Severin Tatiana, Erdner Deana L
Marine Science Institute, The University of Texas at Austin, Port Aransas, TX, United States.
Front Microbiol. 2019 Mar 11;10:385. doi: 10.3389/fmicb.2019.00385. eCollection 2019.
Phytoplankton strongly interact with their associated bacteria, both attached (PA), and free-living (FL), and bacterial community structures can be specific to phytoplankton species. Similarly, responses to environmental stressors can vary by taxon, as exemplified by observed shifts in phytoplankton community structure from diatoms to phytoflagellates after the Deepwater Horizon (DWH) oil spill. Here, we assess the extent to which associated bacteria influence the phytoplankton taxon-specific oil response by exposing xenic and axenic strains of three phytoplankton species to oil and/or dispersant. The dinoflagellates and , and the diatom sp., all harbored significantly distinct bacterial communities that reflected their host oil response. Oil degrading bacteria were detected in both PA and FL communities of the oil resistant dinoflagellates, but their FL bacteria were more efficient in lipid hydrolysis, a proxy for oil degradation capability. Inversely, the growth rate and photosynthetic parameters of the diatom sp. was the most impacted by dispersed oil compared to the dinoflagellates, and oil-degrading bacteria were not significantly associated to its microbiome, even in the dispersed oil treatment. Moreover, the FL bacteria of did not show significant oil degradation. Yet, the lack of consistent significant differences in growth or photosynthetic parameters between the xenic and axenic cultures after oil exposure suggest that, physiologically, the associated bacteria do not modify the phytoplankton oil response. Instead, both oil resistance and phycosphere composition appear to be species-specific characteristics that are not causally linked. This study explores one aspect of what is undoubtedly a complex suite of interactions between phytoplankton and their associated bacteria; future analyses would benefit from studies of genes and metabolites that mediate algal-bacterial exchanges.
浮游植物与其相关细菌（包括附着细菌和自由生活细菌）之间存在强烈的相互作用，并且细菌群落结构可能因浮游植物种类而异。同样，对环境压力源的反应也可能因分类群而异，例如在深水地平线（DWH）漏油事件后观察到浮游植物群落结构从硅藻向植物鞭毛虫转变。在这里，我们通过将三种浮游植物物种的含菌和无菌菌株暴露于油和/或分散剂中，评估相关细菌对浮游植物分类群特异性油反应的影响程度。甲藻和 ，以及硅藻 属，都拥有明显不同的细菌群落，这些群落反映了它们宿主对油的反应。在抗油甲藻的附着细菌和自由生活细菌群落中都检测到了石油降解细菌，但它们的自由生活细菌在脂质水解方面更有效，脂质水解是石油降解能力的一个指标。相反，与甲藻相比，分散油对硅藻 属的生长速率和光合参数影响最大，即使在分散油处理中，石油降解细菌与其微生物群落也没有显著关联。此外， 的自由生活细菌没有显示出明显的石油降解。然而，油暴露后含菌培养物和无菌培养物在生长或光合参数上缺乏一致的显著差异，这表明从生理上讲，相关细菌不会改变浮游植物对油的反应。相反，抗油性和藻际组成似乎都是物种特异性特征，它们之间没有因果联系。本研究探讨了浮游植物与其相关细菌之间无疑是复杂的一系列相互作用的一个方面；未来的分析将受益于对介导藻类 - 细菌交换的基因和代谢物的研究。
