Plants grow in association with diverse soil microbial communities and assemble a taxonomically robust microbiota. Although these microbial partners profoundly influence host physiology, the underlying organizational principles are not yet understood (Berendsen et al., 2012, 2018). In order to develop a simplified, high- throughput approach to investigate such interactions, I am using Chlamydomonas reinhardtii, a model microalgae found in temperate soil habitats (Sasso et al. 2018), as the photoautotrophic host that modulates the surrounding microbiota. Utilizing 16s rRNA amplicon sequencing, high-throughput growth systems and gnotobiotic soil systems, together with bacterial culture collections, I aim at understanding how Chlamydomonas and other soil microalgae can structure bacterial communities and how this compares is to plant systems.