Bacillus hemicentroti sp. nov., a moderate halophile isolated from a sea urchin

Phylogenomic studies and molecular markers clarifying the evolutionary relationships and classification of Pseudalkalibacillus species: proposal for the family Guptibacillaceae fam. nov. harbouring the genera Guptibacillus gen. nov. and Exobacillus gen. nov

The genus Pseudalkalibacillus, created by the reclassification of specific deep-branching Alkalihalobacillus species, exhibits polyphyletic branching. The Genome Taxonomy Database (GTDB) also assigns Pseudalkalibacillus species into two families and three genera. To clarify the evolutionary relationships and classification of Pseudalkalibacillus species, we report detailed investigations using phylogenomic and molecular signature-based approaches. In phylogenomic trees, Pseudalkalibacillus species are distributed within two family-level lineages. One of these clades, containing the type species of Pseudalkalibacillus (viz. Pseudalkalibacillus decolorationis), represents the genus Pseudalkalibacillus, groups within the family Fictibacillaceae. Ten novel conserved signature indels (CSIs) identified in this study are specific for this clade, providing a robust means for the differentiation of the emended genus Pseudalkalibacillus. The remaining Pseudalkalibacillus species form a separate family-level clade, designated as f_HBI72195 in the GTDB. Within this clade, all species except Pseudalkalibacillus caeni form a robust clade designated as Pseudalkalibacillus clade -2 in our work and g_Anaerobacillus_A in the GTDB. We have also identified 15 novel CSIs specific to this clade. As the Pseudalkalibacillus clade -2 is distinct from Pseudalkalibacillus, we propose transferring species from this clade into a new genus, Guptibacillus gen. nov. The species P. caeni branches distinctly from other Pseudalkalibacillus species, and the GTDB considers it a novel genus (g_Bacillus_BR). Six newly identified CSIs are specific to this species, and we are proposing the transfer of this species into a new genus, Exobacillus gen. nov. Two additional identified CSIs are shared by members of the novel family-level taxon (f_HBI72195) comprising the proposed genera Guptibacillus and Exobacillus, for which we are proposing the name Guptibacillaceae fam. nov. Lastly, the results presented here also show that 'Pseudalkalibacillus hemicentroti' and 'Pseudalkalibacillus macyae' are later heterotypic synonyms of Guptibacillus hwajinpoensis. These changes, which reliably depict the evolutionary relationships among Pseudalkalibacillus species, should be helpful in future studies of these organisms.

Two novel alkalitolerant species Pseudalkalibacillus spartinae sp. nov. and Pseudalkalibacillus sedimenti sp. nov

In this study, two novel alkalitolerant strains (FJAT-53046T and FJAT-53715T) were isolated from sediment samples collected in Zhangzhou, PR China. Phylogeny based on 16S rRNA gene sequences suggested that strains FJAT-53046T and FJAT-53715T were new members of the genus Pseudalkalibacillus. The two novel strains showed the highest 16S rRNA gene sequence similarity to Pseudalkalibacillus hwajinpoensis DSM 16206T, with values of 97.4 and 97.6 %, respectively. The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between the two strains and the reference strain were 77.2 and 79.6 %, 20.9 and 30.2 %, respectively, which were below the prokaryotic species delineation thresholds. The ANI and dDDH values between strains FJAT-53046T and FJAT-53715T were 86.0 and 30.2 %, respectively, suggesting that they belonged to different species in the genus Pseudalkalibacillus. The major respiratory quinone in both strains was MK-7 and the major cellular fatty acids were anteiso-C15 : 0 and anteiso-C17 : 0. Diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine were the major polar lipids in both novel strains. Combined with results stemming from the determination of physical and biochemical characteristics, chemical properties, and genome analysis, strains FJAT-53046T and FJAT-53715T are proposed to represent two novel species of the genus Pseudalkalibacillus, for which the names Pseudalkalibacillus spartinae sp. nov. and Pseudalkalibacillus sedimenti sp. nov. are proposed. The type strains are FJAT-53046T (=GDMCC 1.3077T=JCM 35611T) and FJAT-53715T (=GDMCC 1.3076T=JCM 35610T), respectively.

