Cytobacillus citreus sp. nov., isolated from citrus rhizosphere soil

A Gram-stain-positive, rod-shaped and motile strain, designated FJAT-49705^T, was isolated from the citrus rhizosphere soil sample. Strain FJAT-49705^T grew at 20-40 °C (optimum, 30 °C) and pH 6.0-11.0 (optimum, pH 7.0) with 0-5 % (w/v) NaCl (optimum, 2 %). Strain FJAT-49705^T showed high 16S rRNA gene sequence similarity to 'Bacillus dafuensis' FJAT-25496^T (99.7 %) and Cytobacillus solani FJAT-18043^T (98.0 %). In phylogenetic (based on 16S rRNA gene sequences) and phylogenomic trees (based on 71 bacterial single-copy genes), strain FJAT-49705^T clustered with the members of the genus Cytobacillus. MK-7 was the only isoprenoid quinone present. The main polar lipids were diphosphatidylglycerol, phosphatidylethanolamine and an unidentified phospholipid. The major fatty acids were anteiso-C_15 : 0 and iso-C_15 : 0. The genomic DNA G+C content was 36.9 %. The average nucleotide identity (ANI) values between FJAT-49705^T and 'B. dafuensis' FJAT-25496^T and C. solani FJAT-18043^T were below the cut-off level (95-96 %) recommended as the ANI criterion for interspecies identity. Based on the above results, strain FJAT-49705^T represents a novel species of the genus Cytobacillus, for which the name Cytobacillus citreus sp. nov. is proposed. The type strain is FJAT-49705^T (=CCTCC AB 2019243^T= LMG 31580^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.

Oryzisolibacter propanilivorax gen. nov., sp. nov., a propanil-degrading bacterium

Strain EPL6^T, a Gram-negative, motile, short rod was isolated from a propanil and 3,4-dichloroaniline enrichment culture produced from rice paddy soil. Based on the analyses of the 16S rRNA gene sequence, strain EPL6^T was observed to be a member of the family Comamonadaceae, sharing the highest pairwise identity with type strains of the species Alicycliphilus denitrificans K601^T (96.8 %) and Melaminivora alkalimesophila CY1^T (96.8 %). Strain EPL6^T was able to grow in a temperature range of 15-37 °C, pH 6-9 and in the presence of up to 4 % (w/v) NaCl and tested positive for catalase and oxidase reactions. The major respiratory quinone was Q8. The genomic DNA had a G+C content of 69.4±0.9 mol%. The major polar lipids were phosphatidylethanolamine, phosphatidylglycerol and diphosphatidylglycerol, and the major fatty acid methyl esters comprised C16 : 0, C18 : 1ω7c and summed feature 3 (C16 : 1ω7c/iso-C15 : 0 2-OH). Comparison of the genome sequence of strain EPL6^T and of its closest neighbours, Melaminivora alkalimesophila CY1^T and Alicycliphilus denitrificans K601^T, yielded values of ANI ≤84.1 % and of AAI ≤80.3 %. Therefore, the genetic, phylogenetic, phenotypic and chemotaxonomic characteristics support the classification of this organism into a new taxon. Considering the genetic divergence of strain EPL6^T from the type strains of the closest species, which belong to distinct genera, we propose a new genus within the family Comamonadaceae, named Oryzisolibacter propanilivorax gen. nov., sp. nov., represented by the isolate EPL6^T as the type strain of the species (=LMG 28427^T=CECT 8927^T).

