초록
<P><B>Abstract</B></P> <P>This study investigated the effect of nitrogen (N) and phosphorous (P) stress on the production of DHA or EPA and total fatty acids (TFAs) in the marine microalga <I>Tisochrysis lutea</I> and the freshwater microalga <I>Monodus subterraneus</I>. Five N or P starvation/limitation conditions (N sufficient and P limited, N sufficient and P starved, N starved and P sufficient, N starved and P limited, and N and P starved) and one N and P sufficient condition (control) were studied. The results demonstrated that the proportion of DHA or EPA among TFAs and production in the microalgae suspensions decreased (57%, 73% for N stress and 18%, 51% for P stress, respectively) under N or P stress in both microalgae compared with the N and P sufficient group. Differently, DHA dry weight content of <I>T. lutea</I> decreased significantly, and EPA dry weight content of <I>M. subterraneus</I> decreased slightly under N starved conditions. Clear differences in TFA content/production and the relationship between TFA and DHA or EPA production/content and CO<SUB>2</SUB> fixation were observed between the two microalgae. These results give a new sight on the difference between marine microalgae and freshwater microalgae. Meanwhile, it gave a potential application to produce DHA or EPA and TFA combining with CO<SUB>2</SUB> fixation by these microalgae.</P> <P><B>Highlights</B></P> <P> <UL> <LI> DHA or EPA proportion and production decreased under N or P stress for two microalgae. </LI> <LI> TFA content/production and CO<SUB>2</SUB> fixation of two microalgae were obviously different. </LI> <LI> Potential to mitigate CO<SUB>2</SUB> emission with DHA or EPA production by the two microalgae. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>