, Daniel J.
A1  - Lombard, Fabien
A1  - Grossart, Hans-Peter
A1  - Nielsen, Torkel G.
A1  - Munk, Peter
A1  - Riemann, Lasse
T1  - Eukaryotic and cyanobacterial communities associated with marine snow particles in the oligotrophic Sargasso Sea
JF  - Scientific reports
N2  - Marine snow aggregates represent heterogeneous agglomerates of dead and living organic matter. Composition is decisive for their sinking rates, and thereby for carbon flux to the deep sea. For oligotrophic oceans, information on aggregate composition is particularly sparse. To address this, the taxonomic composition of aggregates collected from the subtropical and oligotrophic Sargasso Sea (Atlantic Ocean) was characterized by 16S and 18S rRNA gene sequencing. Taxonomy assignment was aided by a collection of the contemporary plankton community consisting of 75 morphologically and genetically identified plankton specimens. The diverse rRNA gene reads of marine snow aggregates, not considering Trichodesmium puffs, were dominated by copepods (52%), cnidarians (21%), radiolarians (11%), and alveolates (8%), with sporadic contributions by cyanobacteria, suggesting a different aggregate composition than in eutrophic regions. Composition linked significantly with sampling location but not to any measured environmental parameters or plankton biomass composition. Nevertheless, indicator and network analyses identified key roles of a few rare taxa. This points to complex regulation of aggregate composition, conceivably affected by the environment and plankton characteristics. The extent to which this has implications for particle densities, and consequently for sinking rates and carbon sequestration in oligotrophic waters, needs further interrogation.
Y1  - 2019
U6  - https://doi.org/10.1038/s41598-019-45146-7
SN  - 2045-2322
VL  - 9
PB  - Nature Publ. Group
CY  - London
ER  - 
TY  - JOUR
A1  - Numberger, Daniela
A1  - Ganzert, Lars
A1  - Zoccarato, Luca
A1  - Mühldorfer, Kristin
A1  - Sauer, Sascha
A1  - Grossart, Hans-Peter
A1  - Greenwood, Alex D.
T1  - Characterization of bacterial communities in wastewater with enhanced taxonomic resolution by full-length 16S rRNA sequencing
JF  - Scientific reports
N2  - Wastewater treatment is crucial to environmental hygiene in urban environments. However, wastewater treatment plants (WWTPs) collect chemicals, organic matter, and microorganisms including pathogens and multi-resistant bacteria from various sources which may be potentially released into the environment via WWTP effluent. To better understand microbial dynamics in WWTPs, we characterized and compared the bacterial community of the inflow and effluent of a WWTP in Berlin, Germany using full-length 16S rRNA gene sequences, which allowed for species level determination in many cases and generally resolved bacterial taxa. Significantly distinct bacterial communities were identified in the wastewater inflow and effluent samples. Dominant operational taxonomic units (OTUs) varied both temporally and spatially. Disease associated bacterial groups were efficiently reduced in their relative abundance from the effluent by the WWTP treatment process, except for Legionella and Leptospira species which demonstrated an increase in relative proportion from inflow to effluent. This indicates that WWTPs, while effective against enteric bacteria, may enrich and release other potentially pathogenic bacteria into the environment. The taxonomic resolution of full-length 16S rRNA genes allows for improved characterization of potential pathogenic taxa and other harmful bacteria which is required to reliably assess health risk.
Y1  - 2019
U6  - https://doi.org/10.1038/s41598-019-46015-z
SN  - 2045-2322
VL  - 9
PB  - Nature Publ. Group
CY  - London
ER  - 
TY  - JOUR
A1  - Numberger, Daniela
A1  - Dreier, Carole
A1  - Vullioud, Colin
A1  - Gabriel, Gülsah
A1  - Greenwood, Alex D.
A1  - Grossart, Hans-Peter
T1  - Recovery of influenza a viruses from lake water and sediments by experimental inoculation
JF  - PLoS one
N2  - Influenza A viruses (IAV) are zoonotic pathogens relevant to human, domestic animal and wildlife health. Many avian IAVs are transmitted among waterfowl via a faecal-oral-route. Therefore, environmental water where waterfowl congregate may play an important role in the ecology and epidemiology of avian IAV. Water and sediment may sustain and transmit virus among individuals or species. It is unclear at what concentrations waterborne viruses are infectious or remain detectable. To address this, we performed lake water and sediment dilution experiments with varying concentrations or infectious doses of four IAV strains from seal, turkey, duck and gull. To test for infectivity of the IAV strains in a concentration dependent manner, we applied cultivation to specific pathogen free (SPF) embryonated chicken eggs and Madin-Darby Canine Kidney (MDCK) cells. IAV recovery was more effective from embryonated chicken eggs than MDCK cells for freshwater lake dilutions, whereas, MDCK cells were more effective for viral recovery from sediment samples. Low infectious dose (1 PFU/200 mu L) was sufficient in most cases to detect and recover IAV from lake water dilutions. Sediment required higher initial infectious doses (>= 100 PFU/200 mu L).
Y1  - 2019
U6  - https://doi.org/10.1371/journal.pone.0216880
SN  - 1932-6203
VL  - 14
IS  - 5
PB  - PLoS
CY  - San Fransisco
ER  - 
TY  - JOUR
A1  - Tang, Kam W.
