Genome analysis of a halophilic bacterium Halomonas malpeensis YU-PRIM-29T reveals its exopolysaccharide and pigment producing capabilities

Halomonas malpeensis strain YU-PRIM-29T is a yellow pigmented, exopolysaccharide (EPS) producing halophilic bacterium isolated from the coastal region. To understand the biosynthesis pathways involved in the EPS and pigment production, whole genome analysis was performed. The complete genome sequencing and the de novo assembly were carried out using Illumina sequencing and SPAdes genome assembler (ver 3.11.1) respectively followed by detailed genome annotation. The genome consists of 3,607,821 bp distributed in 18 contigs with 3337 protein coding genes and 53% of the annotated CDS are having putative functions. Gene annotation disclosed the presence of genes involved in ABC transporter-dependent pathway of EPS biosynthesis. As the ABC transporter-dependent pathway is also implicated in the capsular polysaccharide (CPS) biosynthesis, we employed extraction protocols for both EPS (from the culture supernatants) and CPS (from the cells) and found that the secreted polysaccharide i.e., EPS was predominant. The EPS showed good emulsifying activities against the petroleum hydrocarbons and its production was dependent on the carbon source supplied. The genome analysis also revealed genes involved in industrially important metabolites such as zeaxanthin pigment, ectoine and polyhydroxyalkanoate (PHA) biosynthesis. To confirm the genome data, we extracted these metabolites from the cultures and successfully identified them. The pigment extracted from the cells showed the distinct UV-Vis spectra having characteristic absorption peak of zeaxanthin (λmax 448 nm) with potent antioxidant activities. The ability of H. malpeensis strain YU-PRIM-29T to produce important biomolecules makes it an industrially important bacterium.

Significance of allochthonous brackish water Halomonas sp. on biodegradation of low and high molecular weight polycyclic aromatic hydrocarbons

The present study is aimed to isolate and identify polycyclic aromatic hydrocarbons (PAHs) degrading bacteria from brackish water and to assess the biodegradation efficiency against low and high molecular weight PAHs. Among 15 isolates, the isolate designated as RM effectively degraded 100 mg/L of phenanthrene (Phe) (67.0%), pyrene (Pyr) (63.0%), naphthalene (NaP) (60.0%), and benzo [a]pyrene (BaP) (58.0%) after 7 days of incubation. Carbon sources, pH, and salinity of the culture medium were optimized to enhance the growth and PAHs biodegradation of the isolate RM. Sucrose was found to be an excellent carbon source to enhance PAHs biodegradation (Phe, 75.0; Pyr, 68.5; NaP, 62.5; and BaP, 59.5%). Furthermore, the isolate showed enhanced degradation at pH 7.0 and 4% salinity. The isolate RM was identified as Halomonas sp. based on partial 16S rDNA gene sequence analysis. The results indicated that the isolate RM (i.e., Halomonas sp.) has the potential to be used in remediation of oil spills in the marine ecosystem.

Biocharacteristics and draft genome sequence of Halomonas hydrothermalis C22, a pyruvate-producing halophilic bacterium isolated from a commercial Spirulina culture in Vietnam

Halophilic bacteria are receiving increasing attention for industrial chemical production processes due to their unique properties. Herein, an alkaliphilic and halophilic bacterium was isolated from a commercial Spirulina culture at Nghe An province in Vietnam and found to secrete pyruvate. Pyruvate is widely used as a starting material in the industrial biosynthesis of pharmaceuticals, and is employed for production of crop protection agents, polymers, cosmetics, and food additives. Phenotypic and chemotaxonomic characterization, and the 16S rRNA gene sequence homology with Halomonas hydrothermalis strain DSM 15,725 (99.2%) predicted that the strain belongs to the Halomonas genus, thus we named this strain as H. hydrothermalis strain C22. We investigated the biocharacteristics and capacity of strain C22 and determined the draft genome sequence comprising 3,934,166 bp with a G + C content of 60.2% encoding 3,668 proteins, 58 tRNAs, 9 rRNAs, and 1 tmRNA. Maximal pyruvate secretion reached 51.1 g/l after 84 h of cultivation. The results will facilitate future studies on the genetic and metabolic diversity of halophilic bacteria and expand our understanding of important bioprocesses in this microorganism.

Transport of crude oil and associated microbial populations by washover events on coastal headland beaches

Storm-driven transport of MC252 oil, sand and shell aggregates was studied on a low-relief coastal headland beach in Louisiana, USA including measurement of alkylated PAHs and Illumina sequencing of intra-aggregate microbial populations. Weathering ratios, constructed from alkylated PAH data, were used to assess loss of 3-ring phenanthrenes and dibenzothiophenes relative to 4-ring chrysenes. Specific aggregate types showed relatively little weathering of 3-ring PAHs referenced to oil sampled near the Macondo wellhead with the exception of certain SRBs sampled from the supratidal environment and samples from deposition areas north of beach. Aggregates mobilized by these storm-driven washover events contains diverse microbial populations dominated by the class Gammaproteobacteria including PAH-degrading genera such as Halomonas, Marinobacter and Idiomarina. Geochemical assessment of porewater in deposition areas, weathering observations, and microbial data suggest that storm remobilization can contribute to susceptibility of PAHs to biodegradation by moving oil to beach microenvironments with more favorable characteristics. (149).

Peritoneal dialysis-related peritonitis due to Halomonas hamiltonii: A first case report

INTRODUCTION

Halomonas hamiltonii is a Gram-negative, halophilic, motile, and nonspore-forming rod bacterium. Although most Halomonas sp. are commonly found in saline environments, it has rarely been implicated as a cause of human infection. Herein, the authors present a case report of continuous ambulatory peritoneal dialysis (CAPD)-related peritonitis attributed to H hamiltonii.

CASE PRESENTATION

An 82-year-old male patient who had been receiving CAPD therapy presented to an emergency department with complaints of abdominal pain and cloudy dialysate that had persisted for 2 days. The peritoneal dialysate was compatible with CAPD peritonitis, with white blood cell count of peritoneal effluent of 810/mm and neutrophils predominated (60%). Two days after culture on blood agar medium, nonhemolytic pink mucoid colonies showed, with cells showing Gram-negative, nonspore-forming rods with a few longer and larger bacilli than usual were found. We also performed biochemical tests and found negative responses in K/K on the triple sugar iron test and H2S and equivocal (very weak) response in the motility test, but positive responses to catalase, oxidase, and urease tests. The partial sequence of the 16S rRNA gene of a bacterium detected by peritoneal fluid culture was utilized for a Basic Local Alignment Search Tool search, which revealed that the organism was H hamiltonii. Intraperitoneal antibiotics were administered for 21 days, and the patient was discharged without clinical problems.

CONCLUSION

We present here the first case report of CAPD-related peritonitis caused by H hamiltonii, which was identified using molecular biological techniques. Although guidelines do not exist for the treatment of infections caused by this organism, conventional treatment for Gram-negative organisms could be effective.

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).

