Jatropha seed cake supplementation for improved fungal growth and later use as animal feed.

The use of Jatropha curcas as a raw material for biodiesel production results in large amounts of a solid residue called Jatropha seed cake (Jc). This residue is composed of lignin, cellulose, toxic compounds and anti-nutritional factors. Though the monomers that make up lignin and tannins could be used in animal feed, the polymer forms are not easily digestible, which necessitates a processing step. White rot fungi are known to produce enzymes capable of degrading these polymers, as well as anti-nutritional factors and some toxic compounds (for example, phorbol ester). Therefore, we evaluated the degradation of lignocellulosic compounds and biomass production by Pleurotus ostreatus in pure Jc or with different levels of added agro-industrial residues. After 45 days incubation, the best performing sample in terms of mycelial growth was pure Jc, followed by those supplemented with 20% eucalypt sawdust (JcEs20), 20% eucalypt bark (JcEb20) and 10% coffee husk (JcCh10). Among them, the JcCh10 presented the lowest lignin content after fungal growth. The content of lignin and cellulose/hemicellulose in this substrate were, respectively, 29.19 and 47.27% lower than pure Jc. Thus, P. ostreatus has the potential to degrade lignocellulosic compounds found in Jc, and this degradation increases the possibility of using this residue as animal feed. Key words: Biofuel, lignocellulosic residues, Jatropha seed cake, Pleurotus ostreatus, biodegradation.