A1  - Backhaus, Liv
A1  - Riemann, Lasse
A1  - Koski, Marja
A1  - Grossart, Hans-Peter
A1  - Munk, Peter
A1  - Nielsen, Torkel Gissel
T1  - Copepod carcasses in the subtropical convergence zone of the Sargasso Sea
BT  - implications for microbial community composition, system respiration and carbon flux
JF  - Journal of plankton research
N2  - The oligotrophic subtropical gyre covers a vast area of the Atlantic Ocean. Decades of time-series monitoring have generated detailed temporal information about zooplankton species and abundances at fixed locations within the gyre, but their live/dead status is often omitted, especially in the dynamic subtropical convergence zone (STCZ) where the water column stratification pattern can change considerably across the front as warm and cold water masses converge. We conducted a detailed survey in the North Atlantic STCZ and showed that over 85% of the copepods were typically concentrated in the upper 200 m. Copepod carcasses were present in all samples and their proportional numerical abundances increased with depth, reaching up to 91% at 300-400 m. Overall, 14-19% of the copepods within the upper 200 m were carcasses. Shipboard experiments showed that during carcass decomposition, microbial respiration increased, and the bacterial community associated with the carcasses diverged from that in the ambient water. Combining field and experimental data, we estimated that decomposing copepod carcasses constitute a negligible oxygen sink in the STCZ, but sinking carcasses may represent an overlooked portion of the passive carbon sinking flux and should be incorporated in future studies of carbon flux in this area.
KW  - Sargasso Sea
KW  - subtropical convergence zone
KW  - zooplankton
KW  - carcasses
KW  - carbon sinking flux
Y1  - 2019
U6  - https://doi.org/10.1093/plankt/fbz038
SN  - 0142-7873
SN  - 1464-3774
VL  - 41
IS  - 4
SP  - 549
EP  - 560
PB  - Oxford Univ. Press
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Rojas-Jimenez, Keilor
A1  - Grossart, Hans-Peter
A1  - Cordes, Erik
A1  - Cortés, Jorge
T1  - Fungal Communities in Sediments Along a Depth Gradient in the Eastern Tropical Pacific
JF  - Frontiers in Microbiology
N2  - Deep waters represent the largest biome on Earth and the largest ecosystem of Costa Rica. Fungi play a fundamental role in global biogeochemical cycling in marine sediments, yet, they remain little explored. We studied fungal diversity and community composition in several marine sediments from 16 locations sampled along a bathymetric gradient (from a depth of 380 to 3,474 m) in two transects of about 1,500 km length in the Eastern Tropical Pacific (ETP) of Costa Rica. Sequence analysis of the V7-V8 region of the 18S rRNA gene obtained from sediment cores revealed the presence of 787 fungal amplicon sequence variants (ASVs). On average, we detected a richness of 75 fungal ASVs per sample. Ascomycota represented the most abundant phylum with Saccharomycetes constituting the dominant class. Three ASVs accounted for ca. 63% of all fungal sequences: the yeast Metschnikowia (49.4%), Rhizophydium (6.9%), and Cladosporium (6.7%). We distinguished a cluster composed mainly by yeasts, and a second cluster by filamentous fungi, but we were unable to detect a strong effect of depth and the overlying water temperature, salinity, dissolved oxygen (DO), and pH on the composition of fungal communities. We highlight the need to understand further the ecological role of fungi in deep-sea ecosystems.
KW  - deep-sea
KW  - aquatic fungi
KW  - biodiversity
KW  - Metschnikowia
KW  - Costa Rica
Y1  - 2020
U6  - https://doi.org/10.3389/fmicb.2020.575207
SN  - 1664-302X
VL  - 11
PB  - Frontiers Media
CY  - Lausanne
ER  - 
TY  - JOUR
A1  - Grossart, Hans-Peter
A1  - Van den Wyngaert, Silke
A1  - Kagami, Maiko
A1  - Wurzbacher, Christian
A1  - Cunliffe, Michael
A1  - Rojas-Jimenz, Keilor
T1  - Fungi in aquatic ecosystems
JF  - Nature reviews. Microbiology
N2  - Fungi are phylogenetically and functionally diverse ubiquitous components of almost all ecosystems on Earth, including aquatic environments stretching from high montane lakes down to the deep ocean. Aquatic ecosystems, however, remain frequently overlooked as fungal habitats, although fungi potentially hold important roles for organic matter cycling and food web dynamics. Recent methodological improvements have facilitated a greater appreciation of the importance of fungi in many aquatic systems, yet a conceptual framework is still missing. In this Review, we conceptualize the spatiotemporal dimensions, diversity, functions and organismic interactions of fungi in structuring aquatic food webs. We focus on currently unexplored fungal diversity, highlighting poorly understood ecosystems, including emerging artificial aquatic habitats.
Y1  - 2019
U6  - https://doi.org/10.1038/s41579-019-0175-8
SN  - 1740-1526
SN  - 1740-1534
VL  - 17
IS  - 6
SP  - 339
EP  - 354
PB  - Nature Publ. Group
CY  - Basingstoke
ER  - 
TY  - GEN
A1  - Numberger, Daniela
A1  - Dreier, Carola
A1  - Vullioud, Colin
A1  - Gabriel, Guelsah
A1  - Greenwood, Alex D.
