Metagenomic analysis further extends the role of Chloroflexi in fundamental biogeochemical cycles.

Chloroflexi members are ubiquitous and have been extensively studied; however, the evolution and metabolic pathways of Chloroflexi members have long been debated. In the present study, the evolution and the metabolic potentials of 17 newly obtained Chloroflexi metagenome-assembled genomes (MAGs) were evaluated using genome and horizontal gene transfer (HGT) analysis. Taxonomic analysis suggests that the MAGs of the present study might be novel. One MAG encodes genes for anoxygenic phototrophy. The HGT analysis suggest that genes responsible for anoxygenic phototrophy in the MAG might have been transferred from Proteobacteria/Chlorobi. The evolution of anaerobic photosynthesis, which has long been questioned, has now been shown to be the result of HGT events. An incomplete Wood-Ljungdahl pathway (with missing genes metF, acsE, fdh, and acsA) was reported in Dehalococcoidetes members. In the present study, MAGs that were not the Dehalococcoidetes members encode genes acsA, acsB, metF and acsE. The genes responsible for sulfate reduction (sat, cysC and sir), dissimilatory sulfite reductase (dsrA and dsrB), and aerobic and anaerobic carbon monoxide oxidation (coxSML and cooSF) were detected in the present study MAGs. The present study expands our knowledge of the possible metabolic potentials of the phylum Chloroflexi and clarifies the evolution of anaerobic photosynthesis.

Alteribacter salitolerans sp. nov., isolated from a saline-alkaline soil.

A Gram-positive strain APA H-16(1)T was isolated from a saline-alkali soil sample collected from Heilongjiang Province, China. Cells were rod shaped, non-motile, endospore forming, and aerobic. Growth occurred at 10-45 °C (optimum, 35 °C), pH 7.0-10.5 (optimum, pH 9.5), and could tolerate NaCl up to 15.0% (w/v). Strain showed low 16S rRNA gene sequence similarities with Alteribacter natronophilus (97.8%), Alteribacter aurantiacus (97.7%), and Alteribacter populi (97.1%). The cell wall peptidoglycan was meso-diaminopimelic acid. The predominant menaquinone was MK-7. The polar lipid profile consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, unidentified aminophospholipids, unidentified phospholipid, and unidentified lipid. The major fatty acids were anteiso-C15:0, and iso-C15:0. The genomic G + C content was 45.1%. The average nucleotide identity and digital DNA-DNA hybridization values between strain APA H-16(1)T and the most closely related species were below the cut-off level (95-96%; 70%) for species delineation. Based on phenotypic, phylogenetic, chemotaxonomic, and genome comparison, strain APA H-16(1)T represents a novel species of the genus Alteribacter, for which the name Alteribacter salitolerans sp. nov. is proposed. The type strain is APA H-16(1)T (= KCTC 43228T = CICC 25092T).

Diversity and function of rhizosphere microorganisms between wild and cultivated medicinal plant Glycyrrhiza uralensis Fisch under different soil conditions.

Glycyrrhiza uralensis Fisch is a widely cultivated traditional Chinese medicine plant. In the present study, culture-independent microbial diversity analysis and functional prediction of rhizosphere microbes associated with wild and cultivated G. uralensis Fisch plant (collected from two locations) were carried. Soil physicochemical parameters were tested to assess their impact on microbial communities. A total of 4428 OTUs belonging to 41 bacterial phyla were identified. In general, cultivated sample sites were dominated by Actinobacteria whereas wild sample sites were dominated by Proteobacteria. The alpha diversity analysis showed the observed species number was higher in cultivated soil samples when compared with wild soil samples. In beta diversity analysis, it was noticed that the weighted-unifrac distance of two cultivated samples was closer although the samples were collected from different regions. Functional annotation based on PICRUST and FAPROTAX showed that the nitrogen metabolism pathway such as nitrate reduction, nitrogen fixation, nitrite ammonification, and nitrite respiration were more abundant in rhizosphere microorganisms of wild G. uralensis Fisch. These results also correlate in redundancy analysis results which show correlation between NO3--N and wild samples, which indicated that nitrogen nutrition conditions might be related to the quality of G. uralensis Fisch.

Physicochemical and Microbial Diversity Analyses of Indian Hot Springs.

