Species Interactions Either Help or Harm Different Microbial Groups During Necromass Decomposition
Dead fungal biomass (“necromass”) is an important yet understudied component of soil, which represents the Earth’s largest terrestrial reservoir of carbon. Necromass is decomposed by a diverse microbial community, including both fungi and bacteria. How these different groups of microbes interact during the process of necromass decomposition, however, is not understood. This study aimed to identify the importance of interactions among the dominant fungal and bacterial taxa that naturally co-occur on decomposing fungal necromass. This was done by growing fungal and bacterial strains isolated from necromass together and separately in a 96-well plate assay, using necromass as the sole carbon source. Results indicated that in nearly all cases, bacterial growth was increased in the presence of a fungus, though the magnitude of this effect depended strongly on which fungal and bacterial species took part in the interaction. In contrast, the effect of bacteria on fungal growth was largely detrimental, with some exceptions. Overall, these results indicate that there are significant cross-domain interactions within the microbial communities colonizing necromass, which likely has important implications for the rates of decomposition and soil biogeochemical cycling.