The relationship between the millions of gut bacteria and their host is one of IFR’s main research areas. Key to understanding these bacteria is knowledge of how the very close relationship between the bacteria and their hosts has evolved to be mutually beneficial to both.

One bacterial species, Lactobacillus reuteri, has been used as a model for this study, and TGAC, a partner of IFR on the Norwich Research Park, has sequenced its genome, funded by the Biotechnology and Biological Sciences Research Council (BBSRC). This collaboration between these two BBSRC institutes will provide new insights into the genomic basis for host adaptation of L. reuteri to the gut and help in the selection of probiotic strains. 

Lactobacillus reuteri has a large host range, from humans to rodents and birds. Previous work had shown that each host species has its own subpopulation of Lactobacillus reuteri strain. These strains differ slightly, and are host specific, and the differences between them are driven by evolutionary pressures from the host.

TGAC sequenced and assembled the genome of a Lactobacillus reuteri strain obtained from pigs to a high quality draft standard and also provided a full annotation. The annotation is needed to identify which genes carry out which functions in the sequence.  They used comparisons between different strains of Lactobacillus reuteri, which have already been made available in the major international sequence databases, to identify a set of genes unique to this particular strain.

The IFR and TGAC researchers are now hoping to use this information to understand exactly what it is that restricts certain Lactobacillus reuteri strains to specific hosts.

Lactobacillus reuteri confers certain health benefits, and has a role in modulating the immune system. A greater understanding of how Lactobacillus reuteri  adapts closely to its host will help in efforts to exploit these health benefits, for example in the production of new probiotics.

The gastro-intestinal tract contains many millions of bacteria, known collectively as the microbiota. IFR is also developing a model microbiota that is representative of the human colonic microbiota.  This will become a powerful tool for investigating the function of the microbiota in the gastro-intestinal tract and how it interacts with its host.  It will also become an integral part of studies investigating the extent, diversity and function of metabolic diversity in the microbiota.

Reference: Genome sequence of a vertebrate gut symbiont Lactobacillus reuteri ATCC 53608, Heavens et al, Journal of Bacteriology doi:10.1128/JB.05282-11