Isolation of Radiation-Resistant Bacteria from Mars Analog Antarctic Dry Valleys by Preselection, and the Correlation between Radiation and Desiccation Resistance

Extreme radiation-resistant microorganisms can survive doses of ionizing radiation far greater than are present in the natural environment. Radiation resistance is believed to be an incidental adaptation to desiccation resistance, as both hazards cause similar cellular damage. Desert soils are, therefore, promising targets to prospect for new radiation-resistant strains. This is the first study to isolate radiation-resistant microbes by using gamma-ray exposure preselection from the extreme cold desert of the Antarctic Dry Valleys (a martian surface analogue). Halomonads, identified by 16S rRNA gene sequencing, were the most numerous survivors of the highest irradiation exposures. They were studied here for the first time for both their desiccation and irradiation survival characteristics. In addition, the association between desiccation and radiation resistance has not been investigated quantitatively before for a broad diversity of microorganisms. Thus, a meta-analysis of scientific literature was conducted to gather a larger data set. A strong correlation was found between desiccation and radiation resistance, indicating that an increase in the desiccation resistance of 5 days corresponds to an increase in the room-temperature irradiation survival of 1 kGy. Irradiation at -79°C (representative of average martian surface temperatures) increases the microbial radiation resistance 9-fold. Consequently, the survival of the cold-, desiccation-, and radiation-resistant organisms isolated here has implications for the potential habitability of dormant or cryopreserved life on Mars.

KEY WORDS

Extremophiles-Halomonas sp.-Antarctica-Mars-Ionizing radiation-Cosmic rays.

Partial characterization of an extracellular polysaccharide produced by the moderately halophilic bacterium Halomonas xianhensis SUR308

A moderately halophilic bacterium, Halomonas xianhensis SUR308 (Genbank Accession No. KJ933394) was isolated from a multi-pond solar saltern at Surala, Ganjam district, Odisha, India. The isolate produced a significant amount (7.87 g l(-1)) of extracellular polysaccharides (EPS) when grown in malt extract-yeast extract medium supplemented with 2.5% NaCl, 0.5% casein hydrolysate and 3% glucose. The EPS was isolated and purified following the conventional method of precipitation and dialysis. Chromatographic analysis (paper, GC and GC-MS) of the hydrolyzed EPS confirmed its heteropolymeric nature and showed that it is composed mainly of glucose (45.74 mol%), galactose (33.67 mol %) and mannose (17.83 mol%). Fourier-transform infrared spectroscopy indicated the presence of methylene and carboxyl groups as characteristic functional groups. In addition, its proton nuclear magnetic resonance spectrum revealed functional groups specific for extracellular polysaccharides. X-ray diffraction analysis revealed the amorphous nature (CIxrd, 0.56) of the EPS. It was thermostable up to 250 °C and displayed pseudoplastic rheology and remarkable stability against pH and salts. These unique properties of the EPS produced by H. xianhensis indicate its potential to act as an agent for detoxification, emulsification and diverse biological activities.

A novel cold-adapted β-galactosidase isolated from Halomonas sp. S62: gene cloning, purification and enzymatic characterization

A novel 1,170 bp β-galactosidase gene sequence from Halomonas sp. S62 (BGalH) was identified through whole genome sequencing and was submitted to GenBank (Accession No. JQ337961). The BGalH gene was heterologously expressed in Escherichia coli BL21(DE3) cells, and the enzymatic properties of recombinant BGalH were studied. According to the polyacrylamide gel electrophoresis results and the sequence alignment analysis, BGalH is a dimeric protein and cannot be classified into one of the known β-galactosidase families (GH1, GH2, GH35, GH42). The optimal pH and temperature were determined to be 7.0 and 45 °C, respectively; the K m and K cat were 2.9 mM and 390.3 s(-1), respectively, for the reaction with the substrate ortho-nitrophenyl-β-D-galactopyranoside. At 0-20 °C, BGalH exhibited 50-70 % activity relative to its activity under the optimal conditions. BGalH was stable over a wide range of pHs (6.0-8.5) after a 1 h incubation (>93 % relative activity) and was thermostable at 50 °C and below (>60 % relative activity). The enzyme hydrolyzes lactose completely in milk over 24 h at 7 °C. The characteristics of this novel β-galactosidase suggest that BGalH may be a good candidate for medical researches and food industry applications.

[Microbial community structure and distribution characteristics in oil contaminated soil]

Molecular biology methods such as PCR-DGGE combined with phylogenetic analysis were used for the soil microbial community structure and distribution profiling. Relationship of microbial community structure and distribution differed in a typical oil contaminated field was studied. Results showed that soil oil content was the main factor to the difference of microbial community structure similarity. The similarity index of microbial community structure and oil content had a significantly negative correlation. The contaminated soil microorganism genus had an uneven distribution. Thus, soil pollution had obvious stress and differentiation for microbial community structure and species relationship. Dominant species in oil contaminated soil were identified as Gulosibacter, Halomonas, Petrobacter, Methylocystis, and Pseudoalteromonas. The findings provide a basis for understanding the microbial characteristics of oil contaminated soil.

Halomonas sp. OKOH--a marine bacterium isolated from the bottom sediment of Algoa Bay--produces a polysaccharide bioflocculant: partial characterization and biochemical analysis of its properties

A bioflocculant-producing bacterium isolated from seawater was identified based on 16S rRNA gene nucleotide sequence to have 99% similarity to that of Halomonas sp. Au160H and the nucleotide sequence was deposited as Halomonas sp. OKOH (Genbank accession number is HQ875722). Influences of carbon source, nitrogen source, salt ions and pH on flocculating activity were investigated. The bioflocculant was optimally produced when glucose (87% flocculating activity) and urea (88% flocculating activity) were used as sources of carbon and nitrogen, respectively. Also, initial pH of 7.0 and Ca²⁺ supported optimal production of the bioflocculant with flocculating activities of 87% respectively. Chemical analyses revealed the bioflocculant to be a polysaccharide.

Halomonas sp. nov., an EPA-producing mesophilic marine isolate from the Indian Ocean

Marine samples from the Indian Ocean were used to isolate and characterize the organisms with respect to their fatty acid profiles. Six mesophilic isolates (MBRI 6, MBRI 8, MBRI 9, MBRI 10, MBRI 12 and MBRI 13) were obtained from three different water samples. They were i) Gram-negative, ii) catalase positive, iii) produced acid from glucose and maltose, iv) tolerated 5 to 15% NaCI v) except MBRI 9, showed pH tolerance in the range of 5.0 to 9.0 with optimum pH 7.0 to 8.0 v) grew well at 30 degrees C and were able to grow in the range of 15 to 45 degrees C. EPA, an essential omega-3 fatty acid, was produced by these isolates in the range of 12 to 60% at 30 degrees C. MBRI 12 was found to be a potential source as it produced 60% EPA. This isolate was further identified by partial 16S rDNA sequencing and phylogenetic analysis revealed that the strain belonged to Gammaproteobacteria and was closely related to Halomonas bolviensis (96% sequence similarity, 570 bp). Thus a new genus of Halomonas may be included in earlier reported EPA- producing prokaryotic genera affiliated to the Gammaproteobacteria.

Production and characterization of a biodegradable poly (hydroxybutyrate-co-hydroxyvalerate) (PHB-co-PHV) copolymer by moderately haloalkalitolerant Halomonas campisalis MCM B-1027 isolated from Lonar Lake, India

Several microorganisms produce polyhydroxyalkanoates (PHA). They are accumulated intracellularly as energy storage compounds. The PHAs are of interest because of their potential in biomedical applications. Halophilic bacteria and archaea are known to produce polyhydroxybutyrate (PHB). This paper describes production of a biodegradable copolymer, PHB-co-PHV by a moderately haloalkalitolerant Halomonas campisalis, isolated from Lonar Lake, India. The production of PHA was in the range of 45-81% on dry cell weight basis when the organism was grown in a production medium containing 1% (w/v) maltose and 0.1% (w/v) yeast extract, at pH ranging from 6 to 9 with an inoculum density of 10(5)-10(7) cells/ml of medium, for incubation period of 15-30 h and at 37 degrees C. The polymer produced by the organism is a hydroxyester with molecular weight of 1.3014 x 10(6). Its melting temperature was 171 degrees C. The (1)H NMR analysis revealed that the polymer was a copolymer of PHB-co-PHV. This could be achieved by providing simple carbon source viz. maltose.

