Bacillus halosaccharovorans sp. nov., a moderately halophilic bacterium from a hypersaline lake

Microbial diversity in polyextreme salt flats and their potential applications

Recent geological, hydrochemical, and mineralogical studies performed on hypersaline salt flats have given insights into similar geo-morphologic features on Mars. These salt-encrusted depressions are widely spread across the Earth, where they are characterized by high salt concentrations, intense UV radiation, high evaporation, and low precipitation. Their surfaces are completely dry in summer; intermittent flooding occurs in winter turning them into transitory hypersaline lakes. Thanks to new approaches such as culture-dependent, culture-independent, and metagenomic-based methods, it is important to study microbial life under polyextreme conditions and understand what lives in these dynamic ecosystems and how they function. Regarding these particular features, new halophilic microorganisms have been isolated from some salt flats and identified as excellent producers of primary and secondary metabolites and granules such as halocins, enzymes, carotenoids, polyhydroxyalkanoates, and exopolysaccharides. Additionally, halophilic microorganisms are implemented in heavy metal bioremediation and hypersaline wastewater treatment. As a result, there is a growing interest in the distribution of halophilic microorganisms around the world that can be looked upon as good models to develop sustainable biotechnological processes for all fields. This review provides insights into diversity, ecology, metabolism, and genomics of halophiles in hypersaline salt flats worldwide as well as their potential uses in biotechnology.

Vertical organization of microbial communities in Salineta hypersaline wetland, Spain

Microbial communities inhabiting hypersaline wetlands, well adapted to the environmental fluctuations due to flooding and desiccation events, play a key role in the biogeochemical cycles, ensuring ecosystem service. To better understand the ecosystem functioning, we studied soil microbial communities of Salineta wetland (NE Spain) in dry and wet seasons in three different landscape stations representing situations characteristic of ephemeral saline lakes: S1 soil usually submerged, S2 soil intermittently flooded, and S3 soil with halophytes. Microbial community composition was determined according to different redox layers by 16S rRNA gene barcoding. We observed reversed redox gradient, negative at the surface and positive in depth, which was identified by PERMANOVA as the main factor explaining microbial distribution. The Pseudomonadota, Gemmatimonadota, Bacteroidota, Desulfobacterota, and Halobacteriota phyla were dominant in all stations. Linear discriminant analysis effect size (LEfSe) revealed that the upper soil surface layer was characterized by the predominance of operational taxonomic units (OTUs) affiliated to strictly or facultative anaerobic halophilic bacteria and archaea while the subsurface soil layer was dominated by an OTU affiliated to Roseibaca, an aerobic alkali-tolerant bacterium. In addition, the potential functional capabilities, inferred by PICRUSt2 analysis, involved in carbon, nitrogen, and sulfur cycles were similar in all samples, irrespective of the redox stratification, suggesting functional redundancy. Our findings show microbial community changes according to water flooding conditions, which represent useful information for biomonitoring and management of these wetlands whose extreme aridity and salinity conditions are exposed to irreversible changes due to human activities.

Metabacillus rhizolycopersici sp. nov., Isolated from the Rhizosphere Soil of Tomato Plants

