Taxonomic diversity of extremophilic prokaryotes adapted to special environmental parameters in Hungary: a review

The taxonomic and metabolic diversity of prokaryotes and their adaptability to extreme environmental parameters have allowed extremophiles to find their optimal living conditions under extreme conditions for one or more environmental parameters. Natural habitats abundant in extremophilic microorganisms are relatively rare in Hungary. Nevertheless, alkaliphiles and halophiles can flourish in shallow alkaline lakes (soda pans) and saline (solonetz) soils, where extreme weather conditions favor the development of unique bacterial communities. In addition, the hot springs and thermal wells that supply spas and thermal baths and provide water for energy use are suitable colonization sites for thermophiles and hyperthermophiles. Polyextremophiles, adapted to multiple extreme circumstances, can be found in the aphotic, nutrient-poor and radioactive hypogenic caves of the Buda Thermal Karst, among others. The present article reviews the organization, taxonomic composition, and potential role of different extremophilic bacterial communities in local biogeochemical cycles, based on the most recent studies on extremophiles in Hungary.

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).

Alkalihalobacillus deserti sp. nov., Isolated from the Saline-Alkaline Soil

A bacterial strain, designated TRPH29^T, was isolated from saline-alkaline soil, collected from the southern edge of the Gurbantunggut desert, Xinjiang, People's Republic of China. The isolate was Gram-staining positive, facultatively anaerobic, straight rods. Growth occurred at 15-40 °C (optimum, 28 °C), pH 8.0-13.0 (optimum, 10.0), and in the presence of 0-15% (w/v) NaCl (optimum, 2%). Phylogenetic analysis using 16S rRNA gene sequence indicated that strain TRPH29^T showed the highest sequence similarities to Alkalihalobacillus krulwichiae (98.31%), Alkalihalobacillus wakoensis (98.04%), and Alkalihalobacillus akibai (97.69%). Average nucleotide identity (ANI) and digital DNA-DNA hybridization values between strain TRPH29^T and Alkalihalobacillus krulwichiae, Alkalihalobacillus wakoensis, Alkalihalobacillus akibai were in the range of 73.62-75.52% and 15.0-21.20%, respectively. Results of genome analyses indicated that the genome size of strain TRPH29^T was 5.05 Mb, with a genomic DNA G + C content of 37.30%. Analysis of the cellular component of strain TRPH29^T revealed that the primary fatty acids were anteiso-C_15:0 and iso-C_15:0, and the polar lipids included diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, an unidentified glycolipid, and an unidentified phospholipid. The predominant respiratory quinone was MK-7. Based on the genomic, phylogenetic, phenotypic and chemotaxonomic analyses, strain TRPH29^T represents a novel species of the genus Alkalihalobacillus, for which the name Alkalihalobacillus deserti sp. nov. is proposed. The type strain is TRPH29^T (= CGMCC 1.19067^T = NBRC 115475^T).

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.

Isolation and Aflatoxin B1-Degradation Characteristics of a Microbacterium proteolyticum B204 Strain from Bovine Faeces

Aflatoxin B₁ (AFB₁) is one of the most harmful mycotoxins, raising serious global health and economic problems. Searching for biological approaches for effective and safe AFB₁ degradation is imminent. In our study, Microbacterium proteolyticum B204 isolated from bovine faeces degraded 77% of AFB₁ after 24 h, becoming the first reported bacteria from the Microbacterium family to possess AFB₁ degradation characteristics. Temperature variation showed little effect on its degradation ratio, demonstrating high thermostability of 75% and 79% after boiling and sterilization, respectively. We suppose that the components playing a key role during this process were proteins, considering the decreased degradation rate caused by Proteinase K. Cell viability detection on HepG2 cells indicated that the degradation products were much less toxic than pure AFB₁. Furthermore, B204 cell-free culture supernatant also degraded AFB₁-contaminated food, such as peanuts, corn and cheese. These results suggested that this strain with AFB₁ degradation properties could be a prospective candidate for application in the food and feed industries.

