Candidatus Izemoplasma, an intermediate in the reductive evolution from Firmicutes to Mollicutes, was proposed to represent a novel class of free-living wall-less bacteria within the phylum Tenericutes. Unfortunately, the paucity of pure cultures has limited further insights into their physiological and metabolic features as well as ecological roles. Here, we report the first successful isolation of an Izemoplasma representative from the deep-sea methane seep, strain zrk13, using a DNA degradation-driven method given Izemoplasma’s prominent DNA-degradation potentials. We further present a detailed description of the physiological, genomic and metabolic traits of the novel strain, which allows for the first time the reconstruction of the metabolic potential and lifestyle of a member of the tentatively defined Candidatus Izemoplasma. On the basis of the description of strain zrk13, the novel species and genus Xianfuyuplasma coldseepsis is proposed. Using a combined biochemical and transcriptomic method, we further show the supplement of organic matter, thiosulfate or bacterial genomic DNA could evidently promote the growth of strain zrk13. In particular, strain zrk13 could degrade and utilize the extracellular DNA for growth in both laboraterial and deep-sea conditions. Moreover, the predicted genes determining DNA-degradation broadly distribute in the genomes of other Izemoplasma members. Given that extracellular DNA is a particularly crucial phosphorus as well as nitrogen and carbon source for microorganisms in the seafloor, Izemoplasma bacteria are thought to be important contributors to the biogeochemical cycling in the deep ocean.

Candidatus Izemoplasma 是从厚壁菌门到软壁菌门还原进化的中间体，被提议代表 Tenericutes 门内一类新的自由生活的无壁细菌。不幸的是，纯培养物的缺乏限制了对其生理和代谢特征以及生态作用的进一步了解。在这里，我们报告了使用 DNA 降解驱动的方法从深海甲烷渗漏中首次成功分离出 Izemoplasma 代表，因为 Izemoplasma 具有突出的 DNA 降解潜力。我们进一步详细描述了新菌株的生理、基因组和代谢特征，这首次允许重建暂时定义的成员的代谢潜力和生活方式Candidatus Izemoplasma。在对菌株zrk13的描述的基础上，发现了新种属的仙府玉原体coldseepsis被提议。使用生化和转录组学相结合的方法，我们进一步表明添加有机物、硫代硫酸盐或细菌基因组DNA可以明显促进菌株zrk13的生长。特别是，菌株 zrk13 可以降解和利用细胞外 DNA 在实验室和深海条件下生长。此外，预测的决定 DNA 降解的基因广泛分布在其他 Izemoplasma 成员的基因组中。鉴于细胞外 DNA 是海底微生物的特别重要的磷源以及氮源和碳源，因此认为 Izemoplasma 细菌是深海生物地球化学循环的重要贡献者。