Heterotrophic Bacteria Enhance the Aggregation of the Marine Picocyanobacteria Prochlorococcus and Synechococcus
Heterotrophic Bacteria Enhance the Aggregation of the Marine Picocyanobacteria Prochlorococcus and Synechococcus
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DOI：
10.3389/fmicb.2019.01864
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发表时间：
2019-08-13
影响因子：
5.2
通讯作者：
Neuer, Susanne
中科院分区：
文献类型：
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作者：
Cruz, Bianca N.;Neuer, Susanne
海洋微蓝细菌是世界海洋中普遍存在的初级生产者，在全球碳循环中发挥着关键作用。最近的证据表明，来自原位调查表明，picocyanobacteria能够下沉的真光区的深度，这在传统上是与较大的，矿物压载细胞。微蓝细菌下沉背后的机制仍然是一个争论点，因为它们太小了，不能自己下沉。为了获得对微蓝细菌在碳输出中的潜在作用的机械理解，我们测试了它们形成“悬浮”（5-60 μ m）和“可见”（约100 μ m）的能力。> 0.1 mm）骨料，以及它们的透明外聚合物颗粒（TEP）的生产-这是海洋骨料形成的关键成分。此外，我们研究了与异养细菌的相互作用是否在原绿球藻和聚球藻中TEP的产生和聚集中起作用，通过比较异生和纯生培养物。我们观察到TEP生产和聚集在无菌聚球藻的分批培养，但不是在无菌原绿球藻。异养细菌增强TEP生产以及悬浮和可见的聚集体形成原绿球藻，而聚球藻，聚集增强TEP没有变化。聚集实验使用的自然浮游生物群落占主导地位的picocyanobacteria导致聚集只有在存在的压载矿物高岭石，只有当聚球藻在其最高的季节性丰度。我们的研究结果指出，两个picocyanobacteria，这可能是介导的异养细菌的相互作用和压舱矿物质的存在下，不同的出口潜力。需要进一步的研究，以澄清的TEP生产和这些picocyanobacteria聚集的细菌的机制作用。
Marine picocyanobacteria are ubiquitous primary producers across the world's oceans, and play a key role in the global carbon cycle. Recent evidence stemming from in situ investigations have shown that picocyanobacteria are able to sink out of the euphotic zone to depth, which has traditionally been associated with larger, mineral ballasted cells. The mechanisms behind the sinking of picocyanobacteria remain a point of contention, given that they are too small to sink on their own. To gain a mechanistic understanding of the potential role of picocyanobacteria in carbon export, we tested their ability to form "suspended" (5-60 mu m) and "visible" (ca. > 0.1 mm) aggregates, as well as their production of transparent exopolymer particles (TEP)-which are a key component in the formation of marine aggregates. Additionally, we investigated if interactions with heterotrophic bacteria play a role in TEP production and aggregation in Prochlorococcus and Synechococcus by comparing xenic and axenic cultures. We observed TEP production and aggregation in batch cultures of axenic Synechococcus, but not in axenic Prochlorococcus. Heterotrophic bacteria enhanced TEP production as well as suspended and visible aggregate formation in Prochlorococcus, while in Synechococcus, aggregation was enhanced with no changes in TEP. Aggregation experiments using a natural plankton community dominated by picocyanobacteria resulted in aggregation only in the presence of the ballasting mineral kaolinite, and only when Synechococcus were in their highest seasonal abundance. Our results point to a different export potential between the two picocyanobacteria, which may be mediated by interactions with heterotrophic bacteria and presence of ballasting minerals. Further studies are needed to clarify the mechanistic role of bacteria in TEP production and aggregation of these picocyanobacteria.