Structure and evolution of Streptomyces interaction networks in soil and in silico

Kalin Vetsigian ¹, Rishi Jajoo , Roy Kishony

⁰Department of Systems Biology, Harvard Medical School, Boston, Massachusetts, United States of America.

Plos Biology +

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November 1, 2011

View abstract on PubMed

Summary

Soil Streptomyces communities are not stable but dynamically maintained through rapid eco-evolutionary processes. Interactions between these antibiotic-producing bacteria drive this constant change, preventing stable ecological states.

Area Of Science

Microbiology
Ecology
Evolutionary Biology

Background

Soil Streptomyces exhibit remarkable genotypic and chemical diversity, producing numerous secondary metabolites.
The ecological mechanisms maintaining this diversity, particularly through strain interactions, remain poorly understood.
Secondary metabolites are known to mediate bacterial warfare and signaling, but interaction networks are not systematically measured.

Purpose Of The Study

To systematically measure pairwise interactions among Streptomyces strains.
To understand the ecological maintenance of genotypic and chemical diversity in soil Streptomyces communities.
To investigate the eco-evolutionary dynamics of these bacterial interactions.

Main Methods

Developed a high-throughput platform to assay all pairwise interactions among 64 Streptomyces isolates.
Recorded over 10,000 time-lapse videos of colony development under varying conditions.
Constructed and analyzed interaction networks, including reciprocity and interaction distribution.
Employed a simple eco-evolutionary model of antibiotic production and resistance.

Main Results

Observed diverse interactions including growth inhibition/promotion and effects on aerial mycelium formation.
Interaction probability is balanced, not close to zero or one, with a bimodal distribution of interactions per strain.
Enriched for interaction reciprocity, especially among strains from the same soil grain.
Identical 16S rRNA sequence isolates showed divergent interaction patterns, indicating rapid evolution.

Conclusions

Streptomyces communities are not stable ecological states but are intrinsically dynamic.
Fast evolution of antibiotic production and resistance drives the observed network properties.
These communities are evolutionarily unstable, subject to constant invasion by novel strains.

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