Ibelings Bas W, Kroon Bernd M A, Mur Luuc R
Laboratory for Microbiology, University of Amsterdam, Nieuwe Achtergracht 127 1018 WS Amsterdam, The Netherlands.
New Phytol. 1994 Nov;128(3):407-424. doi: 10.1111/j.1469-8137.1994.tb02987.x.
Photoacclimation of Scenedesmus protuberans Fritsch and Microcystis aeruginosa Kützing emend. Elenkin to high and fluctuating PPFD was studied in continuous cultures with computer-controlled variable light regimes. The aim of the work was to provide a better understanding of species-specific acclimation to high PPFD (as encountered by cyanobacteria in surface waterblooms), and of suppression of the growth of colony-forming cyanobacteria during periods of prolonged mixing in lakes. The dynamics of a set of variables was followed during the light period, including pigment composition, maximum rate, efficiency and minimum quantum requirement of photosynthesis, PS II cross-sections, and fluorescence variables. Both the green alga and the cyanobacterium displayed strong photo-inhibition of photosynthesis in the sinusoidal light regime, which simulated a natural light regime in the absence of mixing. P , α, QR and the ratio of variable to maximum fluorescence declined, and the number of inactive PS II centres and PS II centres increased towards midday. Introduction of oscillations in the diurnal light regime, simulating different intensities of wind-induced mixing in lakes, mitigated photo-inhibition. Microcystis showed a prompt non-photochemical quenching of fluorescence in all light regimes, even at low to moderate PPFD. The sustained presence of zeaxanthin in Microcystis possibly induced instant, thermal dissipation of excitation energy from the antenna. Microcystis also exhibited a more reluctant acclimation to fluctuating PPFD. Growth rate of Scenedesmus was higher in all light regimes. This implied that if (known) differences in loss processes were ignored, Scenedesmus would outcompete Microcystis in lakes. The results underlined the importance of buoyancy regulation in increasing the daily light dose of cyanobacteria (but at the same time preventing over-excitation), and ultimately in the success in Microcystis in stable lakes.
研究了突出栅藻（Scenedesmus protuberans Fritsch）和铜绿微囊藻（Microcystis aeruginosa Kützing emend. Elenkin）在计算机控制的可变光照条件下的连续培养中对高光强和波动光合有效辐射（PPFD）的光适应情况。这项工作的目的是更好地理解物种对高光强PPFD（如蓝藻在地表水华期间所遇到的情况）的特异性适应，以及湖泊长时间混合期间对形成群体的蓝藻生长的抑制作用。在光照期间跟踪了一组变量的动态变化，包括色素组成、光合作用的最大速率、效率和最小量子需求、PS II截面以及荧光变量。在模拟无混合情况下自然光条件的正弦光照条件下，绿藻和蓝藻均表现出强烈的光合作用光抑制。P、α、QR以及可变荧光与最大荧光的比值下降，中午时分无活性PS II中心和PS II中心的数量增加。在昼夜光照条件中引入振荡，模拟湖泊中风致混合的不同强度，减轻了光抑制。微囊藻在所有光照条件下均表现出迅速的荧光非光化学猝灭，即使在低至中等PPFD时也是如此。微囊藻中持续存在的玉米黄质可能诱导了来自天线的激发能的即时热耗散。微囊藻对波动PPFD的适应也更为迟缓。在所有光照条件下，栅藻的生长速率都更高。这意味着，如果忽略（已知的）损失过程差异，栅藻在湖泊中会比微囊藻更具竞争力。结果强调了浮力调节在增加蓝藻日光照剂量（但同时防止过度激发）以及最终微囊藻在稳定湖泊中成功生存方面的重要性。