An exopolysaccharide produced by the novel halophilic bacterium Halomonas stenophila strain B100 selectively induces apoptosis in human T leukaemia cells

Microbial exopolysaccharides (EPSs) are highly heterogeneous polymers produced by fungi and bacteria and have recently been attracting considerable attention from biotechnologists because of their potential applications in many fields, including biomedicine. We have screened the antitumoural activity of a panel of sulphated EPSs produced by a newly discovered species of halophilic bacteria. We found that the novel halophilic bacterium Halomonas stenophila strain B100 produced a heteropolysaccharide that, when oversulphated, exerted antitumoural activity on T cell lines deriving from acute lymphoblastic leukaemia (ALL). Only tumour cells were susceptible to apoptosis induced by the sulphated EPS (B100S), whilst primary T cells were resistant. Moreover, freshly isolated primary cells from the blood of patients with ALL were also susceptible to B100S-induced apoptosis. The newly discovered B100S is therefore the first bacterial EPS that has been demonstrated to exert a potent and selective pro-apoptotic effect on T leukaemia cells, and thus, we propose that the search for new antineoplastic drugs should include the screening of other bacterial EPSs, particularly those isolated from halophiles.

Metabolic versatility of halotolerant and alkaliphilic strains of Halomonas isolated from alkaline black liquor

Wheat straw black liquor is a notorious pulp mill wastewater with very high pH and pollution load. Two halotolerant and alkaliphilic bacteria, designated as Halomonas sp. 19-A and Y2, were isolated from wheat straw black liquor and shown to be able to use guaiacol, vanillin, dibenzo-p-dioxin, biphenyl and fluorene, as sole carbon and carbazole as sole carbon and nitrogen source at pH 9.5 and in the presence of 10% NaCl. The two strains produced carboxymethylcellulase (CMCase), xylanase, lipase, amylase, and pullulanase. High activities of CMCase, xylanase, and amylase were observed at pH 5.0-11.0 and NaCl concentrations of 0-15%. The metabolic versatility of these Halomonas strains even under extreme pH and salinity conditions makes them promising agents for bioremediation and industrial processes.

Salt-adapted bacteria isolated from the Rouge River and potential for degradation of contaminants and biotechnological applications

The current work extends the phenotypic and molecular characterization of the bacterial culture collection from the Rouge River to gain an understanding of the physiology of the strains and their potential for biotechnological applications. Phenotypic and molecular analyses were performed on six unique strains. Most of the strains tested for hydrolytic activities were positive for the production of enzymes, in contrast to previously described species that showed very little hydrolase activities. Little antibiotic resistance was seen among the strains, although Halobacillus (strain 9-gw1-su5-2) was found to be the most resistant to antibiotics. Results revealed the physiological diversity of the strains in terms of their ability to metabolize unusual and refractory substrates. Of the 31 toxic organic compounds, 2 to 18 were used by the strains. Clostridium (strain 9-gw1-su5-2) exhibited the broadest utilization capability. The isolates were versatile in their nutrient abilities and represented a potential source of bacteria and/or genetic material for the degradation of contaminants and biotechnological applications.

Effect of salinity on vanadate biosorption by Halomonas sp. GT-83: preliminary investigation on biosorption by micro-PIXE technique

Thirty-eight soil samples were collected from crude oil contaminated land in south of Iran. Initial screening of a total of 100 bacterial isolates, resulted in the selection of one isolate with maximum adsorption capacity of 52.7 mg vanadate/g dry weight. It was tentatively identified as Halomonas sp. according to morphological and biochemical properties and named strain GT-83. Removal of vanadate by biosorption with Halomonas sp. GT-83 was very sensitive to solution pH. Vanadate adsorption decreased with increasing pH, with maximum adsorption capacities achieved in at pH 3.0 in the absence and in the presence of increasing concentrations of salt. Vanadate-salt biosorption studies were also performed at this pH value. Equilibrium uptakes of vanadate increased with increasing vanadate concentration up to 600 mg/l. Maximum metal removal (91.8%) took place at pH 3.0 with initial vanadate concentration of 100mg/l, which got reduced (84.8%) in the presence of 50 g/l salt. The equilibrium sorption data were analyzed by using Freundlich isotherm. The specific uptake of vanadate increased at low cell concentration and decreased when cell concentration exceeded 0.75 g/l. The paper also demonstrates the potential value of micro-PIXE in biosorption studies.

[Halomonas chromatireducens sp. nov., a new denitrifying facultatively haloalkaliphilic bacterium from soda salt marshes capable of aerobic chromate reduction]

A heterotrophic bacterial strain AGD 8-3 capable of denitrification under extreme haloalkaline conditions was isolated from soda solonchak soils of the Kulunda steppe (Russia). The strain was classified within the genus Halomonas. According to the results of 16S rRNA gene sequencing, Halomonas axialensis, H. meridiana, and H. aquamarina are most closely related to strain AGD 8-3 (96.6% similarity). Similar to other members of the genus, the strain can grow within a wide range of salinity and pH. The strain was found to be capable of aerobic reduction of chromate and selenite on mineral media at 160 g/l salinity and pH 9.5-10. The relatively low level of phylogenetic similarity and the phenotypic characteristics supported classification of strain AGD 8-3 as a new species Halomonas chromatireducens.

[Halomonas mongoliensis sp. nov. and Halomonas kenyensis sp. nov., new haloalkaliphilic denitrifiers capable of reducing N2O, isolated from soda lakes]

In the course of the search for N2O-utilizing microorganisms, two novel strains of haloalkaliphilic denitrifying bacteria, Z-7009 and AIR-2, were isolated from soda lakes of Mongolia and Kenya. These microorganisms are true alkaliphiles and grow in the pH ranges of 8.0-10.5 and 7.5-10.6, respectively. They are facultative anaerobes with an oxidative type of metabolism, able to utilize a wide range of organic substrates and reduce nitrate, nitrous oxide, and, to a lesser extent, nitrite to gaseous nitrogen. They can oxidize sulfide in the presence of acetate as the carbon source and nitrous oxide (strain Z-7009) or nitrate (strain AIR-2) as the electron acceptor. The strains require Na+ ions. They grow at medium mineralization levels of 0.16-2.2 M Na+ (Z-7009) and 0.04-2.2 M Na+ (AIR-2). The G+C contents of the DNA of strains Z-7009 and AIR-2 are 67.9 and 65.5 mol %, respectively. According to the results of 16S rRNA gene sequencing and DNA-DNA hybridization, as well as on the basis of physiological properties, the strains were classified as new species of the genus Halomonas: Halomonas mongoliensis, with the type strain Z-7009T (=DSM 17332, =VKM B2353), and Halomonas kenyensis, with the type strain AIR-2T (=DSM 17331, =VKM B2354).

Halomonas kribbensis sp. nov., a novel moderately halophilic bacterium isolated from a solar saltern in Korea

A moderately halophilic, Gram-negative bacterium, designated strain BH843T, was isolated from a solar saltern in Korea and subjected to a taxonomic analysis. Strain BH843T grew at salinities of 1–14 % (w/v) NaCl and at temperatures of 10–40 °C. The cells were motile cocci or short rods with single flagella and contained C16 : 0, C19 : 0 cyclo ω8c and C17 : 0 cyclo as the major fatty acids. The G+C content of the genomic DNA was 66 mol% and the predominant ubiquinone was Q-9. Comparative 16S rRNA gene sequence analyses showed that strain BH843T formed a distinct phyletic line within the genus Halomonas, and the levels of 16S rRNA gene sequence similarity with respect to recognized Halomonas species were below 95.1 %. The levels of DNA–DNA relatedness between strain BH843T and the type strains of phylogenetically closely related Halomonas species were below 25 %. On the basis of phenotypic, chemotaxonomic and molecular data, strain BH843T represents a novel species within the genus Halomonas, for which the name Halomonas kribbensis is proposed. The type strain is BH843T (=KCTC 12584T=DSM 17892T).

