期刊
LIMNOLOGY AND OCEANOGRAPHY
卷 58, 期 4, 页码 1501-1512出版社
WILEY
DOI: 10.4319/lo.2013.58.4.1501
关键词
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资金
- National Science Foundation (NSF), Division of Ocean Sciences (OCE) [0942379, 0962309, 1043748]
- NSF [OCE 0850730]
- Directorate For Geosciences
- Division Of Ocean Sciences [962309] Funding Source: National Science Foundation
- Directorate For Geosciences
- Office of Polar Programs (OPP) [1043748] Funding Source: National Science Foundation
We describe interactive effects of total phosphorus (total P = 0.1-4.0 mu mol L-1; added as H2NaPO4), irradiance (40 and 150 mu mol quanta m(-2) s(-1)), and the partial pressure of carbon dioxide (P-CO2; 19 and 81 Pa, i.e., 190 and 800 ppm) on growth and CO2- and dinitrogen (N-2)-fixation rates of the unicellular N-2-fixing cyanobacterium Crocosphaera watsonii (WH0003) isolated from the Pacific Ocean near Hawaii. In semicontinuous cultures of C. watsonii, elevated P-CO2 positively affected growth and CO2- and N-2-fixation rates under high light. Under low light, elevated P-CO2 positively affected growth rates at all concentrations of P, but CO2- and N-2-fixation rates were affected by elevated P-CO2 only when P was low. In both high-light and low-light cultures, the total P requirements for growth and CO2- and N-2-fixation declined as P-CO2 increased. The minimum concentration (C-min) of total P and half-saturation constant (K-1/2) for growth and CO2- and N-2-fixation rates with respect to total P were reduced by 0.05 mu mol L-1 as a function of elevated P-CO2. We speculate that low P requirements under high P-CO2 resulted from a lower energy demand associated with carbon-concentrating mechanisms in comparison with low-P-CO2 cultures. There was also a 0.10 mu mol L-1 increase in C-min and K-1/2 for growth and N-2 fixation with respect to total P as a function of increasing light regardless of P-CO2 concentration. We speculate that cellular P concentrations are responsible for this shift through biodilution of cellular P and possibly cellular P uptake systems as a function of increasing light. Changing concentrations of P, CO2, and light have both positive and negative interactive effects on growth and CO2-, and N-2-fixation rates of unicellular oxygenic diazotrophs like C. watsonii.
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