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The presence of phorbol esters (PEs) with toxic properties limits the use of Jatropha curcas kernel in the animal feed industry. Therefore, suitable methods to detoxify PEs have to be developed to render the material safe as a feed ingredient. In the present study, the biological treatment of the extracted PEs-rich fraction with non-pathogenic fungi (Trichoderma harzianum JQ350879.1, T. harzianum JQ517493.1, Paecilomyces sinensis JQ350881.1, Cladosporium cladosporioides JQ517491.1, Fusarium chlamydosporum JQ350882.1, F. chlamydosporum JQ517492.1 and F. chlamydosporum JQ350880.1) was conducted by fermentation in broth cultures. The PEs were detected by liquid chromatography-diode array detector-electrospray ionization mass spectrometry (LC-DAD-ESIMS) and quantitatively monitored by HPLC using phorbol-12-myristate 13-acetate as the standard. At day 30 of incubation, two T. harzianum spp., P. sinensis and C. cladosporioides significantly (p < 0.05) removed PEs with percentage losses of 96.9%-99.7%, while F. chlamydosporum strains showed percentage losses of 88.9%-92.2%. All fungal strains could utilize the PEs-rich fraction for growth. In the cytotoxicity assay, cell viabilities of Chang liver and NIH 3T3 fibroblast cell lines were less than 1% with the untreated PEs-rich fraction, but 84.3%-96.5% with the fungal treated PEs-rich fraction. There was no inhibition on cell viability for normal fungal growth supernatants. To conclude, Trichoderma spp., Paecilomyces sp. and Cladosporium sp. are potential microbes for the detoxification of PEs.

Seed kernel from Jatropha curcas L. cannot be utilized as animal feed due to the presence of toxic phorbol esters. However, biological treatments may alleviate the concentration of phorbol esters to a safe level. In the present study, two fungal isolates obtained from garden soil and five endophytes from Achillea fragrantissima plant in Saudi Arabia were used for treatments of J. curcas kernel. These fungi were identified as Cladosporium cladosporioides (isolate TUC9), Fusarium chlamydosporum (isolates TUF1, TUF10 and TUF11), Paecilomyces sinensis (isolate TUP8) and Trichoderma harzianum (isolates TUT1 and TUT2), based on their morphological characteristics and internal transcribed spacer regions sequence analysis. Fungal extracts at 250 µg mL[sup -1] of all isolates grown in potato dextrose broth (PDB) did not show cytotoxic effect against both human Chang liver and mouse NTH 3T3 fibroblasts cell lines. Treatment of J. curcas kernel in submerged fermentation showed the ability of all isolates to grow in 30 ml PDB supplemented with 14 g ground Jatropha kernel (5.6 g dry matter) containing 15.57 mg phorbol esters. The levels of phorbol esters decreased from 2.78 mg g[sup-1] dry matter of kernel to 0.06 mg g[sup _1]of spent substrate (97.8%) after 30 d incubation at 28°C by T. harzianum TUT1. Lipase activity was observed in all fungal isolates, but only P. sinensis TUP8, C. cladosporioides TUC9 and F. chlamydosporum TUF10 showed both lipase and esterase activities. Both enzyme activities were significantly higher (p<0.05) in the presence of phorbol esters. © 2014 Friends Science Publishers [ABSTRACT FROM AUTHOR]