Williams, E. Z. Texas A&M University, eli@ocean.tamu.edu
Campbell, L. Z. Texas A&M University, lcampbell@ocean.tamu.edu
DiTullio, G. University of Charleston, ditullioj@cofc.edu

Nitrogen uptake of Prochlorococcus under a range of light conditions was investigated. Prochlorococcus isolates from three locations were used: Mediterranean Sea (CCMP 1378), Sargasso Sea (CCMP 1375), and Pacific Ocean (H36-16). Cultures grown on ammonia, urea or nitrate and acclimated to either high (60 uEin/m^2*sec) or low-light (5 uEin/m^2*sec), were starved overnight, spiked with a single nitrogen source, and disappearance of the addition was measured after a two hour incubation period. The Sargasso strain acclimated to high-light and urea nitrogen source had a high initial uptake, alpha [(attomoles-N/cell*hour)/(uEin/m^2*sec)], of 2.84, whereas the ammonia culture of the same strain had a smaller alpha, 0.51. The high-light Mediterranean strain had an alpha of 0.86 for ammonia and 0.17 for urea. The high-light Pacific strain showed the highest alphas with initial ammonia uptake at 2.87, urea at 1.17, and nitrate at 3.51. Photoinhibition was minimal for the high-light acclimated cultures, with the exception of the ammonia uptake in the Pacific strain. The low-light acclimated culture showed similar photoinhibition and lower alphas for all but the ammonia uptake of the Sargasso strain. Uptake differences point to the possibility that Prochlorococcus strains have evolved unique nitrogen preferences.
Day: Thursday, Feb. 4
Time: Poster
Location: Sweeney Center
Code: CS55TH1118S