Biomedical subjects

Jürgen Rullkötter

Publications and source records attributed to Jürgen Rullkötter.

3 recordsLinked to original sources

PubMed2003

Mycosporine-glutamicol-glucoside: a natural UV-absorbing secondary metabolite of rock-inhabiting microcolonial fungi.

Microcolonial ascomycetes are known to inhabit bare rock surfaces in cold and hot deserts and thus are habitually exposed to high levels of solar radiation. Several of these stress-tolerant fungal isolates, cultivated in the laboratory under daylight illumination, were studied for the presence of effective UV-radiation protection substances. Liquid chromatography/mass spectrometry (LC/MS) and liquid chromatography/tandem mass spectrometry (LC/MS/MS) analyses allowed for efficient separation and structure clarification of two mycosporines. It was demonstrated that both mycosporine-glutamicol-glucoside and mycosporine-glutaminol-glucoside are natural and constitutive secondary metabolites of microcolonial fungi. The function and relation of these substances in the fungal cell are discussed.

Ascomycota↗

PubMed2002

Phospholipid analysis as a tool to study complex microbial communities in marine sediments.

To complement information on microbial communities in marine sediments that can be obtained using microbiological methods, we developed an analytical procedure to trace microbial lipids in environmental samples. We focused on analyzing intact phospholipids as these membrane constituents are known to be biomarkers for viable cells. Analysis of intact phospholipids from a fractionated and preconcentrated sediment extract was achieved using liquid chromatography-electrospray ionization-mass spectrometry (HPLC-ESI-MS). The combined analysis of phospholipid types and their fatty acid substituents allowed a differentiation between various groups of microorganisms living in the sediment. For comparison three strains of marine sulfate-reducing bacteria (SRB) were analysed for their lipid content.

Bacteria↗

PubMed2002

Microbial diversity of a heavily polluted microbial mat and its community changes following degradation of petroleum compounds.

We studied the microbial diversity of benthic cyanobacterial mats inhabiting a heavily polluted site in a coastal stream (Wadi Gaza) and monitored the microbial community response induced by exposure to and degradation of four model petroleum compounds in the laboratory. Phormidium- and Oscillatoria-like cyanobacterial morphotypes were dominant in the field. Bacteria belonging to different groups, mainly the Cytophaga-Flavobacterium-Bacteriodes group, the gamma and beta subclasses of the class Proteobacteria, and the green nonsulfur bacteria, were also detected. In slurry experiments, these communities efficiently degraded phenanthrene and dibenzothiophene completely in 7 days both in the light and in the dark. n-Octadecane and pristane were degraded to 25 and 34% of their original levels, respectively, within 7 days, but there was no further degradation until 40 days. Both cyanobacterial and bacterial communities exhibited noticeable changes concomitant with degradation of the compounds. The populations enriched by exposure to petroleum compounds included a cyanobacterium affiliated phylogenetically with Halomicronema. Bacteria enriched both in the light and in the dark, but not bacteria enriched in any of the controls, belonged to the newly described Holophaga-Geothrix-Acidobacterium phylum. In addition, another bacterial population, found to be a member of green nonsulfur bacteria, was detected only in the bacteria treated in the light. All or some of the populations may play a significant role in metabolizing the petroleum compounds. We concluded that the microbial mats from Wadi Gaza are rich in microorganisms with high biodegradative potential.

Alkanes↗