Abstract

The detoxification of Jatropha curcas seed cake is of major interest for the biodiesel industry to add economic value to this residue and also to reduce the environmental damage caused by its inappropriate disposal. In this context, the treatment of this residue with white rot fungus, Pleurotus ostreatus, can be a viable alternative because it produces enzymes capable of degrading different lignocellulosic residues and toxic compounds. In this study, the capacity of P. ostreatus to degrade phorbol esters found in Jatropha seed cake and the potential to transform this residue in animal feed was evaluated. After 60 days of incubation with the fungus, the phorbol ester concentration was reduced by 99% (final concentration of only 2 x 10^-4 mg g^-1 dry mass). This value is lower than the level observed in the non-toxic Mexican variety. Also, we showed that fungal growth improved some features desirable for animal feed, such as, increases the in vitro digestibility, decreases lignin and cellulose content and increases the protein content. Therefore, P. ostreatus is able to degrade phorbol esters found in Jatropha seed cake and has the potential to be used as animal feed.

Key words: Physic nut, toxic compounds, phorbol ester, biodiesel, lignocellulosic residue.