Cirri Emilio, De Decker Sam, Bilcke Gust, Werner Markus, Osuna-Cruz Cristina Maria, De Veylder Lieven, Vandepoele Klaas, Werz Oliver, Vyverman Wim, Pohnert Georg
Institute of Inorganic and Analytical Chemistry, Friedrich Schiller University Jena, Jena, Germany.
Protistology and Aquatic Ecology, Department of Biology, Ghent University, Ghent, Belgium.
Front Microbiol. 2019 Aug 2;10:1790. doi: 10.3389/fmicb.2019.01790. eCollection 2019.
Diatoms are unicellular algae with a fundamental role in global biogeochemical cycles as major primary producers at the base of aquatic food webs. In recent years, chemical communication between diatoms and associated bacteria has emerged as a key factor in diatom ecology, spurred by conceptual and technological advancements to study the mechanisms underlying these interactions. Here, we use a combination of physiological, transcriptomic, and metabolomic approaches to study the influence of naturally co-existing bacteria, sp. and sp., on the sexual reproduction of the biofilm inhabiting marine pennate diatom . While sp. severely reduces the reproductive success of cultures, sp. slightly enhances it. Contrary to our expectation, we demonstrate that the effect of the bacterial exudates is not caused by altered cell-cycle regulation prior to the switch to meiosis. Instead, sp. exudates cause a reduced production of diproline, the sexual attraction pheromone of . Transcriptomic analyses show that this is likely an indirect consequence of altered intracellular metabolic fluxes in the diatom, especially those related to amino acid biosynthesis, oxidative stress response, and biosynthesis of defense molecules. This study provides the first insights into the influence of bacteria on diatom sexual reproduction and adds a new dimension to the complexity of a still understudied phenomenon in natural diatom populations.
硅藻是单细胞藻类，作为水生食物网底层的主要初级生产者，在全球生物地球化学循环中起着重要作用。近年来，随着研究这些相互作用潜在机制的概念和技术进步，硅藻与相关细菌之间的化学通讯已成为硅藻生态学的关键因素。在这里，我们结合生理学、转录组学和代谢组学方法，研究自然共存的细菌sp.和sp.对栖息于生物膜的海洋羽纹硅藻有性繁殖的影响。虽然sp.严重降低了培养物的繁殖成功率，但sp.则略有提高。与我们的预期相反，我们证明细菌分泌物的影响不是由减数分裂前细胞周期调控的改变引起的。相反，sp.分泌物导致双脯氨酸（的性吸引信息素）产量降低。转录组分析表明，这可能是硅藻细胞内代谢通量改变的间接结果，尤其是那些与氨基酸生物合成、氧化应激反应和防御分子生物合成相关的代谢通量。这项研究首次深入了解了细菌对硅藻有性繁殖的影响，并为自然硅藻种群中一个仍未充分研究的现象的复杂性增添了新的维度。
