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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.)

Two novel species, designated strains SYSU G04041 T and SYSU G04536 T , were isolated from hot spring sediments collected in Yunnan, PR China. Phenotypic and chemotaxonomic analyses, and whole-genome sequencing were used to determine the taxonomic positions of the candidate strains. Phylogenetic analysis using 16S rRNA gene sequence indicated that strain SYSU G04041 T showed the highest sequence similarity to Thermomonas haemolytica A50-7-3 T (97.5 %), and SYSU G04536 T showed the highest sequence similarity to Thermomonas hydrothermalis SGM-6 T (98.2 %). The strains could be differentiated from other species of the genus Thermomonas by their distinct phenotypic and genotypic characteristics. Cells of strains SYSU G04041 T and SYSU G04536 T were aerobic, motile and Gram-stain-negative. Growth both occurred optimally at 45 °C and pH 7.0 for SYSU G04041 T and SYSU G04536 T . In addition, the predominant respiratory quinone in both isolates was ubiquinone Q-8. The major fatty acids (>10 %) of strain SYSU G04041 T were C 16 : 0 , iso-C 15 : 0 and iso-C 16 : 0 , while the major fatty acids (>10 %) of strain SYSU G04536 T were iso-C 15 : 0 and iso-C 16 : 0 . The main detected polar lipids in strains SYSU G04041 T and SYSU G04536 T included phosphatidylethanolamine, diphosphatidylglycerol and phosphatidylglycerol. The G+C contents of the genomic DNA of strains SYSU G04041 T and SYSU G04536 T based on draft genomic sequences were 72.5 and 68.3 %, respectively. On the basis of phenotypic, genotypic and phylogenetic data, strains SYSU G04041 T and SYSU G04536 T represent two novel species of the genus Thermomonas , for which the names Thermomonas flagellata sp. nov. and Thermomonas alba sp. nov. are proposed, with the type strains SYSU G04041 T (=CGMCC 1.19366 T =KCTC 92228 T ) and SYSU G04536 T (=CGMCC 1.19367 T =KCTC 82839 T ), respectively.

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.

Two anaerobic bacteria, designated strains SYSU GA16112 T and SYSU GA16107, were isolated from a hot spring in Tengchong County, Yunnan Province, south-west PR China. Phylogenetic analyses based on 16S rRNA gene sequences showed that strains SYSU GA16112 T and SYSU GA16107 belong to the family Dysgonamonadaceae . Cells of strains SYSU GA16112 T and SYSU GA16107 were Gram-stain-negative, rod-shaped and non-motile. The major fatty acids (>10 %) of strains SYSU GA16112 T and SYSU GA16107 were identified as anteiso-C 15 : 0 and anteiso-C 17 : 0 3OH. The polar lipid profile of strain SYSU GA16112 T was found to consist of phosphatidylethanolamine, two unidentified aminophospholipids, two unidentified phosphoglycolipids, two unidentified aminolipids and one unidentified polar lipid, while that of strain SYSU GA16107 consisted of phosphatidylethanolamine, two unidentified polar lipids, three unidentified aminophospholipids, two unidentified phosphoglycolipids and one unidentified aminolipid. The genomic DNA G+C contents of strains SYSU GA16112 T and SYSU GA16107 were determined to be 41.90 and 41.89 %, respectively, and the average nucleotide identity value between them was 99.99 %. Based on their morphological and physiological properties, and results of phylogenetic analyses, strains SYSU GA16112 T and SYSU GA16107 are considered to represent a novel species of a novel genus, for which the name Seramator thermalis gen. nov., sp. nov. (type strain SYSU GA16112 T =CGMCC 1.5281 T =KCTC 15753 T ) is proposed.

Lignocellulose is considered a major source of renewable energy that serve as an alternative to the fossil fuels. Members of the genus Clostridium are some of the many microorganisms that have the ability to degrade lignocellulose efficiently to sugar, which can be further converted to biofuel. In this study, we isolated twelve Clostridium strains from hot spring samples of Yunnan and Tibet, of which isolates SYSU GA15002 T and SYSU GA17076 showed low 16S rRNA gene sequence identity profiles to any of the validly named Clostridium strains (<94.0%). Studies using a polyphasic taxonomy approach concluded that the two isolates represent one novel species of the genus Clostridium, for which we propose the name Clostridium thermarum sp. nov., with SYSU GA15002 T as the type strain of the species. Isolate SYSU GA15002 T has an optimum growth temperature at 45°C. Fermentation of the substrates cellobiose, cellulose, xylan and untreated straw powder by this strain results in the production of ethanol, along with acetate and formate. The complete pathways for the conversion of cellulose and xylan to ethanol is also predicted from the genome of isolate SYSU GA15002 T , which revealed a single step conversion of lignocellulosic biomass through consolidated bioprocessing. This paper is a comprehensive study encompassing isolation, polyphasic taxonomy, lignocellulose biodegradation and the genomic information of Clostridium in Yunnan-Tibet hot springs., (Copyright © 2020 Elsevier GmbH. All rights reserved.)

