Papers by Lubos Polerecky
We describe stromatolites forming at an altitude of 3570 m at the shore of a volcanic lake Socomp... more We describe stromatolites forming at an altitude of 3570 m at the shore of a volcanic lake Socompa, Argentinean Andes. The water at the site of stromatolites formation is alkaline, hypersaline, rich in inorganic nutrients, very rich in arsenic, and warm (20-24uC) due to a hydrothermal input. The stromatolites do not lithify, but form broad, rounded and low-domed bioherms dominated by diatom frustules and aragonite micro-crystals agglutinated by extracellular substances. In comparison to other modern stromatolites, they harbour an atypical microbial community characterized by highly abundant representatives of Deinococcus-Thermus, Rhodobacteraceae, Desulfobacterales and Spirochaetes. Additionally, a high proportion of the sequences that could not be classified at phylum level showed less than 80% identity to the best hit in the NCBI database, suggesting the presence of novel distant lineages. The primary production in the stromatolites is generally high and likely dominated by Microcoleus sp. Through negative phototaxis, the location of these cyanobacteria in the stromatolites is controlled by UV light, which greatly influences their photosynthetic activity. Diatoms, dominated by Amphora sp., are abundant in the anoxic, sulfidic and essentially dark parts of the stromatolites. Although their origin in the stromatolites is unclear, they are possibly an important source of anaerobically degraded organic matter that induces in situ aragonite precipitation. To the best of our knowledge, this is so far the highest altitude with documented actively forming stromatolites. Their generally rich, diverse and to a large extent novel microbial community likely harbours valuable genetic and proteomic reserves, and thus deserves active protection. Furthermore, since the stromatolites flourish in an environment characterized by a multitude of extremes, including high exposure to UV radiation, they can be an excellent model system for studying microbial adaptations under conditions that, at least in part, resemble those during the early phase of life evolution on Earth.
Limnology and …, Jan 1, 2010
Aquatic invertebrates that ingest large numbers of bacteria produce substantial amounts of the gr... more Aquatic invertebrates that ingest large numbers of bacteria produce substantial amounts of the greenhouse gas N 2 O because of incomplete denitrification in their anoxic gut. We investigated the influence of two key environmental factors, temperature and NO { 3 availability, on N 2 O emission from larvae of Chironomus plumosus in field and laboratory experiments. Larvae collected from lake sediments emitted between 2 and 73 pmol N 2 O ind. 21 h 21 during the warm season, but took up maximally 227 pmol N 2 O ind. 21 h 21 during winter. Larvae kept in laboratory microcosms emitted between 14 and 122 pmol N 2 O ind. 21 h 21 , and N 2 O uptake was never observed. For both types of larvae, the rate of N 2 O emission was stimulated by temperature (when the NO { 3 concentration in the water column was higher than 25-50 mmol L 21 ) and by NO { 3 (when the temperature was higher than 4-10uC). Modeling based on experimentally determined ventilation parameters and sedimentary O 2 and NO { 3 turnover rates predicted that NO { 3 concentrations inside the burrow and in the sediment surrounding the burrow fluctuated and were on average lower than those in the water column. In contrast, NO { 3 concentrations measured in the gut and hemolymph of the microcosm-incubated larvae were at least as high as in the water column. This suggests that N 2 O emission from C. plumosus larvae is controlled by NO { 3 availability in the water column, but is decoupled, by a hitherto unknown mechanism, from NO { 3 present in the immediate surroundings of the larva.
PloS one, Jan 1, 2012
Background: Coral reefs degrade globally at an alarming rate, with benthic algae often replacing ... more Background: Coral reefs degrade globally at an alarming rate, with benthic algae often replacing corals. However, the extent to which benthic algae contribute to coral mortality, and the potential mechanisms involved, remain disputed. Recent laboratory studies suggested that algae kill corals by inducing hypoxia on the coral surface, through stimulated microbial respiration.
