Seasonality of Glacial Snow and Ice Microbial Communities.

Blooms of microalgae on glaciers and ice sheets are amplifying surface ice melting rates, which are already affected by climate change. Most studies on glacial microorganisms (including snow and glacier ice algae) have so far focused on the spring and summer melt season, leading to a temporal bias, and a knowledge gap in our understanding of the variations in microbial diversity, productivity, and physiology on glacier surfaces year-round. Here, we investigated the microbial communities from Icelandic glacier surface snow and bare ice habitats, with sampling spanning two consecutive years and carried out in both winter and two summer seasons. We evaluated the seasonal differences in microbial community composition using Illumina sequencing of the 16S rRNA, 18S rRNA, and ITS marker genes and correlating them with geochemical signals in the snow and ice. During summer, Chloromonas, Chlainomonas, Raphidonema, and Hydrurus dominated surface snow algal communities, while Ancylonema and Mesotaenium dominated the surface bare ice habitats. In winter, algae could not be detected, and the community composition was dominated by bacteria and fungi. The dominant bacterial taxa found in both winter and summer samples were Bacteriodetes, Actinobacteria, Alphaproteobacteria, and Gammaproteobacteria. The winter bacterial communities showed high similarities to airborne and fresh snow bacteria reported in other studies. This points toward the importance of dry and wet deposition as a wintertime source of microorganisms to the glacier surface. Winter samples were also richer in nutrients than summer samples, except for dissolved organic carbon-which was highest in summer snow and ice samples with blooming microalgae, suggesting that nutrients are accumulated during winter but primarily used by the microbial communities in the summer. Overall, our study shows that glacial snow and ice microbial communities are highly variable on a seasonal basis.

Vegetation state changes in the course of shrub encroachment in an African savanna since about 1850 CE and their potential drivers.

Shrub encroachment has far-reaching ecological and economic consequences in many ecosystems worldwide. Yet, compositional changes associated with shrub encroachment are often overlooked despite having important effects on ecosystem functioning.We document the compositional change and potential drivers for a northern Namibian Combretum woodland transitioning into a Terminalia shrubland. We use a multiproxy record (pollen, sedimentary ancient DNA, biomarkers, compound-specific carbon (δ13C) and deuterium (δD) isotopes, bulk carbon isotopes (δ13Corg), grain size, geochemical properties) from Lake Otjikoto at high taxonomical and temporal resolution.We provide evidence that state changes in semiarid environments may occur on a scale of one century and that transitions between stable states can span around 80 years and are characterized by a unique vegetation composition. We demonstrate that the current grass/woody ratio is exceptional for the last 170 years, as supported by n-alkane distributions and the δ13C and δ13Corg records. Comparing vegetation records to environmental proxy data and census data, we infer a complex network of global and local drivers of vegetation change. While our δD record suggests physiological adaptations of woody species to higher atmospheric pCO2 concentration and drought, our vegetation records reflect the impact of broad-scale logging for the mining industry, and the macrocharcoal record suggests a decrease in fire activity associated with the intensification of farming. Impact of selective grazing is reflected by changes in abundance and taxonomical composition of grasses and by an increase of nonpalatable and trampling-resistant taxa. In addition, grain-size and spore records suggest changes in the erodibility of soils because of reduced grass cover. Synthesis. We conclude that transitions to an encroached savanna state are supported by gradual environmental changes induced by management strategies, which affected the resilience of savanna ecosystems. In addition, feedback mechanisms that reflect the interplay between management legacies and climate change maintain the encroached state.

Activity concentrations of 238U and 226Ra in two European black shales and their experimentally-derived leachates.

