Identity of epibiotic bacteria on symbiontid euglenozoans in O2-depleted marine sediments: evidence for symbiont and host co-evolution
Identity of epibiotic bacteria on symbiontid euglenozoans in O2-depleted marine sediments: evidence for symbiont and host co-evolution
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DOI：
10.1038/ismej.2010.121
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发表时间：
2011-02-01
期刊：
影响因子：
11
通讯作者：
Bernhard, J. M.
中科院分区：
文献类型：
--
作者：
Edgcom, V. P.;Breglia, S. A.;Bernhard, J. M.
一个独特的裸藻动物亚群，被称为“共生体”，已被描述为缺氧和硫化物海洋环境。根据定义，该组的所有成员都携带与宿主表面之下的底层细胞衍生细胞器密切相关的表生体。我们已经使用分子系统发育和超微结构的证据，以确定这组的两个成员，Calkinsia aureus和B.bacati，手工挑选的两个单独的缺氧，硫化物环境的沉积物中的杆状epibiont。我们确定他们的epibionts密切相关的硫或硫化物氧化成员的peproteobacteria。在深海生境中，变形杆菌通常作为初级定居者、初级生产者和/或共生体发挥重要作用。对于这两种不同的宿主来说，附着生物可能在为周围环境解毒方面发挥作用。这两个共生体宿主上几乎相同的杆状附着生物为这两组伙伴之间的共同进化历史提供了证据。这一假设是支持全等树拓扑结构推断从18 S和16 S rDNA的主机和细菌epibionts，分别。真核宿主很可能作为一个能动的基质，将表生体运送到相对于好氧/缺氧界面的理想位置，从而使它们的生长速度最大化，也许还允许宿主培养食物来源。由于共生体分离物和来自该分支的额外的小亚基rDNA基因序列现已从世界各地的许多地方被回收，共生体可能比目前已知的更广泛和多样。The ISME Journal（2011）5，231-243; doi：10.1038/ismej.2010.121; 2010年8月5日在线发表
A distinct subgroup of euglenozoans, referred to as the 'Symbiontida,' has been described from oxygen-depleted and sulfidic marine environments. By definition, all members of this group carry epibionts that are intimately associated with underlying mitochondrion-derived organelles beneath the surface of the hosts. We have used molecular phylogenetic and ultrastructural evidence to identify the rod-shaped epibionts of the two members of this group, Calkinsia aureus and B.bacati, hand-picked from the sediments of two separate oxygen-depleted, sulfidic environments. We identify their epibionts as closely related sulfur or sulfide-oxidizing members of the epsilon proteobacteria. The epsilon proteobacteria generally have a significant role in deep-sea habitats as primary colonizers, primary producers and/or in symbiotic associations. The epibionts likely fulfill a role in detoxifying the immediate surrounding environment for these two different hosts. The nearly identical rod-shaped epibionts on these two symbiontid hosts provides evidence for a co-evolutionary history between these two sets of partners. This hypothesis is supported by congruent tree topologies inferred from 18S and 16S rDNA from the hosts and bacterial epibionts, respectively. The eukaryotic hosts likely serve as a motile substrate that delivers the epibionts to the ideal locations with respect to the oxic/anoxic interface, whereby their growth rates can be maximized, perhaps also allowing the host to cultivate a food source. Because symbiontid isolates and additional small subunit rDNA gene sequences from this clade have now been recovered from many locations worldwide, the Symbiontida are likely more widespread and diverse than presently known. The ISME Journal (2011) 5, 231-243; doi:10.1038/ismej.2010.121; published online 5 August 2010