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Updated: Jun 10, 2026

Isolation and Screening from Soil Biodiversity for Fungi Involved in the Degradation of Recalcitrant Materials
Published on: May 16, 2022
Biodegradation of Jatropha curcas phorbol esters in soil
Rakshit K Devappa1, Harinder Ps Makkar, Klaus Becker
1Institute for Animal Production in the Tropics and Subtropics (480b), University of Hohenheim, 70593 Stuttgart, Germany.
Background:
Jatropha curcas seed cake is generated as a by-product during biodiesel production. Seed cake containing toxic phorbol esters (PEs) is currently used as a fertiliser and thus it is of eco-toxicological concern. In the present study the fate of PEs in soil was studied.
Results:
Two approaches for the incorporation of PEs in soil were used. In the first, silica was bound to PEs, and in the second, seedcake was used. At day 0, the concentration of PEs in soil was 2.6 and 0.37 mg g(-1) for approach 1 and 2 respectively. PEs from silica bound PEs were completely degraded after 19, 12, 12 days (at 130 g kg(-1) moisture) and after 17, 9, 9 days (at 230 g kg(-1) moisture) at room temperature, 32 degrees C and 42 degrees C respectively. Similarly at these temperatures PEs from seed cake were degraded after 21, 17 and 17 days (at 130 g kg(-1) moisture) and after 23, 17, and 15 days (at 230 g kg(-1) moisture). Increase in temperature and moisture increased rate of PEs degradation. Using the snail (Physa fontinalis) bioassay, mortality by PE-amended soil extracts decreased with the decrease in PE concentration in soil.
Conclusion:
Jatropha PEs are biodegradable. The degraded products are innocuous.
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