CAS and Shandong Province Key Laboratory of Experimental Marine Biology & Center of Deep Sea Research, Institute of Oceanology, Chinese Academy of Sciences , Qingdao, Shandong, China.
Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology , Qingdao, Shandong, China.
mBio. 2023 Aug 31;14(4):e0095823. doi: 10.1128/mbio.00958-23. Epub 2023 Aug 8.
Wall-less bacteria are broadly distributed in diverse habitats. They evolved from a common ancestor within the phylum through reductive evolution. Here, we report the cultivation, characterization, and polyphasic taxonomic analysis of the novel free-living wall-less bacterium, zrk29. We demonstrated that strain zrk29 had a strong ability to degrade DNA and RNA both under laboratory conditions and in the deep sea. We found that nucleic acids induced strain zrk29 to release chronic bacteriophages which supported strain zrk29 and other marine bacteria to metabolize nucleic acids without lysing host cells. We also showed that strain zrk29 tolerated high hydrostatic pressure via two pathways: (i) by transporting cations into its cells to increase intracellular osmotic pressure and (ii) by adjusting the unsaturated fatty acid chain content in its cell membrane phospholipids to increase cell membrane fluidity. This study extends our understanding of free-living wall-less bacteria and provides a useful model to explore the unique adaptation mechanisms of deep-sea microbes. IMPORTANCE The unique physiology and survival strategies of the bacterium-a typical wall-less bacterium-have fascinated scientists and the public, especially in extreme deep-sea environments where there is high hydrostatic pressure (HHP) and limited availability of nutrients. Here, we have isolated a novel free-living strain from deep-sea sediment and have found that it metabolizes nucleic acids with the support of chronic bacteriophages. This strain tolerates HHP stress by increasing intracellular osmotic pressure and the unsaturated fatty acid chain content of phospholipids in its cell membrane. Our results provide insights into the unique physiology of deep-sea free-living bacteria and highlight the significant role that chronic bacteriophages play in assisting wall-less bacteria to adapt to harsh conditions.
无壁细菌广泛分布于各种生境中。它们通过还原进化从门内的共同祖先中进化而来。在这里，我们报告了新型自由生活无壁细菌 zrk29 的培养、表征和多相分类分析。我们证明，在实验室条件下和深海中，菌株 zrk29 具有很强的降解 DNA 和 RNA 的能力。我们发现，核酸诱导菌株 zrk29 释放慢性噬菌体，这些噬菌体支持菌株 zrk29 和其他海洋细菌在不裂解宿主细胞的情况下代谢核酸。我们还表明，菌株 zrk29 通过两种途径耐受高静压：（i）通过将阳离子运入细胞内增加细胞内渗透压，（ii）通过调整细胞膜磷脂中的不饱和脂肪酸链含量来增加细胞膜流动性。这项研究扩展了我们对自由生活无壁细菌的理解，并为探索深海微生物独特的适应机制提供了有用的模型。
这种细菌是一种典型的无壁细菌，其独特的生理学和生存策略引起了科学家和公众的关注，尤其是在深海环境中，那里存在高静压（HHP）和有限的营养物质。在这里，我们从深海沉积物中分离出一种新型的自由生活菌株，并发现它在慢性噬菌体的支持下代谢核酸。该菌株通过增加细胞内渗透压和细胞膜磷脂中的不饱和脂肪酸链含量来耐受 HHP 应激。我们的研究结果为深海自由生活细菌的独特生理学提供了新的认识，并强调了慢性噬菌体在帮助无壁细菌适应恶劣环境方面的重要作用。