A1  - Grossart, Hans-Peter
T1  - Correction: Recovery of influenza A viruses from lake water and sediments by experimental inoculation (vol 14, e0216880, 2019)
T2  - PLoS one
Y1  - 2019
U6  - https://doi.org/10.1371/journal.pone.0218882
SN  - 1932-6203
VL  - 14
IS  - 6
PB  - PLoS
CY  - San Fransisco
ER  - 
TY  - JOUR
A1  - Tiegs, Scott D.
A1  - Costello, David M.
A1  - Isken, Mark W.
A1  - Woodward, Guy
A1  - McIntyre, Peter B.
A1  - Gessner, Mark O.
A1  - Chauvet, Eric
A1  - Griffiths, Natalie A.
A1  - Flecker, Alex S.
A1  - Acuna, Vicenc
A1  - Albarino, Ricardo
A1  - Allen, Daniel C.
A1  - Alonso, Cecilia
A1  - Andino, Patricio
A1  - Arango, Clay
A1  - Aroviita, Jukka
A1  - Barbosa, Marcus V. M.
A1  - Barmuta, Leon A.
A1  - Baxter, Colden V.
A1  - Bell, Thomas D. C.
A1  - Bellinger, Brent
A1  - Boyero, Luz
A1  - Brown, Lee E.
A1  - Bruder, Andreas
A1  - Bruesewitz, Denise A.
A1  - Burdon, Francis J.
A1  - Callisto, Marcos
A1  - Canhoto, Cristina
A1  - Capps, Krista A.
A1  - Castillo, Maria M.
A1  - Clapcott, Joanne
A1  - Colas, Fanny
A1  - Colon-Gaud, Checo
A1  - Cornut, Julien
A1  - Crespo-Perez, Veronica
A1  - Cross, Wyatt F.
A1  - Culp, Joseph M.
A1  - Danger, Michael
A1  - Dangles, Olivier
A1  - de Eyto, Elvira
A1  - Derry, Alison M.
A1  - Diaz Villanueva, Veronica
A1  - Douglas, Michael M.
A1  - Elosegi, Arturo
A1  - Encalada, Andrea C.
A1  - Entrekin, Sally
A1  - Espinosa, Rodrigo
A1  - Ethaiya, Diana
A1  - Ferreira, Veronica
A1  - Ferriol, Carmen
A1  - Flanagan, Kyla M.
A1  - Fleituch, Tadeusz
A1  - Shah, Jennifer J. Follstad
A1  - Frainer, Andre
A1  - Friberg, Nikolai
A1  - Frost, Paul C.
A1  - Garcia, Erica A.
A1  - Lago, Liliana Garcia
A1  - Garcia Soto, Pavel Ernesto
A1  - Ghate, Sudeep
A1  - Giling, Darren P.
A1  - Gilmer, Alan
A1  - Goncalves, Jose Francisco
A1  - Gonzales, Rosario Karina
A1  - Graca, Manuel A. S.
A1  - Grace, Mike
A1  - Grossart, Hans-Peter
A1  - Guerold, Francois
A1  - Gulis, Vlad
A1  - Hepp, Luiz U.
A1  - Higgins, Scott
A1  - Hishi, Takuo
A1  - Huddart, Joseph
A1  - Hudson, John
A1  - Imberger, Samantha
A1  - Iniguez-Armijos, Carlos
A1  - Iwata, Tomoya
A1  - Janetski, David J.
A1  - Jennings, Eleanor
A1  - Kirkwood, Andrea E.
A1  - Koning, Aaron A.
A1  - Kosten, Sarian
A1  - Kuehn, Kevin A.
A1  - Laudon, Hjalmar
A1  - Leavitt, Peter R.
A1  - Lemes da Silva, Aurea L.
A1  - Leroux, Shawn J.
A1  - Leroy, Carri J.
A1  - Lisi, Peter J.
A1  - MacKenzie, Richard
A1  - Marcarelli, Amy M.
A1  - Masese, Frank O.
A1  - Mckie, Brendan G.
A1  - Oliveira Medeiros, Adriana
A1  - Meissner, Kristian
A1  - Milisa, Marko
A1  - Mishra, Shailendra
A1  - Miyake, Yo
A1  - Moerke, Ashley
A1  - Mombrikotb, Shorok
A1  - Mooney, Rob
A1  - Moulton, Tim
A1  - Muotka, Timo
A1  - Negishi, Junjiro N.
A1  - Neres-Lima, Vinicius
A1  - Nieminen, Mika L.
A1  - Nimptsch, Jorge
A1  - Ondruch, Jakub
A1  - Paavola, Riku
A1  - Pardo, Isabel
A1  - Patrick, Christopher J.
A1  - Peeters, Edwin T. H. M.
A1  - Pozo, Jesus
A1  - Pringle, Catherine
A1  - Prussian, Aaron
A1  - Quenta, Estefania
A1  - Quesada, Antonio
A1  - Reid, Brian
A1  - Richardson, John S.
