@article{AdelElbeheryAzizetal.2016, author = {Adel, Mustafa and Elbehery, Ali H. A. and Aziz, Sherry K. and Aziz, Ramy K. and Grossart, Hans-Peter and Siam, Rania}, title = {Viruses-to-mobile genetic elements skew in the deep Atlantis II brine pool sediments}, series = {Scientific reports}, volume = {6}, journal = {Scientific reports}, publisher = {Nature Publ. Group}, address = {London}, issn = {2045-2322}, doi = {10.1038/srep32704}, pages = {8882 -- 8888}, year = {2016}, abstract = {The central rift of the Red Sea has 25 brine pools with different physical and geochemical characteristics. Atlantis II (ATIID), Discovery Deeps (DD) and Chain Deep (CD) are characterized by high salinity, temperature and metal content. Several studies reported microbial communities in these brine pools, but few studies addressed the brine pool sediments. Therefore, sediment cores were collected from ATIID, DD, CD brine pools and an adjacent brine-influenced site. Sixteen different lithologic sediment sections were subjected to shotgun DNA pyrosequencing to generate 1.47 billion base pairs (1.47 x 10(9) bp). We generated sediment-specific reads and attempted to annotate all reads. We report the phylogenetic and biochemical uniqueness of the deepest ATIID sulfur-rich brine pool sediments. In contrary to all other sediment sections, bacteria dominate the deepest ATIID sulfur-rich brine pool sediments. This decrease in virus-to-bacteria ratio in selected sections and depth coincided with an overrepresentation of mobile genetic elements. Skewing in the composition of viruses-to-mobile genetic elements may uniquely contribute to the distinct microbial consortium in sediments in proximity to hydrothermally active vents of the Red Sea and possibly in their surroundings, through differential horizontal gene transfer.}, language = {en} } @article{AichnerDubbertKieletal.2022, author = {Aichner, Bernhard and Dubbert, David and Kiel, Christine and Kohnert, Katrin and Ogashawara, Igor and Jechow, Andreas and Harpenslager, Sarah-Faye and H{\"o}lker, Franz and Nejstgaard, Jens Christian and Grossart, Hans-Peter and Singer, Gabriel and Wollrab, Sabine and Berger, Stella Angela}, title = {Spatial and seasonal patterns of water isotopes in northeastern German lakes}, series = {Earth system science data : ESSD}, volume = {14}, journal = {Earth system science data : ESSD}, number = {4}, publisher = {Copernicus}, address = {G{\"o}ttingen}, issn = {1866-3508}, doi = {10.5194/essd-14-1857-2022}, pages = {1857 -- 1867}, year = {2022}, abstract = {Water stable isotopes (delta O-18 and delta H-2) were analyzed in samples collected in lakes, associated with riverine systems in northeastern Germany, throughout 2020. The dataset (Aichner et al., 2021; https://doi.org/10.1594/PANGAEA.935633) is derived from water samples collected at (a) lake shores (sampled in March and July 2020), (b) buoys which were temporarily installed in deep parts of the lake (sampled monthly from March to October 2020), (c) multiple spatially distributed spots in four selected lakes (in September 2020), and (d) the outflow of Muggelsee (sampled biweekly from March 2020 to January 2021). At shores, water was sampled with a pipette from 40-60 cm below the water surface and directly transferred into a measurement vial, while at buoys a Limnos water sampler was used to obtain samples from 1 m below the surface. Isotope analysis was conducted at IGB Berlin, using a Picarro L2130-i cavity ring-down spectrometer, with a measurement uncertainty of < 0.15 parts per thousand (delta O-18) and < 0.0 parts per thousand (delta H-2). The data give information about the vegetation period and the full seasonal isotope amplitude in the sampled lakes and about spatial isotope variability in different branches of the associated riverine systems.}, language = {en} } @article{AmalfitanoCornoEckertetal.2017, author = {Amalfitano, Stefano and Corno, Gianluca and Eckert, Ester and Fazi, Stefano and Ninio, Shira and Callieri, Cristiana and Grossart, Hans-Peter and Eckert, Werner}, title = {Tracing particulate matter and associated microorganisms in freshwaters}, series = {Hydrobiologia : acta hydrobiologica, hydrographica, limnologica et protistologica}, volume = {800}, journal = {Hydrobiologia : acta hydrobiologica, hydrographica, limnologica et protistologica}, publisher = {Springer}, address = {Dordrecht}, issn = {0018-8158}, doi = {10.1007/s10750-017-3260-x}, pages = {145 -- 154}, year = {2017}, abstract = {Sediment resuspension represents a key process in all natural aquatic systems, owing to its role in nutrient cycling and transport of potential contaminants. Although suspended solids are generally accepted as an