Diversity of Rhodopirellula and related planctomycetes in a North Sea coastal sediment employing carB as molecular marker.

Rhodopirellula is an abundant marine member of the bacterial phylum Planctomycetes. Cultivation studies revealed the presence of several closely related Rhodopirellula species in European coastal sediments. Because the 16S rRNA gene does not provide the desired taxonomic resolution to differentiate Rhodopirellula species, we performed a comparison of the genomes of nine Rhodopirellula strains and six related planctomycetes and identified carB, coding for the large subunit of carbamoylphosphate synthetase, as a suitable molecular marker. In this study, we investigated the diversity of Rhodopirellula in coastal intertidal surface sediments of Sylt island, North Sea, using the 16S rRNA and carB genes as molecular markers. The carB clone and pyrosequencing libraries revealed the presence of 12 species of Rhodopirellula and of 66 species in closely related undescribed genera, a diversity that was not detected with a 16S rRNA gene library. This study demonstrates that the carB gene is a powerful molecular marker for detecting Rhodopirellula species in the environment and may be used for the taxonomic evaluation of new strains

(Acido)bacterial diversity in space and time

Recent technological achievements enabled microbiologists to fully grasp the vast diversity of microbial life that is resident in soils, highly complex matrices of alternating micro-habitats on very small scales. Since then, microbial community composition has been catalogued for many different terrestrial habitats. This triggered the investigation and definition of processes which shape these communities. In most cases, the environment determines community composition, and similar habitats may feature similar microbial communities despite being far apart. However, some habitats have been described as subjected to pronounced neutral processes, which are dispersal, ecological drift or speciation. The balance between these process types is now the subject of many studies looking at microbial communities. It is also clear that these processes need to be monitored on both temporal and spatial scales, as the two dimensions are inseparably interlinked. However, most microbial studies deal with only one aspect, but do not control for the other. In this work, the outcome of a highly sophisticated plot scale experiment is presented encompassing 358 sampling locations distributed between six intra-annual sampling points on a 10 m x 10 m unfertilized grassland site in the Swabian Alb. RNA was extracted from the A-horizon of each soil and the hypervariable region 3 of the ribosomal small subunit was amplified and sequenced with barcoded Illumina sequencing. Roughly 400 million eubacterial reads were obtained. The dataset was used to assess the population dynamics of Acidobacteria, as well as the spatio-temporal co-occurenze of functionally depending microorganism. Additionally, preliminary results motivated the assessment of common methods for the examination of rhizospheric communities. In combination, the diversity of bacterial communities in space and time was tested from different angles, reflecting different research question, and they all revealed a far more complex reality than previously thought

Nontrivial damping of quantum many-body dynamics

Understanding how the dynamics of a given quantum system with many degrees of freedom is altered by the presence of a generic perturbation is a notoriously difficult question. Recent works predict that, in the overwhelming majority of cases, the unperturbed dynamics is just damped by a simple function, e.g., exponentially as expected from Fermi's golden rule. While these predictions rely on random-matrix arguments and typicality, they can only be verified for a specific physical situation by comparing to the actual solution or measurement. Crucially, it also remains unclear how frequent and under which conditions counterexamples to the typical behavior occur. In this work, we discuss this question from the perspective of projection-operator techniques, where exponential damping of a density matrix occurs in the interaction picture but not necessarily in the Schr\"odinger picture. We show that a nontrivial damping in the Schr\"odinger picture can emerge if the dynamics in the unperturbed system possesses rich features, for instance due to the presence of strong interactions. This suggestion has consequences for the time dependence of correlation functions. We substantiate our theoretical arguments by large-scale numerical simulations of charge transport in the extended Fermi-Hubbard chain, where the nearest-neighbor interactions are treated as a perturbation to the integrable reference system

Far-infrared photo-conductivity of electrons in an array of nano-structured antidots

We present far-infrared (FIR) photo-conductivity measurements for a two-dimensional electron gas in an array of nano-structured antidots. We detect, resistively and spectrally resolved, both the magnetoplasmon and the edge-magnetoplasmon modes. Temperature-dependent measurements demonstrates that both modes contribute to the photo resistance by heating the electron gas via resonant absorption of the FIR radiation. Influences of spin effect and phonon bands on the collective excitations in the antidot lattice are observed.Comment: 5 pages, 3 figure

Magneto- and barocaloric properties of the ferro-antiferromagnetic sawtooth chain

Materials that are susceptible to pressure and external magnetic fields allow the combined use of both for caloric processes. Here we report investigations of the ferromagnetic-antiferromagnetic sawtooth chain that due to its critical behavior not only allows for both barocaloric as well as magnetocaloric processes but also features very large cooling rates in the vicinity of the quantum critical point.Comment: 6 pages, 7 figure

Geographic distribution at subspecies resolution level: closely related Rhodopirellula species in European coastal sediments.

Members of the marine genus Rhodopirellula are attached living bacteria and studies based on cultured Rhodopirellula strains suggested that three closely related species R. baltica, 'R. europaea' and 'R. islandica' have a limited geographic distribution in Europe. To address this hypothesis, we developed a nested PCR for a single gene copy detection of a partial acetyl CoA synthetase (acsA) from intertidal sediments collected all around Europe. Furthermore, we performed growth experiments in a range of temperature, salinity and light conditions. A combination of Basic Local Alignment Search Tool (BLAST) and Minimum Entropy Decomposition (MED) was used to analyze the sequences with the aim to explore the geographical distribution of the species and subspecies. MED has been mainly used for the analysis of the 16S rRNA gene and here we propose a protocol for the analysis of protein-coding genes taking into account the degeneracy of the codons and a possible overestimation of functional diversity. The high-resolution analysis revealed differences in the intraspecies community structure in different geographic regions. However, we found all three species present in all regions sampled and in agreement with growth experiments we demonstrated that Rhodopirellula species do not have a limited geographic distribution in Europe

Manganese reduction and associated microbial communities in Antarctic surface sediments

The polar regions are the fastest warming places on earth. Accelerated glacial melting causes increased supply of nutrients such as metal oxides (i.e., iron and manganese oxides) into the surrounding environment, such as the marine sediments of Potter Cove, King George Island/Isla 25 de Mayo (West Antarctic Peninsula). Microbial manganese oxide reduction and the associated microbial communities are poorly understood in Antarctic sediments. Here, we investigated this process by geochemical measurements of in situ sediment pore water and by slurry incubation experiments which were accompanied by 16S rRNA sequencing. Members of the genus Desulfuromusa were the main responder to manganese oxide and acetate amendment in the incubations. Other organisms identified in relation to manganese and/or acetate utilization included Desulfuromonas, Sva1033 (family of Desulfuromonadales) and unclassified Arcobacteraceae. Our data show that distinct members of Desulfuromonadales are most active in organotrophic manganese reduction, thus providing strong evidence of their relevance in manganese reduction in permanently cold Antarctic sediments.Fil: Wunder, Lea C.. Universitat Bremen; AlemaniaFil: Breuer, Inga. Universitat Bremen; AlemaniaFil: Willis Poratti, Graciana. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. Dirección Nacional del Antártico. Instituto Antártico Argentino; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universitat Bremen; AlemaniaFil: Aromokeye, David A.. Universitat Bremen; AlemaniaFil: Henkel, Susann. Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung; AlemaniaFil: Richter Heitmann, Tim. Universitat Bremen; AlemaniaFil: Yin, Xiuran. Universitat Bremen; AlemaniaFil: Friedrich, Michael W.. Universitat Bremen; Alemani