Understanding Genome Evolution with the Help of Plasmid Gene Pools


Understanding how genomes of organisms change over time underlies much of biology and its practical applications. Plasmids are DNA molecules that can replicate independently of chromosomal DNA in a cell. This enables organisms to “collect” and move genes to other organisms through lateral gene transfer (like “genomic email”) and contributes to prokaryotic genome evolution. To understand the depth and breadth of the prokaryote plasmid gene pool, scientists have isolated, sequenced, and compared plasmids from two wastewater sludge communities. The authors studied the “mobilome,” a name for the mobile elements in a community genome, by specifically targeting, separating, and purifying closed circular supercoiled DNAs (CCSD) originating from the plasmids. They found that the plasmids isolated from the sludge wastewater microbial communities turned out to contain primarily uncharacterized coding sequences. Besides lending credence to the idea that plasmids are crucial to genome innovation, evolution, and community structure and functioning,
this study generated a large library of new genes involved in wastewater sludge degradation and processing that could enable new approaches to microbial wastewater cleanup. The study was enabled by the DOE Joint Genome Institute.


Sentchilo, V., A. P. Mayer, L. Guy, R. Miyazaki, S. G. Tringe, K. Barry, S. Malfatti, A. Goessmann, M. Robinson-Rechavi, and J. R. van der Meer. 2013. “Community-Wide Plasmid Gene Mobilization and Selection,” The ISME Journal, DOI: 10.1038/ismej.2013.13.