important quality parameter, current monitoring programs cover quantitative aspects only. Established methodologies do not provide information on origin, fate, and risks associated with uncontrolled inputs of solids in waters. Here we discuss the analytical approaches to assess the occurrence and ecological relevance of resuspended particulate matter in freshwaters, with a focus on the dynamics of associated contaminants and microorganisms. Triggered by the identification of specific physical-chemical traits and community structure of particle-associated microorganisms, recent findings suggest that a quantitative determination of microorganisms can be reasonably used to trace the origin of particulate matter by means of nucleic acid-based assays in different aquatic systems.}, language = {en} } @article{AriasAndresKettnerMikietal.2018, author = {Arias Andr{\´e}s, Mar{\´i}a de Jes{\´u}s and Kettner, Marie Therese and Miki, Takeshi and Grossart, Hans-Peter}, title = {Microplastics: New substrates for heterotrophic activity contribute to altering organic matter cycles in aquatic ecosystems}, series = {The science of the total environment : an international journal for scientific research into the environment and its relationship with man}, volume = {635}, journal = {The science of the total environment : an international journal for scientific research into the environment and its relationship with man}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0048-9697}, doi = {10.1016/j.scitotenv.2018.04.199}, pages = {1152 -- 1159}, year = {2018}, abstract = {Heterotrophic microbes with the capability to process considerable amounts of organic matter can colonize microplastic particles (MP) in aquatic ecosystems. Weather colonization of microorganisms on MP will alter ecological niche and functioning of microbial communities remains still unanswered. Therefore, we compared the functional diversity of biofilms on microplastics when incubated in three lakes in northeastern Germany differing in trophy and limnological features. For all lakes, we compared heterotrophic activities of MP biofilms with those of microorganisms in the surrounding water by using Biolog (R) EcoPlates and assessed their oxygen consumption in microcosm assays with and without MP. The present study found that the total biofilm biomass was higher in the oligo-mesotrophic and dystrophic lakes than in the eutrophic lake. In all lakes, functional diversity profiles of MP biofilms consistently differed from those in the surrounding water. However, solely in the oligo-mesotrophic lake MP biofilms had a higher functional richness compared to the ambient water. These results demonstrate that the functionality and hence the ecological role of MP-associated microbial communities are context-dependent, i.e. different environments lead to substantial changes in biomass build up and heterotrophic activities of MP biofilms. We propose that MP surfaces act as new niches for aquatic microorganisms and that the constantly increasing MP pollution has the potential to globally impact carbon dynamics of pelagic environments by altering heterotrophic activities. (C) 2018 Elsevier B.V. All rights reserved.}, language = {en} } @article{AriasAndresKluemperRojasJimenezetal.2018, author = {Arias-Andres, Maria and Kluemper, Uli and Rojas-Jimenez, Keilor and Grossart, Hans-Peter}, title = {Microplastic pollution increases gene exchange in aquatic ecosystems}, series = {Environmental pollution}, volume = {237}, journal = {Environmental pollution}, publisher = {Elsevier}, address = {Oxford}, issn = {0269-7491}, doi = {10.1016/j.envpol.2018.02.058}, pages = {253 -- 261}, year = {2018}, abstract = {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.}, language = {en} } @misc{AriasAndresRojasJimenezGrossart2018, author = {Arias-Andres, Maria and Rojas-Jimenez, Keilor and Grossart, Hans-Peter}, title = {Collateral effects of microplastic pollution on aquatic microorganisms}, series = {Trends in Analytical Chemistry}, volume = {112}, journal = {Trends in Analytical Chemistry}, publisher = {Elsevier}, address = {Oxford}, issn = {0165-9936}, doi = {10.1016/j.trac.2018.11.041}, pages = {234 -- 240}, year = {2018}, abstract = {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.}, language = {en} } @article{AttermeyerGrossartFluryetal.2017, author = {Attermeyer, Katrin and Grossart, Hans-Peter and Flury, Sabine and Premke, Katrin}, title = {Bacterial processes and biogeochemical changes in the water body of kettle holes - mainly driven by autochthonous organic matter?