Optimization of the biosynthesis of naphthoquinones by endophytic fungi isolated of Ferocactus latispinus

The aim of this work was the isolation of endophytic cacti fungi producer of pigments. Twenty different endophytic fungi were isolated from Ferocactus latispinus using a standard method. One of these was an orange pigment producer and was identified with molecular biology techniques amplifying internal transcribe spacer region. The fungus identified was Fusarium solani; it is a producer of polyketides from naphthoquinones family. Experiments with different carbon and nitrogen sources were performed, and it was found that both glycerol and ammonia sulphate promote the naphthoquinones biosynthesis. It was also found that the carbon/nitrogen ratio and pH value had an effect on this biosynthesis phenomenon; increasing productivity being observed at the initial C: N ratio of 59.6, pH 6 and time of 113.3 h. This C: N ratio exhibited a stress condition for fungi in the pigment biosynthesis process in liquid media. The optimum value of total naphthoquinones (476 μmol/L) was obtained using a central rotable composite design.