AME 74:85-94 (2015)  -  DOI: https://doi.org/10.3354/ame01730

ABSTRACT: Previous studies have shown that viral infection can affect the lipid distribution of phytoplankton, specifically the fatty acid (FA) distribution, and has been hypothesized to affect the nutritional value of phytoplankton for higher trophic levels. Here, we report the bulk FA distribution as well as the FA distribution of individual intact polar lipid (IPL) classes of the alga Phaeocystis globosa infected with the lytic virus PgV-07T. Analysis of the virus PgV-07T itself showed that it contained shorter, more saturated bulk and IPL-bound FAs than the host. Viral infection did not affect the bulk or IPL-bound FA distribution after 24 h post-infection when cell lysis was initiated, but after 48 h the bulk FAs remaining in the particulate phase of the infected cultures contained 22% less polyunsaturated FAs (PUFAs) compared to the control cultures. This change in the bulk FAs was mainly due to the generation of PUFAs that occurred in the control cultures, suggesting that infection prevented P. globosa PUFA accumulation. Two of the 7 IPL classes, the monogalactosyldiacylglycerols and the sulfoquinovosyldiacylglycerols, showed about a 10% reduction in the percentage of PUFAs upon viral infection. In contrast, the digalactosyldiacylglycerols exhibited a 15% increase in PUFAs. This difference between the IPL-PUFAs and the bulk FAs is possibly due to a contribution to the bulk FA pool of e.g. triacylglycerols. Overall, these results suggest that grazing on infected cells and filter feeder uptake of post-lysis cell debris could lead to a transfer of relatively lower amounts of PUFAs to higher trophic levels.

KEY WORDS: Phaeocystis globosa · Virus · Fatty acids · Intact polar lipids