Detoxification of Jatropha curcas seed cake by a new soil-borne Enterobacter cloacae strain

Jatropha curcas seed cake is a by-product generated after oil extraction from J. curcas seeds. Although the protein content is high, the cake contains phorbol esters and antinutritional factors such as phytates, trypsin inhibitors, lectins and tannins. Therefore, it cannot be directly used in food or feed. In this study, the toxic compounds and antinutrients present in J. curcas seed cake were detoxified by fermentation with Enterobacter Z11, a soil-borne isolate. Solid-state fermentation was undertaken under optimized conditions: deoiled cake, 5·0 g; initial moisture content, 50%; temperature, 30°C; and inoculum, 2 × 10⁶ cells per gram of cake. Postfermentation, bacterial growth, pH and the amount of antinutrients were studied. Fermentation reduced the content of phorbol esters, phytates, lectins, tannins and trypsin inhibitors by 51·6, 82·6, 88·9, 37·8 and 90·5%, respectively.

The strain of Enterobacter cloacae Z11 was originally isolated from the soil. To the best of our knowledge, E. cloacae has never been used to remove toxins and antinutritional factors in Jatropha curcas seed cake (JSC). Under the optimized condition, fermentation with the Enterobacter strain decreased the phorbol esters content in JSC by 51·6%, and phytates, tannins, lectins and trypsin inhibitors contents by 83, 38, 89 and 90%, respectively. This study provided a new method with potential to render the seed cake suitable for use in feed. Further study is needed to focus on remaining toxicity and nutritional value post-treatment.