[Rhodobaculum claviforme gen. nov., sp. nov., a New Alkaliphilic Nonsulfur Purple Bacterium].

Two alkaliphilic strains of nonsulfur purple bacteria (NPB), B7-4 and B8-2, were isolated from southeast Siberia moderately saline alkaline steppe lakes with pH values above 9.0. The isolates were motile, polymorphous cells (from short rods to long spindly cells) 2.0-3.2 x 9.6-20.0 µm. Intracellular membranes of vesicular type were mostly located at the cell periphery. The microorganisms contained bacteriochlorophyll a and carotenoids of the spheroidene and spirilloxanthin series. The photosynthetic apparatus was represented by LH2 and LH1 light-harvesting complexes. In the presence of organic compounds, the strains grew aerobically in the dark or anaerobically in the light. Capacity for photo- and chemoautotrophic growth was not detected. The cbbl gene encoding RuBisCO was not revealed. Optimal growth of both strains occurred at 2% NaCl (range from 0.5 to 4%), pH 8.0-8.8 (range from 7.5 to 9.7), and 25-35 degrees C. The DNA G+C content was 67.6-69.8 mol %. Pairwise comparison of the nucleotides of the 16S rRNA genes revealed that strains B7-4 and B8-2 belonged to the same species (99.9% homology) and were most closely related to the aerobic alkaliphilic bacteriochlorophyll a-containing anoxygenic phototrophic bacterium (APB) Roseibacula alcaliphilum De (95.2%) and to NPB strains Rhodobaca barguzinensis VKM B-2406(T) (94.2%) and Rbc. bogoriensis LBB1(T) (93.9%). The isolates were closely related to the NPB Rhodobacter veldkampii DSM 11550(T) (94.8%) and to aerobic bacteriochlorophyll a-containing bacteria Roseinatronobacter monicus ROS 35(T) and Roseicitreum antarcticul ZS2-28(T) (93.5 and 93.9%, respectively). New strains were described as a new NPB genus and species of the family Rhodobacteriaceae, Rhodobaculum claviforme gen. nov., sp. nov., with B7-4(T) (VKM B-2708, LMG 28126) as the type strain.

Acuticoccus yangtzensis gen. nov., sp. nov., a novel member in the family Rhodobacteraceae, isolated from the surface water of the Yangtze Estuary.

A novel bacterium, strain JL1095(T), was isolated from the surface water of the Yangtze Estuary, China (31° N, 122° E). Cells were Gram negative, aerobic, oval-shaped with one peak end and motile by gliding. Cells divided by binary fission. Growth occurred at 15-50 °C (optimum at 35 °C), 2-10 % (w/v) NaCl (optimum at ~3 %) and pH 6.0-9.0 (optimum at pH ~ 7.6). Strain JL1095(T) was able to utilize various sole-carbon-source, such as Tween 40, Tween 80, acetic acid, L-arabinose, D,L-lactic acid, urocanic acid, methyl-pyruvate, α-hydroxy butyric acid, ß-hydroxy butyric acid, and γ-hydroxy butyric acid. The major cellular fatty acids were C16:0, C18:0, C19:0 ω8c cyclo, C20:1 ω7c, and Summed Feature 8. The whole respiratory ubiquinone was Q-10. The genomic DNA G+C content of strain JL1095(T) was 51.5 %. According to the phylogenetic analysis, strain JL1095(T) formed a monophyletic branch at the periphery of the evolutionary radiation occupied by the genera Labrenzia, Pannonibacter, Stappia, Wenxnia, and Amaricoccus. The sequence similarity was 92.8 % with the most closely relating strain Stappia indica B106(T), and 92.6 % with the type species Stappia stellulatum IAM 12621(T). Based on the biochemical characteristics, chemotaxonomy and phylogenetic analysis, strain JL1095(T) is considered to be a novel genus which belongs to the family Rhodobacteraceae. The novel strain is named Acuticoccus yangtzensis gen. nov., sp. nov. The type strain of Acuticoccus yangtzensis is JL1095(T) (=CGMCC 1.12795 = DSM 28604).

In vivo and in vitro observations of polyhydroxybutyrate granules formed by Dinoroseobacter sp. JL 1447.

