Natural Whole-Cell Oil Microcapsules as Innovative Diets for Live Feeds

Abstract

Aquaculture plays an increasingly important role in meeting the world’s food needs. To meet the demands of an ever growing human population, improvements in finfish larvae feed are needed. Rotifers are a widely used live feed for finfish larvae, but lack certain key nutrients such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). In order to enrich rotifers while avoiding decreased water quality from excess oil, this study investigated the encapsulation of EPA and DHA within the oleaginous yeast, Yarrowia lipolytica. A 23 factorial experiment was conducted to determine the effects of altering the culture conditions to improve EPA and DHA concentrations within the yeast. The factors investigated were hydrolysis of enrichment oil, temperature, and oxygen presence. Additionally, this research studied the utilization of a waste feedstock, papaya seed oil, in order to culture Y. lipolytica. This study demonstrated that the factor of hydrolysis and the interaction between temperature and oxygen to be statistically significant (P<0.05), with the best combination of hydrolysis, 25oC, and oxygen presence yielding an enriched yeast with 9.88 mg/g EPA per dry cell weight and 9.71 mg/g DHA per dry cell weight, and 27% total lipid by weight. For utilization of waste papaya seed oil, it was determined that an ethanol pretreatment of the papaya seeds prior to lipid extraction was able to minimize the anti-microbial compound benzyl isothiocyanate concentrations within the oil, thus allowing for Y. lipolytica culturing. Taken together the results of this study show the possibility of pretreating papaya seeds to unlock the oil’s utilization as a waste feedstock for culturing Y. lipolytica and the ability to alter culture conditions to influence EPA and DHA concentrations within this yeast.