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2013

Development of a miniaturised screening method for fungal mutants with enhanced production of specific natural compounds

Kramer, A., Paun, L., Labes, A., Kempken, F., & Imhoff, J. F. (2013). Development of a miniaturised screening method for fungal mutants with enhanced production of specific natural compounds. In VAAM Jahrestagung 2013. Abgerufen von http://oceanrep.geomar.de/22029/
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2013

Conference Paper

Annemarie Kramer

Linda Paun

Antje Labes

Frank Kempken

Johannes Imhoff
Habitat specific provocation of secondary metabolite production by marine bacteria ? microbial communication and pharmaceutical use

Oesterwalbesloh, J., Wiese, J., Labes, A., & Imhoff, J. F. (2013). Habitat specific provocation of secondary metabolite production by marine bacteria ? microbial communication and pharmaceutical use. In VAAM Jahrestagung 2013. Abgerufen von http://oceanrep.geomar.de/20913/
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2013

Conference Paper

Jan Oesterwalbesloh

Jutta Wiese

Antje Labes

Johannes Imhoff
Higher yields of cyclodepsipetides from Scopulariopsis brevicaulis by random mutagenesis

Paun, L., Kramer, A., Hihlal, E., Labes, A., Imhoff, J. F., & Kempken, F. (2013). Higher yields of cyclodepsipetides from Scopulariopsis brevicaulis by random mutagenesis. In 27. Fungal Genetics Conference. Abgerufen von http://oceanrep.geomar.de/22016/

Abstract

The ascomycete Scopulariopsis brevicaulis, which was isolated from the marine sponge Tethya aurantium, produces two cyclodepsipeptides, scopularides A and B [1]. Both peptides exhibit activity against several tumor cell lines. Within the EU-project MARINE FUNGI (EU FP7, 265926) one of our aims is to enhance the production of these secondary metabolites. We are in the process to establish two ways of random mutagenesis by both UV radiation and transposon-mediated. To this end we created UV-mutants and a miniaturised screening method was developed. UV-radiation was performed at 312 nm and the survival rate was set to 1 \%. With this method a mutant library was established. To screen these mutants for higher secondary metabolites production, we developed a miniaturised screening method which includes decreased cultivation volume, fast extraction and an optimised LC-MS analysis format. Using the UV mutagenesis, we were able to identify several mutants with a higher scopularide production in comparison to the wild type. One of these mutants, which produces three times more biomass and more than double the amount of scopularide A, has been used for another round of mutation. Next generation sequencing is being employed to identify the molecular genetic basis of the observed mutations. In parallel we employ transposable elements to introduce mutants [2]. The impact of transposons on gene expression as well as their ability to cause major mutations within the genome or single genes makes them an interesting tool for random mutagenesis [3, 4, 5]. We employ the Vader transposon in its homologous host and found that Vader mostly integrates within or very close to genes. Thus it appears to be a useful tool for transposon-mediated mutagenesis in A. niger (6). At current we try to enhance its usability by modifying the Vader element.
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2013

Conference Paper

Linda Paun

Annemarie Kramer

ElKbir Hihlal

Antje Labes

Johannes Imhoff

Frank Kempken

2012

Beneficial effects of 2,4-diacetylphloroglucinol- producing pseudomonads on the marine alga Saccharina latissima

Nagel, K., Schneemann, I., Kajahn, I., Labes, A., Wiese, J., & Imhoff, J. F. (2012). Beneficial effects of 2,4-diacetylphloroglucinol- producing pseudomonads on the marine alga Saccharina latissima. Aquatic Microbial Ecology, 67, 239–249. Abgerufen von http://oceanrep.geomar.de/19108/ (Original work published 2025)

Abstract

Pseudomonas strains were shown to be regularly associated with the brown macroalga Saccharina latissima from the Baltic Sea, studied over several years, and were identified as producers of the antimicrobially active compound 2,4-diacetylphloroglucinol. These findings support the assumption of a stable association between the Pseudomonas spp. strains and S. latissima in the Baltic Sea. The metabolite profile of the Pseudomonas spp. comprised monoacetylphloroglucinol, 2,4-diacetylphloroglucinol, pyoluteorin and several rhizoxins, which exhibited broad-spectrum antibiotic activities against Gram-positive and Gram-negative bacteria as well as against fungi. Because the antibiotic activities included the inhibition of the 2 algal pathogens Pseudoalteromonas elyakovii and Algicola bacteriolytica, we propose a beneficial effect of these marine pseudomonads on their host S. latissima.
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2012

