Comparison of microbial communities and multicellular eukaryotes, implications of modeling

1. Can Microbial Communities be
understood as Multicellular
Organisms and vice versa?
Pizza Club – Eugen Bauer

2. Chondromyces crocatus
Anabaena
Escherichia coli
Bacteria as Multicellular Organisms, James
Shapiro, Scientific American, 1988

3. Motivation
• Multicellular eukaryotes have been compared with
each other, but not with bacteria
• Is it worthwhile to do this comparison, if not then why?
• What is the basic mechanism of differentiation?
• Use same methods to study microbial communities
as well as multicellular systems
• In particular computational methods

4. Evo-Devo of Multicellularity
Eukaryote
Differentiation Tissue/Organ
Prokaryote

5. Evo-Devo of Multicellularity
Eukaryote
Differentiation Tissue/Organ
Population Differentiation Biofilm
Prokaryote

6. Evo-Devo of Multicellularity
Eukaryote
Differentiation Tissue/Organ
Population Differentiation Biofilm
Prokaryote

7. Evo-Devo of Multicellularity
Eukaryote
Differentiation Tissue/Organ
Population Differentiation Biofilm
Prokaryote

8. Cell Differentiation (in C.elegans)
Developmental Biology 6th edition, Gilbert, 2000
Two modes of differentiation:
1. Asymmetric cell division
• Cell polarity
• Internal concentration
• Structural differences
2. Induction by other cells
• Diffusion via gradients
• Cell to cell contact
• Gap-junctions
 Spatial and temporal
transcription in development
Hoescht dye P-granules

9. Evo-Devo of Multicellularity
Eukaryote
Differentiation Tissue/Organ
Population Differentiation Biofilm
Prokaryote

10. Cell Differentiation (in B.subtilis)
Liu et al, Nature, 2015
• Glutamine is needed to
grow (biomass)
• Glutamate + Ammonium
 Glutamine
• Ammonium can be
produced under limiting
conditions
 Trade off between
competition and cooperation
 Spatial and temporal
nutrient gradients lead to
differentiation

11. Multicellularity Comparison
Prokaryotes / Biofilms
• Extrinsic signals
• Spatio-temporal nutrient
gradients
• Reversible differentiation
(all cells are the same)
• Differentiation through
metabolism
• Quorum sensing /
metabolic exchange
• Darwinistic processes
• Egoistic cell interest
Eukaryotes / Tissues
• In- and extrinsic signals
• Spatio-temporal
transcription factors
• Re- and Irreversible
differentiation
• Differentiation through
epigenetics
• Cell to cell interactions /
diffusion
• Cellular Darwinism
• Cellular determination

12. Modeling Tissues & Communities
Dependent
Autonomous
Mixed bag “Superorganism” model
Free exchange of compounds
Common objective
Egoistic objective, free exchange
No transparency / interactions
Biofilms
Tissues

13. Discussion
• Development of microbial communities and
eukaryotic multicellularity has some common
patterns (e.g. spatial-temporal gradients)
• Differentiated microbes are more autonomous than
differentiated (determined) cells
• Darwinistic processes govern microbial
communities
• Different modeling approaches to represent cellular
dependencies
• Further reading: Cellular Darwinism

14. Thank you for the
attention