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.

Assessment of lipolytic activity of isolated microorganisms from the savannah of the Tocantins / Avaliação da atividade lipolítica de microrganismos isolados do Cerrado tocantinense

Current study assesses the biodiversity and selects lipase-producer microorganisms with industrial interest, from the savannah of the state of Tocantins, Brazil. Seventeen pequi microorganisms (Caryocar brasiliense) were isolated in the decomposition stage and 35 microorganisms were retrieved from the soil fraction under the collected pequi. Yarrowia lypolitica strain was used as positive control in all assays. The 52 strains were subjected to tests in a solid medium with Tween 20 for checking halos formed by crystals, indicating lipase production by inoculated strains. Another test to confirm lipase producers was conducted in microplates with liquid medium and enriched with p-nitrophenyl palmitate (pNPP) monitored at 410 ηm. The AS16 and AP5 strains showed the highest activity for test conditions, namely, 0.072 and 0.067 U mL-1 respectively. Rates were higher than the lipase activity of Yarrowia lypolitica(0.052 U mL-1), a reference strain in current assay.

O atual estudo avalia a biodiversidade e selecionou microorganismos produtores de lipases de interesse industrial, a partir do cerrado tocantinense. O principal objetivo deste trabalho é avaliar a biodiversidade e selecionar microrganismos do cerrado tocantinense, produtores de lipases de interesse industrial. Foram isolados 17 microrganismos de Pequi (Caryocar brasiliense) em estágio de decomposição e também 35 microrganismos provenientes da fração do solo que se encontrava abaixo do pequi coletado. Foi utilizada uma cepa de Yarrowia lypolitica como controle positivo em todos os ensaios. Todas as 52 cepas foram submetidas a testes em meio sólido, utilizando Tween 20 para a verificação da presença de halos formados por cristais, indicando produção de lipase pelas linhagens inoculadas. Outro teste para confirmação dos produtores de lipase foi realizado em microplacas contendo meio líquido e enriquecido com pNPP (Palmitato de p-nitrofenila), monitorado a 410 ηm. As cepas AS16 e AP5 apresentaram as maiores atividades para as condições de ensaio a que foram submetidas: 0,072 e 0,067 U mL-1 respectivamente, sendo estes valores maiores que a atividade lipolítica da Yarrowia lypolitica (0,052 U mL-1), considerada como cepa referência para este trabalho.