Effects of Nitrogen Limitation on Dunaliella sp.–Alteromonas sp. Interactions: From Mutualistic to Competitive Relationships
Effects of Nitrogen Limitation on Dunaliella sp.–Alteromonas sp. Interactions: From Mutualistic to Competitive Relationships
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DOI：
10.3389/fmars.2016.00123
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发表时间：
2016-07
影响因子：
3.7
通讯作者：
Myriam Le Chevanton;M. Garnier;E. Lukomska;Nathalie Schreiber;J. Cadoret;B. Saint-Jean;G. Bougaran
中科院分区：
文献类型：
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作者：
Myriam Le Chevanton;M. Garnier;E. Lukomska;Nathalie Schreiber;J. Cadoret;B. Saint-Jean;G. Bougaran
光合微生物和非光合微生物之间的相互作用在自然水生环境中起着至关重要的作用，细菌和微藻对氮循环的贡献可以导致竞争和互利关系。氮与磷和铁一样，被认为是海洋初级生产的主要限制性营养素之一，其可获得性在时间和地理上有很大差异。由于这些原因，重要的是要了解如何光合和异养微生物之间的竞争和互利的相互作用受到氮限制。在先前在分批培养中进行的研究中，添加交替单胞菌属的选定细菌菌株导致绿色盐藻属的最终生物量增加，这是由于较高的氮掺入到藻类细胞中。目前的工作重点是测试的潜力相同的微藻-细菌协会和氮的相互作用在恒化器限制氮。在两种稀释率下比较无菌培养物和混合培养物，以评估氮限制对相互作用的影响。添加细菌导致微藻细胞大小增加，以及碳掺入减少，这是由高氮限制加剧。对微藻、细菌、非生命颗粒物和溶解有机物等不同组分的生化分析表明，细菌从微藻释放的富碳颗粒物中吸收碳。微藻释放的溶解性有机氮显然没有被细菌吸收，这对交替单胞菌在恒化器中溶解性有机氮的生物转化提出了质疑。在较低的氮素限制下，杜氏藻获得铵态氮的效率更高。总的来说，我们揭示了微藻和细菌之间的竞争铵时，这是在连续的，但有限的供应。随着氮素限制的增加，对矿质氮的竞争也增加。从我们的研究中，我们认为，微藻和细菌之间的竞争或互惠关系在很大程度上取决于两种微生物的生理生态状态。自然和人工生态系统中微藻-细菌相互作用的结果在很大程度上取决于环境因素。我们的研究结果表明，需要提高这些微生物球员之间的相互作用的理解。
Interactions between photosynthetic and non-photosynthetic microorganisms play an essential role in natural aquatic environments and the contribution of bacteria and microalgae to the nitrogen cycle can lead to both competitive and mutualistic relationships. Nitrogen is considered to be, with phosphorus and iron, one of the main limiting nutrients for primary production in the oceans and its availability experiences large temporal and geographical variations. For these reasons, it is important to understand how competitive and mutualistic interactions between photosynthetic and heterotrophic microorganisms are impacted by nitrogen limitation. In a previous study performed in batch cultures, the addition of a selected bacterial strain of Alteromonas sp. resulted in a final biomass increase in the green alga Dunaliella sp. as a result of higher nitrogen incorporation into the algal cells. The present work focuses on testing the potential of the same microalgae–bacteria association and nitrogen interactions in chemostats limited by nitrogen. Axenic and mixed cultures were compared at two dilution rates to evaluate the impact of nitrogen limitation on interactions. The addition of bacteria resulted in increased cell size in the microalgae, as well as decreased carbon incorporation, which was exacerbated by high nitrogen limitation. Biochemical analyses for the different components including microalgae, bacteria, non-living particulate matter, and dissolved organic matter, suggested that bacteria uptake carbon from carbon-rich particulate matter released by microalgae. Dissolved organic nitrogen released by microalgae was apparently not taken up by bacteria, which casts doubt on the remineralization of dissolved organic nitrogen by Alteromonas sp. in chemostats. Dunaliella sp. obtained ammonium-nitrogen more efficiently under lower nitrogen limitation. Overall, we revealed competition between microalgae and bacteria for ammonium when this was in continuous but limited supply. Competition for mineral nitrogen increased with nitrogen limitation. From our study we suggest that competitive or mutualistic relationships between microalgae and bacteria largely depend on the ecophysiological status of the two microorganisms. The outcome of microalgae–bacteria interactions in natural and artificial ecosystems largely depends on environmental factors. Our results indicate the need to improve understanding of the interaction/s between these microbial players.