Lipidomic and transcriptomic analysis of the increase in
eicosapentaenoic acid under cobalamin deficiency of Schizochytrium sp.
Abstract
Schizochytrium sp. is a heterotrophic microorganism capable of
accumulating polyunsaturated fatty acids, and has achieved industrial
production of docosahexaenoic acid (DHA). It also has the potential for
eicosapentaenoic acid (EPA) production. In this study, it was found that
the cell growth, lipid synthesis and fatty acid composition of
Schizochytrium sp. were significantly affected by the level of cobalamin
in the medium, especially with regards to the content of EPA in the
fatty acids. The content of EPA in the fatty acids increased 17.91
times, reaching 12.0%, but cell growth and lipid synthesis were
significantly inhibited under cobalamin deficiency. The response
mechanism for this phenomenon was revealed through combined lipidomic
and transcriptomic analysis. Although cell growth was inhibited under
cobalamin deficiency, the genes encoding key enzymes in central carbon
metabolism were still up-regulated to provide precursors (Acetyl-CoA)
and reducing power (NADPH) for the synthesis and accumulation of fatty
acids. Moreover, the main lipid subclasses observed during cobalamin
deficiency were glycerolipids (including glycerophospholipids), with EPA
primarily distributed in them. The genes involved in the biosynthesis of
these lipid subclasses were significantly up-regulated, such as the key
enzymes in the Kennedy pathway for the synthesis of triglycerides. Thus,
this study provided insights into the specific response of
Schizochytrium sp. to cobalamin deficiency and identified a subset of
new genes that can be engineered for modification.