Metamobilomics – expanding our knowledge on the pool of plasmid encoded traits in natural environments using high-throughput sequencing

A metamobilome is defined as a metagenome of circular genetic elements within a certain community. Metagenomic analyses of plasmids provide insights into the composition and structure of environmental plasmid communities. It is a promising method that will provide information about the types of plasmids that are present within environmental samples, and will give overviews about occurrences of plasmids as well as accessory genetic elements carried on these plasmids. A metamobilome library was constructed by combining multiple displacement amplification with pyrosequencing. This method provided a fast, efficient and unbiased strategy to investigate the communal gene pool of circular genetic elements (the metamobilome). We compared our wastewater metamobilome library with a wastewater metagenome library, against chromosomes, plasmids, phages and IS element databases, respectively. This showed that very few strictly chromosomal reads were present in our metamobilome library. Furthermore, data analysis showed that our library was strongly enriched for genes encoding plasmid-selfish traits, such as stability and conjugation, and most strikingly several hundred new putative plasmid replicases have been recovered.