Anion-type modulates the effect of salt stress on saline lake bacteria

Beside sodium chloride, inland saline aquatic systems often contain other anions than chloride such as hydrogen carbonate and sulfate. Our understanding of the biological effects of salt composition diversity is limited; therefore, the aim of this study was to examine the effect of different anions on the growth of halophilic bacteria. Accordingly, the salt composition and concentration preference of 172 strains isolated from saline and soda lakes that differed in ionic composition was tested using media containing either carbonate, chloride or sulfate as anion in concentration values ranging from 0 to 0.40 mol/L. Differences in salt-type preference among bacterial strains were observed in relationship to the salt composition of the natural habitat they were isolated from indicating specific salt-type adaptation. Sodium carbonate represented the strongest selective force, while majority of strains was well-adapted to growth even at high concentrations of sodium sulfate. Salt preference was to some extent associated with taxonomy, although variations even within the same bacterial species were also identified. Our results suggest that the extent of the effect of dissolved salts in saline lakes is not limited to their concentration but the type of anion also substantially impacts the growth and survival of individual microorganisms.

Umezawaea beigongshangensis sp. nov., Isolated From the Mash of Baijiu

A Gram-positive, aerobic and non-motile actinobacterial strain, designated REN6^T, was isolated from the mash of Baijiu (Chinese spirits, a kind of distilling liquor is made by cooking, saccharification, fermentation and distillation) collected from Sichuan Province Region, China, and characterized using a polyphasic approach. Morphological and chemotaxonomic properties of strain REN6^T were consistent with the description of the genus Umezawaea, such as the spore arrangement, the abundant aerial mycelium and the fragmented substrate mycelium. The diamino acid of peptidoglycan is meso-diaminopimelic acid. The diagnostic phospholipids were DPG (diphosphatidylglycerol), PG (phosphatidylglycerol), PI (phosphatidylinositol), PE (phosphatidylethanolamine). The major fatty acids were C_16:0, C_17:0, Iso-C_16:0, Iso-C_16:1 H, C_17:1ω6c and C_17:1 ω8c. Menaquinone-9 (MK-9) (H4) was the predominant menaquinones. The genomic DNA G + C contents were 72.7 mol%. Phylogenetic analysis based on 16S rDNA gene sequences demonstrated that strain REN6^T should also be classified in the genus Umezawaea, with U. tangerina (98.7%) and U. endophytica (98.7%). However, it can be distinguished from the closest strains U. tangerina JCM 10302^T based on the low levels of DNA-DNA hybridization 22.1%. Based upon the morphological, physiological, chemotaxonomic and molecular characteristics differences from other members of the genus, a novel species, Umezawaea beigongshangensis sp. nov., is proposed, with REN6^T (= JCM 33954^T = CGMCC 19205^T) as the type strain.

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).

Microbial communities of soda lakes and pans in the Carpathian Basin: a review

In this review, I would like to summarize the current knowledge on the microbiology of soda lakes and pans of the Carpathian Basin. First, the characteristic physical and chemical features of these sites are described. Most of the microbiological information presented deals with prokaryotes and algae, but protists and viruses are also mentioned. Planktonic bacterial communities are dominated by members of the phyla Actinobacteria, Bacteroidetes and Proteobacteria; small-sized trebouxiophycean green algae and Synechococcus/Cyanobium picocyanobacteria are the most important components of phytoplankton. Based on the current knowledge, it seems that mainly temperature, salinity, turbidity and grazing pressure regulate community composition and the abundance of individual microbial groups, but the external nutrient load from birds also has a significant impact on the ecological processes.

Variation in Sodic Soil Bacterial Communities Associated with Different Alkali Vegetation Types

In this study, we examined the effect of salinity and alkalinity on the metabolic potential and taxonomic composition of microbiota inhabiting the sodic soils in different plant communities. The soil samples were collected in the Pannonian steppe (Hungary, Central Europe) under extreme dry and wet weather conditions. The metabolic profiles of microorganisms were analyzed using the MicroResp method, the bacterial diversity was assessed by cultivation and next-generation amplicon sequencing based on the 16S rRNA gene. Catabolic profiles of microbial communities varied primarily according to the alkali vegetation types. Most members of the strain collection were identified as plant associated and halophilic/alkaliphilic species of Micrococcus, Nesterenkonia, Nocardiopsis, Streptomyces (Actinobacteria) and Bacillus, Paenibacillus (Firmicutes) genera. Based on the pyrosequencing data, the relative abundance of the phyla Proteobacteria, Actinobacteria, Acidobacteria, Gemmatimonadetes and Bacteroidetes also changed mainly with the sample types, indicating distinctions within the compositions of bacterial communities according to the sodic soil alkalinity-salinity gradient. The effect of weather extremes was the most pronounced in the relative abundance of the phyla Actinobacteria and Acidobacteria. The type of alkali vegetation caused greater shifts in both the diversity and activity of sodic soil microbial communities than the extreme aridity and moisture.

