High cell density cultivation of Lipomyces starkeyi for achieving highly efficient lipid production from sugar under low C/N ratio

Oleaginous microorganisms such as oleaginous yeasts are well known for the ability to accumulate intracelular lipid more than 20% w/w in certain conditions. Lipomyces starkeyi D35 (Ls-D35 strain) is one of promising oleaginous yeast for lipid production. The purpose of this research is to establish the optimum condition for cell and lipid production of Ls-D35 strain under low C/N ratio (17.9) by high cell density cultivation. The optimum pH for cell and lipid production was achieved at pH 5 by using batch cultivation. Four different feeding strategies were conducted to observe the cell and lipid production of Ls-D35 strain. The highest cell yield was achieved by mixed glucose and xylose as substrates (0.15 w/w substrate) after 96 h and the highest lipid yield was achieved by single xylose feeding (0.13 w/w substrate) after 120 h. Meanwhile, the two most fatty acids content were C18:1 and C16:0 which are similar to the content of vegetable oil. These results showed that Ls-D35 strain could produce high cell and optimum lipid under low initial C/N ratio medium which can be an alternative for biodiesel production and other industrial products.