Two Novel Alkaliphilic Species Isolated from Saline-Alkali Soil in China: Halalkalibacter flavus sp. nov., and Halalkalibacter lacteus sp. nov

The degradation of farmland in China underscores the need for developing and utilizing saline-alkali soil. Soil health relies on microbial activity, which aids in the restoration of the land's ecosystem, and hence it is important to understand microbial diversity. In the present study, two Gram-stain-positive strains HR 1-10T and J-A-003T were isolated from saline-alkali soil. Preliminary analysis suggested that these strains could be a novel species. Therefore, the taxonomic positions of these strains were evaluated using polyphasic analysis. Phylogenetic and 16S rRNA gene sequence analysis indicated that these strains should be assigned to the genus Halalkalibacter. Cell wall contained meso-2,6-diaminopimelic acid. The polar lipids present in both strains were diphosphatidyl-glycerol, phosphatidylglycerol, and an unidentified phospholipid. The major fatty acids (>10%) were anteiso-C15:0, C16:0 and iso-C15:0. Average nucleotide identity and digital DNA#x2013;DNA hybridization values were below the threshold values (95% and 70%, respectively) for species delineation. Based on the above results, the strains represent two novel species of the genus Halalkalibacter, for which the names Halalkalibacter flavus sp. nov., and Halalkalibacter lacteus sp. nov., are proposed. The type strains are HR 1-10T (=GDMCC 1.2946T = MCCC 1K08312T = JCM 36285T), and J-A-003T (=GDMCC 1.2949T = MCCC 1K08417T = JCM 36286T).

Genomic insights of an alkaliphilic bacterium Halalkalibacter alkaliphilus sp. nov. isolated from an Indian Soda Lake

An alkaliphilic, Gram-stain-positive, non-motile, rod-shaped, and spore forming bacterial strain (MEB205^T) was isolated from sediment sample collected from Lonar lake, India. The strain grew optimally at pH 10, NaCl concentration of 3.0% at 37 °C. Phylogenetic analyses based on 16S rRNA gene sequences revealed that strain MEB205^T belonged to the genus Halalkalibacter in the family Bacillaceae and shared the highest sequence similarity with H. okhensis Kh10-101^T (98.9%) followed by H. wakoensis N-1 ^T (98.7%). The assembled genome of strain MEB205^T has a total length of 4.8 Mb with a G + C content of 37.8%. The dDDH and OrthoANI values between strain MEB205^T and H. okhensis Kh10-101 ^T were 29.1% and 84.3%, respectively. Furthermore, the genome analysis revealed the presence of antiporter genes (nhaA and nhaD) and L-ectoine biosynthesis gene required for survival of the strain MEB205^T in alkaline-saline habitat. The major fatty acid was C_15:0 anteiso, C_16:0 and C_15:0 iso (> 10.0%). Diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine were the major polar lipids. meso-diaminopimelic acid was diagnostic diamino acid for cell wall peptidoglycan. Based on the polyphasic taxonomic studies, strain MEB205^T represent a novel species of the genus Halalkalibacter for which the name Halalkalibacter alkaliphilus sp. nov. (Type strain MEB205^T = MCC 3863 ^T = JCM 34004 ^T = NCIMB 15406 ^T) is proposed.

Alkalihalobacterium elongatum gen. nov. sp. nov.: An Antibiotic-Producing Bacterium Isolated From Lonar Lake and Reclassification of the Genus Alkalihalobacillus Into Seven Novel Genera