The production of gas from unconventional resources became an important position in the world energy economics. In 2012, the European Commission's Joint Research Centre estimate 16 trillion cubic meters (Tcm) of technically recoverable shale gas in Europe. Taking into account that the exploitation of unconventional gas can be accompanied by serious health risks due to the release of toxic chemical components and natural occurring radionuclides into the return flow water and their near-surface accumulation in secondary precipitates, we investigated the release of U, Th and Ra from black shales by interaction with drilling fluids containing additives that are commonly employed for shale gas exploitation. We performed leaching tests at elevated temperatures and pressures with an Alum black shale from Bornholm, Denmark and a Posidonia black shale from Lower Saxony, Germany. The Alum shale is a carbonate free black shale with pyrite and barite, containing 74.4 µg/g U. The Posidonia shales is a calcareous shale with pyrite but without detectable amounts of barite containing 3.6 µg/g U. Pyrite oxidized during the tests forming sulfuric acid which lowered the pH on values between 2 and 3 of the extraction fluid from the Alum shale favoring a release of U from the Alum shale to the fluid during the short-term and in the beginning of the long-term experiments. The activity concentration of 238U is as high as 23.9 mBq/ml in the fluid for those experiments. The release of U and Th into the fluid is almost independent of pressure. The amount of uranium in the European shales is similar to that of the Marcellus Shale in the United States but the daughter product of 238U, the 226Ra activity concentrations in the experimentally derived leachates from the European shales are quite low in comparison to that found in industrially derived flowback fluids from the Marcellus shale. This difference could mainly be due to missing Cl in the reaction fluid used in our experiments and a lower fluid to solid ratio in the industrial plays than in the experiments due to subsequent fracking and minute cracks from which Ra can easily be released.

Membrane Lipids as Indicators for Viable Bacterial Communities Inhabiting Petroleum Systems.

Microbial activity in petroleum reservoirs has been implicated in a suite of detrimental effects including deterioration of petroleum quality, increases in oil sulfur content, biofouling of steel pipelines and other infrastructures, and well plugging. Here, we present a biogeochemical approach, using phospholipid fatty acids (PLFAs), for detecting viable bacteria in petroleum systems. Variations within the bacterial community along water flow paths (producing well, topside facilities, and injection well) can be elucidated in the field using the same technique, as shown here within oil production plants in the Molasse Basin of Upper Austria. The abundance of PLFAs is compared to total cellular numbers, as detected by qPCR of the 16S rDNA gene, to give an overall comparison between the resolutions of both methods in a true field setting. Additionally, the influence of biocide applications on lipid- and DNA-based quantification was investigated. The first oil field, Trattnach, showed significant PLFA abundances and cell numbers within the reservoir and topside facilities. In contrast, the second field (Engenfeld) showed very low PLFA levels overall, likely due to continuous treatment of the topside facilities with a glutaraldehyde-based antimicrobial. In comparison, Trattnach is dosed once per week in a batch fashion. Changes within PLFA compositions across the flow path, throughout the petroleum production plants, point to cellular adaptation within the system and may be linked to shifts in the dominance of certain bacterial types in oil reservoirs versus topside facilities. Overall, PLFA-based monitoring provides a useful tool to assess the abundance and high-level taxonomic diversity of viable microbial populations in oil production wells, topside infrastructure, pipelines, and other related facilities.

Anoxybacillusgeothermalis sp. nov., a facultatively anaerobic, endospore-forming bacterium isolated from mineral deposits in a geothermal station.

A novel endospore-forming bacterium designated strain GSsed3T was isolated from deposits clogging aboveground filters from the geothermal power platform of Groß Schönebeck in northern Germany. The novel isolate was Gram-staining-positive, facultatively anaerobic, catalase-positive and oxidase-positive. Optimum growth occurred at 60 °C, 0.5 % (w/v) NaCl and pH 7-8. Analysis of the 16S rRNA gene sequence similarity indicated that strain GSsed3T belonged to the genus Anoxybacillus, and showed 99.8 % sequence similarity to Anoxybacillus rupiensis R270T, 98.2 % similarity to Anoxybacillus tepidamans GS5-97T, 97.9 % similarity to Anoxybacillus voinovskiensis TH13T, 97.7 % similarity to Anoxybacillus caldiproteolyticus DSM 15730T and 97.6 % similarity to Anoxybacillus amylolyticus MR3CT. DNA-DNA hybridization (DDH) indicated only 16 % relatedness to Anoxybacillus rupiensis DSM 17127T. Furthermore, DDH estimation based on genomes analysis indicated only 19.9 % overall nucleotide similarity to Anoxybacillus amylolyticus DSM 15939T. The major respiratory menaquinone was MK-8. The polar lipid profile consisted of phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, one unknown phosphoglycolipid and one unknown phospholipid. The predominant cellular fatty acids were iso-C15 : 0, iso-C17 : 0, C16 : 0, iso-C16 : 0 and anteiso-C17 : 0. The peptidoglycan type was A1γ meso-Dpm-direct. The genomic DNA G+C content of the strain was 46.9 mol%. The phenotypic, genotypic and chemotaxonomic characterization indicated that strain GSsed3T differs from related species of the genus. Therefore, strain GSsed3T is considered to be a representative of a novel species of the genus Anoxybacillus, for which the name Anoxybacillus geothermalis sp. nov. is proposed. The type strain of Anoxybacillus geothermalis is GSsed3T (=CCOS808T =ATCC BAA2555T).

