Halomonas getboli sp. nov., a halotolerant bacteria isolated from a salt flat

A novel Gram-stain-negative, rod-shaped, cream-coloured, motile, halotolerant bacterium, designated as YJPS3-2^T, was isolated from saltern sediment of the Yellow sea in Yongyu-do, Republic of Korea. Strain YJPS3-2^T grew at pH 5.0-10.0 (optimum, pH 7.0), 4-40 °C (optimum, 30 °C) and with 1-15% (w/v) NaCl (optimum 3 %). The 16S rRNA gene sequence analysis indicated that strain YJPS3-2^T was closely related to those of Halomonas halophila F5-7^T (98.75 %), Halomonas salina F8-11^T (98.74 %), Halomonas smyrnensis AAD6^T (98.66 %), Halomonas organivorans G-16.1^T (98.34 %), Halomonas koreensis SS20^T (97.98 %) and Halomonas beimenensis NTU-107^T (96.93 %). The average nucleotide identity and digital DNA-DNA hybridization values between YJPS3-2^T and related type strains were 86.9-91.6 % and 32.0-44.8 %. Strain YJPS3-2^T was characterized as having Q-9 as the predominant respiratory quinone and the principal fatty acids (>10 %) were C_16 : 0 (31.4 %), C_19 : 0 ω8c cyclo (16.3 %), C_17 : 0 cyclo (11.9 %) and C_12 : 0 3-OH (10.4 %). The polar lipids consisted of phosphatidylcholine, diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylglycerol. The DNA G+C content of strain YJPS3-2^T is 68.1mol %. Based on the polyphasic taxonomic evidence presented in this study, YJPS3-2^T should be classified as representing a novel species within the genus Halmonas, for which name Halomonas getboli is proposed, with the type strain YJPS3-2^T (= KCTC 92124^T=KACC 22561^T=JCM 35085^T).

Halomonas binhaiensis sp. nov., isolated from saline-alkali soil

A Gram-stain-negative, aerobic and rod-shaped bacterium, strain Y2R2^T, was isolated from a saline-alkali soil sample collected from Binhai New Area, Tianjin, PR China. Growth of strain Y2R2^T was observed at 10-45 °C (optimum, 30 °C), at pH 6.0-11.0 (optimum, pH 9.0) and in the presence of 0-15 % (w/v) NaCl (optimum, 9.0 %). Phylogenetic analysis based on 16S rRNA gene sequences showed that strain Y2R2^T was affiliated with the genus Halomonas and showed the highest similarity to Halomonas huangheensis BJGMM-B45^T (99.0%) and Halomonas cupida DSM 4740^T (98.4%). The digital DNA-DNA hybridization and average nucleotide identity values of 21.0-22.8 % and 73.3-75.7 % with the closely related species H. huangheensis BJGMM-B45^T, H. cupida DSM 4740^T, H. ventosae AL12^T, H. stenophila N12^T and H. litopenaei SYSU ZJ2214^T were lower than the threshold recommended for species discrimination.The major respiratory quinone of strain Y2R2^T was Q-9 and the major cellular fatty acids consisted of C_16 : 0, C_19 : 0 cyclo ω8c and summed feature 8 (C_18 : 1 ω7c and/or C_18 : 1 ω6c). The DNA G+C content of strain Y2R2^T was 57.0 mol%. On the basis of this polyphasic taxonomic study, strain Y2R2^T is considered to represent a novel species of the genus Halomonas, for which the name Halomonas binhaiensis sp. nov. is proposed. The type strain is Y2R2^T (=CGMCC 1.16974^T=KCTC 72578^T).