An Update on Novel Taxa and Revised Taxonomic Status of Bacteria (Including Members of the Phylum Planctomycetota) Isolated from Aquatic Host Species Described in 2018 to 2021

Increased interest in farmed aquatic species, aquatic conservation measures, and microbial metabolic end-product utilization have translated into a need for awareness and recognition of novel microbial species and revisions to bacterial taxonomy. Because this need has largely been unmet, through a 4-year literature review, we present lists of novel and revised bacterial species (including members of the phylum Planctomycetota) derived from aquatic hosts that can serve as a baseline for future biennial summaries of taxonomic revisions in this field. Most new and revised taxa were noted within oxidase-positive and/or nonglucose fermentative Gram-negative bacilli, including members of the Tenacibaculum, Flavobacterium, and Vibrio genera. Valid and effectively published novel members of the Streptococcus, Erysipelothrix, and Photobacterium genera are additionally described from disease pathogenesis perspectives.

Pseudalkalibacillus salsuginis sp. nov., a novel salt-tolerant bacterium isolated from a saline lake sediment

A salt-tolerant bacterium, designated strain EGI L200015T, was isolated from saline lake sediment in Xinjiang Uygur Autonomous Region, PR China. The taxonomic position of the isolate was determined using polyphasic taxonomic analysis and phylogenomic analysis. Phylogenetic analysis and 16S rRNA gene sequence similarities indicated that EGI L200015T formed a distinct clade with Pseudalkalibacillus berkeleyi KCTC 12718T with sequence identity of 98.3%. The novel isolate could be distinguished from species of the genus Pseudalkalibacillus by its distinct phenotypic, physiological and genotypic characteristics. Cells of EGI L200015T were aerobic, Gram-stain-positive, non-motile and rod-shaped. Optimal growth conditions for EGI L200015T occurred on marine agar 2216 at pH 8.0 at 30 °C. The major respiratory quinone was MK-7, while the major fatty acids (> 10 %) were anteiso-C15 : 0, iso-C15 : 0, iso-C16 : 0 and anteiso-C17 : 0. The detected polar lipids of included diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine. On the basis of the genome sequence data, the DNA G+C content of EGI L200015T was 41.6 %. On the basis of the phenotypic, physiological, genotypic and phylogenetic data, strain EGI L200015T represents a novel species of the genus Pseudalkalibacillus , for which the name Pseudalkalibacillus salsuginis sp. nov. is proposed. The type strain of the proposed novel isolate is EGI L200015T (= KCTC 43363T = CGMCC 1.19260T).

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 (MEB199T) 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-C15:0, iso-C16:0, anteiso-C15:0, and iso-C17:0. The peptidoglycan contained meso-diaminopimelic acid (meso-DAP). Phosphatidylethanolamine, diphosphatidylglycerol, and phosphatidylglycerol were the major polar lipids of MEB199T. Phylogenetic analysis based on 16S rRNA gene sequence showed that strain MEB199T belonged to the family Bacillaceae and exhibited a distinctive position among the members of the genus Alkalihalobacillus (Ahb.). Strain MEB199T shared the highest 16S rRNA gene sequence similarity with Alkalihalobacillus alkalinitrilicus ANL-iso4T (98.36%), whereas with type species Ahb. alcalophilus DSM 485T, it is 94.91%, indicating that strain MEB199T 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 MEB199T and Ahb. alkalinitrilicus ANL-iso4T 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 MEB199T represents a novel species of newly proposed genus for which the name Alkalihalobacterium elongatum gen. nov. sp. nov. is proposed. The type strain is MEB199T (= MCC 2982T, = JCM 33704T, = NBRC 114256T, = CGMCC 1.17254T).