Journal Article

Kerstin Nagel

Imke Schneemann

Inga Kajahn

Antje Labes

Jutta Wiese

Johannes Imhoff

Pseudomonas protegens ? Alga?bacteria association ? 2

4-diacetylphloroglucinol ? Pyoluteorin ? Rhizoxin ? Brown macroalgae

RESISTANT STAPHYLOCOCCUS-AUREUS

FLUORESCENT PSEUDOMONAS

LAMINARIA-SACCHARINA

SECONDARY METABOLITES

IN-VITRO

BACTERIA

PF-5

JAPONICA

STRAINS

AGENT
Differences in bacterial association with macroalgae are product of environmental and chemical interactions = Diferencias de asociaci\ on bacteriana en macroalgas son producto de interacciones qu\ imicas y ambientales

Goecke, F. R., Staufenberger, T., Wiese, J., Labes, A., & Imhoff, J. F. (2012). Differences in bacterial association with macroalgae are product of environmental and chemical interactions = Diferencias de asociaci\ on bacteriana en macroalgas son producto de interacciones qu\ imicas y ambientales. In 3. Latin-American Congress of Algal Biotechnology. Abgerufen von http://oceanrep.geomar.de/19541/
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2012

Conference Paper

Franz Goecke

Tim Staufenberger

Jutta Wiese

Antje Labes

Johannes Imhoff
Secondary metabolites from deep sea bacteria: an efficient route for biodiscovery from extreme habitats

Labes, A., Oesterwalbesloh, J., & Imhoff, J. F. (2012). Secondary metabolites from deep sea bacteria: an efficient route for biodiscovery from extreme habitats. In Extremophiles. Abgerufen von http://oceanrep.geomar.de/15367/
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2012

Conference Paper

Antje Labes

Jan Oesterwalbesloh

Johannes Imhoff
Dual effect of macroalgal extracts on growth of bacteria in Western Baltic Sea

Goecke, F. R., Labes, A., Wiese, J., & Imhoff, J. F. (2012). Dual effect of macroalgal extracts on growth of bacteria in Western Baltic Sea. Revista de Biologia Marina y Oceanografia, 47, 75–86. Abgerufen von http://oceanrep.geomar.de/14347/

Abstract

It is assumed that the biological characteristics of the bacterial strains used in bioactivity tests have strong influences on their susceptibility against antibacterial compounds. Therefore, the selection of bacterial test strains may rush conclusions on the effect of macroalgal extracts and metabolites on bacteria. To proof this assumption, we have analysed the biological activities of crude extracts of 16 macroalgae from the coastal waters of Kiel Fjord (Germany), and tested their effect against a panel of 10 microorganisms comprising 5 standard test strains of bacteria and 5 macroalga-associated bacteria. Fourteen macroalgae (88\%) displayed antibacterial activity against at least one of the test strains. Despite the high proportion of extracts exhibiting antimicrobial activity, only 3 strains of the standard set were susceptible to macroalgal extracts and the overall activities were low (less than 80\% of inhibition). Most of active extracts inhibited Bacillus subtilis, while no inhibition effects were found against Erwinia amylovora, Escherichia coli, and the macroalga-associated bacteria. In contrast, all extracts produced stimulatory growth effects of at least two of the tested bacteria. While growth stimulation of standard set of bacteria was rare (22.5\% of total tests) with exception of plant pathogen Erwinia amylovora and two cases of Staphylococcus lentus, it was common among bacteria associated with macroalgae (77.5\%), especially Bacillus algicola, Pseudomonas marincola and both algal-pathogenic bacteria. This study demonstrates that macroalgal extracts can display different effects, i.e., inhibition or stimulation of bacterial growth depending on the origin of the test strains, which are derived from a standard panel or from the marine environment, respectively.
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2012

