Poster: Late and Moved Abstracts

Abs # 1392: Correlation between thermal stability of thylakoid membranes and lipid polyunsaturation in Chlorella vulgaris and C. sorokiniana

Presenter:	Becker, David W., dbecker@pomona.edu
Authors	Becker, David W. (A)   Kao, John  (A)
Affiliations:	(A): Department of Biology, Pomona College

We have reported previously that Chlorella sorokiniana demonstrates optimal growth and photosynthetic activities at 38-40°C, while C. vulgaris grows optimally at 25°C and exhibits photosynthetic optima at 30-32°C. We hypothesized that a difference in fatty acid composition of thylakoid membrane lipids in the two algal species could account for the differences in temperature optima, with the high temperature species containing longer and/or a higher level of saturation in its thylakoid membrane lipid fatty acids. We purified thylakoid membranes, extracted, hydrolyzed and methylesterified the lipids, then analyzed them by GC/MS. Surprisingly, we found a higher C18:C16 fatty acid ratio in the higher temperature species. We found no difference in total level of unsaturation between the two species, but the ratio of dienoic to trienoic fatty acids was higher in the thylakoid lipids of the high temperature species. This was due to both increases in 16:2 and 18:2 fatty acid levels and a substantial decrease in 18:3 levels.