Porter J, Jost M
Arch Microbiol. 1976 Nov 2;110(23):225-31. doi: 10.1007/BF00690231.
Physiological evidence was obtained for a light shielding role for gas vacuoles in Microcystis aeruginosa Kuetz. emend. Elenkin, by comparing photosynthetic oxygen evolution, growth behaviour and pigment composition of cells with intact or collapsed gas vacuoles. The oxygen evolution rates were strongly dependent on cell concentration, a maximum rate for cells with intact gas vacuoles occurring at about 1.4 X 10(9) cells/ml and for cells with collapsed gas vacuoles at about 2.5 X 10(9) cells/ml. By using light saturation curves for oxygen evolution, it was estimated that at low light intensities up to 30% of the photosynthetically useable light was shielded at a cell concentration of 6 X 10(8) cells/ml. Collapsing the gas vacuoles twice daily did not alter the initial growth rate of the cultures, but enabled them to reach a higher final cell density. Collapsing of gas vacuoles during growth for about four generations resulted in a lower level of all acetone soluble pigments with a greater relative reduction in carotenoids than in chlorophyll a. Collapse of the gas vacuoles does not alter the cell volume. Various optical interactions which could account for light shielding are discussed.
通过比较具有完整或破裂气泡的铜绿微囊藻细胞的光合放氧、生长行为和色素组成，获得了气泡在铜绿微囊藻中具有遮光作用的生理学证据。放氧速率强烈依赖于细胞浓度，具有完整气泡的细胞的最大放氧速率出现在约1.4×10⁹个细胞/毫升时，而具有破裂气泡的细胞的最大放氧速率出现在约2.5×10⁹个细胞/毫升时。通过使用放氧的光饱和曲线，估计在低光强度下，当细胞浓度为6×10⁸个细胞/毫升时，高达30%的光合可用光被屏蔽。每天使气泡破裂两次不会改变培养物的初始生长速率，但能使它们达到更高的最终细胞密度。在生长过程中使气泡破裂约四代导致所有丙酮可溶性色素水平降低，类胡萝卜素的相对减少幅度大于叶绿素a。气泡破裂不会改变细胞体积。讨论了可能导致遮光的各种光学相互作用。
