Single-cell sequencing provides clues about the host interactions of segmented filamentous bacteria (SFB).

Segmented filamentous bacteria (SFB) are host-specific intestinal symbionts that comprise a distinct clade within the Clostridiaceae, designated Candidatus Arthromitus. SFB display a unique life cycle within the host, involving differentiation into multiple cell types. The latter include filaments that attach intimately to intestinal epithelial cells, and from which "holdfasts" and spores develop. SFB induce a multifaceted immune response, leading to host protection from intestinal pathogens. Cultivation resistance has hindered characterization of these enigmatic bacteria. In the present study, we isolated five SFB filaments from a mouse using a microfluidic device equipped with laser tweezers, generated genome sequences from each, and compared these sequences with each other, as well as to recently published SFB genome sequences. Based on the resulting analyses, SFB appear to be dependent on the host for a variety of essential nutrients. SFB have a relatively high abundance of predicted proteins devoted to cell cycle control and to envelope biogenesis, and have a group of SFB-specific autolysins and a dynamin-like protein. Among the five filament genomes, an average of 8.6% of predicted proteins were novel, including a family of secreted SFB-specific proteins. Four ADP-ribosyltransferase (ADPRT) sequence types, and a myosin-cross-reactive antigen (MCRA) protein were discovered; we hypothesize that they are involved in modulation of host responses. The presence of polymorphisms among mouse SFB genomes suggests the evolution of distinct SFB lineages. Overall, our results reveal several aspects of SFB adaptation to the mammalian intestinal tract.

The incidence of type-1 diabetes in NOD mice is modulated by restricted flora not germ-free conditions.

In the NOD mouse, the incidence of type-1 diabetes is thought to be influenced by the degree of cleanliness of the mouse colony. Studies collectively demonstrate that exposure to bacterial antigen or infection in the neonatal period prevents diabetes [1], [2], [3], [4], [5], [6], [7], [8], [9], [10], supporting the notion that immunostimulation can benefit the maturation of the postnatal immune system [11]. A widely accepted extrapolation from this data has been the notion that NOD mice maintained under germ-free conditions have an increased incidence of diabetes. However, evidence supporting this influential concept is surprisingly limited [12]. In this study, we demonstrate that the incidence of diabetes in female NOD mice remained unchanged under germ-free conditions. By contrast, a spontaneous monoculture with a gram-positive aerobic spore-forming rod delayed the onset and reduced the incidence of diabetes. These findings challenge the view that germ-free NOD mice have increased diabetes incidence and demonstrate that modulation of intestinal microbiota can prevent the development of type-1 diabetes.

Germination of spores of Bacillales and Clostridiales species: mechanisms and proteins involved.

Under conditions that are not conducive to growth, such as nutrient depletion, many members of the orders Bacillales and Clostridiales can sporulate, generating dormant and resistant spores that can survive in the absence of nutrients for years under harsh conditions. However, when nutrients are again present, these spores can return to active growth through the process of germination. Many of the components of the spore germination machinery are conserved between spore forming members of the Bacillales and Clostridiales orders. However, recent studies have revealed significant differences between the germination of spores of Clostridium perfringens and that of spores of a number of Bacillus species, both in the proteins and in the signal transduction pathways involved. In this review, the roles of components of the spore germination machinery of C. perfringens and several Bacillus species and the bioinformatic analysis of germination proteins in the Bacillales and Clostridiales orders are discussed and models for the germination of spores of these two orders are proposed.

Paenibacillus pocheonensis sp. nov., a facultative anaerobe isolated from soil of a ginseng field.

