Modification of the interaction betweenEscherichia coli and bacteriophage in saline sediment

The effects of various combinations of light intensity, oxygen concentration, and CO₂ concentration on photosynthesis and growth in several algal types were studied. The results suggest the following. (1) Different algae show different responses to high oxygen concentrations and high light intensities. (2) Inhibition of photosynthesis (CO₂ fixation and growth), if seen, increases with increasing oxygen concentration and with increasing light intensity (at light intensities greater than saturation). (3) The inhibition of net photosynthesis observed cannot be attributed to high light intensity alone. (4) The inhibition cannot be attributed to increased rates of excretion of organic materials under conditions of high oxygen concentration and high light intensity. (5) Increased concentrations of CO₂ can decrease the effect of high oxygen and light in some algae. (6) The decrease in net photosynthesis observed is probably the result of photorespiration. (7) The effect of light intensity, oxygen concentration, or CO₂ concentration on algal photosynthesis should not be studied without considering the effect of the other factors. Some implications of these results, as related to primary productivity measurements, are also discussed.