Data_Sheet_2_Characterization of a Novel Hot-Spring Cyanobacterium Leptodesmis sichuanensis sp. Nov. and Genomic Insights of Molecular Adaptations Into Its Habitat.xlsx

The newly described genus Leptodesmis comprises several strains of filamentous cyanobacteria from diverse, primarily cold, habitats. Here, we sequenced the complete genome of a novel hot-spring strain, Leptodesmis sp. PKUAC-SCTA121 (hereafter A121), isolated from Erdaoqiao hot springs (pH 6.32, 40.8°C), China. The analyses of 16S rRNA/16S-23S ITS phylogenies, secondary structures, and morphology strongly support strain A121 as a new species within Leptodesmis, Leptodesmis sichuanensis sp. nov. Notably, strain A121 is the first thermophilic representative of genus Leptodesmis and more broadly the first Leptodesmis sp. to have its genome sequenced. In addition, results of genome-scale phylogenetic analysis and average nucleotide/amino acid identity as well as in silico DNA-DNA hybridization and patristic analysis verify the establishment of genus Leptodesmis previously cryptic to Phormidesmis. Comparative genomic analyses reveal that the Leptodesmis A121 and Thermoleptolyngbya sichuanensis A183 from the same hot-spring biome exhibit different genome structures but similar functional classifications of protein-coding genes. Although the core molecular components of photosynthesis, metabolism, and signal transduction were shared by the two strains, distinct genes associated with photosynthesis and signal transduction were identified, indicating that different strategies might be used by these strains to adapt to that specific niche. Furthermore, the complete genome of strain A121 provides the first insight into the genomic features of genus Leptodesmis and lays the foundation for future global ecogenomic and geogenomic studies.

新定名的细膜藻属（Leptodesmis）包含数株丝状蓝细菌，分离自多样且主要为寒冷的生境。本研究对一株分离自中国二道桥热泉（pH 6.32，40.8℃）的新型热泉来源菌株细膜藻未定种（Leptodesmis sp.）PKUAC-SCTA121（后文简称A121）的完整基因组进行了测序。通过16S rRNA/16S-23S 内转录间隔区（ITS）系统发育分析、二级结构预测及形态学观察，结果强有力地证实A121菌株为细膜藻属内的一个新种，即四川细膜藻（Leptodesmis sichuanensis sp. nov.）。值得注意的是，A121菌株是细膜藻属内首个嗜热代表菌株，同时也是首个完成全基因组测序的细膜藻属菌株。此外，全基因组规模系统发育分析、平均核苷酸/氨基酸一致性、数字化DNA-DNA杂交（in silico DNA-DNA hybridization）以及支系分析结果证实，此前被归为Phormidesmis属（Phormidesmis）的隐秘类群实则应独立为细膜藻属。比较基因组分析显示，分离自同一热泉生境的A121菌株与四川热细鞘丝藻（Thermoleptolyngbya sichuanensis）A183虽基因组结构存在差异，但编码蛋白基因的功能分类却较为相似。尽管两菌株共享光合作用、代谢以及信号转导的核心分子组分，但二者在与光合作用和信号转导相关的基因上存在显著差异，这表明它们可能采用不同的适应策略以占据该特定生态位。此外，A121菌株的完整基因组首次揭示了细膜藻属的基因组特征，为后续开展全球生态基因组学与地质基因组学研究奠定了基础。