Population dynamics of marine oil-degrading microbial communities

Im Rahmen dieser Studie sollte die Reaktion mariner Mikroorganismengemeinschaften auf den anthropogenen biotechnologischen Eingriff im Falle einer Ölverschmutzung untersucht werden. Hierbei wurden zwei etablierte Methoden der Bioremediation, die Biostimulation (Zugabe von Nährstoffen zum System) sowie die Bioaugmentation (Zugabe von spezialisierten Mikroorganismen zum System) verwendet werden. Zusätzlich wurden spezielle Ölbindemittel auf ihre Verwendbarkeit in ölverschmutztem Meerwasser sowie auf ihren Einfluss auf die ölabbauenden Mikrobengemeinschaften untersucht. Ziel der Studie waren die Entwicklung einer experimentellen Bioremediationsmethode sowie die Untersuchung der Reaktion des Ökosystems Meerwasser auf den Einsatz dieser. Im Verlauf einer Mikrokosmenstudie zur Analyse der Rahmenparameter für die Bioremediationsmethode konnte anhand von verschiedenen DNA-Fingerprinting-Methoden gezeigt werden, dass eine Zugabe von Nährstoffen unter den gewählten Versuchsbedingungen zur Verschiebung der mikrobiellen Gemeinschaftsstruktur zugunsten von Alcanivorax borkumensis führt. Die Geschwindigkeit dieser Veränderung konnte dabei durch Bioaugmentation und Ölbindemittelzugabe beschleunigt sowie die Intensität des Kohlenwasserstoffabbaus verstärkt werden. Ein verstärkter Abbau von polyaromatischen Kohlenwasserstoffen konnte in Anwesenheit der natürlichen Mikroflora des Meeres verzeichnet werden. In einer Mesokosmenstudie wurde eine experimentelle, auf dem Ölbindemittel X-Oil®, Langzeitdüngern und Biomasse von A.borkumensis SK2 basierende Ölbarriere in 500 l Meerwasser, die mit 2,5 l Bunker C-Schweröl versetzt wurden, getestet. Ein schnelles bakterielles Wachstum sowie Biofilmbildung und Emulsifikation wurden beobachtet. DNA-Fingerprint-Analysen zeigten das Wachstum verschiedener Kohlenwasserstoffe verwertender Mikroorganismen, beispielsweise von Bakterien mit Verwandtschaft zu Yeosuana aromativorans, Lutibacterium annuloederans sowie A.borkumensis, welcher exklusiv ...A study was carried out to evaluate the impact of an anthropogenic biotechnological attempt to clean up an experimental marine oil spill on marine oil degrading microbial communities. Two wellestablished bioremediation strategies – biostimulation (addition of nutrients to a polluted ecosystem) and bioaugmentation (addition of selected micororganism to a polluted ecosystem) along with the addition of a state-of-the-art oil sorbent material were tested for their applicability and influence on marine microflora. An initial microcosm study investigating the fundamental parameters of marine bioremediation involving oil sorbents using a variety of DNA-fingerprinting techniques revealed a strong selection of marine microflora for the well-known obligate oil degrading microbe Alcanivorax borkumensis in case of biostimulation. The velocity of this effect furthermore proved to be dependant on other experimental parameters: both bioaugmentation and oil sorbtion showed a significant acceleration of this process as well as improved intensity of oil degradation. Moreover, a 30% increase of degradation of polyaromatic hydrocarbons in comparison to pure cultures of A.borkumensis was detected in microcosm containing marine microflora. Using a mesocosm study, the efficiency of an experimental oil barrier containing the oil sorbent XOil ®, slow release fertilizers and biomass of A.borkumensis SK2 for the oil spill mitigation of 2.5 l of Bunker C heavy fuel oil (IFO 380) in 500 l of seawater was tested. Rapid bacterial growth, biofilm formation of bacteria on interfaces of oil and water, as well as emulsification of heavy fuel was observed. DNA-fingerprinting analysis showed the abundance of a variety of hydrocarbon degrading microbes related to Yeosuana aromativorans, Lutibacterium annuloederans and A.borkumensis. The primary colonizer A.borkumensis was detected exclusively on the surfaces of oil sorbent material XOil ®. A fingerprinting-analysis was conducted using RNA extracted ..

The Threat of Capital Drain: A Rationale for Public Banks?

