Bacterial Populations as Multicellular Organisms

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Bacterial Populations as Multicellular Organisms

• Kathy Lee

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INTRODUCTION

• 1998 Scientific American Bacteria as
  Multicellular Organisms
• Multicellularity- only considered a specialized
  adaptive strategy
• Today

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CORE CONCEPTS OF BACTERIAL MULTICELLULARITY

• Communication and decision-making capabilities
• Examples of communication and behaviors
• Derive adaptive benefits

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INTERCELLULAR COMMUNICATION

• Diverse Classes of Signal Molecules
• AHL signaling
• Oligopeptides
• Differences between AHL signaling and
  Oligopeptides
• Not all the small diffusible molecules are
  signals
• Highly diversified chemical structures

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Signal Response Systems Interpreting Chemical
Messages in an Informationally Rich Environment

• Each cell can make an appropriate decision and
  adjust its activity
• Myxobacteria and Bacillus two good examples of
  complex signal-processing networks
• Complexities will prove to be typical

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COORDINATED MULTICELLULAR BEHAVIORS A GENERAL
BACTERIAL TRAIT

• Bacteria differentiate biochemically and
  morphologically and their interactions
• Colony development and collective motility
  phenomena in bacteria

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• E.coli Colony Development
• Cell-cell interactions occur after the first cell
  division
• B. subtilis Colony Development
• Proteus and Serratia Swarming
• Swarming is the process of rapid migration over
  a surface
• Granule Development in Anaerobic Bioreactors
• Microbial Consortia

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ADAPTIVE BENEFITS FROM MULTICELLULAR COOPERATION

• More efficient proliferation from cellular
  division
• Access to resources and niches that require a
  critical mass and cannot effectively be utilized
  by isolated cells
• Collective defense against antagonists that
  eliminate isolated cells

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Optimization of population survival by
differentiation into distinct cell types

• Sporulation and Formation of Dormant Cells
• Exchange of Genetic Information
• Mutation

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CONCLUSION

• Bacterial multicellularity deepens our
  appreciation of the information-processing
  capabilities of individual bacterial cells.