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

Jie Tang,Lian-Ming Du,Meijin Li,Dan Yao,Maurycy Daroch,Krzysztof Waleron,Malgorzata Waleron,Ying Jiang

doi:10.3389/fmicb.2021.739625

Jie Tang, Lian-Ming Du + Show 6 more

Open Access

https://doi.org/10.3389/fmicb.2021.739625

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Abstract

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.

Highlights

Thermophilic cyanobacteria are unique photoautotrophic microorganisms that can survive and thrive in adverse, thermal environments (Elleuche et al, 2015) with optimum growth and metabolic activities at high temperatures with the support of highly stable enzymes (Patel et al, 2019)
52.6% of protein-coding genes were identified as hypothetical proteins (Supplementary Table 2)
This result was similar to other hot-spring cyanobacteria, e.g., Thermosynechococcus elongatus BP-1 (Yasukazu et al, 2002) or T. sichuanensis A183 (Tang et al, 2021)

Summary

Introduction

Thermophilic cyanobacteria are unique photoautotrophic microorganisms that can survive and thrive in adverse, thermal environments (Elleuche et al, 2015) with optimum growth and metabolic activities at high temperatures with the support of highly stable enzymes (Patel et al, 2019) They exhibit considerable biotechnological potential, e.g., CO2 sequestration and production of biofuels, bioactive compounds, and pigments (Liang et al, 2019; Patel et al, 2019). Reports on novel isolates of thermophilic cyanobacteria are scarce Isolating these microrganisms from different ecosystems is crucial for multidisciplinary studies and provides potential strains and genetic sequence data for biotechnology and industrial applications. Isolated strains provide opportunity for indepth study studies to understand the various characteristics, such as morphology, genomics, and adaptation (Cordeiro et al, 2020; Tang et al, 2021)

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