Conjugation Protocol Optimised for Roseburia inulinivorans and Eubacterium rectale

Abstract

Roseburia and Eubacterium species of the human gut microbiota play an important role in the maintaince of human health, partly by producing butyrate, the main energy source of our colonic epithelial cells. However, our knowledge of the biochemistry and physiology of these bacteria has been limited by a lack of genetic manipulation techniques. Conjugative transposons previously introduced into Roseburia species could not be easily modified, greatly limiting their applicability as genetic modification platforms. Modular plasmid shuttle vectors have previously been developed for Clostridium species, which share a taxonomic order with Roseburia and Eubacterium, raising the possibility that these vectors could be used in these organisms. Here, we describe an optimized conjugation protocol enabling the transfer of autonomously replicating plasmids from an E. coli donor strain into Roseburia inulinivorans and Eubacterium rectale. The modular nature of the plasmids and their ability to be maintained in the recipient bacterium by autonomous replication makes them ideal for investigating heterologous gene expression, and as a platform for other genetic tools including antisense RNA silencing or mobile group II interon gene disruption strategies.