Genomic relatedness of T. thermosaccharolyticum GSU5
The draft genome sequence of T. thermosaccharolyticum GSU5 was obtained in 73 contigs with a total length of 2.7 kbases, with a mean G+C content of 33.9 %. Analysis of the genome using the NCBI Prokaryotic Genomes Automatic Annotation Pipeline (PGAAP) revealed 2668 genes, comprising 2501 predicted coding regions, 102 pseudogenes and 65 RNA genes, including one 16S rRNA gene. The RAST annotation covered 339 subsystems, including 44% of the coding sequences, and classified 897 open reading frames (ORFs) as hypothetical proteins.
Comparison of the 16S rRNA gene of GSU5 against sequences deposited in the Ribosomal Database Project revealed that GSU5 clusters together with other strains of Thermoanaerobacterium thermosaccharolyticum and is closest to strain TG57 (Figure 1).
The overall genomic phylogenetic relatedness of strain GSU5 with other strains of the genus Thermoanaerobacterium was analyzed throughin silico genome comparisons. Values obtained by means ofin silico determination of genome to genome distances between GSU5 and all other available Thermoanaerobacterium genomes corroborate that it belongs to the T. thermosaccharolyticumspecies. Values of 87.30%, 76.40%, 75.40 % and 72.10% were obtained when GSU5 was compared with T. thermosaccharolyticum TG57, T.thermosaccharolyticum DSM 571, T. thermosaccharolyticumM5, and T. thermosaccharolyticum M0795 respectively, while the values obtained with all other strains ranged between 26.40 and 24.20% (Table 1). When Average Nucleotide Identity based on BLAST (ANIb) was calculated, the values obtained (96.28 - 98.04%) when GSU5 was compared with other T. thermosaccharolyticum strains provided further evidence that it belongs to this species (Table 1).
Among the 11 Thermoanaerobacterium genomes available, the best represented species is T. thermosaccharolyticum, with five sequenced strains, followed by T. saccharolyticum , with two strains, and a single representative each for T. xylanolyticumand T. aotearoense . The other two genomes correspond to strains RBIITD and PSU2. When the genome of Thermoanaerobacterium sp. RBIITD was compared against all strains of the genusThermoanaerobacterium DDH values ranged between 21.3 and 24.70 % and ANI values ranged between 75.92 and 79.93 % (Table S1). Similar results were obtained for Thermoanaerobacterium sp. PSU2, with DDH values ranging from 21.30 and 58.30 % and ANI values between 76.68 and 94.20 % (Table S2). These results indicate that these strains do not belong to any of the species with sequenced representatives: T. thermosaccharolyticum, T. saccharolyticum, T. xylanolyticum or T. aotearoense .