Bacterial biofilms dominate microbial life; however, their evolutionary genetics remain incompletely understood. Extensive replication of biofilm selection experiments by secondary school students can provide valuable insights into mechanisms of adaptation. Notably, mutations in a conserved phosphodiesterase, PFLU0185/bmo, dominate evolved populations without changing colony morphology. Phenotypic assays reveal that bmo plays a generalist role and competes with its ancestor and oth