The α-oxoamine synthase gene fum8 is involved in fumonisin B2 biosynthesis in Aspergillus niger

• We characterized functions of fum8, an α-oxoamine synthase gene, in Aspergillus niger.
• The fum8 gene was required for biosynthesis of fumonisin B2.
• The fum8 gene was not essential for vegetative growth and tolerance to high temperature and UV irradiation.
• The fum21 gene encoding a transcription factor was expressed differently from fum8.

One of the secondary metabolite gene clusters of Aspergillus niger possesses highly homologous genes with those within the fumonisin gene cluster of Fusarium spp. At least 14 genes are considered to be present within approximately 50 kb genomic region. A number of strains of A. niger have been shown to produce fumonisin B2 (FB2), however, there has been no direct evidence that the gene cluster is responsible for FB2 production in this fungus. We investigated the involvement of the cluster in FB2 biosynthesis. The disruption of fum8, coding for an α-oxoamine synthase, resulted in loss of FB2 biosynthesis in A. niger, but did not influence the vegetative growth and sensitivity to high temperature or UV irradiation. The gene expression patterns of the transcription factor gene fum21 and fum8 were determined, but were different from those in F. verticillioides.