A1  - Rigosi, Anna
A1  - Rincon, Jose
A1  - Risnoveanu, Geta
A1  - Robinson, Christopher T.
A1  - Rodriguez-Gallego, Lorena
A1  - Royer, Todd V.
A1  - Rusak, James A.
A1  - Santamans, Anna C.
A1  - Selmeczy, Geza B.
A1  - Simiyu, Gelas
A1  - Skuja, Agnija
A1  - Smykla, Jerzy
A1  - Sridhar, Kandikere R.
A1  - Sponseller, Ryan
A1  - Stoler, Aaron
A1  - Swan, Christopher M.
A1  - Szlag, David
A1  - Teixeira-de Mello, Franco
A1  - Tonkin, Jonathan D.
A1  - Uusheimo, Sari
A1  - Veach, Allison M.
A1  - Vilbaste, Sirje
A1  - Vought, Lena B. M.
A1  - Wang, Chiao-Ping
A1  - Webster, Jackson R.
A1  - Wilson, Paul B.
A1  - Woelfl, Stefan
A1  - Xenopoulos, Marguerite A.
A1  - Yates, Adam G.
A1  - Yoshimura, Chihiro
A1  - Yule, Catherine M.
A1  - Zhang, Yixin X.
A1  - Zwart, Jacob A.
T1  - Global patterns and drivers of ecosystem functioning in rivers and riparian zones
JF  - Science Advances
N2  - River ecosystems receive and process vast quantities of terrestrial organic carbon, the fate of which depends strongly on microbial activity. Variation in and controls of processing rates, however, are poorly characterized at the global scale. In response, we used a peer-sourced research network and a highly standardized carbon processing assay to conduct a global-scale field experiment in greater than 1000 river and riparian sites. We found that Earth’s biomes have distinct carbon processing signatures. Slow processing is evident across latitudes, whereas rapid rates are restricted to lower latitudes. Both the mean rate and variability decline with latitude, suggesting temperature constraints toward the poles and greater roles for other environmental drivers (e.g., nutrient loading) toward the equator. These results and data set the stage for unprecedented “next-generation biomonitoring” by establishing baselines to help quantify environmental impacts to the functioning of ecosystems at a global scale.
Y1  - 2019
U6  - https://doi.org/10.1126/sciadv.aav0486
SN  - 2375-2548
VL  - 5
IS  - 1
PB  - American Assoc. for the Advancement of Science
CY  - Washington
ER  - 
TY  - JOUR
A1  - Kolmakova, Olesya V.
A1  - Gladyshev, Michail I.
A1  - Fonvielle, Jeremy Andre
A1  - Ganzert, Lars
A1  - Hornick, Thomas
A1  - Grossart, Hans-Peter
T1  - Effects of zooplankton carcasses degradation on freshwater bacterial community composition and implications for carbon cycling
JF  - Environmental microbiology
N2  - Non-predatory mortality of zooplankton provides an abundant, yet, little studied source of high quality labile organic matter (LOM) in aquatic ecosystems. Using laboratory microcosms, we followed the decomposition of organic carbon of fresh C-13-labelled Daphnia carcasses by natural bacterioplankton. The experimental setup comprised blank microcosms, that is, artificial lake water without any organic matter additions (B), and microcosms either amended with natural humic matter (H), fresh Daphnia carcasses (D) or both, that is, humic matter and Daphnia carcasses (HD). Most of the carcass carbon was consumed and respired by the bacterial community within 15 days of incubation. A shift in the bacterial community composition shaped by labile carcass carbon and by humic matter was observed. Nevertheless, we did not observe a quantitative change in humic matter degradation by heterotrophic bacteria in the presence of LOM derived from carcasses. However, carcasses were the main factor driving the bacterial community composition suggesting that the presence of large quantities of dead zooplankton might affect the carbon cycling in aquatic ecosystems. Our results imply that organic matter derived from zooplankton carcasses is efficiently remineralized by a highly specific bacterial community, but does not interfere with the bacterial turnover of more refractory humic matter.
Y1  - 2018
U6  - https://doi.org/10.1111/1462-2920.14418
SN  - 1462-2912
SN  - 1462-2920
VL  - 21
IS  - 1
SP  - 34
EP  - 49
PB  - Wiley
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Batista, A. M. M.
A1  - Woodhouse, Jason Nicholas
A1  - Grossart, Hans-Peter
A1  - Giani, A.
T1  - Methanogenic archaea associated to Microcystis sp. in field samples and in culture
JF  - Hydrobiologia : acta hydrobiologica, hydrographica, limnologica et protistologica
N2  - Cyanobacterial mass developments impact the community composition of heterotrophic microorganisms with far-reaching consequences for biogeochemical and energy cycles of freshwater ecosystems including reservoirs. Here we sought to evaluate the temporal stability of methanogenic archaea in the water column and further scrutinize their associations with cyanobacteria. Monthly samples were collected from October 2009 to December 2010 in hypereutrophic Pampulha reservoir with permanently blooming cyanobacteria, and from January to December 2011 in oligotrophic Volta Grande reservoir with only sporadic cyanobacteria incidence. The presence of archaea in cyanobacterial cultures was investigated by screening numerous strains of Microcystis spp. from these reservoirs as well as from lakes in Europe, Asia, and North-America. We consistently determined the occurrence of archaea, in particular methanogenic archaea, in both reservoirs throughout the year. However, archaea were only associated with two strains (Microcystis sp. UFMG 165 and UFMG 175) recently isolated from these reservoirs. These findings do not implicate archaea in the occurrence of methane in the epilimnion of inland waters, but rather serve to highlight the potential of microhabitats associated with particles, including phytoplankton, to shelter unique microbial communities.