In the present study, physicochemical and microbial diversity analyses of seven Indian hot springs were performed. The temperature at the sample sites ranged from 32 to 67°C, and pH remained neutral to slightly alkaline. pH and temperature influenced microbial diversity. Culture-independent microbial diversity analysis suggested bacteria as the dominant group (99.3%) when compared with the archaeal group (0.7%). Alpha diversity analysis showed that microbial richness decreased with the increase of temperature, and beta diversity analysis showed clustering based on location. A total of 131 strains (divided into 12 genera and four phyla) were isolated from the hot spring samples. Incubation temperatures of 37 and 45°C and T5 medium were more suitable for bacterial isolation. Some of the isolated strains shared low 16S rRNA gene sequence similarity, suggesting that they may be novel bacterial candidates. Some strains produced thermostable enzymes. Dominant microbial communities were found to be different depending on the culture-dependent and culture-independent methods. Such differences could be attributed to the fact that most microbes in the studied samples were not cultivable under laboratory conditions. Culture-dependent and culture-independent microbial diversities suggest that these springs not only harbor novel microbial candidates but also produce thermostable enzymes, and hence, appropriate methods should be developed to isolate the uncultivated microbial taxa.

Nesterenkonia haasae sp. nov., an alkaliphilic actinobacterium isolated from a degraded pasture in Songnen Plain.

An alkaliphilic actinobacterial strain, designated Hz 6-5T, was isolated from saline-alkaline soil from Songnen Plain in north-eastern China. The isolate formed light yellow-colored colonies and its cells were Gram-staining positive, non-motile, and non-spore-forming short rods. The strain was aerobic with optimal growth at 33 °C, pH 9.0, and in the presence of 0.5% (w/v) NaCl or 3% (w/v) KCl. It was catalase-positive and oxidase-negative. The isolate had highest 16S rRNA gene sequence similarities to the type strains of the species Nesternkonia natronophila M8T (98.2%), N. salmonea GY074T (98.1%), and N. sphaerica GY239T (97.4%), and the isolate formed a subclade with the type strains of these species in the neighbor-joining tree based on the 16S rRNA gene sequences. The phylogenetic tree based on the phylogenomic analysis also showed the same results. The DNA‒DNA relatedness (DDH) values of isolate Hz 6-5T with N. natronophila M8T, N. halophila DSM 16378T, and N. halobia CGMCC 1.2323T were 21.2%, 36.5%, and 32.0%, respectively. The characteristic diamino acid of strain Hz 6-5T was found to be lysine. The respiratory quinones were MK-9, MK-8, MK-7(H4), MK-7(H2) and MK-7 and the major cellular fatty acids (> 10%) were anteiso-C15:0, anteiso-C17:0 and iso-C16:0. The polar lipids detected for strain Hz 6-5T were diphosphatidylglycerol, phosphatidylcholine, phosphatidylglycerol, phosphatidylinositol, an unidentified glycolipid, and two unidentified phospholipids. The DNA G + C content of isolate Hz 6-5T was 60.8%. Based on the results of phylogenetic analysis supported by morphological, physiological, chemotaxonomic, and other differentiating phenotypic evidence, strain Hz 6-5T is considered to represent a novel species of the genus Nesterenkonia, for which the name Nesterenkonia haasae sp. nov. is proposed. The type strain is Hz 6-5T (=CPCC 205100T=NBRC 113521T).

Correction to: Description of Paenibacillus yunnanensis sp. nov., Isolated from a Tepid Spring.

It was brought to our attention that the proposed name Paenibacillus yunnanensis is an illegitimate homonym of Paenibacillus yunnanensis Niu et al. 2015. We therefore propose changing the name of the newly proposed species to Paenibacillus tengchongensis as follows.

Description of Paenibacillus yunnanensis sp. nov., Isolated from a Tepid Spring.

A Gram stain-positive, rod-shaped and motile bacterium, designated SYSU G01003T was isolated from a sediment sample collected from tepid spring in Tengchong, Yunnan province, southwestern China. Growth observed at temperature ranging 28-37 °C (optimum 37 °C) and pH 6.0-8.0 (optimum pH 7.0). Tolerance to NaCl was up to 2.5% (w/v) (optimal in the absence of NaCl). The cell wall peptidoglycan is meso-2,6-diaminopimelic acid and MK-7 as the only respiratory quinone. The polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and unidentified aminophospholipid, phospholipid, and polar lipid. The major fatty acids are C16:0, anteiso-C15:0 and C14:0. The genomic DNA G + C content of the type strain was 54.0 mol%. The average nucleotide identity (ANIb and ANIm) values between SYSU G01003T and Paenibacillus azotifigens LMG 29963T were below the cut-off level (95-96%) recommended as the average nucleotide identity (ANI) criterion for interspecies identity. Based on the above results strain SYSU G01003T represents a novel species of the genus Paenibacillus, for which the name Paenibacillus yunnanensis sp. nov. is proposed. The type strain, SYSU G01003T (=KCTC 43132T = CGMCC 1.17384T).

