Description, Taxonomy, and Comparative Genomics of a Novel species, Thermoleptolyngbya sichuanensis sp. nov., Isolated From Hot Springs of Ganzi, Sichuan, China

Abstract

Thermoleptolyngbya is a newly proposed genus of thermophilic cyanobacteria that are often abundant in thermal environments. However, a vast majority of Thermoleptolyngbya strains were not systematically identified, and genomic features of this genus are also sparse. Here, polyphasic approaches were employed to identify a thermophilic strain, PKUAC-SCTA183 (A183 hereafter), isolated from hot spring Erdaoqiao, Ganzi prefecture, China. Whole-genome sequencing of the strain revealed its allocation to Thermoleptolyngbya sp. and genetic adaptations to the hot spring environment. While the results of 16S rRNA were deemed inconclusive, the more comprehensive polyphasic approach encompassing phenetic, chemotaxic, and genomic approaches strongly suggest that a new taxon, Thermoleptolyngbya sichuanensis sp. nov., should be delineated around the A183 strain. The genome-scale phylogeny and average nucleotide/amino-acid identity confirmed the genetic divergence of the A183 strain from other strains of Thermoleptolyngbya along with traditional methods such as 16S-23S ITS and its secondary structure analyses. Comparative genomic and phylogenomic analyses revealed inconsistent genome structures between Thermoleptolyngbya A183 and O-77 strains. Further gene ontology analysis showed that the unique genes of the two strains were distributed in a wide range of functional categories. In addition, analysis of genes related to thermotolerance, signal transduction, and carbon/nitrogen/sulfur assimilation revealed the ability of this strain to adapt to inhospitable niches in hot springs, and these findings were preliminarily confirmed using experimental, cultivation-based approaches.

Genome-Wide Investigation and Analysis of Microsatellites and Compound Microsatellites in Leptolyngbya-like Species, Cyanobacteria

“…However, the results of phylogenetic and ANI analysis may not be convincing as an ultimately taxonomic assignment given to the polyphyletic traits of Leptolyngbya. Recently, polyphasic approaches successfully separated dozens of Leptolyngbya-like strains as new genera from Leptolyngbya sensu stricto [44,45]. Therefore, reevaluation of these Leptolyngbya-like strains is crucial in the future using polyphasic approaches.…”

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

“…The strain was initially denoted and deposited in the Peking University Algae Collection as PKUAC-SCTA121 and has also been deposited in the Freshwater Algae Culture Collection at the Institute of Hydrobiology (FACHB-collection) with accession number FACHB-3319. Cultivation of the strain and basic physiological studies closely follow previously published material (Tang et al, 2021). In short, the strain was grown in BG11 shake-flasks in at 45 • C, 100 rpm, photoperiod 16 L: 8D (45 µmol m −2 s −1 ).…”

“…Microscopic investigations were also conducted using scanning electron microscopy (SEM) (SU8100, HITACHI, Japan) and transmission electron microscopy (TEM) (HT7800, HITACHI, Japan). All microscopic operation was performed following the procedures as described by Tang et al (2021).…”

“…In silico DDH comparison was performed employing the genome-to-genome distance calculator (GGDC 2.0) 2 (Tang et al, 2021) using the recommended BLAST + alignment and formula 2 (identities/HSP length) (Johansen et al, 2011). Patristic distances between and within the Leptodesmis sp.…”

“…Isolating these microrganisms from different ecosystems is crucial for multidisciplinary studies and provides potential strains and genetic sequence data for biotechnology and industrial applications. Further, 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).…”