Comparative Genomic Analysis of a Novel Strain of Taiwan Hot-Spring Cyanobacterium Thermosynechococcus sp. CL-1

Abstract

<i>Thermosynechococcus</i> is a genus of thermophilic unicellular cyanobacteria that are dominant in microbial mats at about 50-65°C in alkaline hot springs of eastern Asia. We used PacBio SMRT Sequencing to sequence the complete genome of a novel strain of thermophilic cyanobacterium, <i>Thermosynechococcus</i> sp. CL-1, isolated from the Chin-Lun hot spring (pH 9.3, 62°C) in Taiwan. Genome-scale phylogenetic analysis and average nucleotide identity (ANI) results suggested that CL-1 is a new species in the genus <i>Thermosynechococcus</i>. Comparative genome analysis revealed divergent genome structures of <i>Thermosynechococcus</i> strains. In addition, the distinct genetic differences between CL-1 and the other <i>Thermosynechococcus</i> strains are related to photosynthesis, transporters, signal transduction, the chaperone/usher system, nitric oxide protection, antibiotic resistance, prokaryotic immunity systems, and other physiological processes. This study suggests that <i>Thermosynechococcus</i> strains have actively acquired many putative horizontally transferred genes from other bacteria that enabled them to adapt to different ecological niches and stressful conditions in hot springs.