Bacillus tepidiphilus sp. nov., isolated from tepid spring.

A novel Bacillus strain, designated SYSU G01002T, was isolated from a sediment sample collected from tepid spring in Tengchong, Yunnan province, south-west PR China. The 16S rRNA gene sequence analysis showed that the strain SYSU G01002T shared the highest sequence identity with the type strain of Bacillus alkalitolerans (97.7%). Strain SYSU G01002T grew at pH 6.0-8.0 (optimum, pH 7.0), at 28-55 °C (optimum, 45 °C) and in the presence of 0-2.5% (w/v) NaCl (optimum in the absence of NaCl). It contained meso-2,6-diaminopimelic acid as the cell-wall diamino acid and MK-7 as isoprenoid quinone. The major cellular fatty acids were iso-C15:0, iso-C17:0 and C16:0. The polar were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, and unidentified phospholipid. The genomic DNA G + C content was 38.0 mol %. The digital DNA-DNA hybridization and average nucleotide identity values between SYSU G01002T and closely related members of the genus Bacillus were below the cut-off level recommended for interspecies identity. Based on the above results, strain SYSU G01002T represents a novel species of the genus Bacillus, for which the name Bacillus tepidiphilus sp. nov. is proposed. The type strain, 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).

Genome sequence and comparative analysis of DRQ-2, the type strain of Nonomuraea indica.

Strain DRQ-2T (type strain of Nonomuraea indica) is worthy for genome sequencing, due to its ability to produce a wide variety of industrially important enzymes such as amylase, asparaginase, cellulase, gelatinase, glutaminase, and protease. Genome sequencing and comparison of strain DRQ-2T is described in the present work. The genome size was estimated to be 8,288,417 (bp) that consisted of 59 contigs. The G + C content of the genome was 72.4%. A total of 7730 genes were predicted with two rRNAs and 64 tRNAs. The genome analysis of the strain DRQ-2T showed the presence of a wide range of secondary metabolite gene clusters. Pan-Genomes Analysis Pipeline (PGAP) indicated that strain DRQ-2T had large numbers of unique genes. The majority of N. indica DRQ-2T genes encode for hypothetical proteins, indicating the functions of these ortholog clusters were still remain to be determined.

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

A Gram-staining positive, motile, rod-shaped and subterminal endospore-forming bacterium, designated strain SYSU K30005T, was isolated from a soil sample collected from a karst cave in Libo county, Guizhou province, south-western China. Strain SYSU K30005T showed the highest 16S rRNA gene sequence similarity with Lysinibacillus fusiformis (98.6%) and Lysinibacillus sphaericus (98.2%). In phylogenetic tree, strain SYSU K30005T clade with the members of the genus Lysinibacillus. Based on the phylogenetic and 16S gene sequence result, strain SYSU K30005T was affiliated to the genus Lysinibacillus. The growth of SYSU K30005T was observed at 15-37 °C (optimum, 28 °C), pH 6.0-9.0 (optimum, pH 7.0) and in the presence of 0-4% (w/v) NaCl (optimum in 3.5% NaCl). Cell wall peptidoglycan type was A4α (Lys-Asp). The cell-wall sugars of SYSU K30005T were ribose, galactose and mannose and MK-7 was the only quinone. The fatty acids (> 5% of total fatty acids) were iso-C15:0, anteiso-C15:0, iso-C16:0 and iso-C17:0. The polar lipids profile included diphosphatidylglycerol, phosphatideylglycerol, phosphatidylethanolamine and an unidentified phospholipid. The genomic DNA G + C content was 37.2 mol%. The average nucleotide identity values between SYSU K30005T and its closest relatives were below the cut-off level (95-96%) for species delineation. The results support the conclusion that strain SYSU K30005T represents a novel species of the genus Lysinibacillus, for which we proposed the name Lysinibacillus cavernae sp. nov. The type strain is SYSU K30005T (= KCTC 43130T = CGMCC 1.17492T).

Cellulomonas endophytica sp. nov., isolated from Gastrodia elata Blume.