A Gram-positive, aerobic or facultatively anaerobic, rod-shaped, spore-forming bacterium, strain Gsoil 1138(T), was isolated from soil of a ginseng field in Pocheon Province, South Korea, and was characterized in order to determine its taxonomic position. On the basis of 16S rRNA gene sequence analysis, strain Gsoil 1138(T) was shown to belong to the family Paenibacillaceae and was most closely related to the type strains of Paenibacillus chondroitinus (98.2 % similarity) and Paenibacillus alginolyticus (96.5 %). Levels of 16S rRNA gene sequence similarity between strain Gsoil 1138(T) and the type strains of other recognized species of the genus Paenibacillus were below 96.5 %. The G+C content of the genomic DNA of strain Gsoil 1138(T) was 52.1+/-0.2 mol% (mean+/-sd of three determinations). Phenotypic and chemotaxonomic data (MK-7 as the major menaquinone and anteiso-C(15 : 0) and iso-C(16 : 0) as the predominant fatty acids) supported the affiliation of strain Gsoil 1138(T) to the genus Paenibacillus. The results of DNA-DNA hybridization experiments and physiological and biochemical tests allowed strain Gsoil 1138(T) to be distinguished genotypically and phenotypically from recognized species of the genus Paenibacillus. Strain Gsoil 1138(T) is therefore considered to represent a novel species of the genus Paenibacillus, for which the name Paenibacillus pocheonensis sp. nov. is proposed. The type strain is Gsoil 1138(T) (=KCTC 13941(T)=LMG 23404(T)).

Proteocatella sphenisci gen. nov., sp. nov., a psychrotolerant, spore-forming anaerobe isolated from penguin guano.

A novel, obligately anaerobic, psychrotolerant bacterium, designated strain PPP2T, was isolated from guano of the Magellanic penguin (Spheniscus magellanicus) in Chilean Patagonia. Cells were Gram-stain-positive, spore-forming, straight rods (0.7-0.8x3.0-5.0 microm) that were motile by means of peritrichous flagella. Growth was observed at pH 6.7-9.7 (optimum pH 8.3) and 2-37 degrees C (optimum 29 degrees C). Growth was observed between 0 and 4% (w/v) NaCl with optimum growth at 0.5% (w/v). Strain PPP2T was a catalase-negative chemo-organoheterotroph that was capable of fermentative metabolism. Peptone, bacto-tryptone, Casamino acids, oxalate, starch, chitin and yeast extract were utilized as substrates. The major metabolic products were acetate, butyrate and ethanol. Strain PPP2T was resistant to ampicillin, but sensitive to tetracycline, chloramphenicol, rifampicin, kanamycin, vancomycin and gentamicin. The DNA G+C content of strain PPP2T was 39.5 mol%. Phylogenetic analysis revealed that strain PPP2T was related most closely to Clostridium sticklandii SR (approximately 90% 16S rRNA gene sequence similarity). On the basis of phylogenetic analysis and phenotypic characteristics, strain PPP2T is considered to represent a novel species of a new genus, for which the name Proteocatella sphenisci gen. nov., sp. nov. is proposed. The type strain of Proteocatella sphenisci is PPP2T (=ATCC BAA-755T=JCM 12175T=CIP 108034T).

Tellurite resistance and reduction by a Paenibacillus sp. isolated from heavy metal-contaminated sediment.

A gram-positive bacterium (designated as strain TeW) that is highly resistant to tellurite was isolated from sediment. The bacterium can grow in the presence of up to 2,000 micromol/L of potassium tellurite (K2TeO3). Reduction of K2TeO3 to tellurium was indicated by the blackening of the growth medium. No lag in growth was observed when cells unexposed to tellurite were transferred to the growth medium containing K2TeO3, indicating that resistance to tellurite was not inducible. Up to 50 and 90% of the metalloid oxyanion tellurite (TeO(3)(2-)) was removed from the medium by strain TeW during growth in nonstatic (shaking) and static (without shaking) conditions, respectively. The bacterium was identified as a Paenibacillus sp. according to its morphology, physiology, and 16S rDNA sequence homology.

Desmospora activa gen. nov., sp. nov., a thermoactinomycete isolated from sputum of a patient with suspected pulmonary tuberculosis, and emended description of the family Thermoactinomycetaceae Matsuo et al. 2006.

