Group for Aquatic Microbial Ecology, Department of Chemistry, Environmental Microbiology and Biotechnology, University of Duisburg-Essengrid.5718.b, Essen, Germany.
Institute of Molecular Genetics, National Research Center Kurchatov Institute, Moscow, Russia.
Appl Environ Microbiol. 2022 May 24;88(10):e0031522. doi: 10.1128/aem.00315-22. Epub 2022 May 2.
Extreme Antarctic conditions provide one of the closest analogues of extraterrestrial environments. Since air and snow samples, especially from polar regions, yield DNA amounts in the lower picogram range, binning of prokaryotic genomes is challenging and renders studying the dispersal of biological entities across these environments difficult. Here, we hypothesized that dispersal of host-associated bacteriophages (adsorbed, replicating, or prophages) across the Antarctic continent can be tracked via their genetic signatures, aiding our understanding of virus and host dispersal across long distances. Phage genome fragments (PGFs) reconstructed from surface snow metagenomes of three Antarctic stations were assigned to four host genomes, mainly , including spp. We reconstructed the complete genome of a temperate phage with nearly complete alignment to a prophage in the reference genome of Ralstonia pickettii 12D. PGFs from different stations were related to each other at the genus level and matched similar hosts. Metagenomic read mapping and nucleotide polymorphism analysis revealed a wide dispersal of highly identical PGFs, 13 of which were detected in seawater from the Western Antarctic Peninsula at a distance of 5,338 km from the snow sampling stations. Our results suggest that host-associated phages, especially of sp., disperse over long distances despite the harsh conditions of the Antarctic continent. Given that 14 phages associated with two draft genomes isolated from space equipment were identified, we conclude that phages are ideal mobile genetic elements to track dispersal and contamination in ecosystems relevant for astrobiology. Host-associated phages of the bacterium identified in snow samples can be used to track microbial dispersal over thousands of kilometers across the Antarctic continent, which functions as an extraterrestrial analogue because of its harsh environmental conditions. Due to the presence of these bacteria carrying genome-integrated prophages on space-related equipment and the potential for dispersal of host-associated phages demonstrated here, our work has implications for planetary protection, a discipline in astrobiology interested in preventing contamination of celestial bodies with alien biomolecules or forms of life.
极端的南极条件提供了最接近外星环境的模拟之一。由于空气和雪样，特别是来自极地地区的，产生的 DNA 量处于微微克范围内，原核基因组的分类是具有挑战性的，这使得研究这些环境中生物实体的扩散变得困难。在这里，我们假设可以通过它们的遗传特征追踪跨越南极大陆的宿主相关噬菌体（吸附、复制或原噬菌体）的扩散，从而帮助我们了解病毒和宿主在长距离上的扩散。从三个南极站的地表雪宏基因组中重建的噬菌体基因组片段（PGF）被分配到四个主要的宿主基因组中，包括 spp. 我们从 Ralstonia pickettii 12D 的参考基因组中重建了一个具有几乎完整比对的温和噬菌体的完整基因组。来自不同站点的 PGF 在属水平上彼此相关，并与相似的宿主相匹配。宏基因组读取映射和核苷酸多态性分析揭示了高度相似的 PGF 的广泛扩散，其中 13 个在距离雪样采样站 5338 公里的西南极半岛的海水中被检测到。我们的结果表明，尽管南极大陆的条件恶劣，但宿主相关的噬菌体，特别是 spp.，会进行长距离扩散。鉴于从太空设备中分离出的两个 草案基因组中发现了 14 种与噬菌体相关的噬菌体，我们得出结论， 噬菌体是追踪在与天体生物学相关的生态系统中扩散和污染的理想移动遗传元件。在雪样中鉴定的与细菌 相关的宿主相关噬菌体可用于追踪数千公里范围内南极大陆的微生物扩散，由于其恶劣的环境条件，它可以作为一个外星模拟。由于这些在与太空相关的设备上携带基因组整合原噬菌体的细菌的存在以及这里展示的宿主相关噬菌体的扩散潜力，我们的工作对天体生物学中感兴趣防止外星生物分子或生命形式污染天体的行星保护具有重要意义。