A Gram-stain positive, long, rod-shaped, motile, and spore-forming bacterium (MEB199^T) was isolated from a sediment sample collected from Lonar Lake, India. The strain was oxidase and catalase positive. The strain grew optimally at pH 10, NaCl concentration of 3.5% at 37°C. The major fatty acids were iso-C_15:0, iso-C_16:0, anteiso-C_15:0, and iso-C_17:0. The peptidoglycan contained meso-diaminopimelic acid (meso-DAP). Phosphatidylethanolamine, diphosphatidylglycerol, and phosphatidylglycerol were the major polar lipids of MEB199^T. Phylogenetic analysis based on 16S rRNA gene sequence showed that strain MEB199^T belonged to the family Bacillaceae and exhibited a distinctive position among the members of the genus Alkalihalobacillus (Ahb.). Strain MEB199^T shared the highest 16S rRNA gene sequence similarity with Alkalihalobacillus alkalinitrilicus ANL-iso4^T (98.36%), whereas with type species Ahb. alcalophilus DSM 485^T, it is 94.91%, indicating that strain MEB199^T is distinctly related to the genus Alkalihalobacillus. The G + C content of genomic DNA was 36.47 mol%. The digital DNA-DNA hybridization (dDDH) (23.6%) and average nucleotide identity (ANI) (81%) values between strain MEB199^T and Ahb. alkalinitrilicus ANL-iso4^T confirmed the novelty of this new species. The pairwise identity based on the 16S rRNA gene sequence between the species of genus Alkalihalobacillus ranges from 87.4 to 99.81% indicating the heterogeneity in the genus. The different phylogenetic analysis based on the genome showed that the members of the genus Alkalihalobacillus separated into eight distinct clades. The intra-clade average amino acid identity (AAI) and percentage of conserved proteins (POCP) range from 52 to 68% and 37 to 59%, respectively, which are interspersed on the intra-genera cutoff values; therefore, we reassess the taxonomy of genus Alkalihalobacillus. The phenotypic analysis also corroborated the differentiation between these clades. Based on the phylogenetic analysis, genomic indices, and phenotypic traits, we propose the reclassification of the genus Alkalihalobacillus into seven new genera for which the names Alkalihalobacterium gen. nov., Halalkalibacterium gen. nov., Halalkalibacter gen. nov., Shouchella gen. nov., Pseudalkalibacillus gen. nov., Alkalicoccobacillus gen. nov., and Alkalihalophilus gen. nov. are proposed and provide an emended description of Alkalihalobacillus sensu stricto. Also, we propose the Ahb. okuhidensis as a heterotypic synonym of Alkalihalobacillus halodurans. Based on the polyphasic taxonomic analysis, strain MEB199^T represents a novel species of newly proposed genus for which the name Alkalihalobacterium elongatum gen. nov. sp. nov. is proposed. The type strain is MEB199^T (= MCC 2982^T, = JCM 33704^T, = NBRC 114256^T, = CGMCC 1.17254^T).

A phylogenomic and comparative genomic framework for resolving the polyphyly of the genus Bacillus: Proposal for six new genera of Bacillus species, Peribacillus gen. nov., Cytobacillus gen. nov., Mesobacillus gen. nov., Neobacillus gen. nov., Metabacillus gen. nov. and Alkalihalobacillus gen. nov

The genus Bacillus, harbouring 293 species/subspecies, constitutes a phylogenetically incoherent group. In the absence of reliable means for grouping known Bacillus species into distinct clades, restricting the placement of new species into this genus has proven difficult. To clarify the evolutionary relationships among Bacillus species, 352 available genome sequences from the family Bacillaceae were used to perform comprehensive phylogenomic and comparative genomic analyses. Four phylogenetic trees were reconstructed based on multiple datasets of proteins including 1172 core Bacillaceae proteins, 87 proteins conserved within the phylum Firmicutes, GyrA-GyrB-RpoB-RpoC proteins, and UvrD-PolA proteins. All trees exhibited nearly identical branching of Bacillus species and consistently displayed six novel monophyletic clades encompassing 5-23 Bacillus species (denoted as the Simplex, Firmus, Jeotgali, Niacini, Fastidiosus and Alcalophilus clades), interspersed with other Bacillaceae species. Species from these clades also generally grouped together in 16S rRNA gene trees. In parallel, our comparative genomic analyses of Bacillus species led to the identification of 36 molecular markers comprising conserved signature indels in protein sequences that are specifically shared by the species from these six observed clades, thus reliably demarcating these clades based on multiple molecular synapomorphies. Based on the strong evidence from multiple lines of investigations supporting the existence of these six distinct 'Bacillus' clades, we propose the transfer of species from these clades into six novel Bacillaceae genera viz. Peribacillus gen. nov., Cytobacillus gen. nov., Mesobacillus gen. nov., Neobacillus gen. nov., Metabacillus gen. nov. and Alkalihalobacillus gen. nov. These results represent an important step towards clarifying the phylogeny/taxonomy of the genus Bacillus.