Halomonas alkalisoli sp. nov., a novel haloalkalophilic species from saline-alkaline soil, and reclassification of Halomonas daqingensis Wu et al. 2008 as a later heterotypic synonym of Halomonas desiderata Berendes et al. 1996

Two Gram-stain-negative, strictly aerobic, moderately halophilic, non-spore-forming and rod-shaped bacteria, designated M5N1S17T and M5N1S15, were isolated from saline soil in Baotou, China. A phylogenetic analysis based on 16S rRNA gene sequences showed that the two strains clustered closely with Halomonas montanilacus PYC7WT and shared 99.1 and 99.3% sequence similarities, respectively. The average nucleotide identity based on BLAST (ANIb) and MUMmer (ANIm) values of the two strains with each other were 95.5% and 96.7%, respectively, while the ANIb and ANIm values between the two strains and 15 closer Halomonas species were 74.8-91.3% and 84.1-92.6%, respectively. The major polar lipids of M5N1S17T are diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylinositol, and an unidentified phospholipid. The major polar lipids of M5N1S15 are diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylinositol, two unidentified phospholipids, and an unidentified lipid. The predominant ubiquinone in the two strains is Q-9. The major fatty acids of the two strains are C18:1ω6c and/or C18:1ω7c, C16:0, and C16:1ω7c and/or C16:1ω6c. Based on phylogenetic, phenotypic, and physiological results, strains M5N1S17T and M5N1S15 should be identified as a novel species of the genus Halomonas, for which Halomonas alkalisoli sp. nov. is proposed. The type strain is M5N1S17T (= CGMCC 1.19023T = KCTC 92130T). The phylogenetic trees showed that Halomonas daqingensis CGMCC 1.6443T clustered tightly with Halomonas desiderata FB2T, and the two strains shared >98.0% of ANI values with each other. Therefore, we propose the reclassification of H. daqingensis Wu et al. 2008 as a later heterotypic synonym of H. desiderata Berendes et al. 1996.

Halomonas icarae sp. nov., a moderately halophilic bacterium isolated from beach soil in India

A moderately halophilic, Gram-stain-negative, aerobic bacterium, strain D1-1^T, belonging to the genus Halomonas, was isolated from soil sampled at Pentha beach, Odisha, India. Phylogenetic trees reconstructed based on 16S rRNA genes and multilocus sequence analysis of gyrB and rpoD genes revealed that strain D1-1^T belonged to the genus Halomonas and was most closely related to Halomonas alimentaria YKJ-16^T (98.1 %) followed by Halomonas ventosae Al12^T (97.5 %), Halomonas sediminicola CPS11^T (97.5 %), Halomonas fontilapidosi 5CR^T (97.4 %) and Halomonas halodenitrificans DSM 735^T (97.2 %) on the basis of 16S rRNA gene sequence similarity. Sequence identities with other species within the genus were lower than 97.0 %. The digital DNA-DNA hybridization (dDDH) and average nucleotide identity (ANI) values of 22.4-30 % and 79.5-85.4 % with close relatives of H. halodenitrificans DSM 735^T, H. alimentaria YKJ-16^T, H. ventosae Al12^T and H. fontilapidosi 5CR^T were lower than the threshold recommended for species delineation (70 % and 95-96 % for dDDH and ANI, respectively). Further, strain D1-1^T formed yellow-coloured colonies; cells were rod-shaped, motile with optimum growth at 30 °C (range, 4-45 °C) and 2-8 % NaCl (w/v; grew up to 24 % NaCl). The major fatty acids were summed feature 8 (C_18 : 1  ω7c/C_18 : 1  ω6c), summed feature 3 (C_16 : 1  ω7c/C_16 : 1  ω6c) and C_16 : 0 and the main respiratory quinone was ubiquinone Q-9 in line with description of the genus. Based on its chemotaxonomic and phylogenetic characteristics and genome uniqueness, strain D1-1^T represents a novel species in the genus Halomonas, for which we propose the name Halomonas icarae sp. nov., within the family Halomonadaceae. The type strain is D1-1^T (=JCM 33602^T=KACC 21317^T=NAIMCC-B-2254^T).

