Impact of fungal hyphae on growth and dispersal of obligate anaerobic bacteria in aerated habitats

Abstract

Anoxic microsites arising in fungal biofilms may foster the presence of obligate anaerobes even in well-areated environments. Here, we analyzed whether and to which degree fractal hyphae of Coprinopsis cinerea thriving in oxic habitats enable the germination, growth, and dispersal of obligate anaerobic soil bacterium Clostridium acetobutylicum. Time-resolved optical oxygen mapping, microscopy and metabolite analysis revealed the formation and persistence of anoxic circum hyphal niches allowing for spore germination, growth and fermentative activity of the obligate anaerobe in an otherwise oxic environment. Hypoxic liquid films containing 80 {+/-} 10% of atmospheric oxygen saturation around single air-exposed hyphae thereby allowed for efficient clostridial dispersal amid spatially separated (>0.5 cm) anoxic sites. Our results suggest that fungal biomass typical in soil (<550 g g-1soil) may create anoxic microniches and enable activity as well as dispersal of obligate anaerobes near hyphae in an otherwise inhabitable environment.