NEW PATHWAY FOR DEGRADATION OF SULFONATED AZO DYES BY MICROBIAL PEROXIDASES OF PHANEROCHAETE-CHRYSOSPORIUM AND STREPTOMYCES-CHROMOFUSCUS

Pathways for the degradation of 3,5-dimethyl-4-hydroxy-azobenzene-4'-s ulfonic acid (I) and 3-methoxy-4-hydroxyazobenzene-4'-sulfonamide (II) by the manganese peroxidase and ligninase of Phanerochaete chrysospor ium and by the peroxidase of Streptomyces chromofuscus have been propo sed. Twelve metabolic products were found, and their mechanisms of for mation were explained. Preliminary oxidative activation of the dyes re sulted in the formation of cationic species, making the molecules vuln erable to the nucleophilic attack of water. Two types of hydrolytic cl eavage were observed. Asymmetric splitting gave rise to quinone and di azene derivatives, while symmetric splitting resulted in the formation of quinone monoimine and nitroso derivatives. These unstable intermed iates underwent further redox, oxidation, and hydrolytic transformatio n, eventually furnishing 11 organic products and ammonia.