Genome Evolution of Acinetobacter baylyi ADP1 During Laboratory Domestication

The bacterium Acinetobacter baylyi is a model organism known for its extreme natural competence and metabolic versatility. It is capable of transforming environmental DNA at high frequency across all growth phasesstages. The type strain ADP1 was created by random mutagenesis of a precursor strain, BD4, to prevent it from forming cell chains in culture, making it more experimentally tractable. ADP1 has since been distributed between research groups over several decades, and acquireding subsequent mutations during this timeroutine laboratory culture. In this study we compare the genome sequences of Acinetobacter baylyi BD4 and its modern descendants obtained from different laboratories to identify and understand the effects of mutations acquired during each stage of its domestication. We demonstrate that ADP1 variants in use today differ in their competence, growth on different carbon sources, and auto formation of aggregationes. Additionally, we link the global carbon storage regulator CsrA and a transposon insertion removing its C-terminal domain specifically to changes in both overall competence and an almost complete loss of competence during stationary phase. Reconstructing the history of ADP1 and diversity that has evolved in the variants currently in use This work improves our understanding of desirableimportant properties of this experimentally and industrially important bacterium and suggests ways that its reliability can be improved through further genome engineering.