A Gram-stain-positive, facultatively anaerobic and non-motile strain, designated SYSUP0004T, was isolated from the tubers of Gastrodia elata Blume collected from Yunnan Province, PR China. The 16S rRNA gene sequence result showed that the strain SYSUP0004T shared low similarity (97.7 %) with the type strain of Cellulomonas marina. SYSUP0004T grew at pH 6.0-9.0 (optimum, pH 8.0), temperature 4-30 °C (optimum, 28 °C) and could tolerate NaCl up to 4 % w/v (optimum in the absence of NaCl). The cell-wall peptidoglycan type was A4ß with an interpeptide bridge l-ornithine-d-glutamic acid. Cell-wall sugars were mannose, ribose, glucose, galactose and fucose. The menaquinone was MK-9(H4). The major fatty acids were anteiso-C15:0, anteiso-C15 : 1 A, C16 : 0 and anteiso-C17 : 0. The polar lipids of SYSUP0004T were diphosphatidylglycerol, unidentified phosphoglycolipid, phosphatidylinositol mannosides and unidentified glycolipid. The genomic DNA G+C content was 76.5 %. The average nucleotide identity values between SYSUP0004T and members of the genus Cellulomonas were below the cut-off level (95-96 %) recommended as the ANI criterion for interspecies identity. Thus, based on the above results strain SYSUP0004T represents a novel species of the genus Cellulomonas, for which the name Cellulomonas endophytica sp. nov. is proposed. The type strain, SYSUP0004T (=KCTC 49025T=CGMCC 1.16405T).

Vulcaniibacterium gelatinicum sp. nov., a moderately thermophilic bacterium isolated from a hot spring.

The present study aimed to determine the taxonomic positions of strains designated R-5-52-3T, R-5-33-5-1-2, R-5-48-2 and R-5-51-4 isolated from hot spring water samples. Cells of these strains were Gram-stain-negative, non-motile and rod-shaped. The strains shared highest 16S rRNA gene sequence similarity with Vulcaniibacterium thermophilum KCTC 32020T (95.1%). Growth occurred at 28-55 °C, at pH 6-8 and with up to 3 % (w/v) NaCl. DNA fingerprinting, biochemical, phylogenetic and 16S rRNA gene sequence analyses suggested that R-5-52-3T, R-5-33-5-1-2, R-5-48-2 and R-5-51-4 were different strains but belonged to the same species. Hence, R-5-52-3T was chosen for further analysis and R-5-33-5-1-2, R-5-48-2 and R-5-51-4 were considered as additional strains of this species. R-5-52-3T possessed Q-8 as the only quinone and iso-C15:0, iso-C11:0, C16 : 0 and iso-C17 : 0 as major fatty acids. The polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, unidentified polar lipids and two unidentified phospholipids. The genomic G+C content was 71.6 mol%. Heat shock proteins (e.g. Hsp20, GroEL, DnaK and Clp ATPases) were noted in the R-5-52-3T genome, which could suggest its protection in the hot spring environment. Pan-genome analysis showed the number of singleton gene clusters among Vulcaniibacterium members varied. Average nucleotide identity (ANI) values between R-5-52-3T, Vulcaniibacterium tengchongense YIM 77520T and V. thermophilum KCTC 32020T were 80.1-85.8 %, which were below the cut-off level (95-96 %) recommended as the ANI criterion for interspecies identity. Thus, based on the above results, strain R-5-52-3T represents a novel species of the genus Vulcaniibacterium, for which the name Vulcaniibacterium gelatinicum sp. nov. is proposed. The type strain is R-5-52-3T (=KCTC 72061T=CGMCC 1.16678T).

Description of Paenibacillus tepidiphilus sp. nov., isolated from a tepid spring.

