Topdown impact of bacterivorous nematodes on the bacterial community structure:

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Top-down impact of bacterivorous nematodes on the
bacterial community structure a microcosm
experiment
Ilse De Mesel
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Introduction
Nematodes
Grazers
protists
Grazing?
Heterotrophic bacteria
?
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Aims

• Do nematodes have an impact on the bacterial
  community structure
• 2) Are these effects nematode-species
• specific

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Experimental Setup
Microcosm experiment

• Diplolaimelloides meyli
• Diplolaimelloides oschei
• Diplolaimella dievengatensis
• Panagrolaimus paetzoldi

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Denaturing Gradient Gel Electrophoresis
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Denaturing Gradient Gel Electrophoresis
PCR
DNA-extraction
1) Bacterial composition
2) Bacterial diversity
3) Taxonomic information (limited)
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Denaturing Gradient Gel Electrophoresis
Diplolaimella dievengatensis Control
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Denaturing Gradient Gel Electrophoresis
Community composition
Stress 0.25
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Denaturing Gradient Gel Electrophoresis
Diversity
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Denaturing Gradient Gel Electrophoresis
Diversity
Number of bands
Shannon-wiener Index
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Denaturing Gradient Gel Electrophoresis
Diversity
Number of bands
Number of nematodes (log)
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Conclusions
Top-down impact
on bacterial community composition ? species
specific ? even at low densities
on bacterial diversity ? only at high density