Falk Warnecke

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We analysed the phylogenetic relatedness of 16S rRNA genes from freshwater bacteria affiliated with the class Actinobacteria. A polymerase chain reaction assay was developed to identify reliably rare Actinobacteria-related inserts within 16S rRNA gene clone libraries. In 18 libraries constructed from seven freshwater systems, altogether 63 actinobacterial(More)
The occurrence, identity, and activity of microbes from the class Actinobacteria was studied in the surface waters of 10 oligo- to mesotrophic mountain lakes located between 913 m and 2,799 m above sea level. Oligonucleotide probes were designed to distinguish between individual lineages within this group by means of fluorescence in situ hybridization(More)
Humic lakes are systems often characterized by irregular high input of dissolved organic carbon (DOC) from the catchment. We hypothesized that specific bacterial groups which rapidly respond to changes in DOC availability might form large populations in such habitats. Seasonal changes of microbial community composition were studied in two compartments of an(More)
Members of the phylum Bacteroidetes are among the most abundant microbes in coastal marine waters, but it is unclear to which extent the diversity within this phylum is covered by currently available 16S rRNA gene sequence information. We, thus, obtained a comprehensive collection of sequence types affiliated with Bacteroidetes in coastal North Sea surface(More)
Bacterial activity at metal surfaces may result in corrosion induction or corrosion inhibition. An important effect of chemoorganotrophic bacteria under aerobic conditions is the removal of oxygen from the metal surface. This is most effectively done by biofilm-forming microorganisms and causes corrosion inhibition. Anaerobes promote corrosion if they(More)
We tested a previously described protocol for fluorescence in situ hybridization of marine bacterioplankton with horseradish peroxidase-labeled rRNA-targeted oligonucleotide probes and catalyzed reporter deposition (CARD-FISH) in plankton samples from different lakes. The fraction of Bacteria detected by CARD-FISH was significantly lower than after FISH(More)
Ephemeral blooms of filamentous bacteria are a common phenomenon in the water column of oligo- to mesotrophic lakes. It is assumed that the appearance of such morphotypes is favored by selective predation of bacterivorous protists and that filter-feeding zooplankton plays a major role in suppressing these bacteria. The phylogenetic affiliation of the(More)
From enrichments with methanol and ferric pyrophosphate a coculture was isolated which coupled methanol oxidation to carbon dioxide with the reduction of Fe(III) to Fe(II). 16S rRNA gene analysis of the isolated syntrophic partners revealed 99.5% similarity to Clostridium sphenoides and 98.5% to Shewanella putrefaciens. Formation of Fe(II) coupled to(More)
A facultatively anaerobic, marine spirochaete, designated strain SIP1(T), was isolated from interstitial water from a cyanobacteria-containing microbial mat. Cells of strain SIP1(T) were 0.3-0.4x10-12 mum in size, helical with a body pitch of approximately 1.4 mum and motile by means of two to four periplasmic flagella (one, or occasionally two, being(More)
Occurrence of the odours geosmin and 2-methylisoborneol (MIB) in freshwater environments indicates that odour-producing organisms are commonly occurring. In the present study, we assumed actinomycetes to be a major source of the odours. Seasonal concentrations of odours and abundance of Actinobacteria, which includes actinomycetes and other G+ and high GC(More)