Polyhydroxybutyrate (PHB) granules formed by a marine aerobic anoxygenic phototrophic bacterial strain Dinoroseobacter sp. JL 1447 were detected using transmission electron microscopy and atomic force microscopy. When Dinoroseobacter sp. JL 1447 was inoculated into a medium with glucose as the sole carbon source, the formation of PHB granules occurred and accumulated with incubation time, reaching their maximum in the stationary phase cultures. PHB granules, formed in the cytoplasm at the cell poles or future cell poles, were remobilized and used by the cells in late stationary complex cultures. When PHB granules formed, cell length elongated from 0.5 to 1.5 µm and spherical protrusions appeared on the cell surface. The French press method was used to break the cells and isolate the PHB granules. The freshly prepared and intact PHB granules were spherical with a soft, smooth outer envelope without visible substructures. Upon treating PHB granules with sodium dodecyl sulfate, the envelope was destroyed and nearly parted from the granules, and uniform, spherical structures with a central pore appeared on the granule surface.

Influence of plaque-forming bacterium, Rhodobacteraceae sp. on the growth of Chlorella vulgaris.

Experiments were conducted to find out the molecular features, infection process of a special alga plaque-forming microorganism and its potential influence on the biomass of Chlorella vulgaris during the infection process. Direct contact between the algal cell and the bacterium may be the primary steps needed for the bacterium to lyse the alga. Addition of C. vulgaris cells into f/2 medium allowed us obtain the object bacterium. The 16S rRNA gene sequence comparisons results showed that the plaque-forming bacterium kept the closest relationship with Labrenzia aggregata IAM 12614(T) at 98.90%. The existence of the bacterium could influence both the dry weight and lipid content of C. vulgaris. This study demonstrated that direct cell wall disruption of C. vulgaris by the bacterium would be a potentially effective method to utilize the biomass of microalgae.

You are what you talk: quorum sensing induces individual morphologies and cell division modes in Dinoroseobacter shibae.

Dinoroseobacter shibae, a member of the Roseobacter clade abundant in marine environments, is characterized by a pronounced pleomorphism. Cell shapes range from variable-sized ovoid rods to long filaments with a high copy number of chromosomes. Time-lapse microscopy shows cells dividing either by binary fission or by budding from the cell poles. Here we demonstrate that this morphological heterogeneity is induced by quorum sensing (QS). D. shibae utilizes three acylated homoserine lactone (AHL) synthases (luxI1-3) to produce AHLs with unsaturated C18 side chains. A ΔluxI1-knockout strain completely lacking AHL biosynthesis was uniform in morphology and divided by binary fission only. Transcriptome analysis revealed that expression of genes responsible for control of cell division was reduced in this strain, providing the link between QS and the observed phenotype. In addition, flagellar biosynthesis and type IV secretion system (T4SS) were downregulated. The wild-type phenotype and gene expression could be restored through addition of synthetic C18-AHLs. Their effectiveness was dependent on the number of double bonds in the acyl side chain and the regulated trait. The wild-type expression level of T4SS genes was fully restored even by an AHL with a saturated C18 side chain that has not been detected in D. shibae. QS induces phenotypic individualization of D. shibae cells rather than coordinating the population. This strategy might be beneficial in unpredictably changing environments, for example, during algal blooms when resource competition and grazing exert fluctuating selective pressures. A specific response towards non-native AHLs might provide D. shibae with the capacity for complex interspecies communication.

Pelagicola litorisediminis sp. nov., a novel alphaproteobacterium isolated from tidal flat sediment.

A Gram-negative, aerobic, non-motile and rod-shaped or ovoid bacterial strain, designated D1-W8(T), was isolated from a tidal flat on the South Sea in South Korea. Strain D1-W8(T) was found to grow optimally at 25 °C, at pH 7.0-8.0 and in the presence of 2.0-3.0 % (w/v) NaCl. Neighbour-joining, maximum-likelihood and maximum-parsimony phylogenetic trees based on 16S rRNA gene sequences revealed that strain D1-W8(T) clustered with the type strain of Pelagicola litoralis showing 97.1 % sequence identity. 16S rRNA gene sequences of the type strains of other species exhibited lower similarity values. Strain D1-W8(T) was determined to contain Q-10 as the predominant ubiquinone and C18:1 ω7c as the predominant fatty acid. The major polar lipids of strain D1-W8(T) were identified as phosphatidylcholine, phosphatidylglycerol, phosphatidylethanolamine, one unidentified aminolipid and one unidentified lipid. The DNA G+C content of strain D1-W8(T) was determined to be 57.9 mol% and its DNA-DNA relatedness value with the type strain of P. litoralis was 17 %. The differential phenotypic properties, together with the phylogenetic and genetic distinctiveness, revealed that strain D1-W8(T) is separate from P. litoralis. On the basis of the data presented, strain D1-W8(T) is considered to represent a novel species of the genus Pelagicola, for which the name Pelagicola litorisediminis sp. nov. is proposed. The type strain is D1-W8(T) (= KCTC 32327(T) = CECT 8287(T)).