Decolorization of textile azo dyes by newly isolated halophilic and halotolerant bacteria

Studies were carried out on the decolorization of textile azo dyes by newly isolated halophilic and halotolerant bacteria. Among the 27 strains of halophilic and halotolerant bacteria isolated from effluents of textile industries, three showed remarkable ability in decolorizing the widely utilized azo dyes. Phenotypic characterization and phylogenetic analysis based on 16S rDNA sequence comparisons indicate that these strains belonged to the genus Halomonas. The three strains were able to decolorize azo dyes in a wide range of NaCl concentration (up to 20%w/v), temperature (25-40 degrees C), and pH (5-11) after 4 days of incubation in static culture. They could decolorize the mixture of dyes as well as pure dyes. These strains also readily grew in and decolorized the high concentrations of dye (5000 ppm) and could tolerate up to 10,000 ppm of the dye. UV-Vis analyses before and after decolorization and the colorless bacterial biomass after decolorization suggested that decolorization was due to biodegradation, rather than inactive surface adsorption. Analytical studies based on HPLC showed that the principal decolorization was reduction of the azo bond, followed by cleavage of the reduced bond.

Preliminary phenotypic characterization of newly isolated halophilic microorganisms by footprinting: a rapid metabolome analysis

The emerging need for rapid screening and identification methods for microbiological purposes necessitates the combined uses of high-tech instruments. In this work, electrospray ionization mass spectrometry was used to visualize the relation of ten newly isolated moderately halophilic microorganisms, to Halomonas salina DSMZ 5,928 and Halomonas halophila DSMZ 4,770. The method was based on the global analysis of the metabolites in culture media and is termed as metabolic footprinting. Since it was not possible to gain insight into the similarities solely based on the visual inspection of the chromatograms, principal component (PC) analysis was applied on the data. Three PCs alone were able to explain 99% of the information in the data set. The score plots revealed the relation of the new isolates to the two type strains whereas the loading plots gave important clues on the significant ions responsible for the observed clustering. Loading plots also indicated inversely correlated ions that give clues on differing metabolic pathways. The work described here offers a potentially useful way for preliminary rapid phenotypic characterization of new and closely related isolates and a method for screening of similar microorganisms for different and valuable secondary metabolites.

Halomonas avicenniae sp. nov., isolated from the salty leaves of the black mangrove Avicennia germinans in Puerto Rico

A Gram-negative, short rod to oval-shaped bacterium (strain MW2a(T)) was isolated from the surface of leaves of the black mangrove Avicennia germinans and subjected to a polyphasic taxonomic study. Strain MW2a(T) was moderately halophilic, growing at NaCl concentrations in the range 0-25 % (w/v) with optimum growth at 5 % (w/v) NaCl. Growth occurred at 12-40 degrees C (optimum, 30-35 degrees C) and at pH 5.0-9.0 (optimum, pH 7.0-8.0). Strain MW2a(T) was strictly aerobic. Phylogenetic analysis based on the 16S rRNA gene showed that the strain belongs to the genus Halomonas. The closest relative was Halomonas marisflavi, with 98.6 % 16S rRNA gene sequence similarity. The DNA G+C content of strain MW2a(T) was 61.5 mol%, which is in the range of values for Halomonas species. DNA-DNA hybridization with H. marisflavi showed a relatedness of 42 % and lower values were obtained with respect to other related Halomonas species. The major fatty acids were C(16 : 0), C(19 : 0) cyclo omega8c, C(18 : 1)omega7c and C(12 : 0) 3-OH. Overall, the phenotypic, genotypic and phylogenetic results presented in this study demonstrate that strain MW2a(T) represents a novel species within the genus Halomonas. The name Halomonas avicenniae sp. nov. is proposed, with strain MW2a(T) (=CECT 7193(T)=CCM 7396(T)) as the type strain.

Halomonas sinaiensis sp. nov., a novel halophilic bacterium isolated from a salt lake inside Ras Muhammad Park, Egypt

An alkalitolerant and halotolerant bacterium, designated strain Sharm was isolated from a salt lake inside Ras Muhammad. The morphological, physiological and genetic characteristics were compared with those of related species of the genus Halomonas. The isolate grew optimally at pH 7.0, 5-15% NaCl at 35 degrees C. The cells were Gram-negative rods, facultative anaerobes. They accumulated glycine-betaine, as a major osmolyte, and ectoine and glutamate as minor components. The strain Sharm(T) biosynthetised alpha-glucosidase. The polar lipids were phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, and a novel phosphoglycolipid as major components. Ubiquinone with nine repetitive unities (Q9) was the only quinone found and, nC16:0 and C19:0 with cyclopropane were the main cellular fatty acids, accounting for 87.3% of total fatty acids. The G + C content of the genomic DNA was 64.7 mol %. The 16S rRNA sequence analysis indicated that strain Sharm was a member of the genus Halomonas. The closest relatives of the strain Sharm were Halomonas elongata and Halomonas eurihalina. However, DNA-DNA hybridisation results clearly indicated that strain Sham was a distinct species of Halomonas. On the basis of the evidence, we propose to assign strain Sharm as a new species of the genus Halomonas, H. sinaiensis sp. nov, with strain Sharm(T) as the type strain (DSM 18067(T); ATCC BAA-1308(T)).

Halomonas saccharevitans sp. nov., Halomonas arcis sp. nov. and Halomonas subterranea sp. nov., halophilic bacteria isolated from hypersaline environments of China

Three strains of Gram-negative, aerobic, neutrophilic and halophilic bacteria were isolated from samples of a salt lake on the Qinghai–Tibet Plateau and a subterranean saline well in the Si-Chuan Basin of China. These isolates, designated AJ275T, AJ282Tand ZG16T, were investigated using a polyphasic approach. Based on 16S rRNA gene sequence analysis, the isolates could be affiliated to the genusHalomonas. Genomic DNA G+C contents were 65.9 mol% for AJ275T, 56.7 mol% for AJ282Tand 57.6 mol% for ZG16T. The results of DNA–DNA hybridizations, fatty acid analysis and physiological and biochemical tests allowed the isolates to be differentiated genotypically and phenotypically from closely related species. It is proposed that strains AJ275T(=CGMCC 1.6493T=JCM 14606T=LMG 23976T), AJ282T(=CGMCC 1.6494T=JCM 14607T=LMG 23978T) and ZG16T(=CGMCC 1.6495T=JCM 14608T=LMG 23977T) represent the type strains of three novel species in the genusHalomonas:Halomonas saccharevitanssp. nov.,Halomonas arcissp. nov. andHalomonas subterraneasp. nov., respectively.

