Involved in the meta cleavage of catechol to 2-hydroxymuconic semialdehyde. Essential for growth and viability in the presence of catechol and probably involved in the detoxification of catechol. catechol + O2 = (2Z,4E)-2-hydroxy-6-oxohexa-2,4-dienoate + H(+) Strongly induced by catechol, less strongly by 2-methylhydroquinone (2-MHQ) but only weakly by chromanon (6-brom-2-vinyl-chroman-4-on). Belongs to the extradiol ring-cleavage dioxygenase family.