Positive, neutral and egative interactions in cocultures between Pyrococcus furiosus and different methanogenic Archaea

Abstract

The model organism Pyrococcus furiosus has recently been reported to interact with Methanopyrus kandleri in coculture, suggesting a H2 symbiosis. In the current study we further investigated this hypothesis by growing P. furiosus with four other hyperthermophilic methanogens providing evidence that the organisms did not only exert positive effects (P. furiosus/Methanocaldococcus villosus and P. furiosus/Methanocaldococcus infernus) on each other, but also neutral (P. furiosus/Methanocaldococcus jannaschii) and even inhibitory interactions (P. furiosus/Methanotorris igneus) were detected suggesting interspecies relationships not only based on H2 symbiosis. Using various microscopic techniques we further analyzed the coculture with the highest positive interactions (P. furiosus/ M. villosus) concerning its growth behavior on various surfaces, which turned out to be in stark contrast to the previous reported coculture of P. furiosus/M. kandleri. This communication provides new insights into possible interactions of extremophilic Archaea in co-cultures and again raises the question if and how hyperthermophilic Archaea communicate besides metabolic intermediates like H2.