Journal Article

Franz Goecke

Antje Labes

Jutta Wiese

Johannes Imhoff

Microbiology

Marine algae

antibacterial activities

stimulation of bacterial growth

Kiel fjord
Secondary metabolites of fungi from the German Wadden Sea

Silber, J., Ohlendorf, B., Erhard, A., Labes, A., Goodfellow, M., & Imhoff, J. F. (2012). Secondary metabolites of fungi from the German Wadden Sea. In Jahrestagung der Vereinigung für Allgemeine und Angewandte Mikrobiologie. Abgerufen von http://oceanrep.geomar.de/19556/
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2012

Conference Paper

Johanna Silber

Birgit Ohlendorf

Arlette Erhard

Antje Labes

M. Goodfellow

Johannes Imhoff
First crenarchaeal chitinase found in Sulfolobus tokodaii

Staufenberger, T., Imhoff, J. F., & Labes, A. (2012). First crenarchaeal chitinase found in Sulfolobus tokodaii. Microbiological Research, 167, 262–269. Abgerufen von http://oceanrep.geomar.de/12897/

Abstract

This is the first description of a functional chitinase gene within the crenarchaeotes. Here we report of the heterologues expression of the ORF BAB65950 from Sulfolobus tokodaii in E. coli. The resulting protein degraded chitin and was hence classified as chitinase (EC 3.2.4.14). The protein characterization revealed a specific activity of 75 mU/mg using colloidal chitin as substrate. The optimal activity of the enzyme was measured at pH 2.5 and 70 ?C, respectively. A dimeric enzyme configuration is proposed. According to amino acid sequence similarities chitinases are attributed to the two glycoside hydrolase families 18 and 19. The derived amino acid sequence of the S. tokodaii gene differed from sequences of these two glycoside hydrolase families. However, within a phylogenetic tree of protein sequences, the crenarchaeal sequence of S. tokodaii clustered in close proximity to members of the glycoside hydrolase family 18.
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2012

Journal Article

Tim Staufenberger

Johannes Imhoff

Antje Labes

Microbiology

Chitinase

Glycoside hydrolase

Crenarchaea

Protein overexpression
A Novel Phytomyxean Parasite Associated with Galls on the Bull-Kelp Durvillaea antarctica (Chamisso) Hariot

Goecke, F. R., Wiese, J., Nunez, A., Labes, A., Imhoff, J. F., & Neuhauser, S. (2012). A Novel Phytomyxean Parasite Associated with Galls on the Bull-Kelp Durvillaea antarctica (Chamisso) Hariot. PLoS ONE, 7, e45358. Abgerufen von http://oceanrep.geomar.de/19148/

Abstract

Durvillaea antarctica (Fucales, Phaeophyceae) is a large kelp of high ecological and economic significance in the Southern Hemisphere. In natural beds along the central coast of Chile (Pacific Ocean), abnormal growth characterized by evident gall development and discolorations of the fronds/thallus was observed. Analysing these galls by light microscopy and scanning electron microscopy revealed the presence of endophytic eukaryotes showing typical characteristics for phytomyxean parasites. The parasite developed within enlarged cells of the subcortical tissue of the host. Multinucleate plasmodia developed into many, single resting spores. The affiliation of this parasite to the Phytomyxea (Rhizaria) was supported by 18S rDNA data, placing it within the Phagomyxida. Similar microorganisms were already reported once 23 years ago, indicating that these parasites are persistent and widespread in D. antarctica beds for long times. The symptoms caused by this parasite are discussed along with the ecological and economic consequences. Phytomyxean parasites may play an important role in the marine ecosystem, but they remain understudied in this environment. Our results demonstrate for the first time the presence of resting spores in Phagomyxida, an order in which resting spores were thought to be absent making this the first record of a phagomyxean parasite with a complete life cycle so far, challenging the existing taxonomic concepts within the Phytomyxea. The importance of the here described resting spores for the survival and ecology of the phagomyxid parasite will be discussed together with the impact this parasite may have on the strongest seaweed of the world , which is an important habitat forming and economic resource from the Southern Hemisphere.
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2012

Journal Article

Franz Goecke

Jutta Wiese

Alejandra Nunez

Antje Labes

Johannes Imhoff

Sigrid Neuhauser

SP-NOV

LESSONIA-NIGRESCENS

MARINE MACROALGAE

CENTRAL CHILE

NEW-ZEALAND

PHAEOPHYTA

RHODOPHYTA

ALGAE

DURVILLEALES

INFECTIONS

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