Research Fellows Directory
Dr Emmanuelle CROST
Quadram Institute Bioscience
The human body is colonized by a large amount of bacteria that outnumber our human cells by at least 10 times. The vast majority of these bacteria, collectively called microbiota, inhabit our gut, especially the colon. The normal indigenous microbiota is exceedingly complex, consisting of many different species of bacteria belonging to the Firmicutes and the Bacteroidetes phyla. It plays an important role by protecting the normal host from invasion by microorganisms with a greater potential for causing disease. They compete with the pathogens for essential nutrients and for receptors on host cells and/or by producing antimicrobial substances and other inhibitory substances, making the environment inimical to colonization by pathogens.
In this work we focus on Ruminococcus gnavus, a Firmicutes species, especially the strains E1 and ATCC29149 both isolated from human faecal samples. R. gnavus E1 was shown to produce antimicrobial peptides active against the pathogen Clostridium perfringens.
Our aim is to better understand how R. gnavus colonise the healthy gut by focusing on its ability to utilise the sugar moieties present in mucus, the protective layer covering the gut intestine. The work so far involved (1) the identification and characterisation of the main glycosidases involved in mucin degradation, (2) the regulation of their expression when R. gnavus is grown on different sugars using customised microarrays (technique based on DNA/DNA hybridisation, allowing the gene expression profiling of thousand of genes at the same time) and (3) the characterisation of their fermentation products (short chain fatty acids) by NMR. The changes in gene expression will also be investigated in mice colonised by R. gnavus E1.
The proposed study will help us understand how certain microorganisms have become adapted to a particular site or ecologic niche in or on their host and provide knowledge on novel enzymes that may be used in biotechnological/biomedicine applications.
Interests and expertise (Subject groups)