We measured the grazing and growth response of the mixotrophic chrysomonad flagellate Poterioochromonas malhamensis on four closely related picocyanobacterial strains isolated from subalpine lakes in central Europe. The picocyanobacteria represented different pigment types (phycoerythrin-rich, PE, and phycocyanin-rich, PC) and phylogenetic clusters. The grazing experiments were conducted with laboratory cultures acclimated to 10 µmol photon/m²/sec (low light, LL) and 100 µmol photon/m²/sec (moderate light, ML), either in the dark or at four different irradiances ranging from low (6 µmol photon/m²/sec) to high (1,500 µmol photon/m²/sec) light intensity. Poterioochromonas malhamensis preferred the larger, green PC-rich picocyanobacteria to the smaller, red PE-rich picocyanobacterial, and heterotrophic bacteria. The feeding and growth rates of P. malhamensis were sensitive to the actual light conditions during the experiments; the flagellate performed relatively better in the dark and at LL conditions than at high light intensity. In summary, our results found strain-specific ingestion and growth rates of the flagellate; an effect of the preculturing conditions, and, unexpectedly, a direct adverse effect of high light levels. We conclude that this flagellate may avoid exposure to high surface light intensities commonly encountered in temperate lakes during the summer.

中文翻译：

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光会影响混合营养的鞭毛Palerioochromonas malhamensis的微蓝藻放牧和生长反应

我们在欧洲中部亚高山湖泊中分离出的四种紧密相关的微蓝细菌菌株上，测定了混合营养型金眼鞭毛鞭毛波氏嗜铬菌的放牧和生长响应。微型蓝细菌代表不同的色素类型（富含藻红蛋白的PE和富含藻蓝蛋白的PC）和系统发生簇。放牧实验是在黑暗或在四个不同辐照度范围内的实验室培养条件下进行的，培养条件分别为10 µmol光子/ m ² / sec（弱光，LL）和100 µmol光子/ m ² / sec（中等光，ML）。从低（6 µmol光子/ m ² / sec）到高（1,500 µmol光子/ m ² / sec）的光强度。马尔汉姆波罗虫首选较大的绿色，富含PC的微蓝细菌，而不是较小的红色，富含PE的微蓝细菌和异养细菌。实验过程中，对虾的摄食和生长速率对实际光照条件敏感。鞭毛在黑暗和LL条件下的表现要比在高光照强度下好。总而言之，我们的结果发现了鞭毛的特定菌株摄入和生长速率。预培养条件的影响，以及出乎意料的是高光照水平的直接不利影响。我们得出的结论是，这种鞭毛虫可以避免夏季暴露于温带湖泊中常见的高表面光强度下。