Bacillus caeni sp. nov., isolated from mangrove sediment

A Gram-variable, aerobic, motile and irregular rod-shaped bacterium, designated HB172195^T, was isolated from a mangrove sediment sample collected from Bamen Bay mangrove forest, China. Cells of the strain were oxidase-negative but positive for catalase and nitrate reduction. Strain HB172195^T was found to grow at 15-50 °C (optimum, 25-40 °C), pH 5.0-9.0 (optimum, pH 7.0) and in 1.0-11.0 % (w/v) NaCl (optimum, 3-6 %). Chemotaxonomic analysis indicated that the sole respiratory quinone was MK-7 and the cell-wall peptidoglycan was meso-diaminopimelic acid. The predominant cellular fatty acids were anteiso-C_{15 : 0}, anteiso-C_{17 : 0} and C_{16 : 1}ω7c alcohol. The major polar lipids consisted of phosphatidylglycerol, phosphatidylethanolamine, diphosphatidylglycerol and an unidentified phospholipid. The genomic DNA G+C content was 40.9 mol%. Phylogenetic analysis based on 16S rRNA gene sequences showed that the strain was closely related to Bacillus hwajinpoensis SW-72^T (96.3%), Bacillus algicola KMM 3737^T (96.2 %) and Bacillus haemicentroti JSM 076093^T (95.5 %). Based on polyphasic taxonomic characterization, strain HB172195^T is considered to represent a novel species, for which the name Bacillus caeni sp. nov. is proposed. The type strain is HB172195^T (=CGMCC 1.16730^T=JCM 33411^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.

Bacillus endolithicus sp. nov., isolated from pebbles

Strain JC267T was isolated from pebbles collected from Pingleshwar beach, Gujarat, India. Cells are Gram-stain-positive, facultatively anaerobic, non-motile rods forming sub-terminal endospores in swollen ellipsoidal to oval sporangia. Strain JC267T contains anteiso-C15 : 0, iso-C15 : 0, iso-C14 : 0, iso-C16 : 0, C16 : 0 and anteiso-C17 : 0 as major (>5 %) cellular fatty acids. Polar lipids include phosphatidylglycerol, phospholipids (PL1-3), glycolipids (GL1-2) and an unidentified lipid. Cell-wall amino acids are composed of diagnostic meso-diaminopimelic acid, dl-alanine and a small amount of d-glutamic acid. The genomic DNA G+C content of strain JC267T is 45.5 mol%. The 16S rRNA gene sequence of strain JC267T showed highest sequence similarities of < 98.41 % with all species of the genus Bacillus when subjected to EzTaxon-e blast analysis. The reassociation values based on DNA-DNA hybridization of strain JC267T with Bacillus halosaccharovorans IBRC-M 10095T and Bacillus niabensis JCM 16399T were 26 ± 1 % and 34 ± 3 %, respectively. Based on taxonomic data obtained using a polyphasic approach, strain JC267T represents a novel species of the genus Bacillus, for which the name Bacillus endolithicus sp. nov. is proposed. The type strain is JC267T ( = IBRC-M 10914T = KCTC 33579T).

Halotolerant bacteria in the São Paulo Zoo composting process and their hydrolases and bioproducts

Halophilic microorganisms are able to grow in the presence of salt and are also excellent source of enzymes and biotechnological products, such as exopolysaccharides (EPSs) and polyhydroxyalkanoates (PHAs). Salt-tolerant bacteria were screened in the Organic Composting Production Unit (OCPU) of São Paulo Zoological Park Foundation, which processes 4 ton/day of organic residues including plant matter from the Atlantic Rain Forest, animal manure and carcasses and mud from water treatment. Among the screened microorganisms, eight halotolerant bacteria grew at NaCl concentrations up to 4 M. These cultures were classified based on phylogenetic characteristics and comparative partial 16S rRNA gene sequence analysis as belonging to the genera Staphylococcus, Bacillus and Brevibacterium. The results of this study describe the ability of these halotolerant bacteria to produce some classes of hydrolases, namely, lipases, proteases, amylases and cellulases, and biopolymers. The strain characterized as of Brevibacterium avium presented cellulase and amylase activities up to 4 M NaCl and also produced EPSs and PHAs. These results indicate the biotechnological potential of certain microorganisms recovered from the composting process, including halotolerant species, which have the ability to produce enzymes and biopolymers, offering new perspectives for environmental and industrial applications.