}, series = {Aquatic sciences : research across boundaries}, volume = {79}, journal = {Aquatic sciences : research across boundaries}, publisher = {Springer}, address = {Basel}, issn = {1015-1621}, doi = {10.1007/s00027-017-0528-1}, pages = {675 -- 687}, year = {2017}, abstract = {Kettle holes are small inland waters formed from glacially-created depressions often situated in agricultural landscapes. Due to their high perimeter-to-area ratio facilitating a high aquatic-terrestrial coupling, kettle holes can accumulate high concentrations of organic carbon and nutrients, fueling microbial activities and turnover rates. Thus, they represent hotspots of carbon turnover in the landscape, but their bacterial activities and controlling factors have not been well investigated. Therefore, we aimed to assess the relative importance of various environmental factors on bacterial and biogeochemical processes in the water column of kettle holes and to disentangle their variations. In the water body of ten kettle holes in north-eastern Germany, we measured several physico-chemical and biological parameters such as carbon quantity and quality, as well as bacterial protein production (BP) and community respiration (CR) in spring, early summer and autumn 2014. Particulate organic matter served as an indicator of autochthonous production and represented an important parameter to explain variations in BP and CR. This notion is supported by qualitative absorbance indices of dissolved molecules in water samples and C: N ratios of the sediments, which demonstrate high fractions of autochthonous organic matter (OM) in the studied kettle holes. In contrast, dissolved chemical parameters were less important for bacterial activities although they revealed strong differences throughout the growing season. Pelagic bacterial activities and dynamics might thus be regulated by autochthonous OM in kettle holes implying a control of important biogeochemical processes by internal primary production rather than facilitated exchange with the terrestrial surrounding due to a high perimeter-to-area ratio.}, language = {en} } @article{AttermeyerHornickKayleretal.2014, author = {Attermeyer, Katrin and Hornick, T. and Kayler, Z. E. and Bahr, A. and Zwirnmann, E. and Grossart, Hans-Peter and Premke, K.}, title = {Enhanced bacterial decomposition with increasing addition of autochthonous to allochthonous carbon without any effect on bacterial community composition}, series = {Biogeosciences}, volume = {11}, journal = {Biogeosciences}, number = {6}, publisher = {Copernicus}, address = {G{\"o}ttingen}, issn = {1726-4170}, doi = {10.5194/bg-11-1479-2014}, pages = {1479 -- 1489}, year = {2014}, abstract = {Dissolved organic carbon (DOC) concentrations - mainly of terrestrial origin - are increasing worldwide in inland waters. Heterotrophic bacteria are the main consumers of DOC and thus determine DOC temporal dynamics and availability for higher trophic levels. Our aim was to study bacterial carbon (C) turnover with respect to DOC quantity and chemical quality using both allochthonous and autochthonous DOC sources. We incubated a natural bacterial community with allochthonous C (C-13-labeled beech leachate) and increased concentrations and pulses (intermittent occurrence of organic matter input) of autochthonous C (phytoplankton lysate). We then determined bacterial C consumption, activities, and community composition together with the C flow through bacteria using stable C isotopes. The chemical analysis of single sources revealed differences in aromaticity and low-and high-molecular-weight substance fractions (LMWS and HMWS, respectively) between allochthonous and autochthonous C sources. Both DOC sources (allochthonous and autochthonous DOC) were metabolized at a high bacterial growth efficiency (BGE) around 50\%. In treatments with mixed sources, rising concentrations of added autochthonous DOC resulted in a further, significant increase in bacterial DOC consumption of up to 68\% when nutrients were not limiting. This rise was accompanied by a decrease in the humic substance (HS) fraction and an increase in bacterial biomass. Changes in DOC concentration and consumption in mixed treatments did not affect bacterial community composition (BCC), but BCC differed in single vs. mixed incubations. Our study highlights that DOC quantity affects bacterial C consumption but not BCC in nutrient-rich aquatic systems. BCC shifted when a mixture of allochthonous and autochthonous C was provided simultaneously to the bacterial community. Our results indicate that chemical quality rather than source of DOC per se (allochthonous vs. autochthonous) determines bacterial DOC turnover.