Protocatechuate 3,4-Dioxygenase, Bacteria is a type of dioxygenase, specifically a non-heme iron dioxygenase. It catalyzes the cleavage of the aromatic ring of 3,4-dihydroxybenzoate, incorporating both atoms of molecular oxygen into the compound to form β-carboxy-cis,cis-muconate. This enzyme plays a pivotal role in the β-ketoadipate pathway and is present in marine bacteria related to Roseobacter. Protocatechuate 3,4-Dioxygenase can also be isolated from Pseudomonas aeruginosa.