A Gram-positive, endospore-forming, rod-shaped and aerobic bacterium, with swarming and swimming motility, designated strain DBTR6^T, was isolated from the rhizosphere soil of tomato plants. Strain DBTR6^T grew at 20-45 ℃ (optimum 30-37℃), pH 4-9 (optimum 7-8) and at salinities from 0 to 5% (optimum 1%). Phylogenetic analysis using 16S rRNA gene sequences showed this strain belonged to the genus Metabacillus and was most closely related to Metabacillus litoralis DSM 16303 ^T (98.3%) and Metabacillus sediminilitoris MCCC 1K03777^T (98.3%). The DNA G + C content of the genomic DNA was 36.4%. The digital DNA-DNA hybridization value between strain DBTR6^T and reference strains M. sediminilitoris MCCC 1K03777^T and "M. bambusae" BG109^T were less than 70% (26.7% and 26.0%), and the average nucleotide identity score were less than 95% (78.55% and 78.38%), and the Amino Acid Identity values calculated were less than 96% (79.99% and 80.18%), respectively, suggesting that strain DBTR6^T represented a novel species in the genus Metabacillus. Chemotaxonomic analysis showed that strain DBTR6^T contained MK-7 as the major respiratory quinone. The predominant fatty acids (> 10.0%) were iso-C_15:0, anteiso-C_15:0 and C_16:0. The major polar lipids were diphosphatidylglycerol (DPG), phosphatidylethanolamine (PE), phosphatidylglycerol (PG), glycolipids (GL) and three unidentified lipids (L). Based on the differential physiological properties, biochemical characteristics and genotypic data, strain DBTR6^T represents a novel species of the genus Metabacillus, for which the name Metabacillus rhizolycopersici sp. nov. is proposed. The type strain is DBTR6^T (= ACCC 61900 ^T = JCM 35080 ^T).

Metabacillus kandeliae sp. nov., isolated from the rhizosphere soil of a decayed mangrove plant Kandelia candel

In this study, we isolated a novel Gram-stain-positive, aerobic, motile, rod-shaped bacterium, named GX 13764T, from the rhizosphere soil of a decayed mangrove plant Kandelia candel collected from Beihai, Guangxi, PR China, and characterized using a polyphasic taxonomic approach. The strain exhibited yellow-orange, round, convex, shiny, smooth, opaque and 2–3 mm diameter colonies on marine agar 2216 media after 3 days of incubation at 30 °C and was capable of growth at 4–45 °C (optimum, 30 °C), pH 5.0–9.0 (optimum, pH 7.0) and 0–4 % NaCl (w/v; optimum, 2 %). The strain was positive for catalase and negative for the oxidase. The main cellular fatty acid was anteiso-C15:0, iso-C15:0, iso-C16:0 and iso-C14:0. The cell-wall peptidoglycan comprised meso-diaminopimelic acid and the main menaquinone was MK-7. The polar lipids included one diphosphatidylglycerol, one phosphatidylglycerol, two glycolipids, two unidentified phospholipids and three unidentified lipids. Based on 16S rRNA gene analysis, GX 13764T presented the highest sequence similarity to Metabacillus mangrovi KCTC 33872T (97.04 %). The DNA G+C content of the type strain was 44.2 mol%. The average nucleotide identity values between GX 13764T and M. mangrovi KCTC 33872T, Metabacillus idriensis DSM 19097T and Metabacillus indicus LMG 22858T were 69.39, 68.87 and 68.95 %, respectively, with digital DNA–DNA hybridization values of 19.9, 19.5 and 19.5 %, respectively. Based on the polyphasic data, strain GX 13764T should be nominated as a novel species of the genus Metabacillus , for which the name Metabacillus kandeliae sp. nov. is proposed. The type strain is GX 13764T (=MCCC 1K06654T=KCTC 43366T).

Genomic and Physiological Characterization of Metabacillus flavus sp. nov., a Novel Carotenoid-Producing Bacilli Isolated from Korean Marine Mud

The newly isolated strain KIGAM252^T was found to be facultatively anaerobic, Gram-stain-positive, spore-forming, and rod-shaped. They grew at 10–45 °C, pH 6.0–10.0, and were able to tolerate up to 6% NaCl in the growth medium. Phylogenetic analysis indicated that the KIGAM252^T strain was related to the genus Metabacillus. The cell membrane fatty acid composition of strain KIGAM252^T included C_15:0 anteiso and C_15:0 iso (25.6%) as the major fatty acids, and menaquinone 7 was the predominant isoprenoid quinone. The major polar lipids were diphosphatidylglycerol and phosphatidylglycerol. The size of the whole genome was 4.30 Mbp, and the G + C content of the DNA was 43.8%. Average nucleotide and amino acid identity and in silico DNA-DNA hybridization values were below the species delineation threshold. Pan-genomic analysis revealed that 15.8% of all genes present in strain KIGAM252^T was unique to the strain. The analysis of the secondary biosynthetic pathway predicted the carotenoid synthetic gene cluster in the strain KIGAM252^T. Based on these current polyphasic taxonomic data, strain KIGAM252^T represents a novel species of the genus Metabacillus that produces carotenoids, for which we propose the name Metabacillus flavus sp. nov. The type of strain was KIGAM252^T (=KCTC 43261^T = JCM 34406^T).

