Monitoring Yeast Cultures Grown on Corn Stover Hydrolysate for Lipid Production

Microbial oils can be used as an alternative sustainable and renewable feedstock to fossil reserves for producing lubricants and polyurethane materials. Two oleaginous yeasts were grown on non-detoxified corn stover hydrolysate supplemented with corn steep liquor and mineral medium in shake flasks. Trichosporon oleaginosus DSM 11815 displayed the highest lipid production. This strain was further cultivated in a bench bioreactor, using the same culture medium, under a batch regime. Flow cytometry was used to monitor the T. oleaginosus culture using the dual staining technique (SYBR Green and PI) for cell membrane integrity detection. Values of 42.28% (w/w) and 0.06 g/Lh lipid content and lipid productivity, respectively, were recorded for T. oleaginosus cultivated in the bench bioreactor operated under a batch regime. During the cultivation, most of the yeast cells maintained their integrity. T. oleaginosus has the potential to be used as an oil microbial source for a wide range of industrial applications. In addition, it is robust in adverse conditions such as lignocellulosic hydrolysate exposure and oxygen-limiting conditions. Flow cytometry is a powerful and useful tool for monitoring yeast cultivations on lignocellulosic hydrolysates for cell count, size, granularity, and membrane integrity detection.