A novel Gram-positive, aerobic, catalase-positive, filamentous micro-organism, designated strain IMMIB L-1269(T), originating from sputum was characterized using phenotypic and molecular taxonomic methods. It showed cell-wall chemotype III, phospholipid type PII (with phosphatidylethanolamine as the diagnostic phospholipid) and contained an unsaturated menaquinone with seven isoprene units (MK-7) as the predominant isoprenoid quinone. It synthesized long-chain cellular fatty acids of the straight-chain saturated, monounsaturated and iso- and anteiso-branched types (with iso-C(15 : 0), C(16 : 0) and iso-C(17 : 0) predominating) and possessed a DNA G+C content of 49.3 mol%. On the basis of its morphological, biochemical and chemical characteristics, strain IMMIB L-1269(T) did not conform to any presently recognized taxon. Comparative analyses based on 16S rRNA gene sequences confirmed the distinctiveness of the isolate, as it displayed sequence-divergence values greater than 7.7 % with respect to recognized Gram-positive taxa. Phylogenetic treeing analysis served to reinforce the view that strain IMMIB L-1269(T) was distinct from recognized taxa, as it formed a relatively long subline branching within a 16S rRNA gene sequence cluster that encompassed the genera Thermoactinomyces, Laceyella, Mechercharimyces, Thermoflavimicrobium, Planifilum, Seinonella and Shimazuella of the family Thermoactinomycetaceae. On the basis of phenotypic and molecular phylogenetic evidence, strain IMMIB L-1269(T) represents a novel genus and species, for which the name Desmospora activa gen. nov., sp. nov. is proposed. The type strain of Desmospora activa is strain IMMIB L-1269(T) (=DSM 45169(T) =CCUG 55916(T)). An emended description of the family Thermoactinomycetaceae is also given.

Temperature-dependent costs of parasitism and maintenance of polymorphism under genotype-by-environment interactions.

The maintenance of genetic variation for infection-related traits is often attributed to coevolution between hosts and parasites, but it can also be maintained by environmental variation if the relative fitness of different genotypes changes with environmental variation. To gain insight into how infection-related traits are sensitive to environmental variation, we exposed a single host genotype of the freshwater crustacean Daphnia magna to four parasite isolates (which we assume to represent different genotypes) of its naturally co-occurring parasite Pasteuria ramosa at 15, 20 and 25 degrees C. We found that the cost to the host of becoming infected varied with temperature, but the magnitude of this cost did not depend on the parasite isolate. Temperature influenced parasite fitness traits; we found parasite genotype-by-environment (G x E) interactions for parasite transmission stage production, suggesting the potential for temperature variation to maintain genetic variation in this trait. Finally, we tested for temperature-dependent relationships between host and parasite fitness traits that form a key component of models of virulence evolution, and we found them to be stable across temperatures.

Citrinin, a mycotoxin from Penicillium citrinum, plays a role in inducing motility of Paenibacillus polymyxa.

Paenibacillus polymyxa, a Gram-positive low-G+C spore-forming soil bacterium, belongs to the plant growth-promoting rhizobacteria. The swarming motility of P. polymyxa strain E681 was greatly induced by a secondary metabolite, citrinin, produced by Penicillium citrinum KCTC6549 in a dose-dependent manner at concentrations of 2.5-15.0 microg mL(-1) on tryptic soy agar plates containing 1.0% (w/v) agar. Flagellum staining showed that citrinin activated the production of flagella by P. polymyxa. This result was supported by reverse transcriptase-PCR analysis of gene expression, which showed increased transcriptional levels of sigD and hag homologues of P. polymyxa E681 in the presence of citrinin. The results presented here show that a mycotoxin, citrinin, has a newly identified function of inducing bacterial motility by transcriptional activation of related genes. This finding contributes to our understanding of the interactions between bacteria and fungal strains in nature.

Swarming and complex pattern formation in Paenibacillus vortex studied by imaging and tracking cells.

