Phosphate chelation over calcium impacts yeast growth and lipid production from short-chain fatty acids-rich media

Abstract

Some oleaginous yeasts have the ability to produce microbial oils from alternative carbon sources, such as short-chain fatty acids (SCFAs). Nevertheless, there is still a lack of information about the possible effects that media nutrients have on yeast metabolisms when using SCFAs. For instance, inorganic phosphate (PO₄^3-) has been reported to promote yeast growth in literature but its chelating effect over other elements such as calcium (Ca²⁺) is often not considered in fermentation processes while limitation of nitrogen is probably the most studied. Attending at the need to better understand the role of PO₄^3-, this work assessed the lipid production capacity of Yarrowia lipolytica ACA DC 50109, both in synthetic and real SCFAs-rich media, at different SCFAs concentrations and PO₄^3-:Ca²⁺ ratios. Reducing PO₄^3-:Ca²⁺ ratio was identified to be an important factor to improve yeast growth, reaching the highest lipid content (52.7 ± 0.9 % w/w) and lipid yield (0.31 ± 0.01 w/w) in media without PO₄^3-. These results demonstrated the importance of Ca²⁺ availability in the medium and nutrients interactions in yeast growth that are often underestimated.