Department of Molecular Genetics and Microbiology, Pontificia Universidad Católica de Chilegrid.7870.8, Santiago, Chile.
Department of Physiology, Genetics, and Microbiology, University of Alicante, Alicante, Spain.
Microbiol Spectr. 2021 Dec 22;9(3):e0069421. doi: 10.1128/Spectrum.00694-21. Epub 2021 Nov 17.
Viruses exert diverse ecosystem impacts by controlling their host community through lytic predator-prey dynamics. However, the mechanisms by which lysogenic viruses influence their host-microbial community are less clear. In hot springs, lysogeny is considered an active lifestyle, yet it has not been systematically studied in all habitats, with phototrophic microbial mats (PMMs) being particularly not studied. We carried out viral metagenomics following mitomycin C induction experiments in PMMs from Porcelana hot spring (Northern Patagonia, Chile). The compositional changes of viral communities at two different sites were analyzed at the genomic and gene levels. Furthermore, the presence of integrated prophage sequences in environmental metagenome-assembled genomes from published Porcelana PMM metagenomes was analyzed. Our results suggest that virus-specific replicative cycles (lytic and lysogenic) were associated with specific host taxa with different metabolic capacities. One of the most abundant lytic viral groups corresponded to cyanophages, which would infect the cyanobacteria , the most active and dominant primary producer in thermophilic PMMs. Likewise, lysogenic viruses were related exclusively to chemoheterotrophic bacteria from the phyla , , and . These temperate viruses possess accessory genes to sense or control stress-related processes in their hosts, such as sporulation and biofilm formation. Taken together, these observations suggest a nexus between the ecological role of the host (metabolism) and the type of viral lifestyle in thermophilic PMMs. This has direct implications in viral ecology, where the lysogenic-lytic switch is determined by nutrient abundance and microbial density but also by the metabolism type that prevails in the host community. Hot springs harbor microbial communities dominated by a limited variety of microorganisms and, as such, have become a model for studying community ecology and understanding how biotic and abiotic interactions shape their structure. Viruses in hot springs are shown to be ubiquitous, numerous, and active components of these communities. However, lytic and lysogenic viral communities of thermophilic phototrophic microbial mats (PMMs) remain largely unexplored. In this work, we use the power of viral metagenomics to reveal changes in the viral community following a mitomycin C induction experiment in PMMs. The importance of our research is that it will improve our understanding of viral lifestyles in PMMs via exploring the differences in the composition of natural and induced viral communities at the genome and gene levels. This novel information will contribute to deciphering which biotic and abiotic factors may control the transitions between lytic and lysogenic cycles in these extreme environments.
病毒通过裂解性捕食者-猎物动态来控制其宿主群落，从而对生态系统产生多种影响。然而，溶原病毒影响其宿主微生物群落的机制尚不清楚。在温泉中，溶原性被认为是一种活跃的生活方式，但它尚未在所有栖息地中得到系统研究，特别是在光养微生物席（PMM）中尚未得到研究。我们在智利北部巴塔哥尼亚的 Porcelana 温泉的 PMM 中进行了丝裂霉素 C 诱导实验后的病毒宏基因组学研究。我们在基因组和基因水平上分析了两个不同地点的病毒群落组成变化。此外，还分析了已发表的 Porcelana PMM 宏基因组中环境宏基因组组装基因组中整合的前噬菌体序列的存在。我们的研究结果表明，病毒特异性复制周期（裂解和溶原）与具有不同代谢能力的特定宿主分类群相关。最丰富的裂解病毒群之一对应于蓝藻噬菌体，它们将感染蓝细菌，这是嗜热 PMM 中最活跃和占主导地位的初级生产者。同样，溶原病毒仅与门、和的化能异养细菌有关。这些温和噬菌体具有感应或控制宿主中与应激相关过程的辅助基因，例如孢子形成和生物膜形成。总之，这些观察结果表明，在嗜热 PMM 中，宿主的生态角色（代谢）和病毒生活方式类型之间存在联系。这对病毒生态学具有直接影响，其中溶原-裂解开关由营养物质丰度和微生物密度决定，但也由宿主群落中占主导地位的代谢类型决定。温泉中栖息的微生物群落主要由有限种类的微生物组成，因此已成为研究群落生态学和了解生物和非生物相互作用如何塑造其结构的模型。研究表明，温泉中的病毒是这些群落中普遍存在的、大量的和活跃的组成部分。然而，嗜热光养微生物席（PMM）的裂解和溶原病毒群落仍在很大程度上未被探索。在这项工作中，我们使用病毒宏基因组学的力量，通过在 PMM 中进行丝裂霉素 C 诱导实验，揭示病毒群落的变化。我们的研究的重要性在于，它将通过在基因组和基因水平上探索自然和诱导病毒群落组成的差异，提高我们对 PMM 中病毒生活方式的理解。这些新信息将有助于破译哪些生物和非生物因素可能控制这些极端环境中裂解和溶原周期之间的转变。