BACKGROUND: Swarming motility allows microorganisms to move rapidly over surfaces. The Gram-positive bacterium Paenibacillus vortex exhibits advanced cooperative motility on agar plates resulting in intricate colonial patterns with geometries that are highly sensitive to the environment. The cellular mechanisms that underpin the complex multicellular organization of such a simple organism are not well understood. RESULTS: Swarming by P. vortex was studied by real-time light microscopy, by in situ scanning electron microscopy and by tracking the spread of antibiotic-resistant cells within antibiotic-sensitive colonies. When swarming, P. vortex was found to be peritrichously flagellated. Swarming by the curved cells of P. vortex occurred on an extremely wide range of media and agar concentrations (0.3 to 2.2% w/v). At high agar concentrations (> 1% w/v) rotating colonies formed that could be detached from the main mass of cells by withdrawal of cells into the latter. On lower percentage agars, cells moved in an extended network composed of interconnected "snakes" with short-term collision avoidance and sensitivity to extracts from swarming cells. P. vortex formed single Petri dish-wide "supercolonies" with a colony-wide exchange of motile cells. Swarming cells were coupled by rapidly forming, reversible and non-rigid connections to form a loose raft, apparently connected via flagella. Inhibitors of swarming (p-Nitrophenylglycerol and Congo Red) were identified. Mitomycin C was used to trigger filamentation without inhibiting growth or swarming; this facilitated dissection of the detail of swarming. Mitomycin C treatment resulted in malcoordinated swarming and abortive side branch formation and a strong tendency by a subpopulation of the cells to form minimal rotating aggregates of only a few cells. CONCLUSION: P. vortex creates complex macroscopic colonies within which there is considerable reflux and movement and interaction of cells. Cell shape, flagellation, the aversion of cell masses to fuse and temporary connections between proximate cells to form rafts were all features of the swarming and rotation of cell aggregates. Vigorous vortex formation was social, i.e. required > 1 cell. This is the first detailed examination of the swarming behaviour of this bacterium at the cellular level.

Inter- and intra-specific cuticle variation between amphimictic and parthenogenetic species of root-knot nematode (Meloidogyne spp.) as revealed by a bacterial parasite (Pasteuria penetrans).

Specific host-parasite interactions exist between species and strains of plant parasitic root-knot nematodes and the Gram-positive bacterial hyperparasite Pasteuria penetrans. This bacterium produces endospores that adhere to the cuticle of migrating juveniles, germinate and colonise the developing female within roots. Endospore attachment of P. penetrans populations to second-stage juveniles of the root-knot nematode species Meloidogyne incognita and Meloidogyne hapla showed there were interactive differences between bacterial populations and nematode species. Infected females of M. incognita produced a few progeny which were used to establish two nematode lines from single infective juveniles encumbered with either three or 26 endospores. Single juvenile descent lines of each nematode species were produced to test whether cuticle variation was greater within M. hapla lines that reproduce by facultative meiotic parthenogenesis than within lines of M. incognita, which reproduces by obligate parthenogenesis. Assays revealed variability between broods of individual females derived from single second-stage juvenile descent lines of both M. incognita and M. hapla suggesting that progeny derived from a single individual can differ in spore adhesion in both sexual and asexual nematode species. These results suggest that special mechanisms that produced these functional differences in the cuticle surface may have evolved in both sexually and asexually reproducing nematodes as a strategy to circumvent infection by this specialised hyperparasite.

[Phenotypic properties of Sulfobacillus thermotolerans: comparative aspects].

The phenotypic characteristics of the species Sulfobacillus thermotolerans Kr1(T), as dependent on the cultivation conditions, are described in detail. High growth rates (0.22-0.30 h(-1)) and high oxidative activity were recorded under optimum mixotrophic conditions at 40 degrees C on medium with inorganic (Fe(II), S(0), or pyrite-arsenopyrite concentrate) and organic (glucose and/or yeast extract) substrates. In cells grown under optimum conditions on medium with iron, hemes a, b, and, most probably, c were present, indicating the presence of the corresponding cytochromes. Peculiar extended structures in the form of cylindrical cords, never observed previously, were revealed; a mucous matrix, likely of polysaccharide nature, occurred around the cells. In the cells of sulfobacilli grown litho-, organo-, and mixotrophically at 40 degrees C, the enzymes of the three main pathways of carbon utilization and some enzymes of the TCA cycle were revealed. The enzyme activity was maximum under mixotrophic growth conditions. The growth rate in the regions of limiting temperatures (55 degrees C and 12-14 degrees C) decreased two- and tenfold, respectively; no activity of 6-phosphogluconate dehydrogenase, one of the key enzymes of the oxidative pentose phosphate pathway, could be revealed; and a decrease in the activity of almost all enzymes of glucose metabolism and of the TCA cycle was observed. The rate of 14CO2 fixation by cells under auto-, mixo-, and heterotrophic conditions constituted 31.8, 23.3, and 10.3 nmol/(h mg protein), respectively. The activities of RuBP carboxylase (it peaked during lithotrophic growth) and of carboxylases of heterotrophic carbon dioxide fixation were recorded. The physiological and biochemical peculiarities of the thermotolerant sulfobacillus are compared versus moderately thermophilic sulfobacilli.

