Degradation of orcinol by Aspergillus niger.

Aspergillus niger could utilize orcinol (5-methyl-resorcinol or 3,5-dihydroxytoluene) as the sole source of carbon and energy. In the first step of catabolism A. niger hydroxylates orcinol to form 2,3,5-trihydroxytoluene. Its oxidized form, 2-hydroxy-6-methyl-1,4-benzoquinone, was also formed in the culture medium during growth of this organism. Orcinol-grown cells showed a net increase in the intracellular acetate pool, compared with glucose-grown cells. Cell-free extracts of orcinol-grown cells showed higher activity of orcinol hydroxylase, catechol 1,2-oxygenase, and isocitrate lyase than that of glucose-grown cells. Both orcinol-grown and resorcinol-grown cells exhibit similar respiratory activity on all the substrates checked.