KW  - Cyanobacteria
KW  - Methanogenic archaea
KW  - Bacterial community composition
KW  - Microcystis sp
KW  - Tropical reservoir
Y1  - 2018
U6  - https://doi.org/10.1007/s10750-018-3655-3
SN  - 0018-8158
SN  - 1573-5117
VL  - 831
IS  - 1
SP  - 163
EP  - 172
PB  - Springer
CY  - Dordrecht
ER  - 
TY  - JOUR
A1  - Block, Benjamin D.
A1  - Denfeld, Blaize A.
A1  - Stockwell, Jason D.
A1  - Flaim, Giovanna
A1  - Grossart, Hans-Peter
A1  - Knoll, Lesley B.
A1  - Maier, Dominique B.
A1  - North, Rebecca L.
A1  - Rautio, Milla
A1  - Rusak, James A.
A1  - Sadro, Steve
A1  - Weyhenmeyer, Gesa A.
A1  - Bramburger, Andrew J.
A1  - Branstrator, Donn K.
A1  - Salonen, Kalevi
A1  - Hampton, Stephanie E.
T1  - The unique methodological challenges of winter limnology
JF  - Limnology and Oceanography: Methods
N2  - Winter is an important season for many limnological processes, which can range from biogeochemical transformations to ecological interactions. Interest in the structure and function of lake ecosystems under ice is on the rise. Although limnologists working at polar latitudes have a long history of winter work, the required knowledge to successfully sample under winter conditions is not widely available and relatively few limnologists receive formal training. In particular, the deployment and operation of equipment in below 0 degrees C temperatures pose considerable logistical and methodological challenges, as do the safety risks of sampling during the ice-covered period. Here, we consolidate information on winter lake sampling and describe effective methods to measure physical, chemical, and biological variables in and under ice. We describe variation in snow and ice conditions and discuss implications for sampling logistics and safety. We outline commonly encountered methodological challenges and make recommendations for best practices to maximize safety and efficiency when sampling through ice or deploying instruments in ice-covered lakes. Application of such practices over a broad range of ice-covered lakes will contribute to a better understanding of the factors that regulate lakes during winter and how winter conditions affect the subsequent ice-free period.
Y1  - 2018
U6  - https://doi.org/10.1002/lom3.10295
SN  - 1541-5856
VL  - 17
IS  - 1
SP  - 42
EP  - 57
PB  - Wiley
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Arias-Andres, Maria
A1  - Rojas-Jimenez, Keilor
A1  - Grossart, Hans-Peter
T1  - Collateral effects of microplastic pollution on aquatic microorganisms
BT  - An ecological perspective
JF  - Trends in Analytical Chemistry
N2  - Microplastics (MP) provide a unique and extensive surface for microbial colonization in aquatic ecosystems. The formation of microorganism-microplastic complexes, such as biofilms, maximizes the degradation of organic matter and horizontal gene transfer. In this context, MP affect the structure and function of microbial communities, which in turn render the physical and chemical fate of MP. This new paradigm generates challenges for microbiology, ecology, and ecotoxicology. Dispersal of MP is concomitant with that of their associated microorganisms and their mobile genetic elements, including antibiotic resistance genes, islands of pathogenicity, and diverse metabolic pathways. Functional changes in aquatic microbiomes can alter carbon metabolism and food webs, with unknown consequences on higher organisms or human microbiomes and hence health. Here, we examine a variety of effects of MP pollution from the microbial ecology perspective, whose repercussions on aquatic ecosystems begin to be unraveled. (C) 2018 Elsevier B.V. All rights reserved.