2011 GSA Annual …, Jan 1, 2011
... JONES, Daniel S. 1 , POLERECKY, Lubos 2 , DEMPSEY, Brian A. 3 , GALDENZI, Sandro 4 , and MACA... more ... JONES, Daniel S. 1 , POLERECKY, Lubos 2 , DEMPSEY, Brian A. 3 , GALDENZI, Sandro 4 , and MACALADY, Jennifer L. 1 , (1) Geosciences, Pennsylvania State University, University Park, PA 16802, [email protected], (2) Max Planck Institute for Marine Microbiology ...
frontiersin.org
Frontiers | Sulfur Respiration in a Marine Chemolithoautotrophic Beggiatoa Strain | Frontiers in ... more Frontiers | Sulfur Respiration in a Marine Chemolithoautotrophic Beggiatoa Strain | Frontiers in Microbial Physiology and Metabolism publishes articles on the most outstanding discoveries across the research spectrum of Frontiers | Sulfur Respiration in a Marine Chemolithoautotrophic ...
… engineering in intertidal …
PloS one, Jan 1, 2012
Due to its extreme salinity and high Mg concentration the Dead Sea is characterized by a very low... more Due to its extreme salinity and high Mg concentration the Dead Sea is characterized by a very low density of cells most of which are Archaea. We discovered several underwater fresh to brackish water springs in the Dead Sea harboring dense microbial communities. We provide the first characterization of these communities, discuss their possible origin, hydrochemical environment, energetic resources and the putative biogeochemical pathways they are mediating. Pyrosequencing of the 16S rRNA gene and community fingerprinting methods showed that the spring community originates from the Dead Sea sediments and not from the aquifer. Furthermore, it suggested that there is a dense Archaeal community in the shoreline pore water of the lake. Sequences of bacterial sulfate reducers, nitrifiers iron oxidizers and iron reducers were identified as well. Analysis of white and green biofilms suggested that sulfide oxidation through chemolitotrophy and phototrophy is highly significant. Hyperspectral analysis showed a tight association between abundant green sulfur bacteria and cyanobacteria in the green biofilms. Together, our findings show that the Dead Sea floor harbors diverse microbial communities, part of which is not known from other hypersaline environments. Analysis of the water's chemistry shows evidence of microbial activity along the path and suggests that the springs supply nitrogen, phosphorus and organic matter to the microbial communities in the Dead Sea. The underwater springs are a newly recognized water source for the Dead Sea. Their input of microorganisms and nutrients needs to be considered in the assessment of possible impact of dilution events of the lake surface waters, such as those that will occur in the future due to the intended establishment of the Red Sea2Dead Sea water conduit.
Nordic Marine …, Jan 1, 2010
The large filamentous cyanobacteria Aphanizomenon sp., Anabaena sp. and Nodularia sp. are the thr... more The large filamentous cyanobacteria Aphanizomenon sp., Anabaena sp. and Nodularia sp. are the three main nitrogen fixers in the Baltic Sea. During summer, these species form massive blooms in the photic zone, gaining the energy required for nitrogen fixation through photosynthesis. Fixation of atmospheric dinitrogen occurs in specialized cells, the so--called heterocysts, and is rapidly transferred to the vegetative cells. Previous studies have reported, that attached and non--attached microorganisms profit from the release of nutrients by the cyanobacteria. However, up to now the transfer of fixed nitrogen from cyanobacterial cells to the associated microorganisms has not been directly shown in the environment. In this study we used a combination of stable isotope incubations, isotope ratio mass spectrometry and nanoscale secondary ion mass spectrometry (nanoSIMS) to measure N and C-uptake by single microbial cells associated with blooming cyanobacteria. By using Halogen in--situ hybridization coupled to nano--scale secondary ion mass spectrometry (HISH--SIMS) we identified the epibionts and the freeliving bacteria and at the same time measured their nitrogen and carbon uptake rates. We showed that the community of profiting organisms is dominated by Alphaproteobacteria, Gammaproteobacteria and Cytophaga as well as single celled eukaryotes which are highly enriched in both 15N and 13C in comparison to the hosting heterocysts and vegetative cells. These results show for the first time that fixed nitrogen and carbon are rapidly transfered to bacteria and eukaryotes in the Baltic Sea.