Metabacillus elymi sp. nov., isolated from the Rhizosphere of Elymus tsukushiensis, a plant native to the Dokdo Islands, Republic of Korea

Dokdo islands in Republic of Korea, is not suited to survive plant because strong wind, low organic content and high salinity. Nevertheless, 64 taxa of plants have a symbiotic relationship with microbe. The Metabacillus elymi KUDC1714^T was isolated from the rhizosphere of Elymus tsukushiensis collected from Dokdo Islands. This bacterial strain was Gram-stain positive, non-motile, non-spore forming, aerobic and rod-shape bacteria with 0.4-0.5 × 2.5-3.0 μm in size. Colonies were smooth, yellowish-white circular and 2.0-3.0 mm in diameter. KUDC1714^T was capable of growing at 10-45 °C (optimum, 30 °C), pH 7-11 (optimum, pH 8) and 0-8.0% (w/v) NaCl (optimum, 1.0-2.0%). Flagella were not observed by transmission electron microscopy. Phylogenetic analyses, based on 16S rRNA gene sequences, showed that KUDC1714^T belonged to the genus Metabacillus formed a phyletic lineage within the genus Metabacillus of the family Bacillaceae. The strain KUDC1714^T was most closely related to Metabacillus sediminilitoris DSL-17 ^T (98.2%), Metabacillus litoralis SW-211 ^T (98.2%) and Metabacillus halosaccharovorans E33^T (97.7%) based on 16S rRNA gene sequence. In silico DNA-DNA hybridization using genome-to-genome distance calculator were analysed at 25.8% and 23.5% in strain KUDC1714^T and Metabacillus sediminilitoris DSL-17 ^T, and strain KUDC1714^T and Metabacillus litoralis SW-211 ^T, respectively. Strain KUDC1714^T and its closet type strain were all below cut-off point of the average nucleotide identity and average amino acid identity values. The genome contains 5197 CDSs, 3 rRNAs, 118 tRNAs, 5 ncRNAs. The genomic DNA G + C content was 34.8 mol%. Its polar lipids were diphosphatidylglycerol, phosphatidylglycerol and its major fatty acids were anteiso-C_15:0 and iso-C_15:0. The strain KUDC1714^T contained menaquinone-7 as major isoprenoid quinone. Based on its genetic data, physiological and biochemical characteristics, strain KUDC1714^T should be considered a novel species of the genus Metabacillus, for which we propose the name Metabacillus elymi sp. nov. the type strain is KUDC1714^T (= KCTC 33222 ^T, = DSM 27608 ^T).

Metabacillus schmidteae sp. nov., Cultivated from Planarian Schmidtea mediterranea Microbiota

Taxonogenomics combines phenotypic assays and genomic analysis as a means of characterizing novel strains. We used this strategy to study Marseille-P9898T strain, an aerobic, motile, Gram-negative, spore-forming, and rod-shaped bacterium isolated from planarian Schmidtea mediterranea. Marseille-P9898T is catalase-positive and oxidase-negative. The major fatty acids detected are 12-methyl-tetradecanoic acid, 13-methyl-tetradecanoic acid, and hexadecanoic acid. Marseille-P9898T strain shared more than 98% sequence similarity with the Metabacillus niabensis strain 4T19T (98.99%), Metabacillus halosaccharovorans strain E33T (98.75%), Metabacillus malikii strain NCCP-662T (98.19%), and Metabacillus litoralis strain SW-211T (97.15%). Marseille-P9898 strain belongs to Metabacillus genus. Genomic analysis revealed the highest similarities with Ortho-ANI and dDDH, 85.76% with Metabacillus halosaccharovorans, and 34.20% with Bacillus acidicola, respectively. These results show that the Marseille-P9898T strain is a novel bacterial species from Metabacillus genus, for which we propose the name of Metabacillus schmidteae sp. nov. (Type strain Marseille-P9898T = CSUR P9898T = DSM 111480T).

