Modern outperforms Archival AM1 when grown on nutrient broth. A) Representative growth curves of Modern (black circles) and Archival (gray squares) AM1 grown on nutrient broth (NB). Note that growth - particularly for the Archival strain - slows considerably during late exponential phase, signifying density-dependent growth inhibition. B) Change in the proportion of either Modern or Archival AM1 mixed in co-culture with a fluorescently labeled Modern reference as measured by flow cytometry. Values represent the mean plus SEM of at least three biological replicates grown in 48-well plates (A) or flasks (B).