Pannonibacter indica sp. nov., a highly arsenate-tolerant bacterium isolated from a hot spring in India.

A novel aerobic bacterium, strain HT23(T), able to grow on 500 mM sodium arsenate was isolated from a hot-spring sediment sample collected from Athamallik, Orissa, India. Cells of this isolate were Gram negative. Heterotrophic growth was observed at pH 6.0-11.0 and 20-45 °C. Optimum growth was observed at 37 °C and pH 7.0-10.0. The major polar lipids are diphosphatidyl glycerol, phosphatidyl glycerol, phosphatidyl ethanolamine, phosphatidyl choline and phosphatidyl monomethyl ethanolamine. The major isoprenoid quinone was Q-10. 16S rRNA gene sequence analysis indicated that the bacterium clustered with the genus Pannonibacter and showed 98.9 % similarity with Pannonibacter phragmitetus C6-19(T) (DSM 14782(T)) and 98 % with the P. phragmitetus group B and P. phragmitetus group E strains. Levels of DNA-DNA relatedness between the strain HT23(T) and P. phragmitetus C6-19(T) (DSM 14782(T)) and other strains of P. phragmitetus group B and group E strains were below 55 %. On the basis of phenotypic and chemotaxonomic characteristics, 16S rRNA gene sequence analysis and DNA-DNA hybridization data, strain HT23(T) is considered to represent a novel species of the genus Pannonibacter, for which the name Pannonibacter indica sp. nov. is proposed. The type strain is HT23(T) (=JCM 16851(T) = DSM 23407(T) = LMG 25769(T)).

Defluviimonas denitrificans gen. nov., sp. nov., and Pararhodobacter aggregans gen. nov., sp. nov., non-phototrophic Rhodobacteraceae from the biofilter of a marine aquaculture.

Three Gram-negative bacterial strains were isolated from the biofilter of a recirculating marine aquaculture. They were non-pigmented rods, mesophiles, moderately halophilic, and showed chemo-organoheterotrophic growth on various sugars, fatty acids, and amino acids, with oxygen as electron acceptor; strains D9-3(T) and D11-58 were in addition able to denitrify. Phototrophic or fermentative growth could not be demonstrated. Phylogenetic analysis of the 16S rRNA gene sequences placed D9-3(T) and D11-58, and D1-19(T) on two distinct branches within the alpha-3 proteobacterial Rhodobacteraceae, affiliated with, but clearly separate from, the genera Rhodobacter, Rhodovulum, and Rhodobaca. Based on morphological, physiological, and 16S rRNA-based phylogenetic characteristics, the isolated strains are proposed as new species of two novel genera, Defluviimonas denitrificans gen. nov., sp. nov. (type strain D9-3(T)=DSM 18921(T)=ATCC BAA-1447(T); additional strain D11-58=DSM19039=ATCC BAA-1448) and Pararhodobacter aggregans gen. nov., sp. nov (type strain D1-19(T)=DSM 18938(T)=ATCC BAA-1446(T)).

Hexavalent chromium reduction by Pannonibacter phragmitetus BB isolated from soil under chromium-containing slag heap.

The objective of this study was to find an indigenous Cr(VI)-reducing bacterium that can effectively be used for Cr(VI) remediation in the contaminated soils. The results showed that one isolate from soil under a chromium-containing slag heap at a steel-alloy factory in China had a strong ability of reducing Cr(VI). It can completely reduce 500 mg L(-1) Cr (VI) within 24 h. Based on 16S rRNA gene sequence and similarity analysis, this isolate was identified as Pannonibacter phragmitetus and assigned as strain BB. Images of scanning electron microscopy (SEM) indicated that the cell surface of P. phragmitetus BB remained intact without cell rupture under 500 mg L(-1) Cr (VI) stress. The transmission electron microscopy (TEM) patterns showed that the Cr(VI) reduction products were both bound to the outer surface of the cells and dispersed in the culture medium, thereby suggesting that the reduction of Cr (VI) occurred extracellularly. Elemental analysis by energy dispersive X-ray (EDX) revealed that Cr was the major element comprising the reduction product. Furthermore, X-ray photoelectron spectroscope (XPS) verified that the Cr(VI) reduction product was Cr(III) compounds.