Halomonas montanilacus sp. nov., isolated from hypersaline Lake Pengyanco on the Tibetan Plateau

A Gram-stain-negative, catalase- and oxidase-positive, aerobic, rod-shaped, motile strain (PYC7WT) was isolated from Lake Pengyanco on the Tibetan Plateau. Comparisons based on 16S rRNA gene sequences showed that strain PYC7WT belongs to the genus Halomonas , with Halomonas malpeensis YU-PRIM-29T and Halomonas johnsoniae T68687T as its closest neighbours (96.8 and 96.6 % 16S rRNA gene sequence similarity, respectively), and only 93.1 % 16S rRNA gene sequence similarity to Halomonas elongata ATCC 33173T. The predominant respiratory quinone of strain PYC7WT is Q-9, with Q-8 as a minor component. The major fatty acids are C18 : 1  ω6c and / or C18 : 1  ω7c, C16 : 0, C16 : 1  ω6c and/or C16 : 1  ω7c, and C12 : 0 3OH. The polar lipids of strain PYC7WT include phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, phosphatidylinositol and two unidentified phospholipids. Genome sequencing revealed a genome size of 4.79 Mbp and a G+C content of 62.9 mol%. DNA–DNA hybridization values of strain PYC7WT showed 45, 30 and 38 % relatedness with Halomonas johnsoniae DSM 21197T, Halomonas hamiltonii DSM 21196T and Halomonas stevensii DSM 21198T, respectively. Combining phenotypic, biochemical, genotypic and DNA–DNA hybridization data, we propose that strain PYC7WT represents a novel species within the genus Halomonas and to have the name Halomonas montanilacus sp. nov.; PYC7WT (=CICC 24506T= KCTC 62529T) is the type strain.

The Nitrogen-Removal Efficiency of a Novel High-Efficiency Salt-Tolerant Aerobic Denitrifier, Halomonas Alkaliphile HRL-9, Isolated from a Seawater Biofilter

Aerobic denitrification microbes have great potential to solve the problem of NO₃^--N accumulation in industrialized recirculating aquaculture systems (RASs). A novel salt-tolerant aerobic denitrifier was isolated from a marine recirculating aquaculture system (RAS) and identified as Halomonas alkaliphile HRL-9. Its aerobic denitrification performance in different dissolved oxygen concentrations, temperatures, and C/N ratios was studied. Investigations into nitrogen balance and nitrate reductase genes (napA and narG) were also carried out. The results showed that the optimal conditions for nitrate removal were temperature of 30 °C, a shaking speed of 150 rpm, and a C/N ratio of 10. For nitrate nitrogen (NO₃^--N) (initial concentration 101.8 mg·L^-1), the sole nitrogen source of the growth of HRL-9, the maximum NO₃^--N removal efficiency reached 98.0% after 24 h and the maximum total nitrogen removal efficiency was 77.3% after 48 h. Nitrogen balance analysis showed that 21.7% of NO₃^--N was converted into intracellular nitrogen, 3.3% of NO₃^--N was converted into other nitrification products (i.e., nitrous nitrogen, ammonium nitrogen, and organic nitrogen), and 74.5% of NO₃^--N might be converted to gaseous products. The identification of functional genes confirmed the existence of the napA gene in strain HRL-9, but no narG gene was found. These results confirm that the aerobic denitrification strain, Halomonas alkaliphile HRL-9, which has excellent aerobic denitrification abilities, can also help us understand the microbiological mechanism and transformation pathway of aerobic denitrification in RASs.

Halomonas litopenaei sp. nov., a moderately halophilic, exopolysaccharide-producing bacterium isolated from a shrimp hatchery