Two novel Gram-stain negative, moderately thermophilic, aerobic, rod-shaped strains, designated 3D203 T and 3D207, were isolated from hot spring sediment samples collected from Tibet, western China. Phylogenetic analyses based on 16S rRNA gene sequence similarities showed that two isolates belonged to the genus Microvirga and were most closely related to Microvirga makkahensis SV1470 T (98.5% and 98.4%, respectively) and two strains had 99.8% similarity to each other. The average nucleotide identity (ANI) based on whole genome sequences of two strains and M. makkahensis SV1470 T was 80.8% and 80.78%, respectively. Optimum growth was observed at 45 °C, pH 7.0 and 0.5% NaCl. They both could tolerate to high concentration arsenic. Ubiquinone 10 (Q10) was their predominant quinone. The differences of strains 3D203 T and 3D207 were phosphatidyl dimethyl ethanolamine, phosphatidyl-N-methylethanolamine, phosphatidylglycerol, unidentified glycolipids and unidentified lipids. The major fatty acids (> 5%) were identified C 18:1 ω7c and/or C 18:1 ω6c, C 18:0 and C 16:0 . The genomic DNA G + C contents of strain 3D203 T and 3D207 based on whole genome sequences were 64.8% and 64.7%, respectively. Phenotypic, chemotaxonomic, phylogenetic and genomic analyses suggested that two strains represent a novel species of the genus Microvirga, for which the name Microvirga arsenatis sp. nov. is proposed. The type strain is 3D203 T (= CGMCC 1.17691 T  = KCTC 72653 T ).

A Gram-stain negative, aerobic bacterium, designated strain YIM 78456 T , was isolated from a hot spring sediment, Ngamring county, Tibet, south-west China. The taxonomic position of the isolate was investigated by a polyphasic approach. The novel isolate was found to be aerobic and rod-shaped. Colonies were observed to be pale yellow and circular. The strain was found to grow at pH 7.0-8.0 (optimum, pH 7.0), 45-65 °C (optimum, 55 °C) and in the presence of up to 1.5% NaCl. Comparison of the 16S rRNA gene sequence of strain YIM 78456 T and other members of the genus Thermus showed sequence similarities ranging from 90.3 to 97.3%, with strain YIM 78456 T showing close sequence similarity to Thermus caliditerrae YIM 77925 T (97.3%). The phylogenetic trees based on 16S rRNA gene sequences showed that strain YIM 78456 T forms a distinct clade with T. caliditerrae YIM 77925 T . The predominant menaquinone was identified as MK-8 and the DNA G+C content was determined to be 65.1 mol%. The major cellular fatty acids (> 10%) were identified as iso-C 15:0 , anteiso-C 15:0 and iso-C 17:0 . The polar lipids were found to consist of an aminophospholipid, a phospholipid and glycolipids. On the basis of the morphological and chemotaxonomic characteristics, as well as genotypic data, it is proposed that strain YIM 78456 T represents a novel species of the genus Thermus, for which the name Thermus caldilimi sp. nov. is proposed. The type strain is YIM 78456 T (= KCTC 52948 T  = NBRC 113036 T ).

A novel Gram-stain-positive, obligately anaerobic and thermophilic bacterium, strain SYSU GA15001 T , was isolated from a sample collected from a hot spring located in Tengchong, China. Phylogenetic analysis based on the 16S rRNA gene sequence indicated that strain SYSU GA15001 T belonged to the family Eubacteriaceae, and was closely related to 'Irregularibacter muris' 2PG-426-CC4.2 T (93.6 % similarity), Garciella nitratireducens DSM 15102 T (93.2 %) and Alkalibacter saccharofermentans Z-78920 T (89.7 %). Cells were rods and motile by means of a subpolar flagellum. Spores were formed in old cultures. Optimum growth was observed at 45 °C, at pH 7 and in the presence of 1.5 % (w/v) NaCl. The strain utilized d-arabinose, dulcitol, d-galactose, glucose, lactose, maltose, d-mannose, raffinose, l-rhamnose, d-sorbitol, xylitol, l-alanine, l-arginine, glycine, l-isoleucine, l-leucine, dl-methionine, NH4Cl, l-proline and l-threonine as sole carbon/nitrogen sources. Additionally, complex substrates including beef extract, peptone, starch and yeast extract can also be used as sole energy sources. The major fatty acid methyl esters were C14 : 0, anteiso-C15 : 0 and C18 : 0. The polar lipid profile consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol, an unidentified polar lipid, three unidentified phospholipids and an unidentified glycolipid. The DNA G+C content was determined to be 35.6 mol%. Strain SYSU GA15001 T was physiologically and phylogenetically distinguishable from its closely related genera, and merits assignment as representing the type species of a new genus Rhabdanaerobium, with the name Rhabdanaerobium thermarum gen. nov., sp. nov. The type strain of the type species is SYSU GA15001 T (=CGMCC 1.5219 T =KCTC 15623 T ).