Trichodesmium physiological ecology and phosphate reduction in the western tropical South Pacific
Trichodesmium physiological ecology and phosphate reduction in the western tropical South Pacific
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DOI：
10.5194/bg-15-5761-2018
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发表时间：
2018-10-02
期刊：
影响因子：
4.9
通讯作者：
Dyhrman, Sonya T.
中科院分区：
文献类型：
--
作者：
Frischkorn, Kyle R.;Krupke, Andreas;Dyhrman, Sonya T.
据预测，束毛藻属的N-2固定将支持贫营养海洋的大部分初级生产力，这些海洋被认为是地球上最大的生物群落之一。这些环境中的许多仍然采样不足，限制了我们对这些关键贫营养区的束毛藻生理生态的了解。Trichodesmium菌落，由Trichodesmium宿主及其相关微生物组成的群落，在贫营养的热带西南太平洋（WTSP）收集。这些样品被用来评估主机格拉德分布，主机和微生物组代谢潜力，功能基因表达，重点是确定Trichodesmium生理生态在这个地区。与磷、铁和磷-铁共同限制相关的基因组在整个WTSP样带中动态表达，表明这些资源在驱动该地区束毛藻生理生态方面的重要性。在束毛藻中检测到用于膦酸盐生物合成的基因盒，其表达与束毛藻分支III的丰度共变，所述分支III在该环境中相对于分支I异常丰富。与基因盒的表达相一致，在束毛藻菌落中测量磷酸盐还原为亚磷酸盐和低分子量膦酸盐化合物。还在束毛藻和微生物组中测量了能够使用这种减少磷化合物的基因的表达。总体而言，这些结果突出了在贫营养WTSP的采样不足的区域财团所采用的生理策略，并揭示了先前观察到的高磷还原率在束毛藻菌落的分子机制。
N-2 fixation by the genus Trichodesmium is predicted to support a large proportion of the primary productivity across the oligotrophic oceans, regions that are considered among the largest biomes on Earth. Many of these environments remain poorly sampled, limiting our understanding of Trichodesmium physiological ecology in these critical oligotrophic regions. Trichodesmium colonies, communities that consist of the Trichodesmium host and their associated microbiome, were collected across the oligotrophic western tropical South Pacific (WTSP). These samples were used to assess host Glade distribution, host and microbiome metabolic potential, and functional gene expression, with a focus on identifying Trichodesmium physiological ecology in this region. Genes sets related to phosphorus, iron, and phosphorus-iron co-limitation were dynamically expressed across the WTSP transect, suggestive of the importance of these resources in driving Trichodesmium physiological ecology in this region. A gene cassette for phosphonate biosynthesis was detected in Trichodesmium, the expression of which co-varied with the abundance of Trichodesmium Clade III, which was unusually abundant relative to Clade I in this environment. Coincident with the expression of the gene cassette, phosphate reduction to phosphite and lowmolecular-weight phosphonate compounds was measured in Trichodesmium colonies. The expression of genes that enable use of such reduced-phosphorus compounds were also measured in both Trichodesmium and the microbiome. Overall, these results highlight physiological strategies employed by consortia in an undersampled region of the oligotrophic WTSP and reveal the molecular mechanisms underlying previously observed high rates of phosphorus reduction in Trichodesmium colonies.