Moderately halophilic, alkalitolerantHalomonas campisalis MCM B-365 from Lonar Lake, India

Seven bacterial isolates obtained from sediment and water samples, collected from the alkaline Lonar Lake were identified on the basis of their morphological, physiological and biochemical characteristics and were confirmed by 16S rDNA sequencing to be Halomonas campisalis. They were capable of using a variety of electron donors and were found to grow in the presence of sodium chloride (NaCl) up to 4 M, at pH from 7 to 11, 9 being the optimum. The isolates could grow over a wide range of temperatures (from 4 to 45 degrees C) and showed temperature-dependent salt tolerance. They exhibited requirement of sodium for growth and could grow in any medium where NaCl is replaced by NaNO(3) and Na(2)S(2)O(3) but not in the presence of salts like LiCl, MgCl(2) . 6H(2)O, KCl and NH(4)Cl. One of the seven isolates, ARI 351, was able to produce lipase at pH-9.0, while two isolates, ARI 351 and ARI 360, could accumulate polyhydroxyalkanoic acid (PHA) granules when grown in a medium containing maltose. Thus the H. campisalis isolated from Lonar Lake was different from the previously reported one, with respect to its biotechnological potential for production of Lipase and PHA.

Halomonas shengliensis sp. nov., a moderately halophilic, denitrifying, crude-oil-utilizing bacterium

A moderately halophilic bacterium, designated strain SL014B-85T, was isolated from a crude-oil-contaminated saline soil from Shengli oilfield, Shandong Province, China. Cells were Gram-negative, aerobic, short rods with lateral flagella. Growth occurred at NaCl concentrations of 0–15 % (optimum 5–15 %), at 10–42 °C (optimum 30 °C) and at pH 8.0–9.0 (optimum pH 8.5). The only respiratory quinone was Q9, and the main cellular fatty acids were C18 : 1 ω7c, C16 : 0 and C19 : 0 cyclo ω8c. The G+C content of the DNA was 66.6 mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain SL014B-85T belonged to the genus Halomonas in the Gammaproteobacteria, with highest sequence similarity of 98.1 and 97.8 % to Halomonas alimentaria DSM 15356T and Halomonas ventosae DSM 15911T, respectively. DNA–DNA relatedness values were below 40 % with members of closely related Halomonas species. Results of phenotypic, biochemical and phylogenetic analyses revealed that strain SL014B-85T could be classified as representing a novel species of the genus Halomonas, for which the name Halomonas shengliensis sp. nov. is proposed. The type strain is SL014B-85T (=CGMCC 1.6444T=LMG 23897T).

Halomonas gudaonensis sp. nov., isolated from a saline soil contaminated by crude oil

Two moderately halophilic strains, SL014B-69T and SL014B-62A2, were isolated from a saline soil contaminated with crude oil in Gudao in the coastal Shengli oilfield in China; the isolates were Gram-negative, rod-shaped and carried lateral flagella. Growth occurred at NaCl concentrations of 1–20 % (w/v), at temperatures of 10–42 °C and at pH 8.0–9.0. Strain SL014B-69T had C18 : 1 ω7c (28.61 %), C19 : 1 cyclo ω7c (27.97 %), C16 : 0 (19.66 %) and C12 : 0 3-OH (8.87 %) as the predominant fatty acids and Q9 as the major ubiquinone, with the G+C content of genomic DNA being 64.0 mol%. Phylogenetic analyses based on 16S rRNA gene sequences indicated that the two strains belonged to genus of Halomonas in the Gammaproteobacteria, with the highest 16S rRNA gene sequence similarities of 96.4 % with Halomonas campisalis ATCC 700597T and 96.0 % with Halomonas desiderata FB2T. DNA–DNA relatedness of strain SL014B-69T with strain SL014B-62A2, H. campisalis ATCC 700597T and H. desiderata DSM 9502T was 97.4, 42.9 and 36.8 %, respectively. On the basis of these data, a novel species of the genus Halomonas, Halomonas gudaonensis sp. nov., is proposed for strain SL014B-69T and SL014B-62A2. The type strain is SL014B-69T (=LMG 23610T=CGMCC 1.6133T).

Halomonas gomseomensis sp. nov., Halomonas janggokensis sp. nov., Halomonas salaria sp. nov. and Halomonas denitrificans sp. nov., moderately halophilic bacteria isolated from saline water

A total of 34 Halomonas strains were isolated from saline water in Anmyeondo, Korea. Ten of these strains, considered to belong to novel species, were subjected to a polyphasic taxonomic investigation. The strains were Gram-negative, moderately halophilic, motile and non-spore-forming rods that contained Q-9 as the predominant ubiquinone and C18 : 1 ω7c, C16 : 0 and either summed feature 4 (C16 : 1 ω7c/C15 : 0 iso 2-OH) or C19 : 0 cyclo ω8c as the major fatty acids. Phylogenetic analysis, based on 16S rRNA gene sequencing, showed that the ten isolates formed four separate lineages in the genus Halomonas. Combined phenotypic data and DNA–DNA hybridization data supported the conclusion that they represent four novel species in the genus Halomonas, for which the names Halomonas gomseomensis sp. nov. (type strain M12T=KCTC 12662T=DSM 18042T), Halomonas janggokensis sp. nov. (type strain M24T=KCTC 12663T=DSM 18043T), Halomonas salaria sp. nov. (type strain M27T=KCTC 12664T=DSM 18044T) and Halomonas denitrificans sp. nov. (type strain M29T=KCTC 12665T=DSM 18045T) are proposed.

A novel moderately halophilic bacterium for decolorizing azo dye under high salt condition

Halomonas sp strain GTW was newly isolated from coastal sediments contaminated by chemical wastewater and was identified to be a member of the genus Halomonas by 16S rDNA sequence analysis and physical and biochemical tests. The optimal decolorization conditions were as follows: temperature 30 degrees C, pH 6.5.0-8.5, NaCl 10-20% (w/v) and the optimal carbon source was yeast exact. The results of experiments demonstrated that the bacteria could decolorize different azo dyes under high salt concentration conditions, and the decolorization rate of five tested azo dyes could be above 90% in 24 h. The exploitation of the salt-tolerant bacteria in the bio-treatment system would be a great improvement of conventional biological treatment systems and the bio-treatment concept.

Halomonas indalinina sp. nov., a moderately halophilic bacterium isolated from a solar saltern in Cabo de Gata, Almería, southern Spain

A moderately halophilic bacterium, strain CG2.1T, isolated from a solar saltern at Cabo de Gata, a wildlife reserve located in the province of Almería, southern Spain, was subjected to a polyphasic taxonomic study. This organism was an aerobic, motile, Gram-negative rod that produced orange-pigmented colonies. Strain CG2.1T was able to grow at salinities of 3–25 % (w/v) and at temperatures of 15–40 °C. The pH range for growth was 5–9. Strain CG2.1T was a heterotroph capable of utilizing various carbohydrates as carbon sources. The organism reduced nitrate and showed phenylalanine deaminase activity. The major fatty acids were C18 : 1 ω7c, C16 : 0 and C19 : 0 cyclo ω8c. The DNA G+C content was 60.9 mol%. On the basis of the phenotypic and phylogenetic data, strain CG2.1T appeared to be a member of the genus Halomonas and clustered closely with Halomonas marisflavi (97.1 % 16S rRNA gene sequence similarity). However, the level of DNA–DNA relatedness between the novel isolate and the most closely related Halomonas species was low. On the basis of these data, strain CG2.1T represents a novel member of the genus Halomonas, for which the name Halomonas indalinina is proposed. The type strain is CG2.1T (=CECT 5902T=LMG 23625T).

