Taxonomic Reframe of Some Species of the Genera Haloferax and Halobellus.

Haloferax and Halobellus are the representatives of the family Haloferacaceae and they are dominant in hypersaline ecosystems. Some Haloferax and Halobellus species exhibit a close evolutionary relationship. Genomic, phylogenetic (based on 16S rRNA gene sequence), and phylogenomic analysis were performed to evaluate the taxonomic positions of the genera Haloferax and Halobellus. Based on the results we propose to reclassify Halobellus ramosii as a later heterotypic synonym of Halobellus inordinatus; Haloferax lucentense and Haloferax alexandrinum as later heterotypic synonyms of Haloferax volcanii.

Reclassification of Some Exiguobacterium Species Based on Genome Analysis.

The Exiguobacterium genus comprises Gram-stain-positive and facultatively anaerobic bacteria. Some Exiguobacterium species have previously shown significant high 16S rRNA gene sequence similarities with each other. This study evaluates the taxonomic classification of those Exiguobacterium species through comprehensive genome analysis. Average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values were determined for various Exiguobacterium species pairs. The ANI and dDDH values between Exiguobacterium enclense and Exiguobacterium indicum, Exiguobacterium aquaticum and Exiguobacterium mexicanum, Exiguobacterium soli and Exiguobacterium antarcticum, and Exiguobacterium sibiricum and Exiguobacterium artemiae were above the cut-off level (95-96% for ANI and 70% for dDDH) for species delineation. Based on the findings, we propose to reclassify Exiguobacterium enclense as a later heterotypic synonym of Exiguobacterium indicum, Exiguobacterium aquaticum as a later heterotypic synonym of Exiguobacterium mexicanum, Exiguobacterium soli as a later heterotypic synonym of Exiguobacterium antarcticum and Exiguobacterium sibiricum as a later heterotypic synonym of Exiguobacterium artemiae.

Proposal to transfer Bacillus massiliigorillae to the genus Peribacillus as Peribacillus massiliigorillae comb. nov., and Bacillus sinesaloumensis to the genus Ferdinandcohnia as Ferdinandcohnia sinesaloumensis comb. nov.

The present study was carried out to clarify the taxonomic position of Bacillus massiliigorillae and Bacillus sinesaloumensis. The 16S rRNA gene sequences extracted from the Bacillus sinesaloumensis Marseille-P3516T (FTOX00000000) and Bacillus massiliigorillae G2T (CAVL000000000) genomes showed 98.5 and 99.1% similarity with the type strains of Ferdinandcohnia humi and Peribacillus endoradicis, respectively. The amino acid identity (AAI) values of Bacillus sinesaloumensis Marseille-P3516T were higher with Ferdinandcohnia members, while Bacillus massiliigorillae G2T with Peribacillus members. In phylogenomic and phylogenetic trees, Bacillus sinesaloumensis Marseille-P3516T and Bacillus massiliigorillae G2T clade with members of the genera Ferdinandcohnia and Peribacillus, respectively. Based on the above results, we propose to transfer Bacillus massiliigorillae to the genus Peribacillus as Peribacillus massiliigorillae comb. nov., and Bacillus sinesaloumensis to the genus Ferdinandcohnia as Ferdinandcohnia sinesaloumensis comb. nov.

Proposal to transfer Bacillus dafuensis and Bacillus massiliigabonensis to the genus Cytobacillus as Cytobacillus dafuensis comb. nov., and Cytobacillus massiliigabonensis comb. nov., respectively.

In the present study, the taxonomic position of Bacillus dafuensis and Bacillus massiliigabonensis was evaluated using genome-based comparison. The 16S rRNA gene sequence obtained from the Bacillus dafuensis FJAT-25496T genome showed 99.7% similarity with the type strain of Cytobacillus citreus, while Bacillus massiliigabonensis Marseille-P2639T showed 98.7% similarity with the type species of Cytobacillus solani. The 16S rRNA gene sequence similarity of Bacillus dafuensis FJAT-25496T and Bacillus massiliigabonensis Marseille-P2639T with Cytobacillus members was above the threshold (94.5%) for genus delineation. In phylogenetic (based on 16S rRNA gene sequences) and phylogenomic (based on 71 bacterial single-copy genes) trees, Bacillus dafuensis and Bacillus massiliigabonensis clustered with Cytobacillus members. The 16S rRNA gene sequence, amino acid identity and percentage of conserved proteins analysis indicated Bacillus dafuensis FJAT-25496T and Bacillus massiliigabonensis Marseille-P2639T as a member of the genus Cytobacillus. The digital DNA-DNA hybridization and the average nucleotide identity values of Bacillus dafuensis FJAT-25496T and Bacillus massiliigabonensis Marseille-P2639T with Cytobacillus members was below the cut-off value (70/94%-95%) for species delineation. Based on the results we propose to transfer Bacillus dafuensis and Bacillus massiliigabonensis to the genus Cytobacillus as Cytobacillus dafuensis comb. nov., and Cytobacillus massiliigabonensis comb. nov., respectively.

