The role of biofilm formation in colonic cell adherence by Streptococcus gallolyticus (360G-Wellcome-211951_Z_18_Z)

Streptococcus gallolyticus (S. gallolyticus) is commonly found in the gastrointestinal tract of ruminants. Interestingly it can cause endocarditis in humans by translocating through the GI tract at sites of colonic cancer lesions. Studies have indicated that S. gallolyticus is an excellent colonizer of the intestinal tract, forming strong biofilms via effective adherence properties (Abdulamir et al 2011). However little is known about what mechanisms these bacteria use to colonise the gut and invade the bloodstream. We have assembled a cohort of bloodstream isolates from patients across Europe and are sequencing their genomes. This project will characterise the biofilm forming capacity of the strains and compare the phenotypes of the strong and weak biofilm forming strains in growth conditions that mimic the environment of the colon (anaerobic and rich in bile salts). We will then test representative strains from the strong and weak biofilm forming groups to bind to and invade colonic epithelial cells in order to see whether biofilm forming capacity has an influence on colonic cell adherence and invasion. Finally we will test these strains for translocation across a colonic cell monolayer to see whether biofilm production by S. gallolyticus can facilitate invasion of the gut mucosa in humans.