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Results demonstrate an unique anerobic oxidation of n-alkanes to form (1-methylpentylsuccinate) in a denitrifying bacterium growing on n-hexanes as the only organic substrate. Data reveal that n-hexane is activated by a radical reaction and added on to fumarate cosubstrate to give (1-methylpentylsuccinate).

Author(s): Antje Boetius (corresponding author) [1]; Katrin Ravenschlag [1]; Carsten J. Schubert [1]; Dirk Rickert [2]; Friedrich Widdel [1]; Armin Gieseke [1]; Rudolf Amann [1]; Bo Barker Jørgensen [1]; Ursula [...]

It has been established that anaerobic bacterial communities can convert long-chain alkanes to methane, the most basic hydrocarbon. Providing evidence for alkane conversion to methane and carbon dioxide has repercussions for the understanding of microbial processes during diagenesis. It is suggested that alkanes belong to the previously mainly unknown substrates that maintain slowly growing microbial communities and prompt methane formation in deep, old sediments.

Two new types of sulfate-reducing bacteria which can oxidize alkylbenzenes, o- and m-xylenes have been isolated. The alkylbenzenes were consumed during the growth of the sulfate-reducing enrichment culture with crude oil as the only source of the organic substrates. Two mesophilic, rod-shaped strains, oXyS1 and mXyS2 were detected with o- and m-xylenes as the organic substrates. The resulting 16S rRNA analysis revealed that strains belong to the delta subclass of Proteobacteria.

Hybridization of nucleic acids from a sulfate-enrichment culture growing anaerobically on crude oil revealed the presence of a species of sulfate-reducing bacteria. Fluorescent labeling studies showed that the bacteria do not utilize aromatic hydrocarbons, indicating that the cells do not belong to known Desulfovibrio species. More than 95% of the cells in the culture hybridized with a modified probe, suggesting that the cells may belong to the oxidizing, alkylbenzene-utilizing sulfate-reducing species.

Pure cultures of denitrifying bacteria have the ability to grow under anaerobic conditions using crude oil as a source of organic substrates. The bacteria utilizes toluene, ethylbenzene, and m-xylene from the crude oil and o-xylene and p-xylene to a smaller extent. The compounds used by the bacteria are the most water-soluble oil hydrocarbons and represent groundwater pollutants at places contaminated with oil. The amount of hydrocarbons utilized by the bacteria is however, very small.

A study of anaerobic degradation of crude oil constituents showed that sulphate-reducing bacteria causes anaerobic oxidation of aliphatic and aromatic hydrocarbons in crude oil. The hydrocarbon-degrading bacteria grows under anoxic conditions. This process explains the presence of sulphide in oil deposits, which is formed due to the reduction of sulphate by n-alkanes in the oil.

SW2 and L7, two purple bacterial strains consisting of small rod-shaped nonmotile cells, oxidize colorless ferrous iron to brown ferric iron through a unique phototrophic metabolism pathway, under anoxic conditions. SW2 and L7 also utilize monocarboxylic acids, fructose and glucose, and acetate, glucose and pyruvate, respectively, as phototrophic growth substrates, and display absorption peaks characteristic of bacteriochlorophyll a. The ferrous iron contributes electrons to the anoxygenic phototrophs that are responsible for the accumulation of early banded-iron levels in an anoxic biosphere.

The isolation of a marine sulfate-reducing bacterium that anaerobically degrades toluene was reported. It was demonstrated by measurement of degradation balance that toluene was completely oxidized to CO2. The presence of carbon monoxide dehydrogenase and formate dehydrogenase indicated a terminal oxidation of acetyl coenzyme A via the CO dehydrogenase pathway. However, the results of the consumption of hypothetical intermediates do not support a degradation of toluene via the introduction of a hydroxyl group into the ring. The designation Desulfobacula toluolica is proposed for the new sulfate-reducing bacterium.

Ten vertical profiles of horizontal winds have been measured at high resolution (25 m) in the range from 85 to 103 km during the sodium campaign in summer 1988 at Andenes, northern Norway (69 degrees N). The purposes of this study are to examine the hypothesis that the vertical wavenumber spectrum is controlled by saturation processes and to identify the mechanisms that contribute to saturation of the atmospheric motion spectrum within the observed height range. An analysis of vertical wavenumber spectra and vertical wind shears of the ten horizontal wind measurements is presented. Our results indicate a rather good agreement between the observed and predicted velocity spectra in both amplitude and slope for vertical wavelengths up to about 12.8 km. (This wavelength is given by the height interval covered by the experiment.) Very large wind shears, as high as 40-90 m s to the -1 km to the -1, are observed to be present at various heights, and at certain heights the shears even exceed 100 m s to the -1 km to the -1. Such strong wind shears yield Richardson numbers close to or smaller than 0.25, suggesting that the saturated gravity wave spectrum is associated with the shear instabilities.

• Coal phase-out is vital to address climate change. • Two discourse coalitions sought to influence coal phase-out policy in Germany. • The anti-coal coalition was very stable, congruent and had a strong actor base. • Both coalitions, and their storylines, left their mark on the phase-out law. • Discourse network analysis allows us to systematically study discourse coalitions. Discourse analysis is gaining attention in transition studies. This paper uses discourse network analysis (DNA) to study how discourse coalitions, and the storylines they mobilize, change over time. Drawing from archival data of two daily newspapers, we analyze the struggle over coal phase-out in Germany (2000–2020). We identify an anti-coal discourse coalition, which was stable and ideationally congruent over time. It used climate change as the dominant storyline to delegitimize coal. The phase-out policy decision in 2020 can be interpreted as the success of this coalition. The pro-coal coalition, in contrast, was more dispersed and less consistent in their arguments. Nonetheless, it was able to institutionalize some of its key storylines in the final policies. We argue that DNA is a powerful tool we can mobilize in sustainability transitions research for the study of politics and beyond. [ABSTRACT FROM AUTHOR]