Next, we evaluated a truncated version of the cluster containing HR-PKS bueA, the ER bueB, and the α/β hydrolase bueC to observe the first possible pathway intermediate. However, we did not observe any new peaks in the transformant A. nidulans strains expressing bueA/B/C/G/R compared to the control (Fig. ). For troubleshooting, we verified the correct sequence of vector pYFAC-bueA/B/C/R by next generation sequencing (Fig. ). In the homologous fusarielin cluster, deletion of the epimerase gene results in the production of an unstable compound. Instability of the released product could also explain the lack of accumulation of the first bue cluster intermediate.