China is a hotspot for hot springs and during microbial diversity analysis of Tengchong hot spring, Yunnan province, south-west PR China, two strains designated SYSU G01001T and SY-13 were isolated. SYSU G01001T and SY-13 were Gram-stain-positive, motile and spore-forming. Colonies were white, circular, raised and punctiform. SYSU G01001T and SY-13 grew at pH 6.0-9.0 (optimum pH 8.0) and at 23-37 °C (optimum 28 °C). The 16S rRNA gene sequence similarity between SYSU G01001T and SY-13 was 99.6 % but these strains shared low sequence similarity with Paenibacillus azotifigens (97.5 %) indicating that they represented a novel species. On the basis of the results, SYSU G01001T was selected for further investigations and SY-13 was considered to represent a second strain of the species. The cell wall peptidoglycan of SYSU G01001T was meso-2,6-diaminopimelic acid and MK-7 was the only respiratory quinone. The polar lipids were diphosphatidylglycerol (DPG), phosphatidylglycerol (PG), phosphatidylethanolamine (PE), two unidentified aminolipids (AL), two unidentified amino phospholipids (APL), an unidentified phospholipid (PL) and an unidentified polar lipid (L). The G+C content of the genomic DNA was 53.9 mol%. The average nucleotide identity (ANIb and ANIm) values between SYSU G01001T and Paenibacillus azotifigens LMG 29963T were below the cut-off level (95-96 %) recommended as the average nucleotide identity (ANI) criterion for interspecies identity. On the basis of the above results strain SYSU G01001T represents a novel species of the genus Paenibacillus, for which the name Paenibacillus tepidiphilus sp. nov. is proposed. The type strain is SYSU G01001T (=KCTC 33952T=CGMCC 1.13870T).

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).

Comparative genomics analysis of Nitriliruptoria reveals the genomic differences and salt adaptation strategies.

The group Nitriliruptoria, recently classified as a separate class of phylum Actinobacteria, has five members at present, which belong to halophilic or halotolerant Actinobacteria. Here, we sequenced the genomes of Egicoccus halophilus EGI 80432T and Egibacter rhizosphaerae EGI 80759T, and performed a comparative genomics approach to analyze the genomic differences and salt adaptation mechanisms in Nitriliruptoria. Phylogenetic analysis suggested that Euzebya tangerina F10T has a closer phylogenetic relationship to Euzebya rosea DSW09T, while genomic analysis revealed highest genomic similarity with Nitriliruptor alkaliphilus ANL-iso2T and E. halophilus EGI 80432T. Genomic differences of Nitriliruptoria were mainly observed in genome size, gene contents, and the amounts of gene in per functional categories. Furthermore, our analysis also revealed that Nitriliruptoria possess similar synthesis systems of solutes, such as trehalose, glutamine, glutamate, and proline. On the other hand, each member of Nitriliruptoria species possesses specific mechanisms, K+ influx and efflux, betaine and ectoine synthesis, and compatible solutes transport to survive in various high-salt environments.

Description of Paenibacillus antri sp. nov. and Paenibacillus mesophilus sp. nov., isolated from cave soil.

Two Gram-positive, rod-shaped, motile, endospore-forming strains, SYSU K30003T and SYSU K30004T, were isolated from cave soil sampled in Xingyi County, Guizhou Province, south-west PR China. The 16S rRNA gene sequence results indicated that strains SYSU K30003T and SYSU K30004T had highest sequence similarities to Paenibacillus thermoaerophilus DSM 26310T (93.2 %) and Paenibacillus haemerocallicola KCTC 33185T (97.8 %), respectively. Optimum growth for both strains occurred at pH 7.0 and 37 °C. Both strains contained meso-2,6-diaminopimelic acid in their cell-wall peptidoglycan and MK-7 was the only isoprenoid quinone detected. The polar lipid profile of strain SYSU K30004T consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, two aminophospholipids, an unidentified glycolipid, unidentified phospholipids and two unidentified polar lipids. The polar lipid profile of strain SYSU K30003T contained diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol and an unidentified glycolipid. The major fatty acids (>5 %) of strain SYSU K30003T were anteiso-C15:0, C16 : 0, anteiso-C17 : 0 and iso-C16 : 0, while those of strain SYSU K30004T were anteiso-C15:0, C16:0, anteiso-C17 : 0, iso-C15 : 0, iso-C16:0 and iso-C17 : 0. The genome G+C contents of strains SYSU K30003T and SYSU K30004T were 59.0 and 53.6 mol%, respectively. The average nucleotide identity values between strains SYSU K30003T and SYSU K30004T and other closely related Paenibacillus members were below the cut-off level (95-96 %) for species identification. Based on the results of phenotypic, chemotaxonomic and genome analyses, strains SYSU K30003T and SYSU K30004T represent two novel species of the genus Paenibacillus, for which the names Paenibacillus antri sp. nov. and Paenibacillus mesophilus sp. nov. are proposed. The type strains are SYSU K30003T (=KCTC 33956T=CGMCC 1.13505T) and SYSU K30004T (=KCTC 33957T=CGMCC 1.13872T).

Genomic Insights of "Candidatus Nitrosocaldaceae" Based on Nine New Metagenome-Assembled Genomes, Including "Candidatus Nitrosothermus" Gen Nov. and Two New Species of "Candidatus Nitrosocaldus".

