Helping You Find Full Text Journal Articles

Search Results:

Author: Heinz Wilkes (26)


Nov
2017

Metaproteomic analysis targets proteins, the catalytic entities in the habitat, thereby providing direct insights into the metabolic activity of the community studied. A major challenge still remaining for metaproteomics is the effective and comprehensive extraction of proteins from environmental samples, due to their high complexity with respect to organismic diversity and abundance range. Moreover, in certain habitats, the inherent matrix may interfere with protein extraction.

View Full Text PDF Listings View primary source full text article PDFs.

View Full Text PDF Listings View primary source full text article PDFs.

Sep
2017

Natural oil seeps offer the opportunity to study the adaptation of ecosystems and the associated microbiota to long-term oil exposure. In the current study, we investigated a land-to-sea transition ecosystem called "Keri Lake" in Zakynthos Island, Greece. This ecosystem is unique due to asphalt oil springs found at several sites, a phenomenon already reported 2500 years ago.

View Full Text PDF Listings View primary source full text article PDFs.

Aug
2017

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.

View Full Text PDF Listings View primary source full text article PDFs.

Dec
1969

Hydrocarbons are abundant in anoxic environments and pose biochemical challenges to their anaerobic degradation by microorganisms. Within the framework of the Priority Program 1319, investigations funded by the Deutsche Forschungsgemeinschaft on the anaerobic microbial degradation of hydrocarbons ranged from isolation and enrichment of hitherto unknown hydrocarbon-degrading anaerobic microorganisms, discovery of novel reactions, detailed studies of enzyme mechanisms and structures to process-oriented in situ studies. Selected highlights from this program are collected in this synopsis, with more detailed information provided by theme-focused reviews of the special topic issue on 'Anaerobic biodegradation of hydrocarbons' [this issue, pp.

View Full Text PDF Listings View primary source full text article PDFs.

Dec
1969

Anaerobic Degradation of p-Alkylated Benzoates and Toluenes.

J Mol Microbiol Biotechnol 2016 10;26(1-3):63-75. Epub 2016 Mar 10.
Ralf Rabus, Matthias Boll, Bernard Golding, Heinz Wilkes
The anaerobic degradation of 4-alkylbenzoates and 4-alkyltoluenes is to date a rarely reported microbial capacity. The newly isolated Alphaproteobacterium Magnetospirillum sp. strain pMbN1 represents the first pure culture demonstrated to degrade 4-methylbenzoate completely to CO2 in a process coupled to denitrification.

View Full Text PDF Listings View primary source full text article PDFs.

Dec
1969

The glycyl radical enzyme-catalyzed addition of n-alkanes to fumarate creates a C-C-bond between two concomitantly formed stereogenic carbon centers. The configurations of the two diastereoisomers of the product resulting from n-hexane activation by the n-alkane-utilizing denitrifying bacterium strain HxN1, i.e.

View Full Text PDF Listings View primary source full text article PDFs.

Dec
1969

Anaerobic metabolism of hydrocarbons proceeds either via addition to fumarate or by hydroxylation in various microorganisms, e.g., sulfate-reducing or denitrifying bacteria, which are specialized in utilizing n-alkanes or alkylbenzenes as growth substrates.

View Full Text PDF Listings View primary source full text article PDFs.

Jun
2015

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.

View Full Text PDF Listings View primary source full text article PDFs.

Dec
1969

The fate of cyclohexane, often used as a model compound for the biodegradation of cyclic alkanes due to its abundance in crude oils, in anoxic marine sediments has been poorly investigated. In the present study, we obtained an enrichment culture of cyclohexane-degrading sulfate-reducing bacteria from hydrocarbon-contaminated intertidal marine sediments. Microscopic analyses showed an apparent dominance by oval cells of 1.

View Full Text PDF Listings View primary source full text article PDFs.

Dec
2014

The betaproteobacteria "Aromatoleum aromaticum" pCyN1 and "Thauera" sp. strain pCyN2 anaerobically degrade the plant-derived aromatic hydrocarbon p-cymene (4-isopropyltoluene) under nitrate-reducing conditions. Metabolite analysis of p-cymene-adapted "A.

View Full Text PDF Listings View primary source full text article PDFs.

Nov
2014

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.

View Full Text PDF Listings View primary source full text article PDFs.

May
2013

Among the dominant deltaproteobacterial sulfate-reducing bacteria (SRB), members of the genus Desulfobacula are not only present in (hydrocarbon-rich) marine sediments, but occur also frequently in the anoxic water bodies encountered in marine upwelling areas. Here, we present the 5.2 Mbp genome of Desulfobacula toluolica Tol2, which is the first of an aromatic compound-degrading, marine SRB.

View Full Text PDF Listings View primary source full text article PDFs.

May
2012

The betaproteobacterium "Aromatoleum aromaticum" EbN1 utilizes eight different plant-derived nonhydroxylated (e.g. cinnamate) and hydroxylated (e.

View Full Text PDF Listings View primary source full text article PDFs.

May
2012

The pathway for anaerobic degradation of 4-methylbenzoate was studied in the denitrifying alphaproteobacterium Magnetospirillum sp. strain pMbN1. Adaptation studies with whole cells indicated substrate-dependent induction of the capacity to degrade 4-methylbenzoate.

View Full Text PDF Listings View primary source full text article PDFs.

View Full Text PDF Listings View primary source full text article PDFs.