Two Gram-stain negative, moderately halophilic, exopolysaccharide-producing bacteria, designated strains SYSU ZJ2214^T and SYSU XM8, were isolated from rearing water and larvae from shrimp hatcheries, respectively. Cells of the strains were aerobic, motile and short-rod-shaped. They grew at NaCl concentrations of 0.5-22 % (w/v), at 4-45 °C and at pH 6-9. Pairwise comparison of 16S rRNA gene sequences revealed that strains SYSU ZJ2214^T and SYSU XM8 were most closely related to Halomonas denitrificans M29^T (98.3 and 98.2 % similarity, respectively). Strains SYSU ZJ2214^T and SYSU XM8 shared an average nucleotide identity of 99.9 % between them. The DNA G+C contents were calculated at 64.1 % for both strains from the draft genome information. The major cellular fatty acids (>5 %) were summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c), summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c), C16 : 0 and C12 : 0 3-OH, and the predominant respiratory quinone was ubiquinone Q-9. Their main polar lipids were diphosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, four unidentified phospholipids and three unidentified lipids. On the basis of phenotypic, genotypic and phylogenetic data, strains SYSU ZJ2214^T and SYSU XM8 merit recognition as representatives of a novel species of the genus Halomonas, for which the name Halomonas litopenaei sp. nov. is proposed. The type strain is SYSU ZJ2214^T (=NBRC 111829^T=KCTC 42974^T).

Halomonas aestuarii sp. nov., a moderately halophilic bacterium isolated from a tidal flat

Strain Hb3^T was isolated from a tidal flat in Jeollabuk-do Gunsan, Republic of Korea. Cells were Gram-stain-negative, oxidase- and catalase-positive, rod-shaped and motile. The strain grew optimally at 25-35 °C, at pH 6.0-6.5 and with 3.0-10.0 % (w/v) NaCl. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain Hb3^T belonged to the genus Halomonas. Strain Hb3^T was related most closely to Halomonas ventosae Al12^T (98.6 % 16S rRNA gene sequence similarity), Halomonas denitrificans M29^T (98.6 %) and Halomonas saccharevitans AJ275^T (98.4 %). Moreover, multilocus sequence analysis using the gyrB, rpoD and secA genes supported the phylogenetic position of strain Hb3^T. The genomic G+C content of strain Hb3^T was 67.9 mol%. DNA-DNA hybridization values for strain Hb3^T versus H. ventosae Al12^T, H. denitrificans M29^T and H. saccharevitans AJ275^T were 38.0, 54.5 and 47.4 %, respectively. The major quinone was ubiquinone Q-9 and the major fatty acids were C18 : 1ω7c, summed feature 3 (C16 : 1ω6c and/or C16 : 1ω7c), C16 : 0 and C19 : 0 cyclo ω8c. Diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, amino lipid, six unidentified phospholipids and an unidentified lipid comprised the polar lipid profile. On the basis of the data presented in this report, strain Hb3^T represents a novel species of the genus Halomonas. The name Halomonas aestuarii sp. nov. is proposed for this novel species. The type strain is Hb3^T (=KCTC 52253^T=JCM 31415^T).

Halomonas urumqiensis sp. nov., a moderately halophilic bacterium isolated from a saline-alkaline lake

A moderately halophilic, aerobic bacterium, strain BZ-SZ-XJ27T, belonging to the genus Halomonas, was isolated from a saline-alkaline lake in the Xinjiang Uyghur Autonomous Region of China. Phylogenetic analysis based on 16S rRNA gene sequences and a multilocus sequence analysis using the 16S rRNA, gyrB and rpoD genes demonstrated that strain BZ-SZ-XJ27T represents a member of the genus Halomonas. On the basis of 16S rRNA gene sequence similarity, the closest relatives were Halomonas campaniensis 5AGT, H. fontilapidosi 5CRT, H. korlensis XK1T and H. sinaiensis ALO SharmT, with similarities of 96.2-97.2 %. DNA-DNA hybridization with H. korlensis CGMCC 1.6981T (the nearest phylogenetic neighbour) and H. campaniensis DSM 15293T (the highest 16S rRNA gene sequence similarity) showed relatedness values of 53 and 38 %, respectively, demonstrating the separateness of the three taxa. The bacterium stained Gram-negative and the cells were motile and rod-shaped. The strain formed creamy-white colonies and grew under optimal conditions of 1.42 M Na+ (range 0.22-4.32 M Na+), pH 8.0-8.5 (range pH 6.0-10.0) and 39 °C (range 4-43 °C). The dominant fatty acids were summed feature 8 (C18 : 1ω7c/C18 : 1ω6c; 36.6 %), C16 : 0 (25.9 %) and summed feature 3 (C16 : 1ω7c/C16 : 1ω6c; 21.2 %). The dominant polar lipids were two unknown phospholipids, phosphatidylethanolamine and phosphatidylglycerol, and the main respiratory quinones were ubiquinone 9 (Q-9; 89 %) and ubiquinone 8 (Q-8; 10 %). The genomic DNA G+C content was 61.7 ± 0.8 mol% (Tm). On the basis of phenotypic, chemotaxonomic and phylogenetic features, strain BZ-SZ-XJ27T is proposed to represent a novel species, Halomonas urumqiensis sp. nov., within the genus Halomonas of the family Halomonadaceae. The type strain is BZ-SZ-XJ27T ( = JCM 30202T = CGMCC 1.12917T).