Phytoextraction efficiency of Pteris vittata grown on a naturally As-rich soil and characterization of As-resistant rhizosphere bacteria

This study evaluated the phytoextraction capacity of the fern Pteris vittata grown on a natural arsenic-rich soil of volcanic-origin from the Viterbo area in central Italy. This calcareous soil is characterized by an average arsenic concentration of 750 mg kg⁻¹, of which 28% is bioavailable. By means of micro-energy dispersive X-ray fluorescence spectrometry (μ-XRF) we detected As in P. vittata fronds after just 10 days of growth, while a high As concentrations in fronds (5,000 mg kg⁻¹), determined by Inductively coupled plasma-optical emission spectrometry (ICP-OES), was reached after 5.5 months. Sixteen arsenate-tolerant bacterial strains were isolated from the P. vittata rhizosphere, a majority of which belong to the Bacillus genus, and of this majority only two have been previously associated with As. Six bacterial isolates were highly As-resistant (> 100 mM) two of which, homologous to Paenarthrobacter ureafaciens and Beijerinckia fluminensis, produced a high amount of IAA and siderophores and have never been isolated from P. vittata roots. Furthermore, five isolates contained the arsenate reductase gene (arsC). We conclude that P. vittata can efficiently phytoextract As when grown on this natural As-rich soil and a consortium of bacteria, largely different from that usually found in As-polluted soils, has been found in P. vittata rhizosphere.

Metabacillus sediminilitoris sp. nov., a marine bacterium isolated from a tidal sediment

A Gram-stain-positive, endospore-forming, motile and rod-shaped bacterium, designated as strain DSL-17^T, was isolated from a tidal sediment of the East China Sea and characterized phylogenetically and phenotypically. The strain could grow at 16-47 °C (optimum 37 °C), at pH 6.0-10.0 (optimum 6.0) and with 1-7% (w/v) NaCl (optimum 3 %). Phylogenetic analysis based on 16S rRNA gene sequences showed that strain DSL-17^T was related to members of the genus Metabacillus and shared the highest similarity with Metabacillus litoralis SW-211^T (98.6 %), followed by Metabacillus halosaccharovorans E33^T (97.9 %), Metabacillus crassostreae JSM 100118^T (97.7 %), Metabacillus niabensis 4T19^T (97.7 %) and Metabacillus malikii NCCP-662^T (97.5 %). 16S rRNA gene sequence similarities between strain DSL-17^T and other members of the genus Metabacillus were below 96.6 %. The sole respiratory quinone was MK-7. Strain DSL-17^T had a cell-wall peptidoglycan based on meso-diaminopimelic acid. The polar lipids were diphosphatidylglycerol (DPG), phosphatidylglycerol (PG), three unidentified glycolipids and six unidentified lipids. The strain had iso-C_15 : 0, anteiso-C_15 : 0, iso-C_14 : 0, C_16 : 0 and iso-C_16 : 0 as major fatty acids. The G+C content of the genomic DNA was 35.7 mol%. The combined genotypic and phenotypic data indicated that strain DSL-17^T represents a novel species of the genus Metabacillus, for which the name Metabacillus sediminilitoris sp. nov. is proposed The type strain is DSL-17^T (=MCCC 1K03777^T=DSM 109843^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.