Isolation and characterization of a bacteriophage with an unusually large genome from the Great Salt Plains National Wildlife Refuge, Oklahoma, USA

In this study we present a bacteriophage isolated from the Great Salt Plains National Wildlife Refuge (GSP) that is shown to have a genome size of 340 kb, unusually large for a bacterial virus. Transmission electron microscopy analysis of the virion showed this to be a Myoviridae, the first reported to infect the genus Halomonas. This temperate phage, PhigspC, exhibits a broad host range, displaying the ability to infect two different Halomonas spp. also isolated from the GSP. The phage infection process demonstrates a high level of tolerance towards temperature, pH and salinity; however, free virions are rapidly inactivated in water unless supplemented with salt. We show that susceptibility to osmotic shock is correlated with the density of the packaged DNA (rho(pack)). Lysogens of Halomonas salina GSP21 were detrimental to host fitness at 10% salinity, but the lysogen was able to grow faster than the wild type at 20% salinity. From these results we propose that the extensive genome of PhigspC may encode environmentally relevant genes (ERGs); genes that are perhaps not essential for the phage life cycle but increase host and phage fitness in some environmental conditions.

Antibacterial and antilarval activity of deep-sea bacteria from sediments of the West Pacific Ocean

Deep-sea microorganisms are a new source of bioactive compounds. In this study, crude ethyl acetate extracts of 176 strains of deep-sea bacteria, isolated from sediments of the West Pacific Ocean, were screened for their antibacterial activity against four test bacterial strains isolated from marine biofilms. Of these, 28 deep-sea bacterial strains exhibited antibacterial activity against one or more of the bacteria tested. Active deep-sea bacterial strains belonged mainly to the genera of Pseudomonas, Psychrobacter and Halomonas. Additionally, antilarval activity of 56 deep-sea bacterial strains was screened using Balanus amphitrite larvae. Seven bacterial strains produced metabolites that had strong inhibitive effects on larval settlement. None of these metabolites showed significant toxicity. The crude extract of one deep-sea Streptomyces strain could completely inhibit larval settlement at a concentration of 25 microg ml(-1).

Halomonas alkaliantarctica sp. nov., isolated from saline lake Cape Russell in Antarctica, an alkalophilic moderately halophilic, exopolysaccharide-producing bacterium

The taxomony of strain CRSS (DSM 15686(T)=ATCC BAA-848(T)) isolated from Cape Russell in Antarctica (Ross Sea, 74 52.35 S 163 53.03 E) was investigated in a polyphasic approach. The morphological, physiological and genetic characteristics were compared with that of related species of the genus Halomonas. The isolate grew optimally at pH 9.0, 10% NaCl at 30 degrees C. The cells were Gram-negative aerobic rods able to produce exopolysaccharide. They accumulated glycine-betaine, as a major osmolyte, with minor components ectoine and glutamate. The strain CRSS biosynthetised alpha-glucosidase. The polar lipid profile consisted of phosphatidylethanolamine, phosphatidylglycerol and diphosphatidylglycerol as major components. Ubiquinone with nine repetitive unities (Q9) was the only quinone found and the fatty acid composition was dominated by C18:1 (53%). The G+C content of DNA was 55.0mol% and its phylogenetic position was established by 16S rRNA gene sequencing as a member of the genus Halomonas. For physiological, chemotaxonomic and genetic features (DNA-DNA hybridisation) it is proposed to classify the isolate as a new species for which we propose the name Halomonas alkaliantarctica sp. nov.

Bioconversion of ferulic acid to vanillic acid by Halomonas elongata isolated from table-olive fermentation

Halomonas elongata strain Mar (=CCUG 52759) isolated from table-olive fermentation is the first halophilic bacterium to be shown to transform ferulic acid to vanillic acid under hypersaline conditions. During growth on ferulic acid, this strain was capable of promoting the formation of a significant amount of vanillic acid and trace quantities of vanillin. The products were confirmed by high-performance liquid chromatography and gas chromatography-mass spectrometry analyses. Based on the different metabolites identified, an oxidative side chain degradation pathway of ferulic acid bioconversion to vanillic acid was suggested. Phylogenetic analysis of 16S rRNA gene revealed that this isolated strain Mar was identified as H. elongata. To increase the formation of vanillic acid, a resting cell method using H. elongata strain Mar was performed. The optimal yield of vanillic acid (86%) was obtained after a 6 h reaction using 5 mM of ferulic acid and 4 g of dry weight of cells L(-1) pregrown on ferulic acid and harvested at the end of the exponential phase.

Aerobic removal of technetium by a marine Halomonas strain

A novel strain of Halomonas (Tc-202), which has the capability of removing Tc(VII) from solid- and aqueous-phase material aerobically, was isolated from the marine environment. Tc-202 removed 55% of the total 99Tc in solutions at 15 degrees C by reducing Tc(VII) to Tc(V), but other Halomonas strains did not.

Characterization of sediment bacteria involved in selenium reduction

Bacterial reduction of selenium (Se) oxyanions (Se[VI] and Se[IV]) to elemental Se (Se[0]) is one of the major biogeochemical processes removing Se from agricultural drainage water and depositing Se in the sediment. This study was conducted to characterize Se-reducing bacterial populations in Lost Hills evaporation pond sediment and to observe their response to Se(VI) and organic C amendments. Se(VI) was removed from the dissolved phase in the sediment slurries amended with organic C with a decrease in redox potential (Eh). Se(VI) concentrations decreased from 2137 to 79 microg L-1 after 9 days of incubation in a 5% soil slurry. Upon our screening process, 9 Se(VI)- and 14 Se(IV)-reducing bacteria were isolated from sediment slurries and identified by amplification and sequencing of 16S rDNA. Bacillus strains appeared to be dominant in the bacterial assemblages active in Se(VI) and Se(IV) reduction in the sediment. Halomonas pacifica and Staphylococcus warneri were also identified as Se(IV)-reducers. Indigenous bacteria have a significant role in the biogeochemical cycling of Se and may be stimulated by addition of a suitable organic source for Se reduction. The bacterial strains isolated from salt-affected and Se-contaminated Lost Hills evaporation pond sediment may have potential application in removing Se from high salt drainage water.

Characteristics of bacteria showing high denitrification activity in saline wastewater

AIMS

Denitrification efficiency at 10% salinity was compared with that at 2% salinity. The characteristics of bacterial strains isolated from the denitrification system, where an improvement of denitrification efficiency was observed at a high salinity were investigated.

METHODS AND RESULTS

Two continuous feeding denitrification systems for saline solutions of 2% and 10% salinity, were operated. Denitrification efficiency at 10% salinity was higher than that at 2% salinity. The bacterial strains were isolated using the trypticase soy agar (TSA) medium at 30 degrees C. The phylogenetic analysis of 16S rRNA gene sequences of isolates indicated that halophilic species were predominant at 10% salinity.

CONCLUSIONS

The improvement of denitrification efficiency at a high salinity was demonstrated. The strains isolated from the denitrifying system with 10% salinity were halophilic bacteria, Halomonas sp. and Marinobacter sp., suggesting that these bacteria show a high denitrifying activity at 10% salinity.

SIGNIFICANCE AND IMPACT OF THE STUDY

The long-term acclimated sludge used in this study resulted in high denitrification performance at a high salinity, indicating that the design of a high-performance denitrification system for saline wastewater will be possible.

Isolation and characterization ofHalomonassp. strain IMPC, ap-coumaric acid-metabolizing bacterium that decarboxylates other cinnamic acids under hypersaline conditions

A moderately halophilic, mesophilic, Gram-negative, motile, nonsporulating bacterium, designated strain IMPC, was isolated from a table-olive fermentation rich in aromatic compounds, after enrichment on p-coumaric acid under halophilic conditions. Strain IMPC was able to degrade p-coumaric acid. p-hydroxybenzaldehyde and p-hydroxybenzoic acid were detected as breakdown products from p-coumaric acid. Protocatechuic acid was identified as the final aromatic product of p-coumaric acid catabolism before ring fission. Strain IMPC transformed various cinnamic acids with substituent H, OH, CH(3) or OCH(3) in the para- and/or meta-position of the aromatic ring to the corresponding benzoic acids, indicating a specific selection. A beta-oxidation pathway was proposed for these transformations. Phylogenetic analysis of the 16S rRNA gene revealed that this isolate was a member of the genus Halomonas. Strain IMPC was closely related to Halomonas elongata ATCC 33173(T)and Halomonas eurihalina ATCC 49336(T).

