H2 and acetate transfers during xylan fermentation between a butyrate-producing xylanolytic species and hydrogenotrophic microorganisms from the human gut

The aim of this work was to investigate in vitro interrelationships during xylan fermentation between an H-2 and butyrate-producing xylanolytic species recently isolated in our laboratory from human faeces and identified as Roseburia intestinalis and the H-2-utilizing acetogen Ruminococcus hydrogenotrophicus or the methanogen Methanobrevibacter smithii. H-2 transfer between M. smithii or Ru. hydrogenotrophicus and the xylanolytic species was evidenced, confirming the great potential of these H-2-consuming microorganisms to reutilize fermentative H2 during fibre fermentation in the gut. In addition, acetate transfer was demonstrated between the xylanolytic Roseburia sp. and the acetogenic species, both metabolites transfers leading to butyric fermentation of oat xylan without production of H-2.