Isolation and screening of extracellular anticancer enzymes from halophilic and halotolerant bacteria from different saline environments in Iran

It was confirmed that several enzymes have anti-cancer activity. The enzymes L-asparaginase, L-glutaminase, and L-arginase were chosen according to amino acids starvation in cancer cells and screened in halophilic and halotolerant bacteria, given probably less immunological reactions of halophilic or halotolerant enzymes in patients. Out of 110 halophilic and halotolerant strains, isolated from different saline environments in Iran and screened, some could produce a variety of anticancer enzymes. A total of 29, 4, and 2 strains produced L-asparaginase, L-glutaminase, and L-arginase, respectively. According to the phenotypic characteristics and partial 16S rRNA gene sequence analysis, the positive strains-strains with the ability to produce these anticancer enzymes-were identified as the members of the genera: Bacillus, Dietzia, Halobacillus, Rhodococcus, Paenibacillus and Planococcus as Gram-positive bacteria and Pseudomonas, Marinobacter, Halomonas, Idiomarina, Vibrio and Stappia as Gram-negative bacteria. The production of anticancer enzymes was mostly observed in the rod-shaped Gram-negative isolates, particularly in the members of the genera Halomonas and Marinobacter. Most of the enzymes were produced in the stationary phase of growth and the maximum enzyme activity was experienced in strain GBPx3 (Vibrio sp.) for L-asparaginase at 1.0 IU/ml, strain R₂S₂₅ (Rhodococcus sp.) for L-glutaminase at 0.6 IU/ml and strain GAAy3 (Planococcus sp.) for L-arginase at 3.1 IU/ml. The optimum temperature and pH for L-asparaginase and L-glutaminase activities in selected strains were similar to the physiological conditions of human body and the enzymes could tolerate NaCl up to 7.5% concentration.

Antimicrobial Activity of Bacillus Persicus 24-DSM Isolated from Dead Sea Mud

Intorduction:

Dead Sea is a hypersaline lake with 34% salinity, gains its name due to the absence of any living macroscopic creatures. Despite the extreme hypersaline environment, it is a unique ecosystem for various halophilic microorganisms adapted to this environment.

Aims & Objectives:

Halophilic microorganisms are known for various potential biotechnological applications, the purpose of the current research is isolation and screening of halophilic bacteria from Dead Sea mud for potential antimicrobial applications.

Methods & Materials:

Screening for antagonistic bacteria was conducted by bacterial isolation from Dead Sea mud samples and agar plate antagonistic assay. The potential antagonistic isolates were subjected to biochemical characterization and identification by 16S-rRNA sequencing. Among the collected isolates, four isolates showed potential antagonistic activity against Bacillus subtilis 6633 and Escherichia coli 8739. The most active isolate (24-DSM) was subjected for antagonistic activity and minimal inhibitory concentration against different gram positive and negative bacterial strains after cultivation in different salt concentration media. Results: The results of 16S-rRNA analysis revealed that 24-DSM is very closely related to Bacillus persicus strain B48, which was isolated from hypersaline lake in Iran.

Conclusion:

Therefore, the isolate 24-DSM is assigned as a new strain of B. persicusi isolated from the Dead Sea mud. B. persicusi 24-DSM showed higher antimicrobial activity, when it was cultivated with saline medium, against all tested bacterial strains, where the most sensitive bacterial strain was Corynebacterium diphtheria 51696.

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.

Soortia roseihalophila gen. nov., sp. nov., a new taxon in the order Balneolales isolated from a travertine spring, and description of Soortiaceae fam. nov

A novel Gram-stain-negative, slightly halophilic, motile, curved rod with a horseshoe shape, designated strain Bsw-2bT, was isolated from Badab-Soort travertine spring in Iran. Phylogenetic analysis of the 16S rRNA gene sequence revealed that strain Bsw-2bT belongs to the order Balneolales, showing 84.6 % sequence similarity to Gracilimonastropica DSM 19535T and 84.4 % and 83.9 % sequence similarity to Gracilimonas rosea CL-KR2T and Balneola vulgaris DSM 17893T, respectively. In addition, phenotypic and physiological features could clearly differentiate strain Bsw-2bT from species of the most closely related genera, Gracilimonas, Balneola, Aliifodinibius and Fodinibius. The strain was able to grow with 1-3 % (w/v) (optimum at 2 %) NaCl, at temperatures of 28-34 °C (optimum at 30 °C) and between pH 6.0 and 8.0 (optimum at pH 7.0). The major cellular fatty acids of strain Bsw-2bT were iso-C15 : 0, iso-C13 : 0 and iso-C14 : 0. The polar lipid profile of strain Bsw-2bT was composed predominantly of phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylglycerol, an unknown glycolipid and four unknown phospholipids. The DNA G+C content was 40.5 mol%. Based on the evidence from the polyphasic study, strain Bsw-2bT represents a novel species in a novel genus within a new family, for which the name Soortia roseihalophila gen. nov., sp. nov. is proposed, within the new family Soortiaceae fam. nov. The type strain is strain Bsw-2bT (=IBRC-M 10915T=LMG 28547T).