KW  - Microplastics (MP)
KW  - Biofilms
KW  - HGT
KW  - Microbial ecology
KW  - Carbon cycling
KW  - Aquatic ecosystems
KW  - Health risk assessment
Y1  - 2018
U6  - https://doi.org/10.1016/j.trac.2018.11.041
SN  - 0165-9936
SN  - 1879-3142
VL  - 112
SP  - 234
EP  - 240
PB  - Elsevier
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Fabian, Jenny
A1  - Zlatanovic, Sanja
A1  - Mutz, Michael
A1  - Grossart, Hans-Peter
A1  - van Geldern, Robert
A1  - Ulrich, Andreas
A1  - Gleixner, Gerd
A1  - Premke, Katrin
T1  - Environmental control on microbial turnover of leaf carbon in streams
BT  - Ecological function of phototrophic-heterotrophic interactions
JF  - Frontiers in microbiology
N2  - In aquatic ecosystems, light availability can significantly influence microbial turnover of terrestrial organic matter through associated metabolic interactions between phototrophic and heterotrophic communities. However, particularly in streams, microbial functions vary significantly with the structure of the streambed, that is the distribution and spatial arrangement of sediment grains in the streambed. It is therefore essential to elucidate how environmental factors synergistically define the microbial turnover of terrestrial organic matter in order to better understand the ecological role of photoheterotrophic interactions in stream ecosystem processes. In outdoor experimental streams, we examined how the structure of streambeds modifies the influence of light availability on microbial turnover of leaf carbon (C). Furthermore, we investigated whether the studied relationships of microbial leaf C turnover to environmental conditions are affected by flow intermittency commonly occurring in streams. We applied leaves enriched with a C-13-stable isotope tracer and combined quantitative and isotope analyses. We thereby elucidated whether treatment induced changes in C turnover were associated with altered use of leaf C within the microbial food web. Moreover, isotope analyses were combined with measurements of microbial community composition to determine whether changes in community function were associated with a change in community composition. In this study, we present evidence, that environmental factors interactively determine how phototrophs and heterotrophs contribute to leaf C turnover. Light availability promoted the utilization of leaf C within the microbial food web, which was likely associated with a promoted availability of highly bioavailable metabolites of phototrophic origin. However, our results additionally confirm that the structure of the streambed modifies light-related changes in microbial C turnover. From our observations, we conclude that the streambed structure influences the strength of photo-heterotrophic interactions by defining the spatial availability of algal metabolites in the streambed and the composition of microbial communities. Collectively, our multifactorial approach provides valuable insights into environmental controls on the functioning of stream ecosystems.
KW  - algae
KW  - bacteria
KW  - microbial interactions
KW  - C-13 stable isotopes
KW  - PLFA
KW  - terrestrial carbon
KW  - streambed structure
KW  - light
Y1  - 2018
U6  - https://doi.org/10.3389/fmicb.2018.01044
SN  - 1664-302X
VL  - 9
PB  - Frontiers Research Foundation
CY  - Lausanne
ER  - 
TY  - JOUR
A1  - Reverey, Florian
A1  - Ganzert, Lars
A1  - Lischeid, Gunnar
A1  - Ulrich, Andreas
A1  - Premke, Katrin
A1  - Grossart, Hans-Peter
T1  - Dry-wet cycles of kettle hole sediments leave a microbial and biogeochemical legacy
JF  - The science of the total environment : an international journal for scientific research into the environment and its relationship with man
N2  - Understanding interrelations between an environment's hydrological past and its current biogeochemistry is necessary for the assessment of biogeochemical and microbial responses to changing hydrological conditions. The question how previous dry-wet events determine the contemporary microbial and biogeochemical state is addressed in this study. Therefore, sediments exposed to the atmosphere of areas with a different hydrological past within one kettle hole, i.e. (1) the predominantly inundated pond center, (2) the pond margin frequently desiccated for longer periods and (3) an intermediate zone, were incubated with the same rewetting treatment. Physicochemical and textural characteristics were related to structural microbial parameters regarding carbon and nitrogen turnover, i.e. abundance of bacteria and fungi, denitrifiers (targeted by the nirK und nirS functional genes) and nitrate ammonifiers (targeted by the nrfA functional gene). Our study reveals that, in combination with varying sediment texture, the hydrological history creates distinct microbial habitats with defined boundary conditions within the kettle hole, mainly driven by redox conditions, pH and organic matter (OM) composition. OM mineralization, as indicated by CO2-outgassing, was most efficient in exposed sediments with a less stable hydrological past. The potential for nitrogen retention via nitrate ammonification was highest in the hydrologically rather stable pond center, counteracting nitrogen loss due to denitrification. Therefore, the degree of hydrological stability is an important factor leaving a microbial and biogeochemical legacy, which determines carbon and nitrogen losses from small lentic freshwater systems in the long term run.
KW  - Desiccation
KW  - DNRA
KW  - Denitrifiers
KW  - Organic matter mineralization
KW  - Carbon
KW  - Nitrogen
Y1  - 2018
U6  - https://doi.org/10.1016/j.scitotenv.2018.01.220
SN  - 0048-9697
SN  - 1879-1026
VL  - 627
SP  - 985
EP  - 996
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Van den Wyngaert, Silke
A1  - Seto, Kensuke
A1  - Rojas-Jimenez, Keilor
A1  - Kagami, Maiko
A1  - Grossart, Hans-Peter
T1  - A New Parasitic Chytrid, Staurastromyces oculus (Rhizophydiales, Staurastromy-cetaceae fam. nov.), Infecting the Freshwater Desmid Staurastrum sp.