Tropicibacter naphthalenivorans gen. nov., sp. nov., a polycyclic aromatic hydrocarbon-degrading bacterium isolated from Semarang Port in Indonesia.

An aerobic, Gram-negative, motile bacterium, strain C02(T), was isolated from seawater obtained from Semarang Port in Indonesia. Cells of strain C02(T) were peritrichously flagellated and rod-shaped. Strain C02(T) was able to degrade naphthalene, alkylnaphthalenes and phenanthrene. 16S rRNA gene sequence analysis revealed that this strain was affiliated with the family Rhodobacteraceae in the class Alphaproteobacteria and was related most closely to Marinovum algicola FF3(T) (95.7 % similarity) and Thalassobius aestuarii JC2049(T) (95.2 %). The DNA G+C content of strain C02(T) was 64.6 mol%. The major cellular fatty acids were C(18 : 1)omega7c (50.9 % of the total), C(16 : 0) (17.9 %), 11 methyl C(18 : 1)omega7c (14.7 %), C(18 : 1)omega9c (2.9 %) and C(19 : 0) cyclo omega8c (2.4 %), and the predominant respiratory lipoquinone was ubiquinone-10. Based on physiological, chemotaxonomic and phylogenetic data, strain C02(T) is suggested to represent a novel species of a new genus, for which the name Tropicibacter naphthalenivorans gen. nov., sp. nov. is proposed. The type strain of Tropicibacter naphthalenivorans is C02(T) (=JCM 14838(T)=DSM 19561(T)).

Tropicimonas isoalkanivorans gen. nov., sp. nov., a branched-alkane-degrading bacterium isolated from Semarang Port in Indonesia.

An aerobic, Gram-negative, motile bacterium, strain B51(T), was isolated from seawater obtained from Semarang Port in Indonesia. Cells of strain B51(T) were peritrichously flagellated and rod-shaped. Strain B51(T) was able to degrade alkanes, branched alkanes and alkylnaphthalenes. 16S rRNA gene sequence analysis revealed that strain B51(T) was affiliated with the family Rhodobacteraceae, and was related most closely to Thioclava pacifica TL 2(T) (94.6 % similarity). The DNA G+C content of strain B51(T) was 66.5 mol%. The major cellular fatty acids were C(18 : 1)omega7c (84.9 %), C(18 : 1)omega9c (13.8 %), C(16 : 0) (8.7 %), C(18 : 0) (6.4 %) and anteiso-C(15 : 0) (5.8 %) and the major quinone was ubiquinone-10. Based on its phenotypic and phylogenetic characteristics, strain B51(T) is considered to represent a novel species of a new genus, for which the name Tropicimonas isoalcanivorans gen. nov., sp. nov. is proposed. The type strain of the type species is B51(T) (=JCM 14837(T)=DSM 19548(T)).

Leisingera aquimarina sp. nov., isolated from a marine electroactive biofilm, and emended descriptions of Leisingera methylohalidivorans Schaefer et al. 2002, Phaeobacter daeponensis Yoon et al. 2007 and Phaeobacter inhibens Martens et al. 2006.

Strain LMG 24366(T) was isolated from a marine electroactive biofilm grown on a stainless steel cathode (Genova, Italy) and was investigated by using a polyphasic taxonomic approach. This study demonstrated that strain LMG 24366(T) represents a novel species within the genus Leisingera, which shared 98.9 % 16S rRNA gene similarity with its nearest phylogenetic neighbour, Leisingera methylohalidivorans. Strain LMG 24366(T) grew on betaine (1 mM) as a sole carbon source, whereas no growth was observed on L-methionine (10 mM). The phenotypic and genotypic analyses showed that strain LMG 24366(T) could be differentiated from established Leisingera species and that it represented a novel species, for which the name Leisingera aquimarina sp. nov. is proposed. The type strain is LMG 24366(T) (=CCUG 55860(T)) and has a DNA G+C content of 61.4 mol%.