}, language = {en} } @article{AttermeyerPremkeHornicketal.2013, author = {Attermeyer, Katrin and Premke, Katrin and Hornick, Thomas and Hilt, Sabine and Grossart, Hans-Peter}, title = {Ecosystem-level studies of terrestrial carbon reveal contrasting bacterial metabolism in different aquatic habitats}, series = {Ecology : a publication of the Ecological Society of America}, volume = {94}, journal = {Ecology : a publication of the Ecological Society of America}, number = {12}, publisher = {Wiley}, address = {Washington}, issn = {0012-9658}, doi = {10.1890/13-0420.1}, pages = {2754 -- 2766}, year = {2013}, abstract = {In aquatic systems, terrestrial dissolved organic matter (t-DOM) is known to stimulate bacterial activities in the water column, but simultaneous effects of autumnal leaf input on water column and sediment microbial dynamics in littoral zones of lakes remain largely unknown. The study's objective was to determine the effects of leaf litter on bacterial metabolism in the littoral water and sediment, and subsequently, the consequences for carbon cycling and food web dynamics. Therefore, in late fall, we simultaneously measured water and sediment bacterial metabolism in the littoral zone of a temperate shallow lake after adding terrestrial particulate organic matter (t-POM), namely, maize leaves. To better evaluate bacterial production (BP) and community respiration (CR) in sediments, we incubated sediment cores with maize leaves of different quality (nonleached and leached) under controlled laboratory conditions. Additionally, to quantify the incorporated leaf carbon into microbial biomass, we determined carbon isotopic ratios of fatty acids from sediment and leaf-associated microbes from a laboratory experiment using C-13-enriched beech leaves. The concentrations of dissolved organic carbon (DOC) increased significantly in the lake after the addition of maize leaves, accompanied by a significant increase in water BP. In contrast, sediment BP declined after an initial peak, showing no positive response to t-POM addition. Sediment BP and CR were also not stimulated by t-POM in the laboratory experiment, either in short-term or in long-term incubations, except for a short increase in CR after 18 hours. However, this increase might have reflected the metabolism of leaf-associated microorganisms. We conclude that the leached t-DOM is actively incorporated into microbial biomass in the water column but that the settling leached t-POM (t-POML) does not enter the food web via sediment bacteria. Consequently, t-POML is either buried in the sediment or introduced into the aquatic food web via microorganisms (bacteria and fungi) directly associated with t-POML and via benthic macroinvertebrates by shredding of t-POML. The latter pathway represents a benthic shortcut which efficiently transfers t-POML to higher trophic levels.}, language = {en} } @article{AttermeyerTittelAllgaieretal.2015, author = {Attermeyer, Katrin and Tittel, Joerg and Allgaier, Martin and Frindte, Katharina and Wurzbacher, Christian and Hilt, Sabine and Kamjunke, Norbert and Grossart, Hans-Peter}, title = {Effects of Light and Autochthonous Carbon Additions on Microbial Turnover of Allochthonous Organic Carbon and Community Composition}, series = {Microbial ecology}, volume = {69}, journal = {Microbial ecology}, number = {2}, publisher = {Springer}, address = {New York}, issn = {0095-3628}, doi = {10.1007/s00248-014-0549-4}, pages = {361 -- 371}, year = {2015}, abstract = {The fate of allochthonous dissolved organic carbon (DOC) in aquatic systems is primarily controlled by the turnover of heterotrophic bacteria. However, the roles that abiotic and biotic factors such as light and DOC release by aquatic primary producers play in the microbial decomposition of allochthonous DOC is not well understood. We therefore tested if light and autochthonous DOC additions would increase allochthonous DOC decomposition rates and change bacterial growth efficiencies and community composition (BCC). We established continuous growth cultures with different inocula of natural bacterial communities and alder leaf leachates (DOCleaf) with and without light exposure before amendment. Furthermore, we incubated DOCleaf together with autochthonous DOC from lysed phytoplankton cultures (DOCphyto). Our results revealed that pretreatments of DOCleaf with light resulted in a doubling of bacterial growth efficiency (BGE), whereas additions of DOCphyto or combined additions of DOCphyto and light had no effect on BGE. The change in BGE was not accompanied by shifts in the phylogenetic structure of the BCC, but BCC was influenced by the DOC source. Our results highlight that a doubling of BGE is not necessarily accompanied by a shift in BCC and that BCC is more strongly affected by resource properties.}, language = {en} }