Crossfeeding relationship between Ruminococcus gauvreauii IPLA60001 and Ruminocoides biliarensis IPLA60002

Little is known about the bacteria that reside in human gallbladder and the mechanisms that allow them to survive within this harsh environmental niche. Furthermore, certain bacterial species are considered to exhibit antagonistic activities whilst others may form mutualistic interactions through, for example, cross-feeding. We isolated two new strains from healthy human bile samples, one belonging to Ruminococcus gauvreauii, of Lachnospiraceae family, and other constituting a new specie in Ruminococcaceae family, named Ruminocoides biliarensis. The two strains differed markedly in their carbohydrate metabolism as R. gauvreauii mainly metabolised sugar alcohols, including inositol, to form acetate as unique fermentation product, and Rc. biliarensis mainly metabolised resistant starches to mainly form formate and acetate as fermentation end products. Both strains exhibited resistance to different bile salts, and the ability to sporulate. Amino acid and vitamin biosynthesis profiles also markedly differed between the two bile isolates. Finally,RNAseq was used to analyse the co-cultures of both isolates, to analyze the activities involved in the possible cross-feeding relationship. Overall design: The analysis contains 4 different samples, that belongs to: the pure culture of R.gauvreauii in M2 medium supplemented to D-glucose in 8hours, the pure culture of R.biliarensis in M2 medium supplemented to Starch from Rice in 8hours, the coculture of R.gauvreauii and R. biliarensis in M2 medium supplemented to Starch from Rice in 6hours and the coculture of R.gauvreauii and R. biliarensis in M2 medium supplemented to Starch from Rice in 8hours. Each sample was studied by triplicate