Transfer of Bacillus tepidiphilus Narsing Rao et al. 2021 to the genus Peribacillus as Peribacillus tepidiphilus comb. nov.

In the present study, the taxonomic position of Bacillus tepidiphilus was re-evaluated. Bacillus tepidiphilus (B. tepidiphilus) SYSU G01002T showed the highest 16S rRNA gene sequence similarity with the type strain Peribacillus alkalitolerans (P. alkalitolerans) (97.7%). In the phylogenetic (based on 16S rRNA sequence) and phylogenomic (based on 71 bacterial single-copy genes) trees, B. tepidiphilus SYSU G01002T clade with the members of the genus Peribacillus. The amino acid identity (AAI) value of B. tepidiphilus SYSU G01002T was highest with P. alkalitolerans KCTC 33631T (73.6%). The AAI value between B. tepidiphilus SYSU G01002T and P. alkalitolerans KCTC 33631T was above the cutoff level for genus delineation. The average nucleotide identity (ANI) between B. tepidiphilus and P. alkalitolerans KCTC 33631T was 74.1%, which was below the ANI value (95-96%) for species delineation. Based on the phylogenetic, phylogenomic, AAI, and ANI analysis, Bacillus tepidiphilus is proposed to transfer to the genus Peribacillus as Peribacillus tepidiphilus comb. nov. The type strain is SYSU G01002T (= KCTC 43131T = CGMCC 1.17491T).

Lysinibacillus antri sp. nov., isolated from cave soil.

A Gram-stain-positive, motile, rod-shaped and endospore-forming strain, SYSU K30002T, was isolated from a soil sample collected from a karst cave in Xingyi county, Guizhou province, south-west China. SYSU K30002T grew at 28-40 °C (optimum, 37 °C), at pH 5.0-8.0 (optimum, pH 7.0) and in the presence of 0-4 % (w/v) NaCl (optimum in the absence of NaCl). The cell-wall peptidoglycan type was A4α (Lys-Asp). The cell-wall sugars of SYSU K30002T were ribose, galactose and mannose, and MK-7 was the menaquinone. The major fatty acids were iso-C15 : 0, C16 : 1 ω7c alcohol and iso-C16 : 0. The polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and two unidentified phospholipids. The G+C content of the genomic DNA was 36.1 mol%. The average nucleotide identity values between SYSU K30002T and its closest relatives were below the cut-off level (95-96 %) for species delineation. Based on phenotypic, chemotaxonomic and genome comparisons, strain SYSU K30002T represents a novel species of the genus Lysinibacillus, for which the name Lysinibacillusantri sp. nov. is proposed. The type strain is SYSU K30002T (=KCTC 33955T=CGMCC 1.13504T).

Amycolatopsis alkalitolerans sp. nov., isolated from Gastrodia elata Blume.

A Gram-staining positive and nonmotile strain designated SYSUP0005T was isolated from tubers of Gastrodia elata Blume. The 16S rRNA gene sequence result showed that strain SYSUP0005T shared highest sequence similarity with the type strain of Amycolatopsis cappadoca (95.7%), Amycolatopsis taiwanensis (95.4%), Amycolatopsis pigmentata (95.4%), Amycolatopsis ruanii (95.1%), and Amycolatopsis helveola (94.8%). Growth occurs at 14-37 °C (optimum temperature, 28 °C), at pH 6-9 (optimum, pH 8) and in the presence of up to 6% (w/v) NaCl. Strain SYSUP0005T had meso-diaminopimelic acid in its peptidoglycan. The whole cell sugars were galactose, ribose, and xylose. The predominant menaquinone was MK-9(H4) and minor menaquinones were MK-9(H2) and MK-9(H8). The polar lipids were diphosphatidylglycerol (DPG); phosphatidylmonomethylethanolamine (PME), phosphatidylethanolamine (PE), phosphatidylinositol (PI), unidentified glycolipid (GL), and unidentified phospholipid (PL). The genomic DNA G + C content was 69.6 mol%. The major fatty acids were iso-C16:0, anteiso-C17:0, C16:0, iso-C14:0, C17:1 ω6c, C17:0, and Summed Feature 3 (C16:1 ω7c/C16:1 ω6c). On the basis of the phenotypic, phylogenetic, chemotaxonomic characters, and genomic comparison, SYSUP0005T represents a novel species of the genus Amycolatopsis, for which the name Amycolatopsis alkalitolerans sp. nov. is proposed. The type strain is SYSUP0005T (=KCTC 49024T = CGMCC4.7463T).