Localization of the bacterial agent of juvenile oyster disease (Roseovarius crassostreae) within affected eastern oysters (Crassostrea virginica).

The bacterium Roseovarius crassostreae causes seasonal mortalities among commercially produced eastern oysters (Crassostrea virginica) grown in the Northeastern United States. Phylogenetically, the species belongs to a major lineage of marine bacteria (the Roseobacter clade), within which Roseovarius crassostreae is the only known pathogen to be isolated in laboratory culture. The objective of the current study was to determine the location and nature of R. crassostreae interactions with oysters affected by juvenile oyster disease (JOD). Scanning electron microscopy of diseased individuals revealed abundant colonization of the inner shell surfaces by bacteria which were morphologically similar to R. crassostreae. The same types of cells were also observed on and within layers of host-derived conchiolin on the inner valves. Most bacterial cells were alive as determined by the use of a fluorescent viability stain. Further, most were clearly attached at the cell poles, which is consistent with the ability of R. crassostreae to express polar fimbriae. When material from the pallial fluid, soft tissue and inner valve surfaces was cultured, the highest numbers of R. crassostreae were recovered from the inner valves. These samples also contained the greatest abundance of R. crassostreae as a percentage of total colonies. Cloning and sequencing of 16S rRNA genes provided culture-independent evidence of the numerical dominance of R. crassostreae among the bacterial consortia associated with the inner shell surfaces of JOD-affected animals. The ability of R. crassostreae to colonize shell and conchiolin is consistent with the described JOD-pathology and may aid the bacteria in avoiding hemocyte-mediated killing.

[Seasonal changes in the structure of the anoxygenic photosynthetic bacterial community in Lake Shunet, Khakassia].

Seasonal studies of the anoxygenic phototrophic bacterial community of the water column of the saline eutrophic meromictic Lake Shunet (Khakassia) were performed in 2002 (June) and 2003 (February-March and August). From the redox zone down, the lake water was of dark green color. Green sulfur bacteria predominated in every season. The maximum number of green sulfur bacteria was 10(7) cells/ml in summer and 10(6) cells/ml in winter. A multi-syringe stratification sampler was applied for the study of the fine vertical distribution of phototrophs in August 2003; the sampling was performed every five centimeters. A five-centimeter-thick pink-colored water layer inhabited by purple sulfur bacteria was shown to be located above the layer of green bacteria. The species composition and ratio of purple bacterial species depended on the sampling depth and on the season. In summer, the number of purple sulfur bacteria in the layer of pink water was 1.6 x 10(8) cells/ml. Their number in winter was 3 x 10(5) cells/ml. In the upper oxygen-containing layer of the chemocline the cells of purple nonsulfur bacteria were detected in summer. The maximum number of nonsulfur purple bacteria, 5 x 10(2) cells/ml, was recorded in August 2003. According to the results of the phylogenetic analysis of pure cultures of the isolated phototrophic bacteria, which were based on 16S rDNA sequencing, green sulfur bacteria were close to Prosthecochloris vibrioformis, purple sulfur bacteria, to Thiocapsa and Halochromatium species, and purple nonsulfur bacteria, to Rhodovulum euryhalinum and Pinkicyclus mahoneyensis.

Motility is involved in Silicibacter sp. TM1040 interaction with dinoflagellates.

Silicibacter sp. TM1040, originally isolated from a culture of the dinoflagellate Pfiesteria piscicida, senses and responds to the dinoflagellate secondary metabolite dimethylsulfoniopropionate (DMSP) by flagella-mediated chemotaxis behaviour. In this report we show that swimming motility is important for initiating the interaction between the bacterium and dinoflagellate. Following transposon mutagenesis, three mutants defective in wild-type swimming motility (Mot-) were identified. The defects in motility were found to be in homologues of cckA and ctrA, encoding a two-component regulatory circuit, and in a novel gene, flaA, likely to function in flagellar export or biogenesis. Mutation of flaA or cckA results in the loss of flagella and non-motile cells (Fla-), while CtrA- cells possess flagella, but have reduced motility due to increased cell length. All three Mot- mutants were defective in attaching to the dinoflagellate, particularly to regions that colocalized with intracellular organelles. The growth rate of the dinoflagellates was reduced in the presence of the Fla- mutants compared with Fla+ cells. These results indicate that bacterial motility is important for the Silicibacter sp. TM1040-P. piscicida interaction.

