ALBERT

Beschreibung: Professor Dr. Achim Brauer lehnt an der Spüle. Ein kleines Glas Wein gönnt er sich, schließlich ist es keine alltägliche Situation für den GFZWissenschaftler. Gleich wird er einen Vortrag halten. In einem Wohnzimmer.

Beschreibung: A geochemical survey of 197 fluid discharges (cold and thermal waters and bubbling pools) and 15 gas emissions from the western sector of the Sabatini Volcanic District and the Tolfa Mountains (Latium, Central Italy) was carried out in 2007–2008. The chemical and isotopic compositions of the fluid discharges indicate the occurrence of two main sources: 1) relatively shallow aquifers with Ca(Na,K)–HCO3 and Ca(Mg)–HCO3 compositions when trapped in volcanic and sedimentary formations, respectively; and 2) a deep reservoir, which is hosted in the Mesozoic carbonate sequence, rich in CO2 and having a Ca–SO4(HCO3) composition. Dissolution of a CO2-rich gas phase into the shallow aquifers produces high-TDS and high-pCO2 cold waters, while oxidation of deep-derived H2S to SO4 2− generates low-pH (b4) sulfate waters. The δ13C–CO2 values for gas emissions (from−2.8 to+2.7‰vs. VPDB) suggest that the origin of CO2 associated with the deep fluids ismainly related to thermo-metamorphic reactions within the carbonate reservoir, although significant mantle contribution may also occur. However, R/Ra values (0.37–0.62) indicate that He is mainly produced by a crustal source, with a minor component from a crust-contaminated mantle. On the basis of the δ13C–CH4 and δD–CH4 values (from −25.7 to −19.5‰ vs. VPDB and from −152 to −93.4‰ vs. VSMOW, respectively) CH4 production is associated with thermogenic processes, possibly related to abiogenic CO2 reduction within the carbonate reservoir. The δ34S–H2S values (from+9.3 to +10.4‰ vs. VCDT) are consistent with the hypothesis of a sedimentary source of sulfur from thermogenic reduction of Triassic sulfates. Geothermometric evaluations based on chemical equilibria CO2–CH4 and, separately, H2S suggest that the reservoir equilibriumtemperature is up to ~300 °C. The δDand δ18O data indicate thatwater recharging both the shallow and deep aquifers has a meteoric origin. Fluid geochemistry, coupled with gravimetric data and tectonic lineaments, supports the idea that significant contributions from a deep-seated geothermal brine are present in the Stigliano thermal fluid discharges. Exploration surveys investigated this area during 70's–90's for geothermal purposes. Nevertheless, presently the area is still under-exploited. The presence of thermal waters and anomalous heat flow together with the demographic growth of the last years,makes this site a suitable location for direct applications of the geothermal resource.

Beschreibung: Published

Beschreibung: 160-181

Beschreibung: 2.4. TTC - Laboratori di geochimica dei fluidi

Beschreibung: JCR Journal

Beschreibung: reserved

Beschreibung: On two separate occasions during fieldwork in Semporna (eastern Sabah, Malaysia), sea anemones of the family Edwardsiidae were observed attempting to feed on the nudibranch species Nembrotha lineolata and Phyllidia ocellata. These are the first in situ observations of nudibranch predation by sea anemones. This new record is compared with known information on sea slug predators.

Beschreibung: Future impacts of ocean acidification on reproduction of exposed marine organisms with consequences at the population level still have to be properly analyzed and understood. For fertilization, eggs of echinoderms are directly released into seawater where the acrosome reaction takes place. Therefore, gametes are directly exposed unprotected to the detrimental conditions of an acidified environment. There is evidence that internal pH levels of cells change within 15-30 min conditioned by the external pH to which the eggs are exposed. Internal pH of the eggs plays an important role in the metabolic functionality of the signaling pathways and enzymatic activations induced by the contact with the sperm. These processes prohibit polyspermy and initiate normal embryonic development. We selected a species of sea urchin from the Arctic (Strongylocentrotus droebachiensis) to study the effect of sea water acidification on fertilization success. First results on fertilization experiments under various pH conditions (180 µatm, 380 µatm, 980 µatm, 1400 µatm and 3000 µatm) at natural temperatures and with two different approaches (with or without pre-incubation of the eggs) will be presented. Dramatic effects on fertilization success and embryonic development were identified under prognostic future pH conditions. We will discuss the vulnerability of the process of fertilization under past, present and future conditions.

