71 research outputs found
Construction of a Man Nationalism, Identity, Vercingetorix and the Gauls
This paper intends to explore the past representations of Vercingetorix and the Gauls as defined by Julius Caesar and connect them to significant French events throughout the long nineteenth and twentieth centuries in order to establish a link between the Gauls, French nationalism, and French identity
Nitrogen oxidation consortia dynamics influence the performance of full-scale rotating biological contactors.
Ammonia oxidising microorganisms (AOM) play an important role in ammonia removal in wastewater treatment works (WWTW) including rotating biological contactors (RBCs). Environmental factors within RBCs are known to impact the performance of key AOM, such that only some operational RBCs have shown ability for elevated ammonia removal. In this work, long-term treatment performance of seven full-scale RBC systems along with the structure and abundance of the ammonia oxidising bacteria (AOB) and archaea (AOA) communities within microbial biofilms were examined. Long term data showed the dominance of AOB in most RBCs, although two RBCs had demonstrable shift toward an AOA dominated AOM community. Next Generation Sequencing of the 16S rRNA gene revealed diverse evolutionary ancestry of AOB from RBC biofilms while nitrite-oxidising bacteria (NOBs) were similar to reference databases. AOA were more abundant in the biofilms subject to lower organic loading and higher oxygen concentration found at the distal end of RBC systems. Modelling revealed a distinct nitrogen cycling community present within high performing RBCs, linked to efficient control of RBC process variables (retention time, organic loading and oxygen concentration). We present a novel template for enhancing the resilience of RBC systems through microbial community analysis which can guide future strategies for more effective ammonia removal. To best of the author's knowledge, this is the first comparative study reporting the use of next generation sequencing data on microbial biofilms from RBCs to inform effluent quality of small WWTW
<i>amoA</i> Gene Abundances and Nitrification Potential Rates Suggest that Benthic Ammonia-Oxidizing Bacteria and Not Archaea Dominate N Cycling in the Colne Estuary, United Kingdom
ABSTRACT
Nitrification, mediated by ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA), is important in global nitrogen cycling. In estuaries where gradients of salinity and ammonia concentrations occur, there may be differential selections for ammonia-oxidizer populations. The aim of this study was to examine the activity, abundance, and diversity of AOA and AOB in surface oxic sediments of a highly nutrified estuary that exhibits gradients of salinity and ammonium. AOB and AOA communities were investigated by measuring ammonia monooxygenase (
amoA
) gene abundance and nitrification potentials both spatially and temporally. Nitrification potentials differed along the estuary and over time, with the greatest nitrification potentials occurring mid-estuary (8.2 μmol N grams dry weight [gdw]
−1
day
−1
in June, increasing to 37.4 μmol N gdw
−1
day
−1
in January). At the estuary head, the nitrification potential was 4.3 μmol N gdw
−1
day
−1
in June, increasing to 11.7 μmol N gdw
−1
day
−1
in January. At the estuary head and mouth, nitrification potentials fluctuated throughout the year. AOB
amoA
gene abundances were significantly greater (by 100-fold) than those of AOA both spatially and temporally.
Nitrosomonas
spp. were detected along the estuary by denaturing gradient gel electrophoresis (DGGE) band sequence analysis. In conclusion, AOB dominated over AOA in the estuarine sediments, with the ratio of AOB/AOA
amoA
gene abundance increasing from the upper (freshwater) to lower (marine) regions of the Colne estuary. These findings suggest that in this nutrified estuary, AOB (possibly
Nitrosomonas
spp.) were of major significance in nitrification.
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Mineralization and nitrification: Archaea dominate ammonia-oxidising communities in grassland soils
In grasslands, N mineralization and nitrification are important processes and are controlled by several factors, including the in situ microbial community composition. Nitrification involves ammonia oxidising archaea (AOA) and bacteria (AOB) and although AOA and AOB co-exist in soils, they respond differently to environmental characteristics and there is evidence of AOA/AOB niche differentiation. Here, we investigated temporal variation in N mineralization and nitrification rates, together with bacterial, archaeal and ammonia-oxidiser communities in grassland soils, on different geologies: clay, Greensand and Chalk. Across geologies, N mineralization and nitrification rates were slower in the autumn than the rest of the year. Turnover times for soil ammonium pools were <24 h, whilst several days for nitrate. In clay soils, bacterial, archaeal, AOA, and AOB communities were clearly distinct from those in Chalk and Greensand soils. Spatially and temporally, AOA were more abundant than AOB. Notably, Nitrososphaera were predominant, comprising 37.4% of archaeal communities, with the vast majority of AOA found in Chalk and Greensand soils. AOA abundance positively correlated with nitrate concentration, whereas AOB abundance correlated with ammonium and nitrite concentrations, suggesting that these N compounds may be potential drivers for AOA/AOB niche differentiation in these grassland soils
Dynamics and distribution of bacterial and archaeal communities in oil-contaminated temperate coastal mudflat mesocosms
