Melanin has an important role in conidial pigmentation and tolerance to environmental stress in filamentous fungi. A white koji fungus,
Aspergillus luchuensis mut.
kawachii, was isolated as an albino mutant from the black koji fungus,
Aspergillus luchuensis. In this study, we found that
A. luchuensis mut.
kawachii produces black colored conidia by complementation of the wild type
pksP gene, which encodes a polyketide synthase involved in the biosynthesis of dihydroxynaphthalene(DHN)-melanin. The
pksP complementation and overexpression did not affect the colony size or conidial surface structure in
A. luchuensis mut.
kawachii, but did cause an increase in the number of conidia per colony area. In addition, the
pksP overexpression strain produced a larger amount of dark yellowish pigment during the hyphal growth than the control strain. Moreover, the conidia of
pksP complementation and overexpression strains showed higher resistance against ultraviolet light, hydrogen peroxide, and ion beams than that of the control strain. These findings will help expand our understanding of the characteristic features of
A. luchuensis mut.
kawachii.
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