Rubellimicrobium thermophilum gen. nov., sp. nov., a red-pigmented, moderately thermophilic bacterium isolated from coloured slime deposits in paper machines.

Six red-pigmented strains of the Alphaproteobacteria with optimal growth between 45 and 54 degrees C were previously isolated from coloured biofilms in two fine-paper machines and one pulp dryer. The strains were found to be resistant to 15 p.p.m. 2,2-dibromo-3-nitrilopropionamide, a common industrial biocide. 16S RNA gene sequence similarity of the isolates was 99.7-100 %. Ribotyping using the restriction enzymes PvuII and EcoRI showed that four of the isolates (C-lvk-R2A-1, C-lvk-R2A-2(T), C-R2A-52d and C-R2A-5d) belong to a single species. 16S rRNA gene-based phylogenetic analysis revealed that, together with Rhodobacter blasticus ATCC 33485(T), the isolates form a deep line of descent (94.7-94.9 % sequence similarity) within the family Rhodobacteraceae loosely affiliated with the Rhodobacter/Paracoccus clade. The isolates were strictly aerobic and oxidase-positive (catalase was weakly positive) and utilized a wide range of substrates including pentoses, hexoses, oligosaccharides and sugar alcohols. The predominant constituents in their cellular fatty acid profiles were C(19 : 0) cyclo omega8c (39-44 %), C(18 : 0) (21-24 %) and C(16 : 0) (21-23 %). Fatty acids present in smaller amounts included C(18 : 1)omega7c, C(10 : 0) 3-OH, C(18 : 1)omega7c 11-methyl, C(20 : 2)omega6,9c and C(17 : 0) cyclo, amongst others. Polar lipids included diphosphatidylglycerol, phosphatidylcholine and an unidentified aminolipid, but not phosphatidylethanolamine. Carotenoid pigments were synthesized but bacteriochlorophyll a was not. The polyamine patterns consisted of the major compounds putrescine, spermidine and sym-homospermidine. The major respiratory lipoquinone was ubiquinone Q-10. The DNA G+C content was 69.4-70.2 mol%. On the basis of the phylogenetic and phenotypic evidence, the biofilm isolates were classified in a new genus, Rubellimicrobium gen. nov.; four of the isolates are assigned to the type species, Rubellimicrobium thermophilum gen. nov., sp. nov. Strain C-lvk-R2A-2(T) (=CCUG 51817(T) = DSM 16684(T) = HAMBI 2421(T)) is the type strain of Rubellimicrobium thermophilum.

Palleronia marisminoris gen. nov., sp. nov., a moderately halophilic, exopolysaccharide-producing bacterium belonging to the 'Alphaproteobacteria', isolated from a saline soil.

Strain B33(T) is a moderately halophilic, exopolysaccharide-producing, Gram-negative, non-motile rod isolated from a hypersaline soil bordering a saline saltern on the Mediterranean seaboard in Murcia (Spain). The bacterium is chemoheterotrophic and strictly aerobic. It contains a pink pigment but does not synthesize bacteriochlorophyll a. It requires 0.66 M Na+, 0.1 M Mg2+ and 0.1 M K+ for optimum growth. It does not produce acid from carbohydrates. It cannot grow with carbohydrates, organic acids, sugars, alcohols or amino acids as sole sources of carbon and energy. Its major fatty-acids are 18 : 1omega7c (68.9 %) and 19 : 0 cyclo omega8c (12.8 %). The sole respiratory lipoquinone found in strain B33T is ubiquinone-10. The DNA G+C content is 64.2 mol%. 16S rRNA gene sequence comparisons show that the isolate is a member of the Roseobacter clade within the class 'Alphaproteobacteria'. The similarity values with Roseivivax halodurans and Roseivivax halotolerans are 88.2 and 88.0 % respectively and 92.2 % with Salipiger mucosus. DNA-DNA hybridization values with these species are <30 %. In the light of the polyphasic evidence gathered in this study it is proposed that the isolate be classified as a novel genus and species with the name Palleronia marisminoris gen. nov., sp. nov. The proposed type strain is strain B33T (=CECT 7066T=LMG 22959T).