Brevibacterium renqingii sp. nov., isolated from the Daqu of Baijiu

Two bacterial strains, designated REN4^T and REN4-1, were isolated from daqu sample collected from baijiu factory located in Shanxi, China. The two strains shared highly similar 16S rRNA gene sequences (99.67% identities) and formed a monophyletic clade within the Brevibacterium 16S rRNA gene tree, showing 97.56-97.85% 16S rRNA gene sequence identities with type strains Brevibacterium permense VKM Ac-2280 ^T, Brevibacterium sediminis FXJ8.269 ^T, Brevibacterium oceani BBH7^T and Brevibacterium epidermidis NCIMB 702286 ^T. They contained MK-8(H₂) as the most predominant menaquinone, antesio-C_15:0, antesio-C_17:0, Iso-C_16:0 and Iso-C_17:0 as the major cellular fatty acids, DPG (diphosphatidylglycerol), PG (phosphatidylglycerol), PGL (phosphatidylglycerollipids), and PL (phospholipids) as the main polar lipids. The genomic DNA G + C content of strains REN4 and REN4-1 were 64.35, 65.82 mol%. Moreover, the low DNA-DNA relatedness values, physiological and biochemical characteristics, and taxonomic analysis allowed the differentiation of strains REN4^T and REN4-1 from the other recognized species of the genus Brevibacterium. Therefore, strain REN4^T represents a novel species of the genus Brevibacterium, for which the name Brevibacterium renqingii sp. nov. is proposed, with the type strain REN4^T (= JCM 33953 T = KCTC 49366 ^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.

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

Two alkaliphilic strains, designated FJAT-45086^T and FJAT-45122^T, 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-45086^T were anteiso-C_15:0, C_16:0, iso-C_15:0, C_16:1ω11c and anteiso-C_17:0, whereas strain FJAT-45122^T consisted of iso-C_15:0, anteiso-C_15:0, iso-C_17:1ω10c, iso-C_17:0, anteiso-C_17:0, C_16:0 and C16:1ω11c. The genome G + C content of strains FJAT-45086^T and FJAT-45122^T was 37.8 and 38.2 mol%, respectively. The polar lipids of strain FJAT-45086^T were diphosphatidyl glycerol (DPG), phosphatidyl glycerol (PG), phosphatidyl ethanolamine (PE), and phosphatidyl choline (PC), whereas strain FJAT-45122^T consisted of DPG, PG, phosphatidyl methyl ethanolamine (PME) and an unidentified aminophospholipids (UAPL). The average nucleotide identity values of strains FJAT-45086^T and FJAT-45122^T were below the cut-off level (95-96%) for species delineation. Based on the results, strains FJAT-45086^T and FJAT-45122^T 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-45122^T (=DSM 104631^T = CCTCC AB 2016254^T), FJAT-45086^T (=DSM 104056^T = CCTCC AB 2016232^T).

A Newly Isolated Bacillus subtilis Strain Named WS-1 Inhibited Diarrhea and Death Caused by Pathogenic Escherichia coli in Newborn Piglets

Bacillus subtilis is recognized as a safe and reliable human and animal probiotic and is associated with bioactivities such as production of vitamin and immune stimulation. Additionally, it has great potential to be used as an alternative to antimicrobial drugs, which is significant in the context of antibiotic abuse in food animal production. In this study, we isolated one strain of B. subtilis, named WS-1, from apparently healthy pigs growing with sick cohorts on one Escherichia coli endemic commercial pig farm in Guangdong, China. WS-1 can strongly inhibit the growth of pathogenic E. coli in vitro. The B. subtilis strain WS-1 showed typical Bacillus characteristics by endospore staining, biochemical test, enzyme activity analysis, and 16S rRNA sequence analysis. Genomic analysis showed that the B. subtilis strain WS-1 shares 100% genomic synteny with B. subtilis with a size of 4,088,167 bp. Importantly, inoculation of newborn piglets with 1.5 × 10¹⁰ CFU of B. subtilis strain WS-1 by oral feeding was able to clearly inhibit diarrhea (p < 0.05) and death (p < 0.05) caused by pathogenic E. coli in piglets. Furthermore, histopathological results showed that the WS-1 strain could protect small intestine from lesions caused by E. coli infection. Collectively, these findings suggest that the probiotic B. subtilis strain WS-1 acts as a potential biocontrol agent protecting pigs from pathogenic E. coli infection.

