Use of the black yeast Phaeococcomyces fungal melanin model system for preparation of 1,3,6,8-tetrahydroxynaphthalene and the other components of the DHN fungal melanin pathway

Compounds of the dihydroxynaphthalene (DHN) fungal melanin pathway are in short supply worldwide, especially 1,3,6,8-tetrahydroxynaphthalene, the chemically unstable starting point of the pathway, and are not commercially available. This is becoming an impediment to physiological survey work in the DHN pathway. We describe the use of our black yeast Phaeococcomyces DHN melanin model system to produce sufficient amounts of 1,3,6,8-tetrahydroxynaphthalene for physiological studies, using a simple modified culture method that uses an oxygen-scavenging growth medium containing cysteine and thioglycollate, which is also sealed with an oxygen-excluding layer of the black yeast. The medium also contains the DHN pathway reductase enzyme inhibitor tricyclazole, which causes excretion of 1,3,6,8-tetrahydroxynaphthalene and 1,3,8dihydroxynaphthalene. The presence of oxygen scavengers and the thick yeast growth prevents oxidation of the hydroxynaphthalenes. Most of the other components of the DHN fungal melanin pathway can be produced using the black yeast or using a scytalone dehydratase negative mutant of the black yeast that accumulates scytalone.