Cultivation of Yarrowia lipolytica on a hydrolysate based on food waste

Abstract: Interest in replacing fish oil and fish meal as fish feed ingredients with more socially, environmen-tally, and economically sustainable alternatives has increased in recent years. One such alternative could be the use of yeast biomass. In this report, the growth characteristics of the yeast Yarrowia lipolytica on a hydrolysate originating from food waste have been analyzed. The yeast was grown on a filtrated hydrolysate, which was produced in several filtering steps using paper and glass fiber filters, where two degrees of purity were used for the cultivations, e.g., minimally, and sterile filtered hydrolysate. The yeast was cultivated in small bioreactors where the growth characteristics on the different substrates were analyzed. Another parameter that was investigated was the pH (6.2 and 5.5) effect on the yeast growth. Also, the impact of pH at harvest was analyzed by harvesting the biomass at low and high pH levels. During all cultivations, samples were taken for the analysis of volatile fatty acids and lactate by High-Performance Liquid Chromatography (HPLC). The main findings of this project were firstly, that Y. lipolytica could grow on both sterile and minimally fil-tered hydrolysate. Secondly, the yeast seemed to prefer acetate and propionate over lactate. Thirdly, that the method used for filtration worked well for the preparation of yeast cultivation medium.