Desertibacillus haloalkaliphilus gen. nov., sp. nov., isolated from a saline desert

Two Gram-stain-positive, rod-shaped and endospore-forming bacteria that represent a single species, designated strains KJ1-10-99^T and KJ1-10-93, were isolated from a saline desert of Little Rann of Kutch, Gujarat, India. Analysis of 16S rRNA gene sequences revealed that the isolates belonged to the family Bacillaceae and were closely related to each other with 16S rRNA gene sequence similarity of 99.9 %. However, these two isolates formed a novel phylogenetic branch within this family. Both strains were aerobic, catalase and oxidase positive, and could grow optimally at 37 °C and pH 9. Further, strains KJ1-10-99^T and KJ1-10-93 grew optimally at a NaCl concentration of 7.5 and 15 % (w/v), respectively. Both strains shared highest sequence similarity with Fermentibacillus polygoni IEB3^T (96.90 %) followed by Bacillus nanhaiisediminis NH3^T (96.3 %) and Bacillus alkalinitrilicus ANL-iso4^T (96.3 %). The major cellular fatty acids were anteiso-C15 : 0, anteiso-C17:0, C16 : 0, and iso-C15 : 0. The major polar lipids were diphosphatidylglycerol and phosphatidylglycerol in both strains. The predominant isoprenoid quinone was MK-7 in both the strains. The peptidoglycan contained meso-diaminopimelic acid (meso-DAP) as the diagnostic diamino acid. The DNA G+C content of strains KJ1-10-99^T and KJ1-10-93 were 48.7 and 48.9 mol% respectively. Both strains could be distinguished from closest phylogenetic neighbours based on a number of phenotypic properties. On the basis of polyphasic taxonomic analysis and phylogenetic data, we conclude that the strains KJ1-10-99^T (=LMG 29918^T=KCTC 33878^T) and KJ1-10-93 (=LMG 29919=KCTC 33877) represent a novel species of a new genus in the family Bacillaceae, order Bacillales, for which the name Desertibacillus haloalkaliphilus gen. nov., sp. nov. is proposed.

Evolution in the Bacillaceae

The family Bacillaceae constitutes a phenotypically diverse and globally ubiquitous assemblage of bacteria. Investigation into how evolution has shaped, and continues to shape, this family has relied on several widely ranging approaches from classical taxonomy, ecological field studies, and evolution in soil microcosms to genomic-scale phylogenetics, laboratory, and directed evolution experiments. One unifying characteristic of the Bacillaceae , the endospore, poses unique challenges to answering questions regarding both the calculation of evolutionary rates and claims of extreme longevity in ancient environmental samples.

Bacillus daqingensis sp. nov., a halophilic, alkaliphilic bacterium isolated from saline-sodic soil in Daqing, China

