Study of degradation of phorbol ester in soil with HPLC and brine shrimp (Artemia sp.) bioassay.

• Main Author: Yeo, Eunice.
• Other Authors: Hong Yan
• Format: Final Year Project
• Language: English
• Published: 2011
• Subjects: DRNTU::Science::Biological sciences
• Online Access: http://hdl.handle.net/10356/44901
• Institution: Nanyang Technological University

Jatropha curcas (Jatropha) seeds are usually extracted to obtain oil for use in production of biodiesel. During oil extraction process, nutrient-rich seedcake is produced, and is often applied to crops as fertilizers. However, seedcake contains toxic phorbol esters (PEs); as such there is an eco-toxicological concern on leeching of PEs into soil, then water bodies, and subsequently its potential bio-accumulated impact on living communities. In this project, fate of PEs in Jatropha oil after contact with different soils was examined quantitatively with HPLC, and toxicity using brine shrimp (Artemia) bioassay. Two types of soil were used – clay and black soil, and were subjected to autoclaved and non-autoclaved conditions. Jatropha oil was mixed with soil and left under the sun for various duration of 0-9 days; re-extracted, before testing with 48-hour old Artemia nauplii. For all soils, Artemia showed 100% mortality with re-extracted oil from day 0, and almost complete loss of toxicity (<5% mortality) was obtained from day 4 onwards. As such, it was suggested that Jatropha PEs are photodegraded when exposed to sunlight, and such degradation is independent of microorganisms. With LC50 of ~2.5% Jatropha oil, Artemia is a sensitive and cost effective bioassay system for PE toxicity.