Proposal of six species of moderately thermophilic, acidophilic, endospore-forming bacteria: Alicyclobacillus contaminans sp. nov., Alicyclobacillus fastidiosus sp. nov., Alicyclobacillus kakegawensis sp. nov., Alicyclobacillus macrosporangiidus sp. nov., Alicyclobacillus sacchari sp. nov. and Alicyclobacillus shizuokensis sp. nov.

Moderately thermophilic, acidophilic, spore-forming bacteria (146 strains) were isolated from various beverages and environments. Based on the results of sequence analysis of the hypervariable region of the 16S rRNA gene, eight of the strains represent novel species of the genus Alicyclobacillus. These strains were designated 3-A191(T), 4-A336(T), 5-A83J(T), 5-A167N, 5-A239-2O-A(T), E-8, RB718(T) and S-TAB(T). Phylogenetic analyses of 16S rRNA and DNA gyrase B subunit (gyrB) nucleotide sequences confirmed that the eight strains belonged to the Alicyclobacillus clade. Cells of the eight strains were Gram-positive or Gram-variable, strictly aerobic and rod-shaped. The strains grew well under acidic and moderately thermal conditions, produced acid from various sugars, contained menaquinone 7 as the major isoprenoid quinone and did not produce guaiacol. omega-Alicyclic fatty acids were the predominant lipid component of strains 4-A336(T), 5-A83J(T), 5-A167N, RB718(T) and S-TAB(T). No omega-alicyclic fatty acids were detected in strains 3-A191(T), 5-A239-2O-A(T) or E-8, but iso- and anteiso-branched fatty acids and small amounts of straight-chain saturated fatty acids were detected instead. According to the DNA-DNA hybridization data and distinct morphological, physiological, chemotaxonomical and genetic traits, the eight strains represent six novel species within the genus Alicyclobacillus, for which the following names are proposed: Alicyclobacillus contaminans sp. nov. (type strain 3-A191(T)=DSM 17975(T)=IAM 15224(T)), Alicyclobacillus fastidiosus sp. nov. (type strain S-TAB(T)=DSM 17978(T)=IAM 15229(T)), Alicyclobacillus kakegawensis sp. nov. (type strain 5-A83J(T)=DSM 17979(T)=IAM 15227(T)), Alicyclobacillus macrosporangiidus sp. nov. (type strain 5-A239-2O-A(T)=DSM 17980(T)=IAM 15370(T)), Alicyclobacillus sacchari sp. nov. (type strain RB718(T)=DSM 17974(T)=IAM 15230(T)) and Alicyclobacillus shizuokensis sp. nov. (type strain 4-A336(T)=DSM 17981(T)=IAM 15226(T)).

Paenibacillus ginsengisoli sp. nov., a novel bacterium isolated from soil of a ginseng field in Pocheon Province, South Korea.

A Gram-positive, aerobic or facultative anaerobic, motile, spore-forming bacterial strain, designated Gsoil 1638T, was isolated from a soil sample of a ginseng field in Pocheon province (South Korea), and was characterized taxonomically by using a polyphasic approach. It grew well on nutrient agar medium, utilized a fairly narrow spectrum of carbon sources and tolerated 10% NaCl. The isolate was positive for catalase and oxidase tests but negative for the degradation of macromolecules such as casein, collagen, starch, chitin, CM-cellulose, xylan and DNA. The G + C content of the genomic DNA was 50.7 mol%. The predominant isoprenoid quinone was menaquinone 7 (MK-7). The major fatty acids were anteiso-C15:0 (44%) and C16:0 (25%). Comparative 16S rRNA gene sequence analysis showed that strain Gsoil 1638T fell within the radiation of the cluster comprising Paenibacillus species and joined Paenibacillus anaericanus DSM 15890T with a bootstrap value of 100%. These two strains shared 99.5% 16S rRNA gene sequence similarity with each other. The phylogenetic distance from any other validly described species within the genus Paenibacillus was less than 96.2%. DNA-DNA relatedness value between strain Gsoil 1638T and its closest phylogenetic neighbor, Paenibacillus anaericanus, was 62%. On the basis of its phenotypic properties and phylogenetic distinctiveness, strain Gsoil 1638T (= KCTC 13931T = LMG 23406T = CCUG 52472T) was classified in the genus Paenibacillus as the type strain of a novel species, for which the name Paenibacillus ginsengisoli sp. nov. is proposed.