An alkaliphilic, moderately halophilic, bacterium, designated strain X10-1(T), was isolated from saline-alkaline soil in Daqing, Heilongjiang Province, China. Strain X10-1(T) was determined to be a Gram-positive aerobe with rod-shaped cells. The isolate was catalase-positive, oxidase-negative, non-motile, and capable of growth at salinities of 0-16% (w/v) NaCl (optimum, 3%). The pH range for growth was 7.5-11.0 (optimum, pH 10.0). The genomic DNA G+C content was 47.7 mol%. Its major isoprenoid quinone was MK-7 and its cellular fatty acid profile mainly consisted of anteiso-C15:0, anteiso-C17:0, iso-C15:0, C16:0, and iso-C16:0. The peptidoglycan contained meso-diaminopimelic acid as the diagnostic diamino acid. The predominant polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, and phosphatidylglycerol. Phylogenetic analysis based on 16S rRNA gene sequences showed that X10-1(T) is a member of the genus Bacillus, being most closely related to B. saliphilus DSM15402(T) (97.8% similarity) and B. agaradhaerens DSM 8721(T) (96.2%). DNA-DNA relatedness to the type strains of these species was less than 40%. On the basis of the phylogenetic, physiological, and biochemical data, strain X10-1(T) represents a novel species of the genus Bacillus, for which the name Bacillus daqingensis sp. nov. is proposed. The type strain is X10-1(T) (=NBRC 109404(T) = CGMCC 1.12295(T)).

Bacillus ligniniphilus sp. nov., an alkaliphilic and halotolerant bacterium isolated from sediments of the South China Sea

An alkaliphilic and halotolerant Gram-stain-positive bacterium, which was isolated from sediment samples from the South China Sea, was subjected to a taxonomic study. The isolate, strain L1T, grew well at a wide range of temperatures and pH values, 10.0-45.0 °C and pH 6-11, with optima at 30 °C and pH 9.0, respectively. The growth of strain L1T occurred at total salt concentrations of 0-10% (w/v) with an optimum at 2% (w/v). Phylogenetic analysis based on 16S rRNA sequence comparison indicated that the isolate represented a member of the genus Bacillus. The strains most closely related to strain L1T were Bacillus nanhaiisediminis JCM 16507T, Bacillus halodurans DSM 497T and Bacillus pseudofirmus DSM 8715T, with 16S rRNA similarities of 96.5%, 95.9% and 95.7%, respectively. DNA-DNA hybridization of strain L1T with the type strains of the most closely related species, B. nanhaiisediminis JCM 16507T, B. halodurans DSM 497T and B. pseudofirmus DSM 8715T, showed reassociation values of about 21.7%, 14.3% and 13.9%, respectively. The DNA G+C content of strain L1T was 40.76 mol%. The predominant isoprenoid quinone was menaquinone 7 (MK-7). The cell-wall peptidoglycan contained meso-diaminopimelic acid as the diagnostic diamino acid. The predominant cellular fatty acids of strain L1T were iso-C14 : 0 and anteiso-C15:0. The major polar lipids were diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylglycerol. Based on the phenotypic and phylogenetic characteristics, it is proposed that strain L1T (=JCM 18543T=DSM 26145T) should be classified as the type strain of Bacillus ligniniphilus sp. nov.

Bacillus luteus sp. nov., isolated from soil

Two bacterial strains (JC167T and JC168) were isolated from a soil sample collected from Mandpam, Tamilnadu, India. Colonies of both strains were orange and cells Gram-stain-positive. Cells were small rods, and formed terminal endospores of ellipsoidal to oval shape. Both strains were positive for catalase, oxidase and hydrolysis of starch/gelatin, and negative for chitin hydrolysis, H2S production, indole production and nitrate reduction activity. Major fatty acids of both strains (>5%) were anteiso-C15:0, iso-C16:0, iso-C15:0, anteiso-C17:0, iso-C14:0 and C16:0 with minor (<5 but >1%) amounts of iso-C17:0, anteiso-C17:0 B/iso-C17:0 I and C16:1ω11c. Diphosphatydilglycerol, phosphatidylethanolamine and phosphatidylglycerol were the major polar lipids of both strains. Cell wall amino acids were L-alanine, D-alanine, D-glutamic acid and meso-diaminopimelic acid. β-Carotene and five unidentified carotenoids were present in both strains. Mean genomic DNA G+C content was 53.4±1 mol% and the two strains were closely related (mean DNA-DNA hybridization>90%). 16S rRNA gene sequence comparisons of both strains indicated that they represent species of the genus Bacillus within the family Bacillaceae of the phylum Firmicutes. Both strains had a sequence similarity of 97.6% with Bacillus saliphilus 6AGT and <96.8% with other members of the genus Bacillus. Sequence similarity between strain JC167T and 168 was 100%. Strain JC167T showed 25.8±1% reassociation (based on DNA-DNA hybridization) with B. saliphilus DSM 15402T (=6AGT). Distinct morphological, physiological and genotypic differences from previously described taxa support the classification of strain JC167T as a representative of a novel species of the genus Bacillus, for which the name Bacillus luteus sp. nov. is proposed. The type strain is JC167T (=KCTC 33100T=LMG 27257T).

