Diversity and Functional Variation of Denitrifying Bacterial Communities in the Cape Fear River Estu

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Diversity and Functional Variation of
Denitrifying Bacterial Communities in the Cape
Fear River Estuary

• Brian Shirey
• Marine Biology

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Project Goals

• Provide insight into denitrifying bacterial
  community structure
• Examine relationships between bacteria and their
  environment
• Provide answers to questions

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Whats The Big Deal About Bacteria?

• The good
• The bad
• And the ugly

Salmonella typhimurium
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Denitrifying Bacteria

• Anaerobic
• Utilize nitrate during respiration
• Comprise over 50 different genera
• Ubiquitous

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Ecological Importance

• Vital role in global nitrogen cycle

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Ecological Importance cont.

• Contribution to global warming
• Production of greenhouse gasses

NO3- NO2- N2O
NO N2
Nitrogen oxides
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Ecological Importance cont.

• Effective in bioremediation
• Reduction of nitrate entering ground and surface
  waters

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Global Significance

• Understanding the mechanisms of denitrification
  is critical to our understanding of the global
  nitrogen cycle
• Applied methodologies promote a healthy,
  balanced, captive ecosystem

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Experimental Design

• Collect samples
• Perform bacterial diversity and phylogenetic
  analysis
• Perform community functionality analysis

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Sediment Sampling

• Sediments collected from 5 sites along the cape
  fear river estuary

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Measuring Bacterial Diversity

• DNA sequencing
• Isolation of functional genes encoding for
  nitrate reductase
• Comparative analysis
• Along environmental gradients
• T-RFLP analysis
• Profile of community structure

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Measuring Functional Diversity

• Incubation experiments
• Designed to monitor denitrifying activity

Control
NaCl
Nitrate
Anaerobic Enrichment Cultures
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Research Hypothesis

• Different components of a community will respond
  to different environmental inputs to maintain
  community functionality

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Questions To Be Answered

• Do denitrifying bacteria show the capability to
  readily adapt to sudden changes in their
  environment?
• Is survivorship of denitrifying bacteria greatly
  reduced in sub optimal conditions?
• To what degree do environmental conditions
  determine community structure?

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Schedule

• Phase 1
• Sequencing all DNA, setting up and initialize
  incubation experiment
• Phase 2
• Completing incubation experiment and performing
  T-RFLP analysis
• Phase 3
• Analyze data, write paper

Phase 1
Phase 2
Phase 3
Jan. Feb. March April May June July Aug.
Sep. Oct. Nov. Dec.
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Conclusion

• Denitrifying bacteria have a tremendous impact on
  the biosphere
• Our biosphere is fueled by an underlying
  microbial world
• The global community and the microbial community
  are eternally linked
• Bacterial community as a window into past,
  present, and future

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QUESTIONS?