This paper yields a rationale for why subsidized public banks may be desirable from a regional perspective in a financially integrated economy. We present a model with credit rationing and heterogeneous regions in which public banks prevent a capital drain from poorer to richer regions by subsidizing local depositors, for example, through a public guarantee. Under some conditions, cooperative banks can perform the same function without any subsidization; however, they may be crowded out by public banks. We also discuss the impact of the political structure on the emergence of public banks in a political-economy setting and the role of interregional mobility

Conversion of Uric Acid into Ammonium in Oil-Degrading Marine Microbial Communities: a Possible Role of Halomonads

Uric acid is a promising hydrophobic nitrogen source for biostimulation of microbial activities in oil-impacted marine environments. This study investigated metabolic processes and microbial community changes in a series of microcosms using sediment from the Mediterranean and the Red Sea amended with ammonium and uric acid. Respiration, emulsification, ammonium and protein concentration measurements suggested a rapid production of ammonium from uric acid accompanied by the development of microbial communities containing hydrocarbonoclastic bacteria after 3 weeks of incubation. About 80 % of uric acid was converted to ammonium within the first few days of the experiment. Microbial population dynamics were investigated by Ribosomal Intergenic Spacer Analysis and Illumina sequencing as well as by culture-based techniques. Resulting data indicated that strains related to Halomonas spp. converted uric acid into ammonium, which stimulated growth of microbial consortia dominated by Alcanivorax spp. and Pseudomonas spp. Several strains of Halomonas spp. were isolated on uric acid as the sole carbon source showed location specificity. These results point towards a possible role of halomonads in the conversion of uric acid to ammonium utilized by hydrocarbonoclastic bacteria.With exception of XH and JC, all authors were supported by the FP7 Project ULIXES (FP7-KBBE-2010-266473). This work was further funded by grant BIO2011-25012 from the Spanish Ministry of the Economy and Competitiveness. FM was supported by Università degli Studi di Milano, European Social Fund (FSE) and Regione Lombardia (contract BDote Ricerca^). DD acknowledges support of KAUST, King Abdullah University of Science and Technology. PG acknowledges the support of the European Commission through the project Kill-Spill (FP7, Contract Nr 312139).Peer Reviewe

Erythropoietin enhances hippocampal long-term potentiation and memory

<p>Abstract</p> <p>Background</p> <p>Erythropoietin (EPO) improves cognition of human subjects in the clinical setting by as yet unknown mechanisms. We developed a mouse model of robust cognitive improvement by EPO to obtain the first clues of how EPO influences cognition, and how it may act on hippocampal neurons to modulate plasticity.</p> <p>Results</p> <p>We show here that a 3-week treatment of young mice with EPO enhances long-term potentiation (LTP), a cellular correlate of learning processes in the CA1 region of the hippocampus. This treatment concomitantly alters short-term synaptic plasticity and synaptic transmission, shifting the balance of excitatory and inhibitory activity. These effects are accompanied by an improvement of hippocampus dependent memory, persisting for 3 weeks after termination of EPO injections, and are independent of changes in hematocrit. Networks of EPO-treated primary hippocampal neurons develop lower overall spiking activity but enhanced bursting in discrete neuronal assemblies. At the level of developing single neurons, EPO treatment reduces the typical increase in excitatory synaptic transmission without changing the number of synaptic boutons, consistent with prolonged functional silencing of synapses.</p> <p>Conclusion</p> <p>We conclude that EPO improves hippocampus dependent memory by modulating plasticity, synaptic connectivity and activity of memory-related neuronal networks. These mechanisms of action of EPO have to be further exploited for treating neuropsychiatric diseases.</p

Bioprospecting reveals class III ω-transaminases converting bulky ketones and environmentally relevant polyamines

Amination of bulky ketones, particularly in (R) configuration, is an attractive chemical conversion; however, known ω-transaminases (ω-TAs) show insufficient levels of performance. By applying two screening methods, we discovered 10 amine transaminases from the class III ω-TA family that were 38% to 76% identical to homologues. We present examples of such enzymes preferring bulky ketones over keto acids and aldehydes with stringent (S) selectivity. We also report representatives from the class III ω-TAs capable of converting (R) and (S) amines and bulky ketones and one that can convert amines with longer alkyl substituents. The preference for bulky ketones was associated with the presence of a hairpin region proximal to the conserved Arg414 and residues conforming and close to it. The outward orientation of Arg414 additionally favored the conversion of (R) amines. This configuration was also found to favor the utilization of putrescine as an amine donor, so that class III ω-TAs with Arg414 in outward orientation may participate in vivo in the catabolism of putrescine. The positioning of the conserved Ser231 also contributes to the preference for amines with longer alkyl substituents. Optimal temperatures for activity ranged from 45 to 65°C, and a few enzymes retained ≥50% of their activity in water-soluble solvents (up to 50% [vol/vol]). Hence, our results will pave the way to design, in the future, new class III ω-TAs converting bulky ketones and (R) amines for the production of high-value products and to screen for those converting putrescine