Halomonas zincidurans sp. nov., a heavy-metal-tolerant bacterium isolated from the deep-sea environment

A Gram-stain-negative, aerobic, rod-like, motile by peritrichous flagella and moderately halophilic bacterium, designated strain B6(T), was isolated a deep-sea sediment collected from the South Atlantic Ocean. The isolate grew with 0.5-15 % (w/v) NaCl, at 4-37 °C and pH 5.0-8.5 and showed a high tolerance to zinc, manganese, cobalt and copper ions. The major fatty acids were C16 : 0, C19 : 0 cyclo ω8c, C12 : 0 3-OH and C12 : 0. The predominant ubiquinone was Q-9. The genomic DNA G+C content was 61.1 mol%. Phylogenetic analysis based on 16S rRNA gene comparisons indicated that strain B6(T) belonged to the genus Halomonas, and the closest relative was Halomonas xinjiangensis TRM 0175(T) (96.1 %). Based upon the phenotypic, chemotaxonomic and genetic data, strain B6(T) represents a novel species from the genus Halomonas, for which the name Halomonas zincidurans sp. nov. is proposed. The type strain is B6(T) ( = CGMCC 1.12450(T) = JCM 18472(T)).

Quorum sensing in some representative species of halomonadaceae

Cell-to-cell communication, or quorum-sensing (QS), systems are employed by bacteria for promoting collective behaviour within a population. An analysis to detect QS signal molecules in 43 species of the Halomonadaceae family revealed that they produced N-acyl homoserine lactones (AHLs), which suggests that the QS system is widespread throughout this group of bacteria. Thin-layer chromatography (TLC) analysis of crude AHL extracts, using Agrobacterium tumefaciens NTL4 (pZLR4) as biosensor strain, resulted in different profiles, which were not related to the various habitats of the species in question. To confirm AHL production in the Halomonadaceae species, PCR and DNA sequencing approaches were used to study the distribution of the luxI-type synthase gene. Phylogenetic analysis using sequence data revealed that 29 of the species studied contained a LuxI homolog. Phylogenetic analysis showed that sequences from Halomonadaceae species grouped together and were distinct from other members of the Gammaproteobacteria and also from species belonging to the Alphaproteobacteria and Betaproteobacteria.

Halomonas ramblicola sp. nov., a moderately halophilic bacterium from Rambla Salada, a Mediterranean hypersaline rambla

