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Special Seminar - Steven Quistad: Experimental manipulation of Selfish Genetic Elements (SGEs) links genes to microbial community function

  • rescheduled: new date on March 22
  • Date: Mar 22, 2019
  • Time: 11:00 - 12:00
  • Speaker: Steven Quistad from the École Supérieure de Physique et de Chimie Industrielles de la ville de Paris (ESPCI), France
  • More information on the speaker can be found here: http://www.stevenquistad.com/
  • Location: MPI Plön
  • Room: Lecture hall
  • Host: Paul Rainey

Abstract:

Microbial communities underpin earth’s biological and biogeochemical processes. Selfish Genetic Elements (SGEs) drive the evolution of microbial communities via the direct transfer of DNA between host cells. While some SGEs may transfer genes that provide the host with a selective advantage more often SGE invasion results in a neutral or negative impact on host fitness. Therefore, the survival of most SGEs is dependent on their ability to successfully transfer to a new host cell. Here we set out to design an experiment that would promote SGE transfer with the goal of observing SGE eco-evolutionary dynamics and their subsequent impact on the evolution of microbial communities. Ten microbial communities were founded from compost and grown in minimal media supplemented with a piece of cellulose paper serving as the sole carbon source. Following establishment, the founding communities were split into two transfer regimes: Vertical and Horizontal. In the Vertical regime each of the ten communities were homogenized every two weeks and transferred to fresh medium with a new piece of cellulose paper. In the Horizontal regime each transfer involved the founding microbial community as well as an “SGE-cocktail” sampled from all ten bottles, thus providing the opportunity for SGEs to move between Horizontal but not Vertical communities. Using comparative metagenomics, we provide evidence for large-scale movement of genetic material between Horizontal communities including predicted genes involved with ecologically relevant traits such as iron acquisition, virulence factors, and transcription. As a general proxy for community function we also measured the ammonia concentrations during the course of the two-week incubation period. Surprisingly, we found that the Horizontal communities had significantly higher ammonia production compared to their Vertical counterparts. To our knowledge these data describe for the first time the emergence of a functional impact of SGEs on a complex microbial community through direct experimentation.

 
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