Phenotypic and Physiological Characterization of the Epibiotic Interaction Between TM7x and Its Basibiont Actinomyces.
Phenotypic and Physiological Characterization of the Epibiotic Interaction Between TM7x and Its Basibiont Actinomyces.
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DOI：
10.1007/s00248-015-0711-7
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发表时间：
2016-01
影响因子：
3.6
通讯作者：
Shi W
中科院分区：
文献类型：
--
作者：
Bor B;Poweleit N;Bois JS;Cen L;Bedree JK;Zhou ZH;Gunsalus RP;Lux R;McLean JS;He X;Shi W
尽管在自然界中有许多专性表生共生（一种生物生活在另一种生物的表面上）的例子，但在两种细菌之间很少观察到这种相互作用。在这里，我们进一步描述了一个新报道的人类口腔专性寄生细菌TM 7 x（原候选门TM 7的栽培成员），和它的basibiont放线菌溶齿菌物种（XH 001）之间的相互作用，提供了一个模型系统，研究在域细菌的表寄生共生。详细的显微镜研究表明，这两个合作伙伴显示广泛的形态变化共生生长过程中。XH 001细胞表现为短杆在单一培养，但显示细长和菌丝形态时，物理与TM 7 x。有趣的是，即使在没有TM 7 x的情况下，XH 001中这些戏剧性的形态变化也在缺氧条件下诱导。靶向qRT-PCR分析显示，与TM 7 x的物理关联以及氧气消耗都触发了XH 001中关键应激反应基因的上调，并且这些条件以相加的方式起作用。TM 7 x和XH 001在营养充足的条件下以相对均匀的细胞形态共存。然而，当营养耗尽时，TM 7 x相关的XH 001显示出多种细胞形态，包括肿胀的细胞体、棒状末端甚至细胞溶解，并且大部分TM 7 x细胞从超小球菌转化为细长细胞。我们的研究表明，一个高度动态的相互作用epibiont TM 7 x和它的basibiont XH 001在响应物理协会或环境线索，如氧气水平和营养状况，反映在共生生长过程中的形态和生理变化。
Despite many examples of obligate epibiotic symbiosis (one organism living on the surface of another) in nature, such an interaction has rarely been observed between two bacteria. Here, we further characterize a newly reported interaction between a human oral obligate parasitic bacterium TM7x (cultivated member of Candidatus Saccharimonas formerly Candidate Phylum TM7), and its basibiont Actinomyces odontolyticus species (XH001), providing a model system to study epiparasitic symbiosis in the domain Bacteria. Detailed microscopic studies indicate that both partners display extensive morphological changes during symbiotic growth. XH001 cells manifested as short rods in monoculture, but displayed elongated and hyphal morphology when physically associated with TM7x. Interestingly, these dramatic morphological changes in XH001 were also induced in oxygen-depleted conditions, even in the absence of TM7x. Targeted qRT-PCR analyses revealed that both the physical association with TM7x as well as oxygen depletion triggered up-regulation of key stress response genes in XH001, and in combination, these conditions act in an additive manner. TM7x and XH001 co-exist with relatively uniform cell morphologies under nutrient-replete conditions. However, upon nutrient depletion, TM7x-associated XH001 displayed a variety of cell morphologies, including swollen cell body, clubbed ends and even cell lysis, and a large portion of TM7x cells transformed from ultrasmall cocci into elongated cells. Our study demonstrates a highly dynamic interaction between epibiont TM7x and its basibiont XH001 in response to physical association or environmental cues such as oxygen level and nutritional status, as reflected by their morphological and physiological changes during symbiotic growth.