Isolation and identification of oleogenic yeasts from milk and dairy products and optimisation of single cell oil production conditions

In this thesis study, oleogenic yeasts were isolated from 115 different sources such as milk, yoghurt, cheese, butter, buttermilk, cream and whey obtained from Burdur and its surrounding provinces and districts, and 112 of 247 yeasts isolated were determined to be oleogenic by Sudan Black B staining. Among these isolates, 12 isolates with high dry biomass yield in the range of 0,4-0,7 g were selected and single cell oil production was carried out and fatty acid compositions of the oils were determined. Genetic identification of A2-1, A2-3 and Y20-6 isolates selected according to dry biomass yield, lipid content and unsaturated fatty acid composition was performed. After identification, biochar-added single cell oil obtained from walnut shell was produced by using the strain belonging to the buttermilk sample coded A2-1, which has high biomass, single cell oil content and total unsaturated fatty acid content among the three strains identified as Clavispora lusitaniae. The results of dry biomass yield, lipid content and fatty acid composition of biochar-added single cell oils produced under the conditions obtained with 5-10 g/L biochar ratio and 96-144 hours incubation time variables were optimised. When the results obtained were evaluated, the optimum incubation time for high single cell oil yield was determined as 127,2 hours and the optimum biochar ratio was determined as 9,40 g/L. The dry biomass yield of single cell oil produced under these conditions was 1,42 g, lipid content was 2,12% and total unsaturated fatty acid content was 55,46%. After production under optimum conditions with the addition of biochar, a 70% increase in single cell oil yield was obtained. The fatty acid composition consisted of 19,26% oleic acid and 22,95% linoleic acid. In addition, gamma-linolenic acid and arachidonic acid were detected in single cell oils produced under optimum conditions.