Sep
2011

Diverse microorganisms have been described to degrade petroleum hydrocarbons anaerobically. Strains able to utilize n-alkanes do not grow with aromatic hydrocarbons, whereas strains able to utilize aromatic hydrocarbons do not grow with n-alkanes. To investigate this specificity in more detail, three anaerobic n-alkane degraders (two denitrifying, one sulfate-reducing) and eight anaerobic alkylbenzene degraders (five denitrifying, three sulfate-reducing) were incubated with mixtures of n-alkanes and toluene.

View Full Text PDF Listings View primary source full text article PDFs.

Feb
2011

Microorganisms can degrade saturated hydrocarbons (alkanes) not only under oxic but also under anoxic conditions. Three denitrifying isolates (strains HxN1, OcN1, HdN1) able to grow under anoxic conditions by coupling alkane oxidation to CO(2) with NO(3) (-) reduction to N(2) were compared with respect to their alkane metabolism. Strains HxN1 and OcN1, which are both Betaproteobacteria, utilized n-alkanes from C(6) to C(8) and C(8) to C(12) respectively.

View Full Text PDF Listings View primary source full text article PDFs.

Oct
2010

An anaerobic nitrate-reducing enrichment culture was established with a cyclic saturated petroleum hydrocarbon, cyclohexane, the fate of which in anoxic environments has been scarcely investigated. GC-MS showed cyclohexylsuccinate as a metabolite, in accordance with an anaerobic enzymatic activation of cyclohexane by carbon-carbon addition to fumarate. Furthermore, long-chain cyclohexyl-substituted cell fatty acids apparently derived from cyclohexane were detected.

View Full Text PDF Listings View primary source full text article PDFs.

Apr
2010

Four different geological sample types (a crude oil, a crude oil asphaltene, a reservoir core extract and a reservoir core asphaltene) have been characterized by negative ionization electrospray mass spectrometry at low and high mass resolution using a double-focusing magnetic sector field mass spectrometer. The mass range, shape of the spectra and the signal distribution of the acidic constituents as well as the average molecular weights, the total ion abundance and signal intensity in the spectra were compared for the different sample types. Nominal mass classes have been evaluated and Kendrick mass plots were generated in order to identify homologous series.

View Full Text PDF Listings View primary source full text article PDFs.

Mar
2010

The identity of the microorganisms capable of anaerobic p-xylene degradation under denitrifying conditions is hitherto unknown. Here, we report highly enriched cultures of freshwater denitrifying bacteria that grow anaerobically with p-xylene as the sole organic carbon source and electron donor. Long curved rods, with 95% 16S rRNA gene sequence identity to Denitratisoma oestradiolicum, dominated the enrichment cultures (>91% of all cells), as detected by phylotype-specific probes.

View Full Text PDF Listings View primary source full text article PDFs.

Jan
2009

The anaerobic biodegradation of naphthalene, an aromatic hydrocarbon in tar and petroleum, has been repeatedly observed in environments but scarcely in pure cultures. To further explore the relationships and physiology of anaerobic naphthalene-degrading microorganisms, sulfate-reducing bacteria (SRB) were enriched from a Mediterranean sediment with added naphthalene. Two strains (NaphS3, NaphS6) with oval cells were isolated which showed naphthalene-dependent sulfate reduction.

View Full Text PDF Listings View primary source full text article PDFs.

Aug
2008

The denitrifying "Aromatoleum aromaticum" strain EbN1 was demonstrated to utilize p-ethylphenol under anoxic conditions and was suggested to employ a degradation pathway which is reminiscent of known anaerobic ethylbenzene degradation in the same bacterium: initial hydroxylation of p-ethylphenol to 1-(4-hydroxyphenyl)-ethanol followed by dehydrogenation to p-hydroxyacetophenone. Possibly, subsequent carboxylation and thiolytic cleavage yield p-hydroxybenzoyl-coenzyme A (CoA), which is channeled into the central benzoyl-CoA pathway. Substrate-specific formation of three of the four proposed intermediates was confirmed by gas chromatographic-mass spectrometric analysis and also by applying deuterated p-ethylphenol.

View Full Text PDF Listings View primary source full text article PDFs.

Oct
2007

The short-chain hydrocarbons ethane, propane and butane are constituents of natural gas. They are usually assumed to be of thermochemical origin, but biological formation of ethane and propane has been also observed. Microbial utilization of short-chain hydrocarbons has been shown in some aerobic species but not in anaerobic species of bacteria.

View Full Text PDF Listings View primary source full text article PDFs.

Feb
2003

Anaerobic degradation of the aromatic hydrocarbon ethylbenzene was studied with sulfate as the electron acceptor. Enrichment cultures prepared with marine sediment samples from different locations showed ethylbenzene-dependent reduction of sulfate to sulfide and always contained a characteristic cell type that formed gas vesicles towards the end of growth. A pure culture of this cell type, strain EbS7, was isolated from sediment from Guaymas Basin (Gulf of California).

View Full Text PDF Listings View primary source full text article PDFs.

Mar
2002

The anaerobic degradation pathway of the saturated hydrocarbon n-hexane in a denitrifying strain (HxN1) was examined by gas chromatography-mass spectrometry of derivatized extracts from cultures grown with unlabeled and deuterated substrate; several authentic standard compounds were included for comparison. The study was focused on possible reaction steps that follow the initial formation of (1-methylpentyl)succinate from n-hexane and fumarate. 4-Methyloctanoic, 4-methyloct-2-enoic, 2-methylhexanoic, 2-methylhex-2-enoic and 3-hydroxy-2-methylhexanoic acids (in addition to a few other methyl-branched acids) were detected in n-hexane-grown but not in n-hexanoate-grown cultures.

View Full Text PDF Listings View primary source full text article PDFs.

Back to top