Study of the white-rot fungal degradation of selected phthalocyanine dyes by capillary electrophoresis and liquid chromatography

The phthalocyanine dyes, Remazol Turquoise Blue G133, Everzol Turquoise Blue and Heligon Blue S4 are found to be biosorbed by Phanerochaete chrysosporium (white-rot fungi) and also metabolised by its ligninolytic extracellular enzymes resulting in dye decolourisation, formation of free copper ions and organic metabolites with ultimate extensive phthalocyanine ring breakdown. It is believed that the ligninolytic extracellular enzyme laccase is involved in the early production of a metabolite M₈ which involves break-up of the conjugated phthalocyanine ring structure but which retains multi-negative charge. Another ligninolytic extracellular enzyme, manganese peroxidase, is believed to be involved in the release of Cu²⁺ from the phthalocyanine structure to give a non-copper-containing phthalocyanine metabolite M₁ with a slightly longer migration time than the parent dye and absorption at 666 nm. The phthalocyanine ring structure is also broken up by metabolic processes that involve desulphonation and oxidation to give phthalimide (M₃) and an unidentified electroactive metabolite M₂. Other minor, unidentified metabolites are observed using capillary electrophoresis and liquid chromatography.