A metagenomics pipeline reveals insertion sequence-driven evolution of the microbiota

Area of Science:

• Microbiology
• Genomics
• Human Microbiome Research

Background:

• Insertion sequence (IS) elements are mobile genetic elements found in bacterial genomes.
• IS elements play a role in bacterial adaptation and genome evolution.
• Understanding IS element dynamics in the human microbiota is crucial for comprehending bacterial adaptation and health.

Purpose of the Study:

• To develop a database and computational pipeline for identifying IS element insertions in the microbiota.
• To investigate the prevalence and targets of IS element insertions in intestinal bacteria across diverse human populations.
• To explore the impact of IS activity on bacterial genome diversification and adaptation within the human gut environment.

Main Methods:

• Development of a curated database of IS elements.
• Creation of a computational pipeline for detecting IS insertions in bacterial genomes.
• Analysis of IS element distribution and insertion sites in intestinal bacteria from human samples.
• Investigation of IS element dynamics under environmental perturbations and during recovery.

Main Results:

• Diverse IS elements were found to insert into intestinal bacteria genomes irrespective of host lifestyle.
• IS insertions preferentially targeted bacterial accessory genes, facilitating adaptation to specific environmental niches.
• IS activity in Bacteroides led to the formation of insertion 'hot spots' within accessory genes.
• IS insertions were observed to be stable and transferable between human hosts.
• Environmental perturbations caused IS elements to be lost from the microbiota, with limited recovery post-homeostasis.

Conclusions:

• IS elements are significant drivers of bacterial genome diversification within the human microbiota.
• IS insertions contribute to bacterial adaptation by modifying accessory genes.
• The stability and transferability of IS elements highlight their role in microbial evolution and population dynamics.
• IS element dynamics are sensitive to environmental changes, impacting bacterial community resilience.
• This study provides a framework for understanding how microbial strain-level variation, influenced by IS elements, affects human health.