These data suggest that UmuDAb does not serve as a direct replacement of LexA for the entire DNA Acetrizoic acid damage regulon in this genus, instead serving a more specialized role in repressing Rubusoside error-prone polymerases. This specialized UmuDAb role invokes an additional DNA damagerelated repressor to regulate gene expression after DNA damage, which is consistent with the failure of RecA to regulate its own induction, seen both in this study and previously for A. baylyi ADP1 and A. baumannii. In having multiple umuDAb-dependent and �Cindependent regulons, the behavior of Acinetobacter in regulating their genes after DNA damage is more like its closer pseudomonad relatives, which contain multiple regulons of DNA damage-induced genes involving different repressor proteins, than it is to enteric bacteria such as E. coli. These Acinetobacter species, like P. aeruginosa, also repressed many more genes than they induced in response to DNA damage, and both genera repressed multiple canonical SOS genes in a lexA-independent manner, and induced nrdAB and prophage genes. Our observation of the 17978 strain possessing DNA damageinducible bacteriophages that encode mutation-inducing polymerase genes may hold significant implications for the evolution of virulence and antibiotic resistance in related strains. CP5 encodes the umuDrumB operon, which this study found to be responsible for at least half of the DNA damage-induced mutagenesis, while CP9 encodes A1S_2015, annotated as an ����error-prone lesion bypass DNA polymerase V���� that might also contribute to mutagenesis after DNA damage. Multiple DNA damage-inducing agents�CUV-C exposure as well as methyl methanesulfonate, dessication, and ciprofloxacin �Care capable of inducing mutagenesis in A. baumannii ATCC 17978 and AB0057. A. baumannii strains AB0057 and 3909 also contain CP5 that encodes the umuDrumB genes, while A. baumannii ATCC 19606 and D1279779, strains not investigated by DiNocera et al., also possess a very similar CP5-like prophage region that encodes umuDrumB.This indicates the possibility of a widespread mechanism in this species for spread of these error-prone polymerase genes in response to multiple stimuli.