Beschreibung: The purpose of the present study was to analyze the composition of marine bacterial communities around the world, and to investigate bacterial isolates regarding the production of antibiotics. This included molecular analyses of marine bacterioplankton, as well as culture-based studies of marine bacterial isolates with antagonistic activity. The work was based on samples collected during the Galathea 3 and LOMROG-II marine research expeditions that have explored many different oceanic regions worldwide. A molecular survey of marine bacterioplankton at 24 worldwide stations investigated the abundance of major bacterial groups, potential biogeographical patterns, and their relation to environmental parameters. The original aim was to determine whether the composition of the total microbiota correlates with the occurrence of culturable bioactive bacteria. No such correlation was found. Quantitative community analyses showed latitudinal patterns in bacterial distribution, revealing significantly different relative abundances of Bacteroidetes, unclassified Bacteria and Vibrio between warmer and colder oceans. Absolute cell numbers of most bacterial groups were positively correlated with nutrient concentrations in warmer oceans, and negatively with oxygen saturation in colder oceans. The finding of differing communities in warmer and colder oceans underlined the presence of biogeographical patterns among marine bacteria and the influence of environmental parameters on bacterial distribution. Studies of antagonistic isolates focused on six bioactive Vibrionaceae isolated during Galathea 3. The six strains were identified as Vibrio coralliilyticus (two strains), V. neptunius (two strains), V. nigripulchritudo (one strain), and Photobacterium halotolerans (one strain) by sequencing of housekeeping genes. Chemical metabolite profiling underlined genetic relationships by showing highly similar production of secondary metabolites for each species. Two known antibiotics were purified; andrimid from V. coralliilyticus and holomycin from P. halotolerans. In addition, two novel cyclic peptides from P. halotolerans and a novel siderophore-like compound from V. nigripulchritudo were isolated. All three compounds interfere with quorum sensing in S. aureus. During LOMROG-II further seventeen strains with antagonistic activity were isolated, affiliating with the Actinobacteria (8 strains), Pseudoalteromonas (4 strains), the Vibrionaceae (3 strains), and Psychrobacter (2 strains). Seven of the eight bioactive Actinobacteria, being isolated from different sources throughout the Arctic Ocean, were related to Arthrobacter davidanieli. Its broad antibiotic spectrum was likely based on production of the known arthrobacilin antibiotics. The eighth actinomycete, tentatively identified as Brevibacterium sp., produces a potentially novel antimicrobial compound. Most studies of antagonistic marine bacteria have been conducted with the aim of isolating novel antimicrobials with potential clinical applications. However, little is known about production and role of these compounds in the natural environment. This thesis took one step in this direction and demonstrated that V. coralliilyticus S2052 produced its antibiotic andrimid when grown with chitin as the sole carbon source. Whilst the strain produced an array of secondary metabolites in laboratory media, it focused on andrimid production with chitin. This indicates that the antibiotic is likely produced in the natural habitat and may serve an ecophysiological function. The finding that two related strains from public culture collections do not produce andrimid and have different biosynthetic temperature optima suggested that V. coralliilyticus may comprise different subspecies with different niches. In summary, the present study shows biogeographical patterns of marine bacterioplankton on a global scale. In addition, the thesis work has demonstrated that marine Vibrionaceae and polar Actinobacteria are a resource of antibacterial compounds and may have potential for future natural product discovery.