JF  - Protist
N2  - Chytrids are a diverse group of ubiquitous true zoosporic fungi. The recent molecular discovery of a large diversity of undescribed chytrids has raised awareness on their important, but so far understudied ecological role in aquatic ecosystems. In the pelagic zone, of both freshwater and marine ecosystems, many chytrid species have been morphologically described as parasites on almost all major groups of phytoplankton. However, the majority of these parasitic chytrids has rarely been isolated and lack DNA sequence data, resulting in a large proportion of "dark taxa" in databases. Here, we report on the isolation and in-depth morphological, molecular and host range characterization of a chytrid infecting the common freshwater desmid Staurastrum sp. We provide first insights on the metabolic activity of the different chytrid development stages by using the vital dye FUN (R)-1 (2-chloro-4-[2,3-dihydro-3-methyl-[benzo-1,3-thiazol-2-yl]-methylidene]-1-phenylquinolinium iodide). Cross infection experiments suggest that this chytrid is an obligate parasite and specific for the genus Staurastrum sp. Phylogenetic analysis, based on ITS1-5.8S-ITS2 and 28S rDNA sequences, placed it in the order Rhizophydiales. Based on the unique zoospore ultrastructure, combined with thallus morphology, and molecular phylogenetic placement, we describe this parasitic chytrid as a new genus and species Staurastromyces oculus, within a new family Staurastromycetaceae. (C) 2017 Elsevier GmbH. All rights reserved.
KW  - Chytrids
KW  - parasite
KW  - phytoplankton
KW  - Staurastromyces oculus
KW  - Staurastrum sp.
Y1  - 2017
U6  - https://doi.org/10.1016/j.protis.2017.05.001
SN  - 1434-4610
VL  - 168
SP  - 392
EP  - 407
PB  - Elsevier
CY  - Jena
ER  - 
TY  - JOUR
A1  - Taube, Robert
A1  - Ganzert, Lars
A1  - Grossart, Hans-Peter
A1  - Gleixner, Gerd
A1  - Premke, Katrin
T1  - Organic matter quality structures benthic fatty acid patterns and the abundance of fungi and bacteria in temperate lakes
JF  - The science of the total environment : an international journal for scientific research into the environment and its relationship with man
N2  - Benthic microbial communities (BMCs) play important roles in the carbon cycle of lakes, and benthic littoral zones in particular have been previously highlighted as biogeochemical hotspots. Dissolved organic matter (DOM) presents the major carbon pool in lakes, and although the effect of DOM composition on the pelagic microbial community composition is widely accepted, little is known about its effect on BMCs, particularly aquatic fungi. Therefore, we investigated the composition of benthic littoral microbial communities in twenty highly diverse lakes in northeast Germany. DOM quality was analyzed via size exclusion chromatography (SEC), fluorescence parallel factor analyses (PRAFACs) and UV-Vis spectroscopy. We determined the BMC composition and biomass using phospholipid-derived fatty acids (PLFA) and extended the interpretation to the analysis of fungi by applying a Bayesian mixed model. We present evidence that the quality of DOM structures the BMCs, which are dominated by heterotrophic bacteria and show low fungal biomass. The fungal biomass increases when the DOM pool is processed by microorganisms of allochthonous origin, whereas the opposite is true for bacteria.
KW  - PLFA
KW  - PARAFAC
KW  - Size exclusion chromatography (SEC)
KW  - Aquatic fungi
KW  - Stable isotopes
KW  - FASTAR
Y1  - 2017
U6  - https://doi.org/10.1016/j.scitotenv.2017.07.256
SN  - 0048-9697
SN  - 1879-1026
VL  - 610
SP  - 469
EP  - 481
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Arias-Andres, Maria
A1  - Kluemper, Uli
A1  - Rojas-Jimenez, Keilor
A1  - Grossart, Hans-Peter
T1  - Microplastic pollution increases gene exchange in aquatic ecosystems
JF  - Environmental pollution
N2  - Pollution by microplastics in aquatic ecosystems is accumulating at an unprecedented scale, emerging as a new surface for biofilm formation and gene exchange. In this study, we determined the permissiveness of aquatic bacteria towards a model antibiotic resistance plasmid, comparing communities that form biofilms on microplastics vs. those that are free-living. We used an exogenous and red-fluorescent E. coli donor strain to introduce the green-fluorescent broad-host-range plasmid pKJKS which encodes for trimethoprim resistance. We demonstrate an increased frequency of plasmid transfer in bacteria associated with microplastics compared to bacteria that are free-living or in natural aggregates. Moreover, comparison of communities grown on polycarbonate filters showed that increased gene exchange occurs in a broad range of phylogenetically-diverse bacteria. Our results indicate horizontal gene transfer in this habitat could distinctly affect the ecology of aquatic microbial communities on a global scale. The spread of antibiotic resistance through microplastics could also have profound consequences for the evolution of aquatic bacteria and poses a neglected hazard for human health.
