| Congresso Brasileiro de Microbiologia 2023 | Resumo: 823-2 | ||||
Resumo:Jatropha curcas is an oilseed plant and its oil has several applications, such as biodiesel production. The seed cake, produced on the oil extraction step, is low-cost and highly nutritious, being a good source for animal feed. However, the high levels of phorbol esters (PEs), which are very toxic, make impossible the use of the Jatropha cake (JC) as animal feed. Most of the PEs are withdrawn together with the extracted oil. However, the remaining PE is still much higher than the safe limit. Thus, several chemical, biological and physical methods were developed to remove the phorbol esters in order to make the seed cake useful and profitable. Solid-state cultivation (SSC) is one of the most promising methods for the detoxification process. In this work, we used the SSC with filamentous fungi lipase producers for the biodetoxification of Jatropha cake. The fungi used were: Penicillium simplicissimum, P. brevicompactum, Trichoderma sp., Rhizopus sp. SSC was carried out at 30° C with initial moisture at 50% until 14 days. After the cultivation, PEs were extracted from the cake and their amount was analyzed using high-performance liquid chromatography (HPLC). The final phorbol esters degradations were: P. brevicompactum (4,66%), P. simplicissimum (5,81%), Rhizopus sp. (35,74%) and Trichoderma sp. (56,36%). For a better understanding of the degradation promoted by Rhizopus sp., an enzymatic kinetic was carried out with lipase and peptidase. The higher lipase activity (0,31U/g) was found on day 6, and the higher peptidase activity (0,82U/g) was found on day 4. An analysis of ergosterol concentration was made to better understand the fungi growth. The ergosterol concentration stabilized on day 5. Moisture, water activity and pH were measured every 24 hours with the intent to check if their levels declined to levels non-sustainable for fungi growth. In the end, none of them were capable of completely degrading the PE. Nonetheless, Rhizopus sp. and Trichoderma sp. capacity to degrade the PE shows that both genera have the potential to degrade the PE completely. It is worth mentioning that the cultures carried out in this work were carried out in non-optimized conditions. Hence, it is expected that a more profound study about the variables, such as temperature, supplementation, granulometry, initial moisture, and others, might increase the degradation. Palavras-chave: Detoxification, Jatropha curcas, phorbol ester, Solid-state cultivation Agência de fomento:Programa Institucional de Bolsas de Iniciação Científica – PIBIC/UFRJ | |||||