Elicitation and biotransformation of 6-pentyl-α-pyrone in Trichoderma atroviride cultures

6-Pentyl-alpha-pyrone (6PP) is a lactone with antibiotic and flavoring properties that is produced by Trichoderma spp. 6PP microbial production has shown low productivity and yield due to product inhibition during the growth of the producing fungus and due to the degradation of this lactone during the culture. Inactivated mycelium and supernatant from four phytopathogenic fungi were independently evaluated as elicitors of 6PP production by Trichoderma atroviride. In addition, the degradation that the molecule undergoes during culturing was studied. Cultures with nonviable mycelium of Rhizoctonia solani, Sclerotium sp. and Fusarium oxysporum 3 significantly promoted T. atroviride growth. In contrast, the supernatant of F. oxysporwn 2 and Sclerotium sp. inhibited mycelial growth by 80% and 44%, respectively. The supernatant of R. solani was the most efficient elicitor, as it increased 6PP-specific productivity and yield by 12-fold and 4.8-fold, respectively. This work demonstrates that the elicitation of 6PP production by T. atroviride is promoted mainly by fungal phytopathogen metabolites. The decrease in 6PP in some cultures was not the result of the volatilization/mycelial absorption of the molecule but was due to a biotransformation by T. atroviride occurred intracellularly in the microsomal fraction.