Phorbol ester biodegradation in Jatropha curcas cake and potential as a substrate for enzyme and Pleurotus pulmonarius edible mushroom production

Jatropha curcas is a model for biorefinery applications. Although J. curcas cake (JCC), a prod-uct of oil extraction, shows potential in animal feed, inactivation of toxic phorbol esters (PE) in residues is necessary. Biological detoxification offers promise for animal feed, as well as for edible mushroom and enzyme production. Here, strains of Aurantioporus pulcherrimus, Ganoderma lucidum, Agaricus sp., Agaricus fuscofibrillosus, Agaricus mediofuscus, Ascopolyporus sp., Panaeolus antillarum, Lentinus strigellus, Amylosporus sp. and Pleurotus pulmonarius were screened for degradation of PE in JCC. These selected macrofungi degraded PE in solid cul-ture over a 30-day period at 28 degrees C. Among the evaluated basidiomycetes, P. pulmonarius dis -played the highest rate of PE degradation, reaching 97% efficiency. To induce the formation of fruiting bodies, P. pulmonarius was further cultivated over 60 days in JCC and five differ-ent JCC formulations, each supplemented with an additional lignocellulosic source, with up to a 99.5% degradation of the toxic compound achieved. Fungal fruiting was observed in four of the formulations tested. Biological efficiency (BE) reached 25% in a formulation of JCC plus sawdust. Ligninases, cellulases, hemicellulases, proteases, phytases, esterases and li-pase activities were quantified from crude extracts of Spent Mushroom Substrate (SMS) from this formulation. Bromatological analyses here also revealed increases in protein content, Neutral Detergent Fiber (NDF), Acid Detergent Fiber (ADF), cellulose and hemicellulose, and a reduction in dry matter, lignin, and ethereal extract. In conclusion, P. pulmonarius was effi-cient in degradation of PE in JCC, with the residue appropriate for animal feed input, for production of edible mushrooms, and as a source of enzymes of biotechnological interest.

Automated summary

This study screened multiple fungal strains for the degradation of toxic phorbol esters (PE) in Jatropha curcas cake (JCC). Among the evaluated basidiomycetes, Pleurotus pulmonarius displayed the highest efficiency in PE degradation, reaching 97%. Further cultivation of P. pulmonarius in JCC formulations supplemented with lignocellulosic sources resulted in successful fruiting body formation and increased degradation of the toxic compound. The residue of JCC was found to be suitable for animal feed and as a source of enzymes.