Fig. 3

In vivo activity of Cortinarius rufoolivaceus NR-PKSs CrPKS1-CrPKS3 in Aspergillus niger. Overlaid extracted ion chromatograms (EICs) of ethyl acetate extracts are shown for m/z 275 [M + H]⁺ to detect the octaketide atrochrysone (1, red) and m/z 233 [M + H]⁺ for the heptaketide product 6-hydroxymusizin (2, black). Top panel: individual EICs for standards of 1 and 2. Below: A. niger expressing the genes for CrPKS1 (A. niger tNAL036), CrPKS2 (tNAL038) and CrPKS3 (tNAL043). A. niger tNAL000 [22], carrying the insertless expression vector phis_SM-Xpress_URA, and the parental strain ATNT16ΔpyrGx24 were included as negative controls to monitor the metabolic background of the host