"Candidatus Nitrosocaldaceae" are globally distributed in neutral or slightly alkaline hot springs and geothermally heated soils. Despite their essential role in the nitrogen cycle in high-temperature ecosystems, they remain poorly understood because they have never been isolated in pure culture, and very few genomes are available. In the present study, a metagenomics approach was employed to obtain "Ca. Nitrosocaldaceae" metagenomic-assembled genomes (MAGs) from hot spring samples collected from India and China. Phylogenomic analysis placed these MAGs within "Ca. Nitrosocaldaceae." Average nucleotide identity and average amino acid identity analysis suggested the new MAGs represent two novel species of "Candidatus Nitrosocaldus" and a novel genus, herein proposed as "Candidatus Nitrosothermus." Key genes responsible for chemolithotrophic ammonia oxidation and a thaumarchaeal 3HP/4HB cycle were detected in all MAGs. Furthermore, genes coding for urea degradation were only present in "Ca. Nitrosocaldus," while biosynthesis of the vitamins, biotin, cobalamin, and riboflavin were detected in almost all MAGs. Comparison of "Ca. Nitrosocaldales/Nitrosocaldaceae" with other AOA revealed 526 specific orthogroups. This included genes related to thermal adaptation (cyclic 2,3-diphosphoglycerate, and S-adenosylmethionine decarboxylase), indicating their importance for life at high temperature. In addition, these MAGs acquired genes from members from archaea (Crenarchaeota) and bacteria (Firmicutes), mainly involved in metabolism and stress responses, which might play a role to allow this group to adapt to thermal habitats.

Two novel alkaliphiles, Bacillus alkalisoli sp. nov., and Bacillus solitudinis sp. nov., isolated from saline-alkali soil.

Two alkaliphilic strains, designated FJAT-45086T and FJAT-45122T, were isolated from alkali soli in Nima County, Tibet, China. Both strains were Gram-positive, rod-shaped and shared low 16S rRNA gene sequence similarity with the members of the genus Bacillus. They contained meso-diaminopimelic acid as the cell-wall diamino acid and MK-7 as the menaquinone. The major fatty acids (>5%) of strain FJAT-45086T were anteiso-C15:0, C16:0, iso-C15:0, C16:1ω11c and anteiso-C17:0, whereas strain FJAT-45122T consisted of iso-C15:0, anteiso-C15:0, iso-C17:1ω10c, iso-C17:0, anteiso-C17:0, C16:0 and C16:1ω11c. The genome G + C content of strains FJAT-45086T and FJAT-45122T was 37.8 and 38.2 mol%, respectively. The polar lipids of strain FJAT-45086T were diphosphatidyl glycerol (DPG), phosphatidyl glycerol (PG), phosphatidyl ethanolamine (PE), and phosphatidyl choline (PC), whereas strain FJAT-45122T consisted of DPG, PG, phosphatidyl methyl ethanolamine (PME) and an unidentified aminophospholipids (UAPL). The average nucleotide identity values of strains FJAT-45086T and FJAT-45122T were below the cut-off level (95-96%) for species delineation. Based on the results, strains FJAT-45086T and FJAT-45122T represent two novel species of the genus Bacillus, for which the names Bacillus alkalisoli sp. nov., and Bacillus solitudinis sp. nov., are proposed. The type strain, FJAT-45122T (=DSM 104631T = CCTCC AB 2016254T), FJAT-45086T (=DSM 104056T = CCTCC AB 2016232T).

Genome-based reclassification of Bacillus okuhidensis as a later heterotypic synonym of Bacillus halodurans.

The present study was carried out to clarify the taxonomic relationship between two closely related Bacillus species, Bacillus okuhidensis Li et al. 2002 and Bacillus halodurans (ex Boyer 1973) Nielsen et al. 1995. The maximum-likelihood tree based on the 16S rRNA gene sequence and the phylogenomic tree based on concatenation of 16 protein-marker genes showed that these species were similar. Average nucleotide identity (ANIm 99.25 %, ANIb 98.2 %) and digital DNA-DNA hybridization values (93.5 %) between B. okuhidensis DSM 13666T and B. halodurans DSM 497T were greater than the threshold values for bacterial species delineation, indicating that they belong to the same species. Therefore, B. okuhidensis Li et al. 2002 should be reclassified as a later heterotypic synonym of B. halodurans (ex Boyer 1973) Nielsen et al. 1995.