Abstract

Isolation, identification and screening of lipid-degrading fungal organisms causing rot of unripe, ripe and dry fruits of Jatropha curcas L. were carried out, and determination of the fungus showing highest lipolytic activity on the substrate analysed from three different locations within Edo State, Nigeria was done using standard methods. Five fungal isolates (Curvularia geniculata, Lasiodiplodia theobromae, Trichoderma harzianum, Mucor sp. and Penicillium sp.) were recovered from the samples. Penicillium sp. had the highest frequency (37.5%) while Mucor sp. and Trichoderma sp. had the lowest (25%). Fungal isolates screened on solid agar showed low extracellular lipolytic activity detected by their non-production of a distinct clear zone of inhibition. In submerged fermentation, the growth of the lipolytic fungi ranged between 0.0492 (Mucor sp.) and 0.1539 g (T. harzianum). Spectrophotometric measurement (at 600 nm) of lipase production varied with Mucor sp. having the highest production of lipase. There was a significant difference (p≥0.05) between growth and lipolytic activities of the fungi. The study showed that Mucor sp. and L. theobromae are lipase producers and efficient lipid degraders. The implication of this is that these fungi could reduce the oil content of J. curcas seed and consequently its economic value.

Key words: Fungal isolate, lipase, Jatropha curcas, Nigeria.