A moderately halophilic bacterium (strain RS-16T) was isolated from saline soil in Rambla Salada, a Mediterranean hypersaline rambla in Murcia, south-east Spain. Cells of strain RS-16T were Gram-negative rods, oxidase-negative and motile by peritrichous flagella. Strain RS-16T required NaCl for growth, and grew between 1 % and 30 % (w/v) NaCl (optimum, 5–7.5 %), at temperatures of between 4 °C and 41 °C (optimum, 32–37 °C), and at pH values of between 5 and 10 (optimum, pH 7). Strain RS-16T was chemo-organotrophic and its metabolism was respiratory with oxygen and nitrate as terminal electron acceptors. It produced acids from d-glucose and myo-inositol, accumulated poly-β-hydroxyalkanoate granules and produced cream colonies on MY 7.5 % (w/v). The DNA G+C content of strain RS-16T was 56.2 mol%. A comparison of 16S rRNA gene sequences confirmed the relationship of strain RS-16T to species of the genus Halomonas . The most phylogenetically related species was Halomonas cerina SP4T (97.4 %16S rRNA gene sequence similarity). In DNA–DNA hybridization assays strain RS-16T showed DNA–DNA relatedness values of 62.7±3.09 %, 64.5±1.97 % and 64.7±1.74 % to Halomonas cerina CECT 7282T, Halomonas cerina CECT 7284 and Halomonas cerina CECT 7283, respectively. The major fatty acids of strain RS-16T were C18 : 1ω7c and C16 : 0, and the predominant respiratory lipoquinone was ubiquinone, with nine isoprene units (Q-9). On the basis of these data, strain RS-16T is considered to represent a novel species of the genus Halomonas , for which the name Halomonas ramblicola sp. nov. is proposed. The type strain is RS-16T ( = CECT 7896T = LMG 26647T).

Phylogenetic diversity of bacterial and archaeal communities inhabiting the saline Lake Red located in Sovata, Romania

Lake Red is one of the saline lakes which were formed as a consequence of salt massif dissolution at the foot of the Gurghiu Mountains (Central Romania) at the end of the nineteenth century. The lake water had approximately 15 % w/v salt content. Phylogenetic diversity of prokaryotes inhabiting the water and sediment of the lake was studied using cultivation and cultivation-independent methods following a sampling in spring 2009. According to the results of 16S rRNA gene-based denaturing gradient gel electrophoresis (DGGE), the richness of Bacteria was higher than Archaea on the basis of the number and position of dominant bands in the gel. Sequences from DGGE bands were affiliated with Gammaproteobacteria (Halomonas and Alkalilimnicola) and Bacteroidetes (Psychroflexus) as well as Euryarchaeota. Cultivation from five different saline media resulted in 101 bacterial strains of which Gammaproteobacteria (Halomonas, Marinobacter and Salinivibrio) were the most abundant. Firmicutes (Bacillus) and Alphaproteobacteria (Aurantimonas and Roseovarius) were also identified among the isolated strains. The 16S rRNA genes from 82 bacterial and 95 archaeal clones were also phylogenetically analyzed. Bacterial clones were related to various genera of Gammaproteobacteria (Alkalilimnicola, Alkalispirillum, Arhodomonas, Halomonas, Saccharospirillum), Bacteroidetes (Gracilimonas, Psychroflexus) and Alphaproteobacteria (Oceanicola, Roseinatronobacter, Roseovarius). All of the archaeal clones sequenced corresponded to a homologous cluster affiliated with Halopelagius.

Halomonas cibimaris sp. nov., isolated from jeotgal, a traditional Korean fermented seafood

Two moderately halophilic, facultatively aerobic, motile bacteria with flagella, designated strains 10-C-3(T) and 30-C-3, were isolated from jeotgal, a traditional Korean fermented seafood. Cells of the strains were observed to be ovoid-rods showing catalase- and oxidase-positive reactions and production of creamy-pink pigments. Growth of strain 10-C-3(T) was observed at 15-35 °C (optimum, 25-30 °C), at pH 5.5-9.0 (optimum, pH 7.0-7.5), and in the presence of 3-15 % (w/v) salts (optimum: 5-10 %). The two strains were found to contain C(18:1) ω7c, C(16:0), summed feature 3 (as defined by the MIDI system, comprising C(16:1) ω7c and/or C(16:1) ω6c), and C(12:0) 3-OH as the major cellular fatty acids. The G+C contents of the genomic DNA of strains 10-C-3(T) and 30-C-3 were determined to be 63.2 and 63.1 mol%, respectively and the respiratory quinone detected was ubiquinone 9 (Q-9) only. Phylogenetic analyses based on 16S rRNA gene sequences indicated that strains 10-C-3(T)and 30-C-3 formed a distinct phyletic lineage within the genus Halomonas and are most closely related to Halomonas fontilapidosi 5CR(T) with 95.2 % of 16S rRNA sequence similarity. Strains 10-C-3(T)and 30-C-3 shared 99.2 % of 16S rRNA gene sequence similarity and their DNA-DNA relatedness value was 96.6 ± 0.9 %. On the basis of phenotypic, chemotaxonomic and molecular features, strains 10-C-3(T)and 30-C-3 represent a novel species of the genus Halomonas, for which the name Halomonas cibimaris sp. nov. is proposed. The type strain is 10-C-3(T) (= KACC 14932(T) = JCM 16914(T)).

