Taxonomic Novelty and Distinctive Genomic Features of Hot Spring Cyanobacteria.
Taxonomic Novelty and Distinctive Genomic Features of Hot Spring Cyanobacteria.
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DOI：
10.3389/fgene.2020.568223
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发表时间：
2020
影响因子：
3.7
通讯作者：
Díez B
中科院分区：
文献类型：
--
作者：
Alcorta J;Alarcón-Schumacher T;Salgado O;Díez B
几种蓝藻是温泉微生物垫中占主导地位的初级生产者。到目前为止，温泉蓝藻分类，以及它们的基因组适应高温的演变，知之甚少，目前只有少数优势属，包括Fischerella和Synechococcus的基因组信息。为了解决这一知识差距，本研究扩展了温泉蓝藻的基因组景观，并跟踪高温环境下进化的全门基因组后果。从全球分布的21个温泉宏基因组中，温度在32至75°C之间，回收了57个中等和高质量的蓝藻宏基因组组装基因组，代表1个目，3个科，15个属和36个种的分类学新奇。93个温泉基因组（包括57个宏基因组组装的基因组）和66个非热基因组的比较基因组学表明，前者具有较小的基因组和较高的GC含量，以及较短的蛋白质，更亲水和碱性，当与非热基因组相比时。此外，温泉植物基因组中的核心辅助正群具有丰富的无机离子代谢、翻译和翻译后修饰等功能。此外，温泉基因组中无机离子转运和氨基酸代谢的丰度增加，以及在蛋白质编码序列的复制和转录功能减少。此外，它们对CRISPR-Cas防御系统对外源核酸的依赖性更高，并且次级代谢生物合成基因簇减少。这表明蓝藻对环境特异性微生物群落的反应存在差异。这项全门范围的研究为蓝藻基因组适应它们占主导地位的特定生态位提供了新的见解，这对于在更温暖的世界中追踪细菌进化途径至关重要，例如目前的全球变暖情景。
Several cyanobacterial species are dominant primary producers in hot spring microbial mats. To date, hot spring cyanobacterial taxonomy, as well as the evolution of their genomic adaptations to high temperatures, are poorly understood, with genomic information currently available for only a few dominant genera, including Fischerella and Synechococcus. To address this knowledge gap, the present study expands the genomic landscape of hot spring cyanobacteria and traces the phylum-wide genomic consequences of evolution in high temperature environments. From 21 globally distributed hot spring metagenomes, with temperatures between 32 and 75°C, 57 medium- and high-quality cyanobacterial metagenome-assembled genomes were recovered, representing taxonomic novelty for 1 order, 3 families, 15 genera and 36 species. Comparative genomics of 93 hot spring genomes (including the 57 metagenome-assembled genomes) and 66 non-thermal genomes, showed that the former have smaller genomes and a higher GC content, as well as shorter proteins that are more hydrophilic and basic, when compared to the non-thermal genomes. Additionally, the core accessory orthogroups from the hot spring genomes of some genera had a greater abundance of functional categories, such as inorganic ion metabolism, translation and post-translational modifications. Moreover, hot spring genomes showed increased abundances of inorganic ion transport and amino acid metabolism, as well as less replication and transcription functions in the protein coding sequences. Furthermore, they showed a higher dependence on the CRISPR-Cas defense system against exogenous nucleic acids, and a reduction in secondary metabolism biosynthetic gene clusters. This suggests differences in the cyanobacterial response to environment-specific microbial communities. This phylum-wide study provides new insights into cyanobacterial genomic adaptations to a specific niche where they are dominant, which could be essential to trace bacterial evolution pathways in a warmer world, such as the current global warming scenario.