Bacillus oceani sp. nov., a new slightly halophilic bacterium, isolated from a deep sea sediment environment

A strictly aerobic, Gram-stain positive, slightly halophilic strain, designated SCSIO 04524(T), was isolated from a deep sea sediment sample collected from the northern South China Sea at a depth of 3415 m. The isolate slightly embedded into the medium after 72 h incubation at 30 °C. Growth was found to occur on media with 0-10 % NaCl but extremely weak growth occurred without supplying NaCl. The predominant menaquinone was determined to be MK-7. The major cellular fatty acid identified was iso-C15:0. The diagnostic polar lipids were determined to be diphosphatidylglycerol, phosphatidyl methylethanolamine, phosphatidylethanolamine and phosphatidylglycerol. The genomic DNA G+C content was determined to be 38 mol%. 16S rRNA gene sequences analysis showed that this strain had the highest similarities with Bacillus carboniphilus JCM 9731(T) (94.7 %) and Bacillus endophyticus 2DT(T) (94.3 %). Phylogenetic analysis revealed that strain SCSIO 04524(T) formed a distinct lineage with Bacillus chungangensis CAU 348(T) and B. carboniphilus JCM 9731(T). Physiological characteristics including utilization of sole nitrogen and carbon sources, and chemotaxonomic properties of cellular fatty acids and polar lipids could readily distinguish strain SCSIO 04524(T) from its most closely related species. Based on this polyphasic taxonomic data, a new species, Bacillus oceani sp. nov., is proposed, with the type strain SCSIO 04524(T) (=DSM 26213(T) = KCTC 33077(T)).

Bacillus daliensis sp. nov., an alkaliphilic, Gram-positive bacterium isolated from a soda lake

A Gram-positive, alkaliphilic bacterium, designated strain DLS13T, was isolated from Dali Lake in Inner Mongolia Autonomous Region, China. The isolate was able to grow at pH 7.5-11.0 (optimum at pH 9), in 0-8 % (w/v) NaCl (optimum at 2 %, w/v) and at 10-45 °C (optimum at 30 °C). Cells of the isolate were facultatively anaerobic, spore-forming rods with peritrichous flagella. The predominant isoprenoid quinone was MK-7 and its cell wall peptidoglycan contained meso-diaminopimelic acid. The major polar lipids consisted of phosphatidylglycerol, diphosphatidylglycerol and phosphatidylethanolamine. The major cellular fatty acids were anteiso-C15:0, anteiso-C17:0 and iso-C15:0. The genomic DNA G+C content of the isolate was 43.9 mol%. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain DLS13T was a member of the genus Bacillus and most closely related to Bacillus saliphilus DSM 15402T (96.9 % similarity). The DNA-DNA relatedness value between strain DLS13T and B. saliphilus DSM 15402T was 38.7±1.9 %. Comparative analysis of genotypic and phenotypic features indicated that strain DLS13T represents a novel species of the genus Bacillus, for which the name Bacillus daliensis sp. nov. is proposed; the type strain is DLS13T (=CGMCC 1.10369T=JCM 17097T=NBRC 107572T).