In their role as primary producers, marine phytoplankton modulate heterotrophic bacterial activities through differences in the types and amounts of organic matter they release. This study investigates the transcriptional response of bacterium Ruegeria pomeroyi, a member of the Roseobacter clade known to affiliate with diverse phytoplankton groups in the ocean, during a shift in phytoplankton taxonomy. The bacterium was initially introduced into a culture of the dinoflagellate Alexandrium tamarense, and then experienced a change in phytoplankton community composition as the diatom Thalassiosira pseudonana gradually outcompeted the dinoflagellate. Samples were taken throughout the 30-day experiment to track shifts in bacterial gene expression informative of metabolic and ecological interactions. Transcriptome data indicate fundamental differences in the exometabolites released by the two phytoplankton. During growth with the dinoflagellate, gene expression patterns indicated that the main sources of carbon and energy for R. pomeroyi were dimethysulfoniopropionate (DMSP), taurine, methylated amines, and polyamines. During growth with the diatom, dihydroxypropanesulfonate (DHPS), xylose, ectoine, and glycolate instead appeared to fuel the bulk of bacterial metabolism. Expression patterns of genes for quorum sensing, gene transfer agent, and motility suggest that bacterial processes related to cell communication and signaling differed depending on which phytoplankton species dominated the co-culture. A remodeling of the R. pomeroyi transcriptome implicating more than a quarter of the genome occurred through the change in phytoplankton regime.
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机译:海洋浮游植物作为主要生产者,通过释放的有机物类型和数量上的差异来调节异养细菌的活动。这项研究调查了浮游生物分类学转变过程中Ruegeria pomeroyi细菌的转录反应,该细菌是玫瑰红细菌进化枝的成员,已知与海洋中多种浮游植物群相关。该细菌最初被引入到鞭毛的鞭毛藻的培养物中,然后随着硅藻Thalassiosira pseudonana逐渐超过鞭毛的藻体,浮游植物群落组成发生了变化。在整个30天的实验过程中均采集了样本,以跟踪细菌基因表达的变化,从而提供有关代谢和生态相互作用的信息。转录组数据表明两种浮游植物释放出的代谢产物的基本差异。在用鞭毛鞭毛藻生长的过程中,基因表达模式表明,波美罗非鱼的主要碳和能量来源是二甲基磺酰丙酸酯(DMSP),牛磺酸,甲基化胺和多胺。在与硅藻一起生长的过程中,二羟基丙烷磺酸盐(DHPS),木糖,ectoine和乙醇酸盐反而助长了细菌的新陈代谢。用于群体感应,基因转移剂和运动性的基因的表达模式表明,与细胞通讯和信号传导有关的细菌过程因共同浮游植物所占主导地位而异。 R. pomeroyi转录组的重塑涉及到超过四分之一的基因组,是通过浮游植物的变化而发生的。
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