Abstract. We present results from a new marine plankton model that combines selective biogeochemical processes with genetic information. The model allows for phytoplankton to adapt to a changing environment by invoking different utilization pathways for acquisition of nutrients (nitrogen and phosphorus) in response to concentration changes. The simulations use simplified environmental conditions represented by a continuously stirred tank reactor, which is populated by 96 different types of phytoplankton that differ in their physiological characteristics and nutrient uptake/metabolism genes. The results show that the simulated phytoplankton community structure is conceptually consistent with observed regional and global phytoplankton biogeography, the genome content from the dominant types of phytoplankton reflects the imposed environmental constraints, and the transcription of the gene clusters is qualitatively simulated according to the environmental changes. The model shows the feasibility of including genomic knowledge into a biogeochemical model and is suited to understanding and predicting changes in marine microbial community structure and function, and to simulating the biological response to rapid environmental changes.