Bacillus solani sp. nov., isolated from rhizosphere soil of a potato field

A novel Gram-stain-positive, endospore-forming bacterium, designated strain FJAT-18043T, was isolated from a soil sample of a potato field in Xinjiang Autonomous Region, China. Cells were rods that were catalase-positive and motile by peritrichous flagella. The strain grew at 20–45 °C (optimum 35 °C), at pH 6.0–10.0 (optimum pH 9) and with 0–10 % (w/v) NaCl (optimum 0 %). Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain FJAT-18043T belonged to the genus Bacillus and exhibited similarities of 97.7, 97.6, 97.2 and 97.2 % with Bacillus eiseniae A1-2T, Bacillus horneckiae DSM 23495T, Bacillus gottheilii WCC 4585T and Bacillus purgationiresistens DS22T, respectively. DNA–DNA relatedness between strain FJAT-18043T and B. eiseniae A1-2 T was lower than 70 % (36.1 %). The menaquinone was identified as MK-7 and the major polar lipids were diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine. The major fatty acids detected were anteiso-C15 : 0, iso-C15 : 0, iso-C16 : 0, anteiso-C17 : 0, C16 : 0 and iso-C14 : 0. The DNA G+C content was 48.8 mol%. Phenotypic, chemotaxonomic and genotypic properties clearly indicated that isolate FJAT-18043T represents a novel species within the genus Bacillus, for which the name Bacillus solani sp. nov. is proposed. The type strain is FJAT-18043T ( = DSM 29501T = CCTCC AB 2014277T).

Hydromonas duriensis gen. nov., sp. nov., isolated from freshwater

An aerobic, Gram-stain-negative rod, designated strain A2P5T, was isolated from the Douro river, in Porto, Portugal. Cells were catalase- and oxidase-positive. Growth occurred at 15–30 °C, at pH 6–8 and in the presence of 1 % (w/v) NaCl. The major respiratory quinone was Q8, the genomic DNA had a G+C content of 47 ± 1 mol%, and phosphatidylethanolamine, phosphatidylglycerol and diphosphatidylglycerol were amongst the major polar lipids. On the basis of 16S rRNA gene sequence analysis, strain A2P5T was observed to be a member of the family Burkholderiaceae, but could not be identified as a member of any validly named genus. The low levels of 16S rRNA gene sequence similarity to other recognized taxa ( < 91 %), together with the comparative analysis of phenotypic and chemotaxonomic characteristics, supported the proposal of a novel species of a new genus within the family Burkholderiaceae. The name Hydromonas duriensis gen. nov., sp. nov. is proposed. The type strain of Hydromonas duriensis is A2P5T ( = LMG 28428T = CCUG 66137T).

Bacillus dabaoshanensis sp. nov., a Cr(VI)-tolerant bacterium isolated from heavy-metal-contaminated soil

A Cr(VI)-tolerant, Gram-staining-positive, rod-shaped, endospore-forming and facultative anaerobic bacterium, designated as GSS04(T), was isolated from a heavy-metal-contaminated soil. Strain GSS04(T) was Cr(VI)-tolerant with a minimum inhibitory concentration of 600 mg l(-1) and was capable of reducing Cr(VI) under both aerobic and anaerobic conditions. Growth occurred with presence of 0-3 % (w/v) NaCl (optimum 1 %), at pH 5.5-10.0 (optimum pH 7.0) and 15-50 °C (optimum 30-37 °C). The main respiratory quinone was MK-7 and the major fatty acids were anteiso-C15:0 and iso-C15:0. The DNA G+C content was 41.1 mol%. The predominant polar lipid was diphosphatidylglycerol. Based on 16S rRNA gene sequence similarity, the closest phylogenetic relative was Bacillus shackletonii DSM 18868(T) (97.6 %). The DNA-DNA hybridization between GSS04(T) and its closest relatives revealed low relatedness (<70 %). The results of phenotypic, chemotaxonomic and genotypic analyses clearly indicated that strain GSS04(T) represents a novel species of the genus Bacillus, for which the name Bacillus dabaoshanensis sp. nov. is proposed. The type strain is GSS04(T) (=CCTCC AB 2013260(T) = KCTC 33191(T)).

