Nitrogen and carbon fixation by Anabaena sp. isolated from a rice paddy and grown under P and light limitations

摘要: Anabaena sp., isolated from a rice paddy, was investigated for its nitrogen fixation as measured by acetylene reduction activity (ARA) in P-limited continuous and light-limited semi-continuous cultures. Growth rate (μ) under P limitation function of cell content (qp). Both the photosynthetic capacity (Pmax) efficiency (α) increased with μ when expressed per cell, but not unit chla. The ARA steady-state cells linearly related to C-fixation rate. This apparently consequence control limitation. In cells, steady state ARA, both at culture light intensity dark, asymptotically μ, dark only about 51% that light. When level grown high switched low level, decreased exponentially time. Dark also showed similar decline, much lower levels. Thus, depended on history, immediate photosynthesis. Steady-state ambient or strong correlation with14C-fixation same light-saturation characteristics their14C-fixation, initial saturation intensity,Ik. ratios Pmax maximum (ARAmax), α slope (αara) were identical. A comparison gross net photosynthesis N2 suggested there little leakage excretion fixed C N.