Genome Sequence of Anoxybacillus geothermalis Strain GSsed3, a Novel Thermophilic Endospore-Forming Species.

Anoxybacillus geothermalis strain GSsed3 is an endospore-forming thermophilic bacterium isolated from filter deposits in a geothermal site. This novel species has a larger genome size (7.2 Mb) than that of any other Anoxybacillus species, and it possesses genes that support its phenotypic metabolic characterization and suggest an intriguing link to metals.

Detection of residual oil-sand-derived organic material in developing soils of reclamation sites by ultra-high-resolution mass spectrometry.

The reconstruction of disturbed landscapes back to working ecosystems is an issue of increasing importance for the oil sand areas in Alberta, Canada. In this context, the fate of oil-sand-derived organic material in the tailings sands used for reclamation is of utmost environmental importance. Here we use electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry of maltene fractions to identify compositional variations over a complete oil sand mining and recultivation process chain. On the basis of bulk compound class distributions and percentages of unique elemental compositions, we identify specific compositional features that are related to the different steps of the process chain. The double bond equivalent and carbon number distributions of the N1 and S1O2 classes are almost invariant along the process chain, despite a significant decrease in overall abundance. We thus suggest that these oil-sand-derived components can be used as sensitive tracers of residual bitumen, even in soils from relatively old reclamation sites. The patterns of the O2, O3, and O4 classes may be applied to assess process-chain-related changes in organic matter composition, including the formation of plant-derived soil organic matter on the reclamation sites. The N1O2 species appear to be related to unidentified processes in the tailings ponds but do not represent products of aerobic biodegradation of pyrrolic nitrogen compounds.

Tracing biogeochemical and microbial variability over a complete oil sand mining and recultivation process.

Recultivation of disturbed oil sand mining areas is an issue of increasing importance. Nevertheless only little is known about the fate of organic matter, cell abundances and microbial community structures during oil sand processing, tailings management and initial soil development on reclamation sites. Thus the focus of this work is on biogeochemical changes of mined oil sands through the entire process chain until its use as substratum for newly developing soils on reclamation sites. Therefore, oil sand, mature fine tailings (MFTs) from tailings ponds and drying cells and tailings sand covered with peat-mineral mix (PMM) as part of land reclamation were analyzed. The sample set was selected to address the question whether changes in the above-mentioned biogeochemical parameters can be related to oil sand processing or biological processes and how these changes influence microbial activities and soil development. GC-MS analyses of oil-derived biomarkers reveal that these compounds remain unaffected by oil sand processing and biological activity. In contrast, changes in polycyclic aromatic hydrocarbon (PAH) abundance and pattern can be observed along the process chain. Especially naphthalenes, phenanthrenes and chrysenes are altered or absent on reclamation sites. Furthermore, root-bearing horizons on reclamation sites exhibit cell abundances at least ten times higher (10(8) to 10(9) cells g(-1)) than in oil sand and MFT samples (10(7) cells g(-1)) and show a higher diversity in their microbial community structure. Nitrate in the pore water and roots derived from the PMM seem to be the most important stimulants for microbial growth. The combined data show that the observed compositional changes are mostly related to biological activity and the addition of exogenous organic components (PMM), whereas oil extraction, tailings dewatering and compaction do not have significant influences on the evaluated compounds. Microbial community composition remains relatively stable through the entire process chain.