KW  - Microplastics
KW  - Aquatic ecosystems
KW  - Biofilm
KW  - Horizontal gene transfer
KW  - Antibiotic resistance
Y1  - 2018
U6  - https://doi.org/10.1016/j.envpol.2018.02.058
SN  - 0269-7491
SN  - 1873-6424
VL  - 237
SP  - 253
EP  - 261
PB  - Elsevier
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Mühlenbruch, Marco
A1  - Grossart, Hans-Peter
A1  - Eigemann, Falk
A1  - Voss, Maren
T1  - Mini-review: Phytoplankton-derived polysaccharides in the marine environment and their interactions with heterotrophic bacteria
JF  - Environmental microbiology
N2  - Within the wealth of molecules constituting marine dissolved organic matter, carbohydrates make up the largest coherent and quantifiable fraction. Their main sources are from primary producers, which release large amounts of photosynthetic products – mainly polysaccharides – directly into the surrounding water via passive and active exudation. The organic carbon and other nutrients derived from these photosynthates enrich the ‘phycosphere’ and attract heterotrophic bacteria. The rapid uptake and remineralization of dissolved free monosaccharides by heterotrophic bacteria account for the barely detectable levels of these compounds. By contrast, dissolved combined polysaccharides can reach high concentrations, especially during phytoplankton blooms. Polysaccharides are too large to be taken up directly by heterotrophic bacteria, instead requiring hydrolytic cleavage to smaller oligo- or monomers by bacteria with a suitable set of exoenzymes. The release of diverse polysaccharides by various phytoplankton taxa is generally interpreted as the deposition of excess organic material. However, these molecules likely also fulfil distinct, yet not fully understood functions, as inferred from their active modulation in terms of quality and quantity when phytoplankton becomes nutrient limited or is exposed to heterotrophic bacteria. This minireview summarizes current knowledge regarding the exudation and composition of phytoplankton-derived exopolysaccharides and acquisition of these compounds by heterotrophic bacteria.
Y1  - 2018
U6  - https://doi.org/10.1111/1462-2920.14302
SN  - 1462-2912
SN  - 1462-2920
VL  - 20
IS  - 8
SP  - 2671
EP  - 2685
PB  - Wiley
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Rojas-Jimenez, Keilor
A1  - Fonvielle, Jeremy Andre
A1  - Ma, Hua
A1  - Grossart, Hans-Peter
T1  - Transformation of humic substances by the freshwater Ascomycete Cladosporium sp.
JF  - Waterbird
N2  - The ecological relevance of fungi in freshwater ecosystems is becoming increasingly evident, particularly in processing the extensive amounts of polymeric organic carbon such as cellulose, chitin, and humic substances (HS). We isolated several fungal strains from oligo-mesotrophic Lake Stechlin, Brandenburg, Germany, and analyzed their ability to degrade polymeric-like substrates. Using liquid chromatography-organic carbon detection, we determined the byproducts of HS transformation by the freshwater fungus Cladosporium sp. KR14. We demonstrate the ability of this fungus to degrade and simultaneously synthesize HS, and that transformation processes were intensified when iron, as indicator of the occurrence of Fenton reactions, was present in the medium. Furthermore, we showed that structural complexity of the HS produced changed with the availability of other polymeric substances in the medium. Our study highlights the contribution of freshwater Ascomycetes to the transformation of complex organic compounds. As such, it has important implications for understanding the ecological contribution of fungi to aquatic food webs and related biogeochemical cycles.
Y1  - 2017
U6  - https://doi.org/10.1002/lno.10545
SN  - 1524-4695
SN  - 1938-5390
VL  - 40
SP  - 282
EP  - 288
PB  - Waterbird SOC
CY  - Washington
ER  - 
TY  - JOUR
A1  - Bizic-Ionescu, Mina
A1  - Ionescu, Danny
A1  - Grossart, Hans-Peter
T1  - Organic Particles: Heterogeneous Hubs for Microbial Interactions in Aquatic Ecosystems
JF  - Frontiers in microbiology
N2  - The dynamics and activities of microbes colonizing organic particles (hereafter particles) greatly determine the efficiency of the aquatic carbon pump. Current understanding is that particle composition, structure and surface properties, determined mostly by the forming organisms and organic matter, dictate initial microbial colonization and the subsequent rapid succession events taking place as organic matter lability and nutrient content change with microbial degradation. We applied a transcriptomic approach to assess the role of stochastic events on initial microbial colonization of particles. Furthermore, we asked whether gene expression corroborates rapid changes in carbon-quality. Commonly used size fractionated filtration averages thousands of particles of different sizes, sources, and ages. To overcome this drawback, we used replicate samples consisting each of 3–4 particles of identical source and age and further evaluated the consequences of averaging 10–1000s of particles. Using flow-through rolling tanks we conducted long-term experiments at near in situ conditions minimizing the biasing effects of closed incubation approaches often referred to as “the bottle-effect.” In our open flow-through rolling tank system, however, active microbial communities were highly heterogeneous despite an identical particle source, suggesting random initial colonization. Contrasting previous reports using closed incubation systems, expression of carbon utilization genes didn’t change after 1 week of incubation. Consequently, we suggest that in nature, changes in particle-associated community related to carbon availability are much slower (days to weeks) due to constant supply of labile, easily degradable organic matter. Initial, random particle colonization seems to be subsequently altered by multiple organismic interactions shaping microbial community interactions and functional dynamics. Comparative analysis of thousands particles pooled togethers as well as pooled samples suggests that mechanistic studies of microbial dynamics should be done on single particles. The observed microbial heterogeneity and inter-organismic interactions may have important implications for evolution and biogeochemistry in aquatic systems.
KW  - particle-associated bacteria
KW  - microbial communities
KW  - inter- and intra-species interactions
KW  - antagonism
KW  - phage
KW  - transcriptome
Y1  - 2018
U6  - https://doi.org/10.3389/fmicb.2018.02569
SN  - 1664-302X
VL  - 9
PB  - Frontiers Research Foundation
CY  - Lausanne
ER  -