Can Microbial Communities be understood as Multicellular Organisms and vice versa?

Pizza Club – Eugen Bauer

Chondromyces crocatus

Anabaena

Escherichia coli

Bacteria as Multicellular Organisms, James Shapiro, Scientific American, 1988

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

Evo-Devo of Multicellularity

Eukaryote

Differentiation Tissue/Organ

Prokaryote

Evo-Devo of Multicellularity

Eukaryote

Differentiation Tissue/Organ

Population Differentiation Biofilm

Prokaryote

Evo-Devo of Multicellularity

Eukaryote

Differentiation Tissue/Organ

Population Differentiation Biofilm

Prokaryote

Evo-Devo of Multicellularity

Eukaryote

Differentiation Tissue/Organ

Population Differentiation Biofilm

Prokaryote

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

Evo-Devo of Multicellularity

Eukaryote

Differentiation Tissue/Organ

Population Differentiation Biofilm

Prokaryote

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

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

Modeling Tissues & CommunitiesDependent

Autonomous

Mixed bag “Superorganism” model

Free exchange of compoundsCommon objective

Egoistic objective, free exchange

No transparency / interactions

Biofilms

Tissues

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

Thank you for the attention