Importance: In this work, one B. subtilis strain (WS-1) was successfully isolated from apparently healthy pigs growing with sick cohorts on one E. coli endemic commercial pig farm in Guangdong, China. The B. subtilis strain WS-1 was identified to inhibit the growth of pathogenic E. coli both in vitro and in vivo, indicating its potential application in protecting newborn piglets from diarrhea caused by E. coli infections. The isolation and characterization will help better understand this bacterium, and the strain WS-1 can be further explored as an alternative to antimicrobial drugs to protect human and animal health.

Bacillus shivajii sp. nov., isolated from a water sample of Sambhar salt lake, India

A novel Gram-stain-positive, rod-shaped, motile, spore-forming, strictly aerobic, alkali- and halo- tolerant bacterium, designated strain AK72^T, was isolated from a water sample collected from Sambhar salt lake, Rajasthan, India. The colony appears circular, shiny, smooth, translucent or slightly pale in colour and convex with an entire margin after 48 h incubation at 37 °C with pH 9. Growth of the bacterium occurred at 10-42 °C (optimum, 25-37 °C), at salinities of 0.5-10 % (w/v) NaCl (optimum 3-5 % NaCl) and pH of 6-10 (optimum pH 9). Strain AK72^T was positive for oxidase, catalase, nitrate reductase, phenylalanine deaminase, ornithine decarboxylase, aesculinase, lipase and urease activities. The predominant fatty acids were iso-C15 : 0, anteiso-C15 : 0 and iso-C16 : 0 and the cell-wall peptidoglycan contained meso-diaminopimelic acid as the diagnostic diamino acid. The major polar lipids of the strain were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, an unidentified aminophospholipid, three unidentified phospholipids and three unidentified lipids. The genomic DNA G+C content of the strain AK72^T was 36.8 mol%. Phylogenetic analysis of the 16S rRNA gene sequence indicated that strain AK72^T was closely related to Bacillus cellulosilyticus (96.5 %) and Bacillus vedderi (96.3 %), but the novel strain AK72^T formed a separate clade with Bacillus aurantiacus whereas B. cellulosilyticus and B. vedderi were clustered in a separate clade. The above data in combination with the phenotypic characteristics and phylogenetic data inferred that strain AK72^T represents a novel species of the genus Bacillus, for which the name Bacillusshivajii sp. nov. is proposed. The type strain is AK72^T (=MTCC 12636^T=KCTC 33981^T=JCM 32183^T).

Nesterenkonia pannonica sp. nov., a novel alkaliphilic and moderately halophilic actinobacterium

An alkaliphilic and moderately halophilic bacterial strain characterized by optimal growth at pH 9.0-10.0 and with 5-7 % (w/v) NaCl, designated BV-35^T, was isolated from water of a soda pan located in Kiskunság National Park, Hungary. Cells of the orange-pigmented colony were Gram-stain-positive, non-motile and non-endospore-forming coccoid rods. The isolate was strictly aerobic, catalase-positive and oxidase-negative. Strain BV-35^T displayed a peptidoglycan similar to type A4α, l-Lys-l-Glu (A11.54 according to www.peptidoglycan-types.info) but containing additionally 4-aminobutyric acid. Menaquinone-7 (MK-7) was the predominant isoprenoid quinone, and anteiso-C15 : 0 and anteiso-C17 : 0 were its major cellular fatty acids. The DNA G+C content of strain BV-35^T was 65.4 mol%. Based on 16S rRNA gene sequence similarities, the novel isolate showed the closest relationship to Nesterenkonia populi GP 10-3^T (97.9 %). The DNA-DNA relatedness between BV-35^T and N. populi was 46.7 %. The distinguishing phenotypic and genetic results of this polyphasic study revealed that strain BV-35^T represents a novel member of the genus Nesterenkonia, for which the name Nesterenkonia pannonica sp. nov. is proposed. The type strain is BV-35^T (=DSM 29786^T=NCAIM B 02606^T).