Mechercharimyces mesophilus gen. nov., sp. nov. and Mechercharimyces asporophorigenens sp. nov., antitumour substance-producing marine bacteria, and description of Thermoactinomycetaceae fam. nov.

A study was carried out to clarify the taxonomy of four Gram-positive, heterotrophic mesophiles isolated from marine lakes in the Republic of Palau. The strains, designated YM3-251(T), YM3-653, YM3-671 and YM11-542(T), formed aerial and substrate mycelia. The cell-wall peptidoglycan contained meso-diaminopimelic acid, glutamic acid and alanine. The G+C content of their genomic DNA was approximately 45 mol%. The major fatty acid was iso-C(15 : 0) and the major isoprenoid quinone was MK-9. The strains formed a distinct group in the 16S rRNA gene tree and shared a range of phenotypic properties that distinguished them from members of related genera in Thermoactinomycetaceae fam. nov. The name proposed to accommodate the new isolates is Mechercharimyces gen. nov., comprising two species based on genotypic and phenotypic criteria, including comparative gyrB and DNA-DNA relatedness data. The names proposed for these taxa are Mechercharimyces mesophilus sp. nov., the type species, and Mechercharimyces asporophorigenens sp. nov., with the type strains YM3-251(T) (=MBIC06230(T)=DSM 44894(T)) and YM11-542(T) (=MBIC06487(T)=DSM 44955(T)), respectively.

Paenibacillus panacisoli sp. nov., a xylanolytic bacterium isolated from soil in a ginseng field in South Korea.

A Gram-positive, facultatively anaerobic, motile, spore-forming bacterium, designated Gsoil 1411T, was isolated from soil of a ginseng field in Pocheon Province (South Korea) and was characterized using a polyphasic approach. Comparative analysis of 16S rRNA gene sequences revealed that strain Gsoil 1411T belongs to the family Paenibacillaceae, with closest sequence similarity to the type strains of Paenibacillus xylanilyticus (95.7%), Paenibacillus illinoisensis (95.2%) and Paenibacillus pabuli (94.8%). Strain Gsoil 1411T showed less than 94% sequence similarity to the type strains of other recognized members of the genus Paenibacillus. In addition, the presence of MK-7 as the major menaquinone, anteiso-C15:0 as a major fatty acid (44.8%) and the presence of PAEN513F and PAEN862F signature sequences suggest that it is affiliated to the genus Paenibacillus. The G+C content of the genomic DNA was 53.9 mol%. On the basis of its phenotypic characteristics and phylogenetic distinctiveness, strain Gsoil 1411T is suggested to represent a novel species within the genus Paenibacillus, for which the name Paenibacillus panacisoli sp. nov. is proposed. The type strain is Gsoil 1411T (=KCTC 13020T=LMG 23405T).

Cohnella thermotolerans gen. nov., sp. nov., and classification of 'Paenibacillus hongkongensis' as Cohnella hongkongensis sp. nov.

