Two distinct lineages of Methylobacterium extorquens AM1. Shortly after its discovery in 1960 (1), a sample of M. extorquens AM1 (“AM1”) was deposited to a culture stock center for storage and distribution (2; Archival AM1). Many researchers, however, use instead a working stock of AM1 that was maintained over fifty years in the lab (3; Modern AM1), and was at one point selected for rifamycin resistance (RifR) . We hypothesized that these conditions may have fostered the accumulation of mutations and unintended evolutionary divergence in the Modern AM1 lineage, and sought to compare our Modern AM1 to the Archival strain. Dashes represent the accumulation of mutations in the Modern lineage.