Jannaschia cystaugens sp. nov., an Alexandrium (Dinophyceae) cyst formation-promoting bacterium from Hiroshima Bay, Japan.

Heterotrophic bacteria isolated from water samples taken from Hiroshima Bay, Japan, and referred to as Alexandrium (Dinophyceae) cyst formation-promoting bacteria, were assigned to the Roseobacter-Sulfitobacter-Silicibacter group within the alpha-Proteobacteria on the basis of nearly complete 16S rRNA gene sequences. Phylogenetic analyses showed that two strains, CFPB-A9T and CFPB-A5, are closely related to each other and that their closest relative was Jannaschia helgolandensis (95.9 % sequence similarity). These strains were Gram-negative, motile, obligately aerobic rods that required sodium ions and 2-7 % sea salts for growth and did not produce bacteriochlorophyll a. Their optimal growth temperature was 25-30 degrees C. The strains had Q-10 as the dominant respiratory quinone. Primary cellular fatty acid in both strains was 18 : 1omega7c. The DNA G + C contents of strains CFPB-A9T and CFPB-A5 were 59.1 and 59.2 mol%, respectively. Based on physiological, biological, chemotaxonomic and phylogenetic data, the strains are considered to represent a novel species, Jannaschia cystaugens sp. nov., with type strain CFPB-A9T (= LMG 22015T = NBRC 100362T).

Salipiger mucescens gen. nov., sp. nov., a moderately halophilic, exopolysaccharide-producing bacterium isolated from hypersaline soil, belonging to the alpha-Proteobacteria.

Salipiger mucescens gen. nov., sp. nov. is a moderately halophilic, exopolysaccharide-producing, Gram-negative rod isolated from a hypersaline habitat in Murcia in south-eastern Spain. The bacterium is chemoheterotrophic and strictly aerobic (i.e. unable to grow under anaerobic conditions either by fermentation or by nitrate or fumarate respiration). It does not synthesize bacteriochlorophyll a. Catalase and phosphatase are positive. It does not produce acids from carbohydrates. It cannot grow with carbohydrates or amino acids as sole sources of carbon and energy. It grows best at 9-10 % w/v NaCl and requires the presence of Na+ but not Mg2+ or K+, although they do stimulate its growth somewhat when present. Its major fatty-acid component is 18 : 1omega7c (78.0 %). The predominant respiratory lipoquinone found in strain A3T is ubiquinone with ten isoprene units. The G + C content is 64.5 mol%. Phylogenetic analyses strongly indicate that this strain forms a distinct line within a clade containing the genus Roseivivax in the subclass alpha-Proteobacteria. The similarity value with Roseivivax halodurans and Roseivivax halotolerans is 94 %. In the light of the polyphasic evidence gathered in this study it is proposed that the isolate be classified as representing a new genus and species, Salipiger mucescens gen. nov., sp. nov. The proposed type strain is strain A3T (= CECT 5855T = LMG 22090T = DSM 16094T).

Oceanicaulis alexandrii gen. nov., sp. nov., a novel stalked bacterium isolated from a culture of the dinoflagellate Alexandrium tamarense (Lebour) Balech.

Five bacterial strains were isolated from a non-toxigenic strain of the marine dinoflagellate Alexandrium tamarense (Lebour) Balech CCMP 116 (NEPCC C116), during a survey of the diversity of bacteria associated with paralytic shellfish toxin-producing cultures of Alexandrium spp. (Dinophyta). All strains were strictly aerobic, Gram-negative, straight or curved rods. Cells were dimorphic, with stalks (or prosthecae) and non-motile or non-stalked and motile, by means of a single polar flagellum. The bacteria grew best at salt concentrations ranging from 2 to 10 % and growth occurred at 10 degrees C, but not at 50 degrees C. The G+C content of the chromosomal DNA of the strains was determined to be 61-62 mol%. Major cellular fatty acids of the bacteria presented a unique profile. 16S rRNA gene sequence analysis showed the five strains to be related to genera of budding bacteria of marine origin in the 'Alphaproteobacteria', namely, Hirschia, Maricaulis and Hyphomonas, although they exhibited substantial differences in morphology, substrate utilization and fatty acid profile to members of these genera. The five strains are proposed to comprise a new species of a new genus, Oceanicaulis alexandrii gen. nov., sp. nov., the type strain of which is C116-18(T) (=DSM 11625(T)=NCIMB 13905(T)).