Examination into the taxonomic position of Bacillus thermotolerans Yang et al., 2013, proposal for its reclassification into a new genus and species Quasibacillus thermotolerans gen. nov., comb. nov. and reclassification of B. encimensis Dastager et al., 2015 as a later heterotypic synonym of B. badius

Two novel Gram-staining positive, rod-shaped, moderately halotolerant, endospore forming bacterial strains 5.5LF 38TD and 5.5LF 48TD were isolated and taxonomically characterized from a landfill in Chandigarh, India. The analysis of 16S rRNA gene sequences of the strains confirmed their closest identity to Bacillus thermotolerans SgZ-8T with 99.9% sequence similarity. A comparative phylogenetic analysis of strains 5.5LF 38TD, 5.5LF 48TD and B. thermotolerans SgZ-8^T confirmed their separation into a novel genus with B. badius and genus Domibacillus as the closest phylogenetic relatives. The major fatty acids of the strains are iso-C_15:0 and iso-C_16:0 and MK-7 is the only quinone. The major polar lipids are diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine. The digital DNA-DNA hybridization (DDH) and ortho average nucleotide identity (ANI) values calculated through whole genome sequences indicated that the three strains showed low relatedness with their phylogenetic neighbours. Based on evidences from phylogenomic analyses and polyphasic taxonomic characterization we propose reclassification of the species B. thermotolerans into a novel genus named Quasibacillus thermotolerans gen. nov., comb. nov with the type strain SgZ-8^T (=CCTCC AB2012108^T=KACC 16706^T). Further our analyses also revealed that B. encimensis SGD-V-25^T is a later heterotypic synonym of Bacillus badius DSM 23^T.

Isolation of hydroquinone (benzene-1,4-diol) metabolite from halotolerant Bacillus methylotrophicus MHC10 and its inhibitory activity towards bacterial pathogens

A halotolerant bacterial isolate-MHC10 with broad spectrum antibacterial activity against clinical pathogens was isolated from saltpans located in Tuticorin and Chennai (India). 16S rRNA gene analysis of MHC10 revealed close similarity to that of Bacillus methylotrophicus. The culture conditions of B. methylotrophicus MHC10 strain were optimized for antibacterial production using different carbon and nitrogen sources, as well as varying temperature, pH, sodium chloride (NaCl) concentrations and incubation periods. The maximum antibacterial activity of B. methylotrophicus MHC10 was attained when ZMB was optimized with 1 % (w/v) glucose, 0.1 % (w/v) soybean meal which corresponded to a C/N ratio of 38.83, temperature at 37 °C, pH 7.0 and 8 % NaCl. The activity remained stable between 72 and 96 h and then drastically decreased after 96 h. Solvent extraction followed by chromatographic purification steps led to the isolation of hydroquinone (benzene-1,4-diol). The structure of the purified compound was elucidated based on FTIR, (1)H NMR, and (13)C NMR spectroscopy. The compound exhibited efficient antibacterial activity against both Gram-positive and Gram-negative bacterial pathogens. The minimum inhibitory concentration (MIC) for Gram-positive pathogens ranged from 15.625 to 62.5 µg/mL(-1), while it was between 7.81 and 250 µg/mL(-1) for Gram-negative bacterial pathogens. This is the first report of hydroquinone produced by halotolerant B. methylotrophicus exhibiting promising antibacterial activity.

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 panacisoli sp. nov., isolated from ginseng soil

A Gram-staining-positive, motile, facultatively anaerobic, endospore-forming and rod-shaped bacterium, designated strain CJ32(T), was isolated from ginseng soil at Geumsan in Korea. The isolate grew optimally at 30 °C, 2% (w/v) NaCl and pH 7.0. Colonies of strain CJ32(T) were beige and circular with an entire margin on LB agar plates. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain CJ32(T) was associated with the genus Bacillus and was most closely related to Bacillus graminis YC6957(T) (97.3% similarity) and Bacillus lentus IAM 12466(T) (97.1%). DNA-DNA hybridization with closely related strains was below 31.3%. The major respiratory isoprenoid quinone was MK-7. The diagnostic diamino acid in the cell-wall peptidoglycan was meso-diaminopimelic acid. The polar lipid profile of strain CJ32(T) consisted of phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol and several unidentified lipids, including phospholipids, aminolipids and aminophospholipids. The predominant fatty acids of strain CJ32(T) were iso-C15:0 and anteiso-C15:0. The G+C content of the genomic DNA was 35.1 mol%. Based on phenotypic, genotypic and phylogenetic data, strain CJ32(T) should be classified within a novel species of the genus Bacillus, for which the name Bacillus panacisoli sp. nov. is proposed. The type strain is strain CJ32(T) ( = KACC 17503(T) = JCM 19226(T)).