Mixotrophic algae that combine photoautotrophy with phagotrophy in a single cell are prevalent in marine ecosystems. Here, we assessed the ability of food ingestion in coccolithophores, an important group of calcifying haptophytes inhabiting the oceans. We tested four species from different coccolithophore lineages (Emiliania huxleyi, Calcidiscus leptoporus, Coccolithus braarudii, and Calyptrosphaera sphaeroidea). For both E. huxleyi and C. leptoporus we included different life phases (haploid and diploid). For C. braarudii we only tested diploid heterococcolithophore cells, while for C. sphaeroidea we only tested haploid holococcolithophore cells. Phagotrophy was assessed using fluorescently labeled bacteria (FLB) as model prey item, under nutrient‐replete and phosphate‐limited conditions. We detected by microscopy ingestion of FLB by all species, except the diploid C. braarudii strain. However, a previous study detected ingestion by haploid cells of C. braarudii. These overall results indicate that mixotrophy and the ability to ingest prey is widespread in coccolithophores. Yet, in all tested species the ingestion of FLB was low (<1% of the population contained prey at all time points over 2 days), namely for E. huxleyi and the diploid cells from C. leptoporus where detection of ingestion was sporadic. Moreover, no clear differences were detected between life phases in E. huxleyi and C. leptoporus under equal circumstances, or between replete and limited growth conditions.

中文翻译：

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在营养丰富和磷酸盐受限的生长过程中，检测到球藻藻类的浮游植物（钙足藻科，七足动物）中的营养障碍。

在单个细胞中将光能自养与吞噬能力结合在一起的混养藻类在海洋生态系统中很普遍。在这里，我们评估了食球藻的食物摄取能力，这是居住在海洋中的重要钙化触藻类植物的重要组成部分。我们测试了来自不同球虫科的四个物种（Emiliaania huxleyi，Calcidiscus leptoporus，Coccolithus braarudii和Calyptrosphaera sphaeroidea）。对于这两种E.贺胥和C. leptoporus我们包括不同的生命阶段（单倍体和二倍体）。对于Braarudii，我们仅测试了二倍体异球藻石细胞，而对于C. sphaeroidea我们仅测试了单倍体全石蜡细胞。在营养丰富和磷酸盐限制的条件下，使用荧光标记细菌（FLB）作为模型猎物来评估营养障碍。我们通过显微镜检查了所有物种的FLB摄取，除了二倍体C. braarudii菌株。然而，先前的研究检测到布拉氏梭菌的单倍体细胞摄取。这些总体结果表明，混合营养和吞食猎物的能力广泛存在于球菌科动物中。然而，在所有测试的物种FLB的摄取低（<人口的1％，含有猎物在所有时间点在2天内），即用于E.贺胥和二倍体细胞从C. leptoporus偶尔检测到摄入情况。此外，是在生命阶段之间没有检测到明显的差异E.贺胥和C. leptoporus下等于的情况下，或之间充满和有限的生长条件。