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A novel actinomycete, designated strain q2 T , was isolated from the saline-alkaline soil, collected from Daqing, Heilongjiang province, China. The results of phylogenetic analysis based on the 16S rRNA gene sequences indicated that strain q2 T belongs to the genus Isoptericola, and showed the highest sequence similarity to Isoptericola halotolerans KCTC 19046 T (98.48%) and Isoptericola chiayiensis KCTC 19740 T (98.13%), respectively. The average nucleotide identity values between strain q2 T and other members of the genus Isoptericola were lower than 95% recommended for distinguishing novel prokaryotic species. Cells of strain q2 T were Gram-staining-positive, aerobic, non-motile, rod-shaped and non-spore-forming. Colonies of strain q2 T were golden-yellow pigmented, tidy edged and smooth surfaced. Growth occurred at 15-37 °C (optimum, 29 °C), pH 7.0-10.0 (optimum, pH 8.0). The predominant respiratory quinones were MK-9(H 4 ) and MK-9(H 2 ). The main detected polar lipids consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol, and phosphatidylinositol mannoside. The peptidoglycan compositions were L-alanine, D-aspartic, L-glutamic acid and L-lysine (type A4α). The major cellular fatty acids (> 10%) were anteiso-C 15:0 , iso-C 15:0 , and anteiso-C 17:0 . The G+C content of the genomic DNA was determined to be 69.7%. Based on the phenotypic, physiological, genotypic, and phylogenetic data, strain q2 T represents a novel species of the genus Isoptericola, for which the name Isoptericola croceus sp. nov. is proposed. The type strain is q2 T (= GDMCC 1.2923 T  = KCTC 49759 T )., (© 2023. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

A thermophilic bacterium, designated strain SYSU G04325 T , was isolated from a hot spring sediment in Yunnan, China. Polyphasic taxonomic analyses and whole-genome sequencing were used to determine the taxonomic position of the strain. Phylogenetic analysis using 16S rRNA gene sequences indicated that strain SYSU G04325 T shows high sequence similarity to Thermoflexibacter ruber NBRC 16677 T (86.2%). The strain can be differentiated from other species of the family Thermoflexibacteraceae by its distinct phenotypic and genotypic characteristics. Cells of the strain SYSU G04325 T were observed to be aerobic, Gram-stain negative and filamentous. Growth was found to occur optimally at 45 ºC and pH 7.0. In addition, the respiratory quinone was identified as menaquinone-7, while the major fatty acids (> 10%) were identified as iso-C 15:0 , iso-C 17:0 and Summed Feature 9 (iso-C 17:1 ω9c). The polar lipids detected included phosphatidylethanolamine, three unidentified phospholipids, one unidentified glycolipid, five unidentified aminolipids and four unidentified polar lipids. The G + C content of the genomic DNA was determined to be 47.6% based on the draft genome sequence. On the basis of phenotypic, genotypic and phylogenetic data, strain SYSU G04325 T is concluded to represent a novel species of a novel genus in the family Thermoflexibacteraceae, for which the name Rhodoflexus caldus gen. nov., sp. nov. is proposed. The type strain of Rhodoflexus caldus is SYSU G04325 T (= MCCC 1K06127 T  = KCTC 82848 T )., (© 2022. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Phylogenomic analyses were performed on the nine species of the genus Meiothermus and four species of the genus Calidithermus. Phylogenetic analysis, low values of genomic relatedness indices and functional diversity analysis indicated that Meiothermus silvanus should not be classified within the clades for Meiothermus and Calidithermus but instead be reclassified as a new genus, for which we propose the name Allomeiothermus gen. nov., with Allomeiothermus silvanus comb. nov. as type species. In addition, the species Meiothermus cateniformans Zhang et al. (Int J Syst Evol Microbial 60:840-844, 2010) should also be reclassified as a later heterotypic synonym of Meiothermus taiwanensis Chen et al. (Int J Syst Evol Microbiol 52:1647-1654, 2002) emend. Raposo et al. (2019). This reclassification is based on the high genomic relatedness indices (98.8% ANI; 90.2% dDDH; 99% AAI) that are above the threshold values necessary for defining a new species, as well as on the observation of overlapping functions on Principal Coordinate Analysis plot generated from Clusters of Orthologous Genes., (© 2022. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Two bacterial strains SYSU G02173 T and SYSU G03142 were isolated from hot springs in Tibet, China. Based on the results of nearly full-length 16S rRNA gene sequences and phylogenetic analyses, strains SYSU G02173 T and SYSU G03142 were assigned to the family Sphingosinicellaceae, and were closest to Sandaracinobacter sibiricus RB16-17  T (96.04% and 96.12% similarity, respectively). Cells of the both new strains were observed to be motile rod-shape, Gram-staining negative. Growth occurred at pH 6-8 (optimal: pH 7.0) and 37-55 °C (optimal: 45 °C) with 0-1.0% (w/v) NaCl in T4 broth. The cells were found to be positive for oxidase and catalase activities. The major respiratory ubiquinone was Q-8. The major fatty acids were identified as summed feature 8 (C 18:1 ω7c and/or C 18:1 ω6c), C 16:0 , C 14:0 2-OH. The major polar lipids were found to consist of sphingoglycolipid, phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, one unidentified phospholipid, one unidentified glycolipid, three unidentified aminolipids and two unidentified polar lipids. The DNA G + C contents of strains SYSU G02173 T and SYSU G03142 were 71.8%. The average nucleotide identity (ANI) value between strain SYSU G02173 T and SYSU G03142 was 99.98%. The amino acid identity (AAI) values between them and their closely related species were below 66.14%. The isolates are characterized by aerobic growth, a yellow endocellular pigment and a higher optimum growth temperature. The results showed that strains SYSU G02173 T and SYSU G03142 represent a novel species of a novel genus in the family Sphingomonadaceae, and thus the name Thermaurantiacus tibetensis (type strain SYSU G02173 T  = KCTC 72052  T  = CGMCC 1.16680  T ) is proposed.