Involved in the gamma-resorcylate (2,6-dihydroxybenzoate) catabolism (Probable). Catalyzes the reversible decarboxylation of gamma-resorcylate to resorcinol (PubMed:29283551). Also catalyzes the decarboxylation of 2,3-dihydroxybenzoate to catechol, 2,4,6-trihydroxybenzoate to benzene-1,3,5-triol, and 2,6-dihydroxy-4-methylbenzoate to 5-methylbenzene-1,3-diol (PubMed:29283551). 2,6-dihydroxybenzoate + H(+) = CO2 + resorcinol 2,3-dihydroxybenzoate + H(+) = catechol + CO2 Binds 1 Mn(2+) ion per subunit. Activity is inhibited by 2-nitroresorcinol (2-NR). kcat is 0.44 sec(-1) with gamma-resorcylate as substrate. kcat is 0.47 sec(-1) with 2,3-dihydroxybenzoate as substrate. kcat is 0.18 sec(-1) with 2,4,6-trihydroxybenzoate as substrate. kcat is 0.38 sec(-1) with 2,6-dihydroxy-4-methylbenzoate as substrate. Aromatic compound metabolism. Homotetramer. Belongs to the metallo-dependent hydrolases superfamily. ACMSD family.