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 sediminis sp. nov., isolated from an electroactive biofilm

A Gram-stain positive, facultative anaerobic, motile, spore-forming rod-shaped bacterium with peritrichous flagella, designated DX-5(T), was isolated from an electroactive biofilm. Growth was observed to occur at 35-60 °C, at pH 7.0-10.0 and with 0.5-10 % (w/v) NaCl (optimum growth: 50 °C, pH 8.0 and 0.5-3 % NaCl). Cells were determined to be catalase- and oxidase-positive. The predominant respiratory quinone was identified as MK-7; the major polar lipids were determined to be diphosphatidylglycerol, phosphatidylglycerol, glycolipid, aminoglycolipid and an unidentified phospholipid; the DNA G+C content was determined to be 46.6 mol%; and the major fatty acids (>5 %) were identified as anteiso-C15:0 (33.6 %), iso-C15:0 (24.1 %) and anteiso-C17:0 (13.4 %). The phylogenetic analysis based on 16S rRNA gene sequence comparisons indicated that strain DX-5(T) should be assigned to the genus Bacillus, and was related most closely to the type strains of B. fortis DSM 16012(T) (96.3 %), B. composti KACC 16872(T) (96.3 %) and B. fordii DSM 16014(T) (95.8 %). Results of phenotypic, chemotaxonomic and genotypic analysis indicated that strain DX-5(T) represents a novel species, for which the name B. sediminis sp. nov. is proposed. The type strain is DX-5(T) (=CGMCC 1.12412(T) = KCTC 33102(T)).

Bacillus salsus sp. nov., a halophilic bacterium from a hypersaline lake

A Gram-staining-positive, endospore-forming, rod-shaped, strictly aerobic, slightly halophilic bacterium, designated strain A24T, was isolated from the hypersaline lake Aran-Bidgol in Iran. Cells of strain A24T were motile rods and produced oval endospores at a terminal position in swollen sporangia. Strain A24T was catalase and oxidase positive. Growth occurred with between 0.5 and 7.5 % (w/v) NaCl and the isolate grew optimally at 3 % (v/w) NaCl. The optimum temperature and pH for growth were 35 °C and pH 8.0, respectively. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain A24T belonged to the genus Bacillus within the phylum Firmicutes and showed the closest phylogenetic similarity with the species Bacillus alkalitelluris BA288T (97.2 %), Bacillus herbersteinensis D-1,5aT (96.0 %) and Bacillus litoralis SW-211T (95.6 %). The G+C content of the genomic DNA of this strain was 35.9 mol%. The polar lipid pattern of strain A24T consisted of phosphatidylglycerol, diphosphatidylglycerol, phosphatidylethanolamine and two unknown phospholipids. The major cellular fatty acids of strain A24T were anteiso-C15 : 0 and iso-C15 : 0. The respiratory quinones were MK-7 (94 %) and MK-6 (4 %). The peptidoglycan contained meso-diaminopimelic acid as the diagnostic diamino acid. All these features confirm the placement of isolate A24T within the genus Bacillus . DNA–DNA hybridization experiments revealed a relatedness of 8 % between strain A24T and Bacillus alkalitelluris IBRC-M 10596T, supporting its placement as a novel species. Phenotypic characteristics, phylogenetic analysis and DNA–DNA relatedness data suggest that this strain represents a novel species of the genus Bacillus , for which the name Bacillus salsus sp. nov. is proposed. The type strain is strain A24T ( = IBRC-M 10078 T = KCTC 13816T).

Bacillus thermotolerans sp. nov., a thermophilic bacterium capable of reducing humus