Isolation of a novel alginate lyase-producing Bacillus litoralis strain and its potential to ferment Sargassum horneri for biofertilizer

Algae have long been used to augment plant productivity through their beneficial effects. Alginate oligosaccharide is believed to be one of the important components to enhance growth and crop yield. In this study, we isolated and characterized a Bacillus litoralis strain, named Bacillus M3, from decayed kelps. We further demonstrated that the M3 strain could secrete alginate lyase to degrade alginate. The crude enzyme exhibited the highest activity (33.74 U/mg) at pH 7.0 and 50°C. The M3 strain was also able to ferment the brown alga Sargassum horneri. Fermentation results revealed that a fermentation period of 8-12 hr was the best harvest time with the highest level of alginate oligosaccharides. Plant growth assay showed that the seaweed fermentation extract had an obvious promotion effect on root and seedling growth of Lycopersicon eseulentum L. Our results suggest that fermentation extract of Sargassum horneri by the novel strain of Bacillus litoralis M3 has significant development potential for biofertilizer production and agriculture application.

A heavy metal tolerant novel bacterium, Bacillus malikii sp. nov., isolated from tannery effluent wastewater

The taxonomic position of a Gram-stain positive and heavy metal tolerant bacterium, designated strain NCCP-662(T), was investigated by polyphasic characterisation. Cells of strain NCCP-662(T) were observed to be rod to filamentous shaped, motile and strictly aerobic, and to grow at 10-50 °C (optimum 30-37 °C) and at pH range of 6-10 (optimum pH 7-8). The strain was found to be able to tolerate 0-12 % NaCl (w/v) and heavy metals (Cr 1200 ppm, Pb 1800 ppm and Cu 1200 ppm) in tryptic soya agar medium. The phylogenetic analysis based on the 16S rRNA gene sequence of strain NCCP-662(T) showed that it belongs to the genus Bacillus and showed high sequence similarity (98.2 and 98.0 %, respectively) with the type strains of Bacillus niabensis 4T19(T) and Bacillus halosaccharovorans E33(T). The chemotaxonomic data showed that the major quinone is MK-7; the predominant cellular fatty acids are anteiso-C15 :0, iso-C14:0, iso-C16:0 and C16:0 and iso-C15:0; the major polar lipids are diphosphatidylglycerol, phosphatidylglycerol along with several unidentified glycolipids, phospholipids and polar lipids. The DNA G+C content was determined to be 36.9 mol%. These data also support the affiliation of strain NCCP-662(T) with the genus Bacillus. The level of DNA-DNA relatedness between strain NCCP-662(T) and B. niabensis JCM 16399(T) was 20.5 ± 0.5 %. On the basis of physiological and biochemical characteristics, phylogenetic analyses and DNA-DNA hybridization data, strain NCCP-662(T) can be clearly differentiated from the validly named Bacillus species and thus represents a new species, for which the name Bacillus malikii sp. nov. is proposed with the type strain NCCP-662(T) (= LMG 28369(T) = DSM 29005(T) = JCM 30192(T)).

