Deacetylates O-acetyl-ADP ribose to yield ADP-ribose and free acetate (PubMed:21257746, PubMed:26481419). Down-regulates ribonuclease 3 (RNase III) activity. Acts by interacting directly with the region of the ribonuclease that is required for dimerization/activation (PubMed:19141481). Overexpression inhibits biofilm formation via an RNase III-independent pathway. This inhibition is RpoS-dependent (PubMed:24267348, PubMed:28582517). Overexpression also results in increased susceptibility to apramycin (PubMed:28034758, PubMed:28582517). 3''-O-acetyl-ADP-D-ribose + H2O = acetate + ADP-D-ribose + H(+) 2''-O-acetyl-ADP-D-ribose + H2O = acetate + ADP-D-ribose + H(+) kcat is 0.48 sec(-1) (PubMed:21257746). kcat is 1.31 sec(-1) (PubMed:26481419). Homodimer (PubMed:19141481). Interacts with RNase III (PubMed:19141481, PubMed:25546632). Interaction with the ribonuclease decreases homodimer formation (PubMed:19141481). Expression is induced by both entry into stationary phase, via RpoS, and cold-shock stress. Belongs to the YmdB family.