PRODUCTION OF SINGLE CELL OIL FROM OLEAGINOUS YEASTS WHEN CULTIVATED ON ENERGY CROPS

Abstract: Microbial oils, also called Single Cell Oil (SCO), have plenty of commercial applications that provide them the potential to solve the current energy crisis. Being subject to scientific studies since many years, the aim of this work was the utilization of cheap raw material for their production.
In the present report we used an abundant and easily cultivated energy crop -Sweet Sorghum- to be the main substrate of our experiments. Two different yeasts, Lipomyces starkeyi and Rhodosporidium toruloides, were cultivated in different growing media to show the efficiency of the different experimental conditions. Concerning the yeast R.toruloides after examining both the evolution of sugar and lipids and the number of colonies for each case, the results suggest that two experimental conditions could be presented as the most effective: no additional nitrogen leads to an increase of the lipids of 6.12 g/kg broth with 5.2x10^8colonies of yeast in 117 hours and the addition of nitrogen without enzyme leads to an increase of lipids of 2.57g/kg broth with 9.7x10^8 colonies of yeasts, in 138 hours. Moreover, when no enzymatic saccharification was applied, lipid production decreased to 4.24 g/kg.
On the other hand, the yeast L.starkeyi was not able to grow on sweet sorghum stalks in the presence of the solids.