Bacillus crassostreae sp. nov., isolated from an oyster (Crassostrea hongkongensis)

A novel Gram-stain-positive, motile, catalase- and oxidase-positive, endospore-forming, facultatively anaerobic rod, designated strain JSM 100118(T), was isolated from an oyster (Crassostrea hongkongensis) collected from the tidal flat of Naozhou Island in the South China Sea. Strain JSM 100118(T) was able to grow with 0-13% (w/v) NaCl (optimum 2-5%), at pH 5.5-10.0 (optimum pH 7.5) and at 5-50 °C (optimum 30-35 °C). The cell-wall peptidoglycan contained meso-diaminopimelic acid as the diagnostic diamino acid. The predominant respiratory quinone was menaquinone-7 and the major cellular fatty acids were anteiso-C15 : 0, iso-C15 : 0, C16 : 0 and C16 : 1ω11c. The polar lipids consisted of diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, an unknown glycolipid and an unknown phospholipid. The genomic DNA G+C content was 35.9 mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain JSM 100118(T) belonged to the genus Bacillus , and was most closely related to Bacillus litoralis SW-211(T) (98.9% 16S rRNA gene sequence similarity), Bacillus halosaccharovorans E33(T) (98.3%), Bacillus niabensis 4T19(T) (97.8%) and Bacillus herbersteinensis D-1,5a(T) (97.1%). The combination of results from the phylogenetic analysis, DNA-DNA hybridization, and phenotypic and chemotaxonomic characterization supported the conclusion that strain JSM 100118(T) represents a novel species of the genus Bacillus , for which the name Bacillus crassostreae sp. nov. is proposed. The type strain is JSM 100118(T) ( = CTCC AB 2010452(T) =DSM 24486(T) =JCM 17523(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 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 halosaccharovorans sp. nov., a moderately halophilic bacterium from a hypersaline lake

A novel Gram-stain-positive, moderately halophilic bacterium, designated strain E33(T), was isolated from water of the hypersaline lake Aran-Bidgol in Iran and characterized taxonomically using a polyphasic approach. Cells of strain E33(T) were motile rods and produced ellipsoidal endospores at a central or subterminal position in swollen sporangia. Strain E33(T) was a strictly aerobic bacterium, catalase- and oxidase-positive. The strain was able to grow at NaCl concentrations of 0.5-25 % (w/v), with optimum growth occurring at 5-15 % (w/v) NaCl. The optimum temperature and pH for growth were 40 °C and pH 7.5-8.0, respectively. On the basis of 16S rRNA gene sequence analysis, strain E33(T) was shown to belong to the genus Bacillus within the phylum Firmicutes and showed the closest phylogenetic similarity with the species Bacillus niabensis 4T19(T) (99.2 %), Bacillus herbersteinensis D-1-5a(T) (97.3 %) and Bacillus litoralis SW-211(T) (97.2 %). The DNA G+C content of the type strain of the novel species was 42.6 mol%. The major cellular fatty acids of strain E33(T) were anteiso-C15 : 0 and iso-C15 : 0, and the polar lipid pattern consisted of diphosphatidylglycerol, phosphatidylglycerol, two unknown glycolipids, an unknown lipid and an unknown phospholipid. The isoprenoid quinones were MK-7 (97 %), MK-6 (2 %) and MK-8 (0.5 %). The peptidoglycan contained meso-diaminopimelic acid as the diagnostic diamino acid. All these features confirm the placement of isolate E33(T) within the genus Bacillus. DNA-DNA hybridization experiments revealed low levels of relatedness between strain E33(T) and Bacillus niabensis IBRC-M 10590(T) (22 %), Bacillus herbersteinensis CCM 7228(T) (38 %) and Bacillus litoralis DSM 16303(T) (19 %). On the basis of polyphasic evidence from this study, a novel species of the genus Bacillus, Bacillus halosaccharovorans sp. nov. is proposed, with strain E33(T) (= IBRC-M 10095(T) = DSM 25387(T)) as the type strain.