Detoxification of Jatropha curcas L. seed cake using endophytic fungi

Abstract

In this work, a solid-state fermentation process was designed for the detoxification of the residual cake of the Jatropha curcas plant using endophytic fungi. For this, flour (defatted with hexane) with and without seed coat were mixed (40 g) with 1x109 fungal spores, at 50% humidity, and incubated for 10 days at 28 °C and 80% relative humidity, in a dark environment. A complete 2k factorial design (presence / absence of 4 fungi=16 treatments) was followed for each type of residual paste. To evaluate the detoxifying capacity, hexane and methanolic extracts were made from the ferments, and lethality tests were performed on Artemia salina calculating the LC50 by means of regression analysis. Those ferments that contained the seed coat showed higher toxicity (LC50=36.1±2.9 µg mL-1) than those prepared with almond flour without seed coat (LC50=126.6±6.9 µg mL-1). Hexane extracts from treatment 1 without seed coat (control, T1) presented high toxicity (LC50=9.2±0.6 µg mL-1) compared to treatment 11 without seed coat (T11: Penicillium sp. CDCU-3 and Nigrospora sp. CHIC-1) which presented a detoxification phenomenon with LC50 of 803.7±50.0 µg mL-1, that is, 87 times less toxic than T1. Furthermore, T11 had more soluble protein content than the rest of the treatments (F=8.006, P<0.001).