A novel thermotolerant bacterium, designated SgZ-8(T), was isolated from a compost sample. Cells were non-motile, endospore-forming, Gram-staining positive, oxidase-negative and catalase-positive. The isolate was able to grow at 20-65 °C (optimum 50 °C) and pH 6.0-9.0 (optimum 6.5-7.0), and tolerate up to 9.0 % NaCl (w/v) under aerobic conditions. Anaerobic growth occurred with anthraquinone-2,6-disulphonate (AQDS), fumarate and NO3(-) as electron acceptors. Phylogenetic analysis based on the16S rRNA and gyrB genes grouped strain SgZ-8(T) into the genus Bacillus, with the highest similarity to Bacillus badius JCM 12228(T) (96.2 % for 16S rRNA gene sequence and 83.5 % for gyrB gene sequence) among all recognized species in the genus Bacillus. The G+C content of the genomic DNA was 49.3 mol%. The major isoprenoid quinone was menaquinone 7 (MK-7) and the polar lipids consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and an unidentified phospholipid. The major cellular fatty acid was iso-C16 : 0. On the basis of its phenotypic and phylogenetic properties, chemotaxonomic analysis and the results of physiological and biochemical tests, strain SgZ-8(T) ( = CCTCC AB 2012108(T) = KACC 16706(T)) was designated the type strain of a novel species of the genus Bacillus, for which the name Bacillus thermotolerans sp. nov. is proposed.

Bacillus persicus sp. nov., a halophilic bacterium from a hypersaline lake

A novel Gram-positive, slightly halophilic bacterium, designated strain B48T, was isolated from soil around the hypersaline lake Aran-Bidgol in Iran and characterized taxonomically using a polyphasic approach. Cells of strain B48T were non-motile rods and produced ellipsoidal endospores at a central or subterminal position in swollen sporangia. Strain B48T was a strictly aerobic bacterium, catalase- and oxidase-positive. The strain was able to grow at NaCl concentrations of 0.5–10.0 % (w/v), with optimum growth occurring at 2.5 % (w/v) NaCl. The optimum temperature and pH for growth were 35 °C and pH 7.5–8.0, respectively. On the basis of 16S rRNA gene sequence analysis, strain B48T was shown to belong to the genus Bacillus within the phylum Firmicutes and showed the closest phylogenetic similarity to the species Bacillus foraminis CV53T (97.4 %) and Bacillus purgationiresistens DS22T (96.9 %). The DNA G+C content of this new isolate was 40.1 mol%. The major cellular fatty acids of strain B48T were iso-C15 : 0 and anteiso-C15 : 0, and its polar lipid pattern consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, an aminophospholipid and two unknown phospholipids. The only quinone present was menaquinone 7 (MK-7). The peptidoglycan contained meso-diaminopimelic acid as the diagnostic diamino acid. All these features confirm the placement of isolate B48T within the genus Bacillus . DNA–DNA hybridization experiments revealed a low level of relatedness between strain B48T and Bacillus foraminis IBRC-M 10625T (8.1 %). On the basis of polyphasic evidence from this study, a new species of the genus Bacillus , Bacillus persicus sp. nov., is proposed, with strain B48T ( = IBRC-M 10115T = DSM 25386T = CECT 8001T) as the type strain.

Bacillus thermocopriae sp. nov., isolated from a compost

A Gram-reaction-positive, facultatively anaerobic, motile, endospore-forming, rod-shaped strain, designated SgZ-7(T), was isolated from a windrow compost pile and was characterized by means of a polyphasic approach. Growth occurred with 0-3 % (w/v) NaCl (optimum 1 %), at pH 6.0-10.0 (optimum pH 7.2) and at 40-60 °C (optimum 50 °C). The main respiratory quinone was MK-7. The predominant polar lipids were phosphatidylethanolamine, phosphatidylglycerol and diphosphatidylglycerol. The major fatty acids were iso-C15 : 0 and anteiso-C15 : 0. The DNA G+C content was 46.6 mol%. The phylogenetic analysis based on 16S rRNA gene sequence comparisons revealed that strain SgZ-7(T) should be assigned to the genus Bacillus and was related most closely to Bacillus drentensis LMG 21831(T) (sequence similarity 97.2 %). The result of the DNA-DNA hybridization experiment revealed a low relatedness (27.2 %) between the isolate and B. drentensis LMG 21831(T). The results of phenotypic, chemotaxonomic and genotypic analyses clearly indicated that strain SgZ-7(T) represents a novel species, for which the name Bacillus thermocopriae sp. nov. is proposed. The type strain is SgZ-7(T) (= CCTCC AB 2012030(T) = KACC 16700(T)).

