Morphological changes of Synechococcus in culture as a result
of protist grazer pressure
Edna Fernández Figueroa1 Suzanne Strom2, and Kerri Fredrickson2
1Eckerd College, 2Western Washington University
Do different amounts of nutrient in growth media alter the morphology of Synechococcus?
Synechococcus was grown in SN, SN/10, SN/50 (all made with local seawater), and SN media made with North Pacific open ocean water to evaluate the relationships among media type, growth rate, and morphology of the cyanobacteria. A fluorometer was used to measure changes in biomass over time in the different nutrient treatments. Epi-fluorescence microscopy was used to quantify differences in Synechococcus morphology. Synechococcus grew more readily in media that had low concentrations of nutrients (SN/50). No significant differences in morphology were observed between the different nutrient concentrations.
Do Synechococcus CC9311 change their morphology as a defense mechanism against grazing protists?
Synechococcus cells were exposed to Ochromonas (a mixotrophic flagellate grazer) and to filtrate from an Ochromonas culture to quantify the response of Synechococcus to grazing pressure. We observed the morphological changes in the different treatments and the amount of Synechococcus ingested by the Ochromonas (in order to evaluate the effectiveness of the morphological changes as defense mechanisms) using epi-fluorescence microscopy. The experiment showed a possible correlation between the presence of filtrate and the formation of microcolonies but not enough to draw definite conclusions. (more)