Extremely halophilic denitrifying bacteria from hypersaline inland lakes, Halovibrio denitrificans sp. nov. and Halospina denitrificans gen. nov., sp. nov., and evidence that the genus name Halovibrio Fendrich 1989 with the type species Halovibrio variabilis should be associated with DSM 3050

Anaerobic enrichments with acetate as electron donor and nitrate as electron acceptor at 4 M NaCl from inland, hypersaline lake sediments from Central Asia resulted in the isolation of several extremely halophilic bacteria that comprised two subgroups, most with vibrio-shaped cells and a single strain with rod-shaped cells. Members of both subgroups were extremely halophilic, with growth occurring in 2–5 M NaCl with an optimum at 2–3 M. 16S rRNA gene sequence analysis showed a close affiliation of the new isolates with Pseudomonas halophila DSM 3050 in the Gammaproteobacteria. However, phenotypic comparison of the denitrifying halophiles with the original description of P. halophila demonstrated that they were more similar to another bacterium isolated from the same source at the same time, the extremely halophilic Halovibrio variabilis, which has since been reclassified as Halomonas variabilis (DSM 3051). Direct cross-comparison showed that the characteristics of these two halophilic bacteria do not correspond with the original descriptions associated with these names and DSM numbers. While it is desirable that this problem be solved, in connection with the present investigations, this is a matter that can only be solved by a Request for an Opinion. On the basis of the phenotypic and genetic comparison of these isolates, it is proposed that the new denitrifying vibrio-shaped isolates represent a novel species, Halovibrio denitrificans sp. nov. (type strain HGD 3T=DSM 15503T=UNIQEM U232T) and that the rod-shaped isolate represents a novel genus and species, Halospina denitrificans gen. nov., sp. nov. (type strain HGD 1-3T=DSM 15505T=UNIQEM U233T).

Halomonas alkaliphila sp. nov., a novel halotolerant alkaliphilic bacterium isolated from a salt pool in Campania (Italy)

A halotolerant and alkaliphilic Gram-negative bacterium, strain 18bAG(T), that grows aerobically at the optimum temperature of 37 degrees C, and at pH 7.5-10 (optimum 9.0), was isolated from a salt pool located in Montefredane in Campania Region (South of Italy). The isolate tolerated high concentration of NaCl up to 20%. Strain 18bAG(T) accumulated osmolytes and polyhydroxybutyrate, produced exopolysaccharide and possessed alpha-glucosidase activity. The predominant respiratory quinones were ubiquinones, Q8 and Q6(6H); phosphoethanolamine, phosphatidylglycerol and diphosphatidylglycerol were the predominant polar lipids. Major fatty acids were C16 : 1, C16 : 0, and C18 : 0. On the basis of 16S rRNA gene sequence similarity, 18bAG(T) was shown to belong to Halomonas genus. Analysis of 16S rRNA gene revealed a high similarity of strain 18bAG(T) to Halomonas venusta (DSM 4743(T)) and Halomonas hydrothermalis (DSM 15725(T)). Level of DNA-DNA relatedness between strain 18bAG(T) and the most related species Halomonas venusta and Halomonas hydrothermalis was 56.0% and 41.2%, respectively. The G+C content (mol%) of DNA was 53.0. The RiboPrinting patterns of Halomonas venusta and 18AG(T) showed a pattern similarity of 0.50. On the basis of genomic information and phenotypic characteristics strain 18bAG(T) represents a new species, for which the name Halomonas alkaliphila sp. nov. is proposed. The type strain is 18bAG(T) (=DSM 16354T =ATCC BAA-953T).

Molecular analysis of halophilic bacterial community for high-rate denitrification of saline industrial wastewater

A denitrification system for saline wastewater utilizing halophilic denitrifying bacteria has not been developed so far. In this study, denitrification performance and microbial community under various saline conditions were investigated using denitrifying sludge acclimated under low-salinity condition for a few years as seed sludge. A continuous denitrification experiment showed that denitrification performance and microbial community at 10% salinity was higher than that at 1% salinity. The microbial community in the denitrification sludge that was acclimated under low salinity was monitored by terminal-restriction fragment length polymorphism (T-RFLP) analysis during acclimation to high-salinity condition. T-RFLP profiles and clone analysis based on 16S rRNA-encoding genes in the sludge of the denitrification system with 10% salinity indicated that the gamma-Proteobacteria, particularly Halomonas spp., were predominant species, suggesting that these bacterial members were possibly responsible for a high denitrification activity under high-salinity conditions. Furthermore, the investigation of denitrification performance under various saline conditions revealed that 4-10% salinity results in the highest denitrification rate, indicating that this salinity was optimal for predominant bacterial species to exhibit denitrification activity. These results indicate the possibility that an appropriate denitrification system for saline wastewater can be designed using acclimated sludge with a halophilic community.

Halomonas taeanensis sp. nov., a novel moderately halophilic bacterium isolated from a solar saltern in Korea

A moderately halophilic, Gram-negative bacterium, strain BH539(T), which was isolated from a solar saltern at Taean in Korea, was considered to be a member of the genus Halomonas. Strain BH539(T) grew at salinities of 1-25% (w/v) and at temperatures of 10-45 degrees C. Cells were short rods that were motile by means of several flagella. Their major fatty acids were C(18:1)omega7c, C(16:0) and C(19:0) cyclo omega8c. The genomic DNA G+C content was about 65 mol% and the predominant ubiquinone was Q-9. Phylogenetic analyses based on 16S rRNA gene sequences indicated that the isolate formed a branch of the species Cobetia marina. However, 23S and 16S rRNA gene sequence similarities revealed that strain BH539(T) was related more closely to the type strains of the genus Halomonas. Phylogenetic analyses based on 23S rRNA gene sequences also indicated that the strain formed a phyletic line within the genus Halomonas. Therefore, it was concluded that strain BH539(T) should be classified within the genus Halomonas, rather than Cobetia. On the basis of physiological and molecular properties, strain BH539(T) represents a novel species of the genus Halomonas, for which the name Halomonas taeanensis sp. nov. is proposed. The type strain is BH539(T) (=KCTC 12284(T)=DSM 16463(T)).

Phylogenetic analysis of bacterial populations in waters of the former Texcoco Lake, Mexico

Molecular techniques were used to compare the compositions of the bacterial communities of the 2 following lagoons from the former soda Texcoco Lake, Mexico: the restored Facultativa lagoon and the Nabor Carrillo lagoon. Ribosomal intergenic spacer analysis (RISA) revealed that bacterial communities of the 2 lagoons were different and presented a relatively low diversity. Clone libraries of 16S rDNA genes were constructed, and significant phylotypes were distinguished by restriction fragment length polymorphism (RFLP). A representative clone from each phylotype was partially sequenced. Molecular identification and phylogenetic analyses based on ribosomal sequences revealed that the Facultativa lagoon harbored mainly γ- and β-Proteobacteria, low G+C Gram-positive bacteria, and several members of the Halobacteriaceae family of archaea. The Nabor Carrillo lagoon mainly included typical halophilic and alkaliphilic low G+C Gram-positive bacteria, γ-Proteobacteria, and β-Proteobacteria similar to those found in other soda lakes. Several probably noncultured new bacterial species were detected. Three strains were isolated from the Nabor Carrillo lagoon, their partial 16S rDNA sequences were obtained. On this basis, they were identified as Halomonas magadiensis (H1), Halomonas eurihalina (H2), and Staphylococcus sciuri (H3). This is the first study that uses molecular techniques to investigate potential genetic diversity in the Texcoco lakes. In this preliminary evaluation, we infer the presence of alkalophilic, halophilic, or haloalkaliphilic bacteria potentially useful for biotechnology.Key words: bacterial diversity, 16S rDNA gene, soda lakes, former soda Texcoco Lake, Mexico, alkaliphiles, halophiles, haloalkaliphiles.