Salt resistance genes revealed by functional metagenomics from brines and moderate-salinity rhizosphere within a hypersaline environment

Hypersaline environments are considered one of the most extreme habitats on earth and microorganisms have developed diverse molecular mechanisms of adaptation to withstand these conditions. The present study was aimed at identifying novel genes from the microbial communities of a moderate-salinity rhizosphere and brine from the Es Trenc saltern (Mallorca, Spain), which could confer increased salt resistance to Escherichia coli. The microbial diversity assessed by pyrosequencing of 16S rRNA gene libraries revealed the presence of communities that are typical in such environments and the remarkable presence of three bacterial groups never revealed as major components of salt brines. Metagenomic libraries from brine and rhizosphere samples, were transferred to the osmosensitive strain E. coli MKH13, and screened for salt resistance. Eleven genes that conferred salt resistance were identified, some encoding for well-known proteins previously related to osmoadaptation such as a glycerol transporter and a proton pump, whereas others encoded proteins not previously related to this function in microorganisms such as DNA/RNA helicases, an endonuclease III (Nth) and hypothetical proteins of unknown function. Furthermore, four of the retrieved genes were cloned and expressed in Bacillus subtilis and they also conferred salt resistance to this bacterium, broadening the spectrum of bacterial species in which these genes can function. This is the first report of salt resistance genes recovered from metagenomes of a hypersaline environment.

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).

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)).

Aquibacillus halophilus gen. nov., sp. nov., a moderately halophilic bacterium from a hypersaline lake, and reclassification of Virgibacillus koreensis as Aquibacillus koreensis comb. nov. and Virgibacillus albus as Aquibacillus albus comb. nov

A novel Gram-stain-positive, moderately halophilic bacterium, designated strain B6BT, was isolated from the water of an Iranian hypersaline lake, Aran-Bidgol, and characterized taxonomically using a polyphasic approach. Cells of strain B6BT were rod-shaped, motile and produced ellipsoidal endospores in terminal positions in non-swollen sporangia. Strain B6BT was a strictly aerobic bacterium and catalase- and oxidase-positive. The strain was able to grow at NaCl concentrations of 0.5–20.0 % (w/v), with optimum growth occurring at 10.0 % (w/v) NaCl. The optimum temperature and pH for growth were 35 °C and pH 7.0. On the basis of 16S rRNA gene sequence analysis, strain B6BT was shown to belong to the phylum Firmicutes and its closest phylogenetic similarities were with the species Virgibacillus koreensis BH30097T (97.5 %), Virgibacillus albus YIM 93624T (97.4 %), Sediminibacillus halophilus EN8dT (96.8 %), Sediminibacillus albus NHBX5T (96.6 %), Virgibacillus carmonensis LMG 20964T (96.3 %) and Paraliobacillus quinghaiensis YIM-C158T (96.0 %), respectively. Phylogenetic analysis revealed that strain B6BT, along with V. koreensis BH30097T and V. albus YIM 93624T, clustered in a separate clade in the family Bacillaceae . The DNA G+C content of the novel isolate was 35.8 mol%. DNA–DNA hybridization experiments revealed low levels of relatedness between strain B6BTand V. koreensis BH30097T (13 %) and V. albus YIM 93624T (33 %). The major cellular fatty acid of strain B6BT was anteiso-C15 : 0 (75.1 %) and its polar lipid pattern consisted of phosphatidylglycerol, diphosphatidylglycerol, an unknown phospholipid and an unknown glycolipid. The isoprenoid quinones were MK-7 (90 %) and MK-6 (3 %). The peptidoglycan contained meso-diaminopimelic acid as the diagnostic diamino acid. All of these features support the placement of isolate B6BT within the phylum Firmicutes . It is closely related to V. koreensis and V. albus , but with features that clearly distinguish it from species of the genus Virgibacillus or of other related genera. On the basis of the polyphasic evidence derived in this study, we propose that strain B6BT be placed within a new genus, as Aquibacillus halophilus gen. nov., sp. nov., with B6BT as the type strain ( = IBRC-M 10775T = KCTC 13828T). We also propose that V. koreensis and V. albus should be transferred to this new genus and be named Aquibacillus koreensis comb. nov. and Aquibacillus albus comb. nov., respectively. The type strain of Aquibacillus koreensis comb. nov. is BH30097T ( = KCTC 3823T = IBRC-M 10657T = JCM 12387T) and the type strain of Aquibacillus albus comb. nov. is YIM 93624T ( = DSM 23711T = IBRC-M 10798T = JCM 17364T).