The potential biotechnological applications of the exopolysaccharide produced by the halophilic bacterium Halomonas almeriensis

We have studied the extracellular polysaccharide (EPS) produced by the type strain, M8(T), of the halophilic bacterium Halomonas almeriensis, to ascertain whether it might have any biotechnological applications. All the cultural parameters tested influenced both bacterial growth and polysaccharide production. EPS production was mainly growth-associated and under optimum environmental and nutritional conditions M8(T) excreted about 1.7 g of EPS per litre of culture medium (about 0.4 g of EPS per gram of dry cell weight). Analysis by anion-exchange chromatography and high-performance size-exclusion chromatography indicated that the exopolysaccharide was composed of two fractions, one of 6.3 × 10(6) and another of 1.5 × 10(4) Daltons. The monosaccharide composition of the high-molecular-weight fraction was mannose (72% w/w), glucose (27.5% w/w) and rhamnose (0.5% w/w). The low-molecular-weight fraction contained mannose (70% w/w) and glucose (30% w/w). The EPS has a substantial protein fraction (1.1% w/w) and was capable of emulsifying several hydrophobic substrates, a capacity presumably related to its protein content. The EPS produced solutions of low viscosity with pseudoplastic behaviour. It also had a high capacity for binding some cations. It contained considerable quantities of sulphates (1.4% w/w), an unusual feature in bacterial polysaccharides. All these characteristics render it potentially useful as a biological agent, bio-detoxifier and emulsifier.

Halomonas stenophila sp. nov., a halophilic bacterium that produces sulphate exopolysaccharides with biological activity

We have undertaken a polyphasic taxonomic study of two halophilic, Gram-negative bacterial strains, N12T and B-100, that produce sulphated exopolysaccharides with biological activity. They were isolated from two different saline soil samples. Both strains grow at NaCl concentrations within the range 3–15 % (w/v) [optimum 5–10 % (w/v)], at 15–37 °C (optimum 20–32 °C) and at pH 6–8 (optimum pH 7–8). Their 16S rRNA gene sequences indicate that they belong to the genus Halomonas in the class Gammaproteobacteria. Their closest relative is Halomonas nitroreducens, to which our strains show maximum 16S rRNA gene sequence similarity values of 98.7 % (N12T) and 98.3 % (B-100). Their DNA G+C contents are 61.9 and 63.8 mol%, respectively. The results of DNA–DNA hybridizations showed 43.9 % relatedness between strain N12T and H. nitroreducens CECT 7281T, 30.5 % between N12T and Halomonas ventosae CECT 5797T, 39.2 % between N12T and Halomonas fontilapidosi CECT 7341T, 46.3 % between N12T and Halomonas maura CECT 5298T, 52.9 % between N12T and Halomonas saccharevitans LMG 23976T, 51.3 % between N12T and Halomonas koreensis JCM 12237T and 100 % between strains N12T and B-100. The major fatty acids of strain N12T are C12 : 0 3-OH (5.42 %), C15 : 0 iso 2-OH/C16 : 1ω7c (17.37 %), C16 : 0 (21.62 %) and C18 : 1ω7c (49.19 %). The proposed name for the novel species is Halomonas stenophila sp. nov. Strain N12T ( = CECT 7744T  = LMG 25812T) is the type strain.