Halomonas koreensis sp. nov., a novel moderately halophilic bacterium isolated from a solar saltern in Korea

A moderately halophilic bacterium, strain SS20T, capable of growing at salinities of 1–20 % (w/v) NaCl was isolated from a solar saltern of the Dangjin area in Korea and was characterized taxonomically. Strain SS20T was a Gram-negative bacterium comprising motile, short rods. Its major cellular fatty acids were C18 : 1 ω7c, C19 : 0 ω8c cyclo and C16 : 0. The DNA G+C content was 70 mol% and the predominant ubiquinone was Q-9. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain SS20T belonged to the genus Halomonas. The levels of 16S rRNA gene sequence similarity to the type strains of Halomonas species were in the range 93·0–97·5 %. The levels of DNA–DNA relatedness between strain SS20T and the type strains of phylogenetically closely related Halomonas species were in the range 5·3–12·3 %. On the basis of physiological and molecular properties, strain SS20T represents a novel species of the genus Halomonas, for which the name Halomonas koreensis sp. nov. is proposed. The type strain is SS20T (=KCTC 12127T=JCM 12237T).

Halomonas organivorans sp. nov., a moderate halophile able to degrade aromatic compounds

A group of moderately halophilic bacteria able to degrade aromatic organic compounds contaminating hypersaline habitats in southern Spain have been isolated and characterized. The taxonomic position of these strains was determined using phenotypic, phylogenetic and genotypic methods. The G+C content of their DNA ranged from 61·0 to 62·9 mol%. DNA–DNA hybridization studies showed that they constitute a genospecies, having DNA–DNA hybridization values of 90–100 %. Analysis of the complete 16S rRNA gene sequence revealed a high level of similarity with members of the genus Halomonas, sharing 98 % 16S rRNA gene sequence similarity with the type strains of Halomonas salina and Halomonas halophila. However, phenotypic differences and the low level of DNA–DNA hybridization suggest the placement of these strains as a novel species within the genus Halomonas. The name Halomonas organivorans sp. nov. is proposed, with strain G-16.1T (=CECT 5995T=CCM 7142T) as the type strain. This novel species of Halomonas is characterized by its ability to use a wide range of organic compounds (benzoic acid, p-hydroxybenzoic acid, cinnamic acid, salicylic acid, phenylacetic acid, phenylpropionic acid, phenol, p-coumaric acid, ferulic acid and p-aminosalicylic acid), and it could be useful for the decontamination of polluted saline habitats.

A taxonomic study to establish the relationship between exopolysaccharide-producing bacterial strains living in diverse hypersaline habitats

This study was undertaken to identify exopolysaccharide-producing bacteria gathered from 18 hypersaline habitats. Phenotypic studies performed with 134 isolates revealed the majority of them to be Gram-negative rods with respiratory metabolism, belonging to the genus Halomonas. A numerical analysis of the 114 phenotypic data showed that at an 80% similarity level most of the strains (121) could be grouped into six phenotypic groups. Phenon A included 25 new isolates and the reference strain of Halomonas eurihalina, and phenon B was formed by 77 new isolates and Halomonas maura. Phenon C was also related to H. maura although to a lesser extent than strains in group B. Three phena (D, E, and F) could not be grouped with any of the reference strains and may represent new taxa; their G + C contents and DNA-DNA hybridization data corroborated this hypothesis. Results of this work proved that the most abundant halophilic species EPS producer in hypersaline habitats was H. maura, followed by H. eurihalina.

Halomonas boliviensis sp. nov., an alkalitolerant, moderate halophile isolated from soil around a Bolivian hypersaline lake

Halomonas boliviensis sp. nov. is proposed for two moderately halophilic, psychrophilic, alkalitolerant bacteria, LC1(T) (=DSM 15516(T)=ATCC BAA-759(T)) and LC2 (=DSM 15517=ATCC BAA-760), both of which were isolated from a soil sample around the lake Laguna Colorada, located at 4300 m above sea level in the south-west region of Bolivia. The bacteria are aerobic, motile, Gram-negative rods that produce colonies with a cream pigment. Moreover, they are heterotrophs that are able to utilize various carbohydrates as carbon sources. The organisms reduce nitrate and show tryptophan deaminase activity. The genomic DNA G+C contents were 51.4 mol% for isolate LC1(T) and 52.6 mol% for isolate LC2. Based on 16S rDNA sequence analysis, isolates LC1(T) and LC2 were identified as members of the genus Halomonas and clustered closely with Halomonas variabilis DSM 3051(T) and Halomonas meridiana DSM 5425(T). However, DNA-DNA relatedness between the new isolates and the closest related Halomonas species was low.

Halomonas anticariensis sp. nov., from Fuente de Piedra, a saline-wetland wildfowl reserve in Málaga, southern Spain

Three Halomonas strains, FP34, FP35T and FP36, which were isolated from soil samples taken from Fuente de Piedra, a saline wetland in the province of Málaga in southern Spain, are described. Phylogenetic analyses based on 16S rRNA gene sequences show that the three isolates belong to the genus Halomonas in the γ-Proteobacteria and form an independent genetic line. Phenotypically, they share the characteristics of Halomonas and differ from the most closely related species, Halomonas campisalis, in the following features: they are strictly aerobic and, because of their production of exopolysaccharides, form cream-coloured, mucoid colonies; they produce phosphatase and grow within narrow pH and temperature ranges; and they are susceptible to kanamycin and streptomycin. Their G+C content varies between 60·0 and 61·4 mol%. The name Halomonas anticariensis sp. nov. is proposed for these isolates. Strain FP35T (=LMG 22089T=CECT 5854T) is the type strain. The bacterium grows best in 7·5 % (w/v) NaCl and does not require magnesium or potassium salts for growth, although they do stimulate growth somewhat when present. Its major fatty acids are 18 : 1ω7c, 16 : 0, 16 : 1ω7c, 15 : 0 iso 2-OH, 12 : 0 3-OH, 12 : 0, 10 : 0 and 19 : 0 cyclo ω8c. Its predominant respiratory lipoquinone is ubiquinone with nine isoprene units (Q-9).

Design of 16S rRNA-targeted oligonucleotide probes and microbial community analysis in the denitrification process of a saline industrial wastewater treatment system

Three 16S rRNA-targeted oligonucleotide probes, namely, PSMg437 targeting several members of the genus Pseudomonas, Hlm474 targeting several members of the genus Halomonas, and Clw844 targeting several members of the genus Colwellia, were designed. The microbial community structure and nitrogen removal ability of nitrate-containing saline wastewater treatment systems with anaerobic packed bed and fluidized bed were monitored. Direct cell counting using fluorescence in situ hybridization (FISH) images revealed that various phylogenetic groups were evenly distributed in the anaerobic packed bed whereas members of the genus Halomonas were dominant particularly in the anaerobic fluidized bed. These results suggest that the microbial communities produced by different flow conditions correlated with denitrification ability in saline industrial wastewater treatment systems.