Mudflats are ecologically important habitats that are susceptible to oil pollution, but intervention is difficult in these fine-grained sediments, and so clean-up usually relies on natural attenuation. Therefore, we investigated the impact of crude oil on the bacterial, diatom and archaeal communities within the upper parts of the diatom-dominated sediment and the biofilm that detached from the surface at high tide. Biodegradation of petroleum hydrocarbons was rapid, with a 50 % decrease in concentration in the 0–2-mm section of sediment by 3 days, indicating the presence of a primed hydrocarbon-degrading community. The biggest oil-induced change was in the biofilm that detached from the sediment, with increased relative abundance of several types of diatom and of the obligately hydrocarbonoclastic Oleibacter sp., which constituted 5 % of the pyrosequences in the oiled floating biofilm on day 3 compared to 0.6 % in the non-oiled biofilm. Differences in bacterial community composition between oiled and non-oiled samples from the 0–2-mm section of sediment were only significant at days 12 to 28, and the 2–4-mm-sediment bacterial communities were not significantly affected by oil. However, specific members of the Chromatiales were detected (1 % of sequences in the 2–4-mm section) only in the oiled sediment, supporting other work that implicates them in anaerobic hydrocarbon degradation. Unlike the Bacteria, the archaeal communities were not significantly affected by oil. In fact, changes in community composition over time, perhaps caused by decreased nutrient concentration and changes in grazing pressure, overshadowed the effect of oil for both Bacteria and Archaea. Many obligate hydrocarbonoclastic and generalist oil-degrading bacteria were isolated, and there was little correspondence between the isolates and the main taxa detected by pyrosequencing of sediment-extracted DNA, except for Alcanivorax, Thalassolituus, Cycloclasticus and Roseobacter spp., which were detected by both methods
Application of in vitro Drug Metabolism Studies in Chemical Structure Optimization for the Treatment of Fibrodysplasia Ossificans Progressiva (FOP)
Currently no approved treatment exists for fibrodysplasia ossificans progressiva (FOP) patients, and disease progression results in severe restriction of joint function and premature mortality. LDN-193189 has been demonstrated to be efficacious in a mouse FOP disease model after oral administration. To support species selection for drug safety evaluation and to guide structure optimization for back-up compounds, in vitro metabolism of LDN-193189 was investigated in liver microsome and cytosol fractions of mouse, rat, dog, rabbit, monkey and human. Metabolism studies included analysis of reactive intermediate formation using glutathione and potassium cyanide (KCN) and analysis of non-P450 mediated metabolites in cytosol fractions of various species. Metabolite profiles and metabolic soft spots of LDN-193189 were elucidated using LC/UV and mass spectral techniques. The in vitro metabolism of LDN-193189 was significantly dependent on aldehyde oxidase, with formation of the major NIH-Q55 metabolite. The piperazinyl moiety of LDN-193189 was liable to NADPH-dependent metabolism which generated reactive iminium intermediates, as confirmed through KCN trapping experiments, and aniline metabolites (M337 and M380), which brought up potential drug safety concerns. Subsequently, strategies were employed to avoid metabolic liabilities leading to the synthesis of Compounds 1, 2, and 3. This study demonstrated the importance of metabolite identification for the discovery of novel and safe drug candidates for the treatment of FOP and helped medicinal chemists steer away from potential metabolic liabilities
Vancomycin exposure and acute kidney injury outcome: A Snapshot From the CAMERA2 Study
Among patients with methicillin-resistant Staphylococcus aureus (MRSA) bacteremia from a prospective randomized clinical trial, acute kidney injury (AKI) rates increased with increasing vancomycin exposure, even within the therapeutic range. AKI was independently more common for the (flu)cloxacillin group. Day 2 vancomycin AUC ≥470 mg·h/L was significantly associated with AKI, independent of (flu)cloxacillin receipt
Characterization of Geographically Distinct Bacterial Communities Associated with Coral Mucus Produced by Acropora spp. and Porites spp
ABSTRACT
Acropora
and
Porites
corals are important reef builders in the Indo-Pacific and Caribbean. Bacteria associated with mucus produced by
Porites
spp. and
Acropora
spp. from Caribbean (Punta Maroma, Mexico) and Indo-Pacific (Hoga and Sampela, Indonesia) reefs were determined. Analysis of pyrosequencing libraries showed that bacterial communities from Caribbean corals were significantly more diverse (H′, 3.18 to 4.25) than their Indonesian counterparts (H′, 2.54 to 3.25). Dominant taxa were
Gammaproteobacteria
,
Alphaproteobacteria
,
Firmicutes
, and
Cyanobacteria
, which varied in relative abundance between coral genera and region. Distinct coral host-specific communities were also found; for example,
Clostridiales
were dominant on
Acropora
spp. (at Hoga and the Mexican Caribbean) compared to
Porites
spp. and seawater. Within the
Gammproteobacteria
,
Halomonas
spp. dominated sequence libraries from
Porites
spp. (49%) and
Acropora
spp. (5.6%) from the Mexican Caribbean, compared to the corresponding Indonesian coral libraries (<2%). Interestingly, with the exception of
Porites
spp. from the Mexican Caribbean, there was also a ubiquity of
Psychrobacter
spp., which dominated
Acropora
and
Porites
libraries from Indonesia and
Acropora
libraries from the Caribbean. In conclusion, there was a dominance of
Halomonas
spp. (associated with
Acropora
and
Porites
[Mexican Caribbean]),
Firmicutes
(associated with
Acropora
[Mexican Caribbean] and with
Acropora
and
Porites
[Hoga]), and
Cyanobacteria
(associated with
Acropora
and
Porites
[Hoga] and
Porites
[Sampela]). This is also the first report describing geographically distinct
Psychrobacter
spp. associated with coral mucus. In addition, the predominance of
Clostridiales
associated with
Acropora
spp. provided additional evidence for coral host-specific microorganisms.
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