Download Bacterial Populations as Multicellular Organisms

Bacterial
Populations as
Multicellular
Organisms
Kathy Lee
INTRODUCTION
• 1998 … Scientific American –
“Bacteria as Multicellular
Organisms”
• Multicellularity- only considered
a specialized adaptive
strategy
• Today
CORE CONCEPTS OF BACTERIAL
MULTICELLULARITY
1. Communication and
decision-making
capabilities
2. Examples of
communication and
behaviors
3. Derive adaptive benefits
INTERCELLULAR
COMMUNICATION
• Diverse Classes of Signal
Molecules
– AHL signaling
– Oligopeptides
• Differences between AHL
signaling and Oligopeptides
• Not all the small diffusible
molecules are signals
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
COORDINATED
MULTICELLULAR BEHAVIORS – A
GENERAL BACTERIAL TRAIT
• Bacteria
differentiate
biochemically
and
morphologicall
y and their
interactions
• Colony
– 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
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
Optimization of population survival by
differentiation into distinct cell types
• Sporulation and
Formation of Dormant
Cells
• Exchange of Genetic
Information
• Mutation
CONCLUSION
• Bacterial multicellularity
deepens our appreciation
of the informationprocessing capabilities of
individual bacterial cells.