The Glomeromycetes form a mutualistic relationship with more than 80% of land plants, the arbuscular mycorrhizal (AM) symbiosis in which they receive up to 20% of the plants photosynthetic carbon. They are a determining property for the assimilation of minerals, especially phosphate, in land plants since the first plants were growing on land, more than 450 million years ago. Inoculation with AM fungi can increase agricultural crop growth yields up to 40%, depending on the soil type, underscoring their importance for plant growth. Due to their widespread and the amounts of available substrate and energy, they seem to be a major constituent that can shape soil ecosystems. In close cooperation with Prof. Caroline Gutjahr from the Max-Planck Institute for Plant Physiology, we study the growth physiology and energy metabolism of Glomeromycetes and its potential consequences on soil ecosystems, also in context with soil bacterial consortia, in defined model systems.