Responsible for meta-cleavage of the first aromatic ring of 2,2',3-trihydroxybiphenyl and 2,3-dihydroxybiphenyl. 2,2',3-trihydroxydiphenyl ether, catechol, 3-methylcatechol, and 4-methylcatechol are oxidized less efficiently and 3,4-dihydroxybiphenyl is oxidized considerably less efficiently. Xenobiotic degradation; dibenzo-p-dioxin degradation; 2-hydroxymuconate and catechol from dibenzo-p-dioxin: step 2/3. Xenobiotic degradation; dibenzofuran degradation; 2-hydroxy-2,4-pentadienoate and salicylate from dibenzofuran: step 2/3. Monomer. Belongs to the extradiol ring-cleavage dioxygenase family.