… Image and Signal …, Jan 1, 2009
Spectrally resolved imaging was applied to study the growth dynamics of phototrophic biofilms com... more Spectrally resolved imaging was applied to study the growth dynamics of phototrophic biofilms comprizing a mixture of one cyanobacterial and one diatom species. Linear spectral unmixing was combined with liquid chromatography to quantitatively discriminate the areal biomass densities of the two populations. The grown biofilms exhibited highly heterogeneous distribution with patches of 1-2 mm in size, although the conditions provided for growth, including substrate roughness, illumination and flow of the overlying water, were homogeneous. The biomass was initially dominated by cyanobacteria, which exhibited an exponential-like growth phase during days 2-7. Their population declined during days 9-17, which coincided with the growth phase of the diatom population. By allowing non-invasive and real-time measurements and data evaluation, the spectral imaging approach constitutes a useful tool for microbial ecologists.
Proceedings of the …, Jan 1, 2012
Environmental …, Jan 1, 2011
Based on combined microsensor measurements of irradiance, temperature and O 2, we compared light ... more Based on combined microsensor measurements of irradiance, temperature and O 2, we compared light energy budgets in photosynthetic microbial mats, with a special focus on the efficiency of light energy conservation by photosynthesis. The euphotic zones in the three studied mats differed in their phototrophic community structure, pigment concentrations and thickness. In all mats, < 1% of the absorbed light energy was conserved via photosynthesis at high incident irradiance, while the rest was dissipated as heat. Under light-limiting conditions, the photosynthetic efficiency reached a maximum, which varied among the studied mats between 4.5% and 16.2% and was significantly lower than the theoretical maximum of 27.7%. The maximum efficiency correlated linearly with the light attenuation coefficient and photopigment concentration in the euphotic zone. Higher photosynthetic efficiency was found in mats with a thinner and more densely populated euphotic zone. Microbial mats exhibit a lower photosynthetic efficiency compared with ecosystems with a more open canopy-like organization of photosynthetic elements, where light propagation is not hindered to the same extent by photosynthetically inactive components; such components contributed about 40-80% to light absorption in the investigated microbial mats, which is in a similar range as in oceanic planktonic systems.
Environmental …, Jan 1, 2012
We describe an open-source freeware programme for high throughput analysis of nanoSIMS (nanometre... more We describe an open-source freeware programme for high throughput analysis of nanoSIMS (nanometrescale secondary ion mass spectrometry) data. The programme implements basic data processing and analytical functions, including display and driftcorrected accumulation of scanned planes, interactive and semi-automated definition of regions of interest (ROIs), and export of the ROIs' elemental and isotopic composition in graphical and text-based formats. Additionally, the programme offers new functions that were custom-designed to address the needs of environmental microbiologists. Specifically, it allows manual and automated classification of ROIs based on the information that is derived either from the nano-SIMS dataset itself (e.g. from labelling achieved by halogen in situ hybridization) or is provided externally (e.g. as a fluorescence in situ hybridization image). Moreover, by implementing post-processing routines coupled to built-in statistical tools, the programme allows rapid synthesis and comparative analysis of results from many different datasets. After validation of the programme, we illustrate how these new processing and analytical functions increase flexibility, efficiency and depth of the nanoSIMS data analysis. Through its custom-made and open-source design, the programme provides an efficient, reliable and easily expandable tool that can help a growing community of environmental microbiologists and researchers from other disciplines process and analyse their nanoSIMS data. Received
Geophysical …, Jan 1, 2011
Page 1. Geophysical Research Abstracts Vol. 13, EGU2011-12045, 2011 EGU General Assembly 2011 © A... more Page 1. Geophysical Research Abstracts Vol. 13, EGU2011-12045, 2011 EGU General Assembly 2011 © Author(s) 2011 A single cell nanoSIMS view on the transfer of fixed nitrogen to bacteria associated with filamentous N-fixing cyanobacteria in the Baltic Sea ...
… : The 2003 Annual …, Jan 1, 2011
... Bird, Paul, Werner, Ursula, Eickert, Gaby, Polerecky, Lubos, Grunwald, Bjorn, Kuhl, Michael, ... more ... Bird, Paul, Werner, Ursula, Eickert, Gaby, Polerecky, Lubos, Grunwald, Bjorn, Kuhl, Michael, Holst, Gerhard and deBeer, Dirk (2003). ... Created: Fri, 24 Aug 2007, 12:51:57 EST - Detailed History. The University of Queensland. Brisbane St Lucia, QLD 4072 +61 7 3365 1111. ...