Halomonas daqiaonensis sp. nov., a moderately halophilic, denitrifying bacterium isolated from a littoral saltern

Two novel Gram-negative, oxidase- and catalase-positive, rod-shaped bacterial strains, designated YCSA28T and YCSA39, were isolated from sediment of Daqiao saltern, Jimo, Qingdao, on the east coast of China. The two strains grew optimally at 28–30 °C, at pH 7.5 and in the presence of 7–8 % (w/v) NaCl. They were assigned to the genus Halomonas, class Gammaproteobacteria, based on 16S rRNA gene sequence analysis. The major cellular fatty acids of the two strains were C18 : 1ω7c (42.9 %), C16 : 0 (23.1 %) and C16 : 1ω7c/ω6c (18.0 %), and Q-9 was the major ubiquinone. The G+C content of the DNA of strains YCSA28T and YCSA39 was 63.7 and 63.9 mol%, respectively. The predominant respiratory lipoquinone, cellular fatty acid profiles and DNA G+C content of strains YCSA28T and YCSA39 were consistent with those of recognized species of the genus Halomonas. Levels of DNA–DNA relatedness between strains YCSA28T and YCSA39, between YCSA28T and Halomonas ventosae Al12T, and between YCSA39 and H. ventosae Al12T were 95, 45 and 50 %, respectively. Together, these data indicated that strains YCSA28T and YCSA39 represent a single novel species of the genus Halomonas, for which the name Halomonas daqiaonensis sp. nov. is proposed. The type strain is YCSA28T ( = CGMCC 1.9150T  = NCCB 100305T  = MCCC 1B00920T).

Halomonas titanicae sp. nov., a halophilic bacterium isolated from the RMS Titanic

A Gram-negative, heterotrophic, aerobic, non-endospore-forming, peritrichously flagellated and motile bacterial strain, designated BH1T, was isolated from samples of rusticles, which are formed in part by a consortium of micro-organisms, collected from the RMS Titanic wreck site. The strain grew optimally at 30–37 °C, pH 7.0–7.5 and in the presence of 2–8 % (w/v) NaCl. We carried out a polyphasic taxonomic study in order to characterize the strain in detail. Phylogenetic analyses based on 16S rRNA gene sequence comparison indicated that strain BH1T clustered within the branch consisting of species of Halomonas. The most closely related type strains were Halomonas neptunia (98.6 % 16S rRNA sequence similarity), Halomonas variabilis (98.4 %), Halomonas boliviensis (98.3 %) and Halomonas sulfidaeris (97.5 %). Other closely related species were Halomonas alkaliphila (96.5 % sequence similarity), Halomonas hydrothermalis (96.3 %), Halomonas gomseomensis (96.3 %), Halomonas venusta (96.3 %) and Halomonas meridiana (96.2 %). The major fatty acids of strain BH1T were C18 : 1 ω7c (36.3 %), C16 : 0 (18.4 %) and C19 : 0 cyclo ω8c (17.9 %). The DNA G+C content was 60.0 mol% (T m). Ubiquinone 9 (Q-9) was the major lipoquinone. The phenotypic features, fatty acid profile and DNA G+C content further supported the placement of strain BH1T in the genus Halomonas. DNA–DNA hybridization values between strain BH1T and H. neptunia CECT 5815T, H. variabilis DSM 3051T, H. boliviensis DSM 15516T and H. sulfidaeris CECT 5817T were 19, 17, 30 and 29 %, respectively, supporting the differential taxonomic status of BH1T. On the basis of the phenotypic, chemotaxonomic and phylogenetic data, strain BH1T is considered to represent a novel species, for which the name Halomonas titanicae sp. nov. is proposed. The type strain is BH1T (=ATCC BAA-1257T =CECT 7585T =JCM 16411T =LMG 25388T).