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General Session 3: Biological oceanography & global change |
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The availability of energy influences the impact of the use of different N chemical sources on energy partitioning among metabolic processes, in the cyanobacterium Synechococcus sp
GS3-44
Mario Giordano, Department of Life and Environmental Sciences, Universit¨¤ Politecnica delle Marche; Ancona, Italy
Zuoxi Ruan* , Marine Biology Institute, Shantou University, Shantou, China
Presenter Email: run@stu.edu.cn
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| The utilization of different chemical forms has a string impact on the physiology of microalgae. We tested the hypothesis that such influence on metabolism is strongly dependent on the availability of energy. More precisely, we hypothesized that, if light is limiting, the use of N sources that require less energy for their assimilation allows for a greater investment of metabolic energy into processes such as CO2 acquisition (through CO2 concentrating mechanisms, CCM), CO2 fixation and C allocation. We first characterized the biochemical components of the N assimilation pathways in Synechococcus sp. Then, we verified the impact of the N source, in both energy limited and energy sufficient conditions, on CCM activity, photosynthesis and elemental and organic cell stoichiometry. These studies were carried out using classical and state of the art methodologies, such as gas exchange measurements, PAM fluorometry, PSI absorption measurements, Fourier Transform Infrared spectroscopy, Total reflection X-ray fluorescence spectrometry. The results we obtained confirmed our hypothesis and will be discussed in relation to evolutionary and ecological issues. |
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