Pore water transport …, Jan 1, 2005
The concept of the study was developed by MB and MHMB and UW conducted the experiments with contr... more The concept of the study was developed by MB and MHMB and UW conducted the experiments with contribution of KB and EW. MB evaluated the data and wrote the manuscript with editorial help from all co-authors. The manuscript has been submitted to ...
Flow of Light Energy in …, Jan 1, 2010
Microbial mats are extremely interesting ecosystems that have been intensively investigated by re... more Microbial mats are extremely interesting ecosystems that have been intensively investigated by researchers from a wide variety of fields. This can be clearly seen from the huge body of literature examined different aspects of microbial mats including structural and functional composition. Microbial mats are highly complex systems with micrometer scale changes in the activity and the structural composition within in the photic zone, primarily, due to the highly heterogeneous light field. The difficulties associated with measuring such small changes in light field have resulted in dealing with microbial mats as a "black box".
Frontiers in …, Jan 1, 2011
The chemolithoautotrophic strain Beggiatoa sp. 35Flor shows an unusual migration behavior when cu... more The chemolithoautotrophic strain Beggiatoa sp. 35Flor shows an unusual migration behavior when cultivated in a gradient medium under high sulfide fluxes. As common for Beggiatoa spp., the filaments form a mat at the oxygen–sulfide interface. However, upon prolonged incubation, a subpopulation migrates actively downward into the anoxic and sulfidic section of the medium, where the filaments become gradually depleted in their sulfur and polyhydroxyalkanoates (PHA) inclusions. This depletion is correlated with the production of hydrogen sulfide. The sulfur- and PHA-depleted filaments return to the oxygen–sulfide interface, where they switch back to depositing sulfur and PHA by aerobic sulfide oxidation. Based on these observations we conclude that internally stored elemental sulfur is respired at the expense of stored PHA under anoxic conditions. Until now, nitrate has always been assumed to be the alternative electron acceptor in chemolithoautotrophic Beggiatoa spp. under anoxic conditions. As the medium and the filaments were free of oxidized nitrogen compounds we can exclude this metabolism. Furthermore, sulfur respiration with PHA under anoxic conditions has so far only been described for heterotrophic Beggiatoa spp., but our medium did not contain accessible organic carbon. Hence the PHA inclusions must originate from atmospheric CO2 fixed by the filaments while at the oxygen–sulfide interface. We propose that the directed migration of filaments into the anoxic section of an oxygen–sulfide gradient system is used as a last resort to preserve cell integrity, which would otherwise be compromised by excessive sulfur deposition occurring in the presence of oxygen and high sulfide fluxes. The regulating mechanism of this migration is still unknown.
Limnology …, Jan 1, 2007
We developed a microsensor for the detection of β-radiation with submillimeter spatial resolution... more We developed a microsensor for the detection of β-radiation with submillimeter spatial resolution. The microsensor consists of a scintillating sphere (diameter 100−300 μm) glued to a tip of an optical fiber (core diameter 140 μm) enclosed in a thin glass capillary. The scintillating sphere was made by embedding YLu scintillation powder and TiO 2 light scattering particles in a methacrylate matrix. Photons generated in the scintillator by the β-particles are guided through the fiber and detected by a photomultiplier connected to the opposite fiber end. The photon counts generated by the photomultiplier are linearly proportional to the volume-specific radioactivity in the sample. The background signal can be suppressed practically to zero if two fibers connected to two photomultipliers working in coincidence are used. This, however, results in slightly diminished sensor performance (lower sensitivity and signal-to-noise ratio). As examples of applications, the diffusion coefficients of 36 Cl − , H 14 CO 3 − , and 45 Ca 2+ in agar-solidified saline water were measured, and the depth distribution of primary productivity in an intact microbial mat was determined from vertical profiles of 14 C after incubation in the light using H 14 CO 3 − as tracer.
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Papers by Lubos Polerecky