Fictibacillus phosphorivorans gen. nov., sp. nov. and proposal to reclassify Bacillus arsenicus, Bacillus barbaricus, Bacillus macauensis, Bacillus nanhaiensis, Bacillus rigui, Bacillus solisalsi and Bacillus gelatini in the genus Fictibacillus

A Gram-positive-staining, aerobic, endospore-forming bacterium (Ca7(T)) was isolated from a bioreactor showing extensive phosphorus removal. Based on 16S rRNA gene sequence similarity comparisons, strain Ca7(T) was grouped in the genus Bacillus, most closely related to Bacillus nanhaiensis JSM 082006(T) (100 %), Bacillus barbaricus V2-BIII-A2(T) (99.2 %) and Bacillus arsenicus Con a/3(T) (97.7 %). Moderate 16S rRNA gene sequence similarities were found to the type strains of the species Bacillus gelatini and Bacillus rigui (96.4 %), Bacillus macauensis (95.1 %) and Bacillus solisalsi (96.1 %). All these species were grouped into a monophyletic cluster and showed very low sequence similarities (<94 %) to the type species of the genus Bacillus, Bacillus subtilis. The quinone system of strain Ca7(T) consists predominantly of menaquinone MK-7. The polar lipid profile exhibited the major compounds diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine. In addition, minor compounds of an unidentified phospholipid and an aminophospholipid were detected. No glycolipids were found in strain Ca7(T), which was consistent with the lipid profiles of B. nanhaiensis, B. barbaricus, B. arsenicus, B. rigui, B. solisalsi, B. macauensis and B. gelatini, but in contrast to B. subtilis. The diagnostic diamino acid of the peptidoglycan was meso-diaminopimelic acid and the polyamine pattern contained predominantly spermidine and spermine. The major fatty acids, which were iso-C15 : 0, anteiso-C15 : 0 and C16 : 0, supported the grouping of strain Ca7(T) in the family Bacillaceae. The strain showed DNA-DNA similarities of 48 % (reciprocal 47 %) to B. nanhaiensis DSM 23009(T), 31 % (reciprocal 36 %) to B. barbaricus V2-BIII-A2(T) and 29 % (reciprocal 39 %) to B. arsenicus DSM 15822(T), respectively. These results clearly demonstrate that strain Ca7(T) is a representative of a novel species, which can be differentiated from its closest relatives by physiological and biochemical tests. Because of the low sequence similarity of strain Ca7(T) to B. subtilis, which was shared by B. nanhaiensis, B. barbaricus, B. arsenicus, B. gelatini, B. rigui, B. solisalsi and B. macauensis, and their unique lipid patterns, we propose that strain Ca7(T) represents a novel species in a novel genus for which the name Fictibacillus phosphorivorans gen. nov., sp. nov. is proposed. The type strain is Ca7(T) (= CCM 8426(T) = LMG 27063(T)). In addition we propose the reclassification of B. nanhaiensis, B. barbaricus, B. arsenicus, B. rigui, B. macauensis, B. solisalsi and B. gelatini as Fictibacillus nanhaiensis comb. nov., Fictibacillus barbaricus comb. nov., Fictibacillus arsenicus comb. nov., Fictibacillus rigui comb. nov., Fictibacillus macauensis comb. nov., Fictibacillus solisalsi comb. nov. and Fictibacillus gelatini comb. nov., respectively [type strains JSM 082006(T) (= DSM 23009(T) = KCTC 13712(T)), V2-BIII-A2(T) ( = CCM 4982(T) = DSM 14730(T)), Con a/3(T) ( = MTCC 4380(T) = DSM 15822(T) = JCM 12167(T)), WPCB074(T) ( = KCTC 13278(T) = JCM 16348(T)), ZFHKF-1(T) ( = JCM 13285(T) = DSM 17262(T)), YC1(T) ( = KCTC 13181(T) = CGMCC 1.6854(T)) and LMG 21881(T) ( = DSM 15866(T)), respectively].