Yarrowia lipolytica biomass-a potential additive to boost metabolic and physiological responses of Nile tilapia.

We studied the effects of Yarrowia lipolytica biomass on digestive enzymes, blood biochemical profile, energy metabolism enzymes, and proximate meat composition of Nile tilapias. The experiment was entirely randomized with four replications. The animals (n = 20 per repetition) were fed with 0%, 3%, 5%, and 7% of biomass for 40 days and then blood and liver were analyzed. There was an increase in the activities of chymotrypsin (5, 7% groups), trypsin (3, 5% groups), and sucrase (7% group) compared to the respective control groups. On the other hand, maltase activity was significantly reduced for all yeast biomass treatments, while the supplementation did not influence lipase and amylase activities. Moreover, the blood triacylglycerol concentrations were increased in the 7% group, while any treatment modified blood total cholesterol, glycemia, and hepatic glycogen content. Y. lipolytica biomass promoted significant increases in meat protein and lipid contents without changes in moisture and ash parameters. Furthermore, Y. lipolytica biomass promoted increases in hexokinase (3% group), phosphofructokinase (5, 7% groups), glucose-6-phosphate dehydrogenase (5% group), citrate synthase (3% group), aspartate aminotransferase and alanine aminotransferase (3% group), and glutamate dehydrogenase (3, 5% groups) compared to the respective control groups. At the same time, no changes were observed in the activity of glucose-6-phosphatase. Y. lipolytica biomass supplementation in tilapias' diet can modulate the digestive system and improve nutrient disponibility to the cells. Moreover, the changes in the metabolic profile and in energy metabolism can be correlated with the improvement of meat composition. Therefore, the Y. lipolytica biomass has a great potential to be used as a feed ingredient for Nile tilapias.

Immunomodulatory effects of Yarrowia lipolytica as a food additive in the diet of Nile tilapia.

The use of yeasts as a dietary additive for fish can act as a source of nutrients and as an immunostimulant. This work aimed to evaluate the effects of the fermented biomass of the yeast Yarrowia lipolytica as a food additive on zootechnical and hematological parameters, and on immune response in the plasma and kidney of Nile Tilapia (Oreochromis niloticus). After supplementation with 3, 5, and 7% of the yeast biomass for 35 days, the blood and tissues of the animals of each experimental group were collected for analysis. The addition of this biomass in the feed promoted an improvement of zootechnical parameters in tilapia. There was also a rise in the number of neutrophils (groups with 3, 5, and 7%) and monocytes (group 3, 5, and 7%) compared with the control group. Moreover, there was an increase in the levels of lysozyme, myeloperoxidase, and nitrite/nitrate content in the blood of animals fed with yeast biomass. On the other hand, there were no observed alterations in survival and hematological parameters of animals fed with yeast biomass. In the analysis of the kidney, the addition of biomass in feed promoted an increase in levels of myeloperoxidase (group with 3%) but did not alter the levels of lysozyme and nitrite/nitrate content. In conclusion, this study demonstrated that Y. lipolytica had growth and immunostimulatory effects on Nile tilapia. These findings strongly suggest the potential application of a Y. lipolytica-based immunostimulant for tilapia aquaculture.

Caracterização e compostos bioativos do óleo da castanha-de-cutia (Couepia edulis) / Physical-chemical characterization of bioactive compounds of the oil from cutia nut (Couepia edulis)

O óleo da castanha-de-cutia (Couepia edulis) foi extraído por prensagem a frio e caracterizado físico quimicamente por meio de métodos analíticos padrão para óleos e gorduras. Foram avaliados o teor de ácidos graxos livres, os índices de acidez, de peróxidos, de iodo, de refração e de saponificação e a matéria insaponificável. A estabilidade oxidativa foi determinada com o uso do equipamento Rancimat; o perfil de ácidos graxos, por cromatografia gasosa e por ressonância magnética nuclear de prótons (RMN-H1) por espectrometria. A análise da composição de tocoferóis foi realizada em cromatografia líquida de alta eficiência, e dos compostos fenólicos totais, por espectrofotometria UV-Vis. Por se tratar de óleo prensado a frio, os resultados dos índices de acidez e de peróxidos confirmaram a estabilidade das amostras prensadas, uma vez que o processo não interfere na qualidade do óleo. Quanto à composição química de ácidos graxos, evidenciaram-se maior percentual de ácidos graxos insaturados, aproximadamente 52,78%, e a presença de ácidos graxos conjugados. O óleo apresentou ainda relevante teor de compostos fenólicos totais, os quais constituem fonte viável de α- e γ-tocoferóis. Por ser fonte de compostos bioativos, há perspectivas de uso do óleo da castanha-de-cutia como matéria-prima para indústrias químicas e farmacêuticas.