A Gram-positive, rod-shaped, endospore-forming organism, strain CCUG 47242T, was isolated from a sample of industrial starch production in Sweden. 16S rRNA gene sequence analysis demonstrated that this isolate was moderately related to species of the genus Paenibacillus, with <94.4 % sequence similarity to all other hitherto described Paenibacillus species. Strain CCUG 47242T showed the greatest sequence similarity (96.5 %) to 'Paenibacillus hongkongensis' HKU3, a strain with a name that has not yet been validly published. Chemotaxonomic data [major menaquinone, MK-7 (98 %); major polar lipids, diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, lysyl-phosphatidylglycerol, two unknown phospholipids, four unknown aminophospholipids; major fatty acids, iso-C16 : 0 and anteiso-C15 : 0] showed some significant differences when compared with the type species of the genus Paenibacillus, Paenibacillus polymyxa. Physiological and biochemical tests allowed clear phenotypic differentiation of strain CCUG 47242T from strain HKU3. On the basis of 16S rRNA gene sequence analysis, in combination with chemotaxonomic data, strains CCUG 47242T and HKU3 represent two novel species of a new genus of endospore-forming bacteria for which we propose the names Cohnella thermotolerans gen. nov., sp. nov. (type strain CCUG 47242T = CIP 108492T = DSM 17683T) and Cohnella hongkongensis sp. nov. (type strain HKU3T = CCUG 49571T = CIP 107898T = DSM 17642T).

Virgibacillus koreensis sp. nov., a novel bacterium from a salt field, and transfer of Virgibacillus picturae to the genus Oceanobacillus as Oceanobacillus picturae comb. nov. with emended descriptions.

A novel Virgibacillus strain, BH30097T, was isolated from a salt field near Taean-Gun on the Yellow Sea in Korea. Cells were Gram-positive rods and bore ellipsoidal endospores in terminal positions. The optimum pH and temperature for growth of this organism were pH 7 and 25 degrees C, respectively. The main respiratory quinone was MK-7 and the major cellular fatty acids were anteiso-C(15 : 0) and iso-C(16 : 0). Analysis based on 16S rRNA gene sequence data revealed that the isolate formed an evolutionary lineage distinct from other Virgibacillus species. Levels of sequence similarity between the isolate and other Virgibacillus species ranged from 93.8 to 96.7 %. DNA-DNA relatedness values between strain BH30097T and a phylogenetically closely related strain, Virgibacillus halodenitrificans KCTC 3790T, were less than 24 %. On the basis of morphological, physiological and chemotaxonomic characteristics, 16S rRNA gene sequence comparison and DNA-DNA hybridization, a novel species, Virgibacillus koreensis sp. nov., is proposed, with the type strain BH30097T (= KCTC 3823T = JCM 12387T). It is also proposed that Virgibacillus picturae be transferred to the genus Oceanobacillus as Oceanobacillus picturae comb. nov. based on its 16S rRNA gene sequences and other taxonomic characteristics.

Nocturnal production of endospores in natural populations of epulopiscium-like surgeonfish symbionts.

Prior studies have described a morphologically diverse group of intestinal microorganisms associated with surgeonfish. Despite their diversity of form, 16S rRNA gene surveys and fluorescent in situ hybridizations indicate that these bacteria are low-G+C gram-positive bacteria related to Epulopiscium spp. Many of these bacteria exhibit an unusual mode of reproduction, developing multiple offspring intracellularly. Previous reports have suggested that some Epulopiscium-like symbionts produce dormant or phase-bright intracellular offspring. Close relatives of Epulopiscium, such as Metabacterium polyspora and Clostridium lentocellum, are endospore-forming bacteria, which raises the possibility that the phase-bright offspring are endospores. Structural evidence and the presence of dipicolinic acid demonstrate that phase-bright offspring of Epulopiscium-like bacteria are true endospores. In addition, endospores are formed as part of the normal daily life cycle of these bacteria. In the populations studied, mature endospores were seen only at night and the majority of cells in a given population produced one or two endospores per mother cell. Phylogenetic analyses confirmed the close relationship between the endospore-forming surgeonfish symbionts characterized here and previously described Epulopiscium spp. The broad distribution of endospore formation among the Epulopiscium phylogenetic group raises the possibility that sporulation is a characteristic of the group. We speculate that spore formation in Epulopiscium-like symbionts may be important for dispersal and may also enhance survival in the changing conditions of the fish intestinal tract.

Planifilum fimeticola gen. nov., sp. nov. and Planifilum fulgidum sp. nov., novel members of the family 'Thermoactinomycetaceae' isolated from compost.

Four thermophilic, Gram-positive strains, designated H0165(T), 500275(T), C0170 and 700375, were isolated from a composting process in Japan. The isolates grew aerobically at about 65 degrees C on a solid medium with formation of substrate mycelia; spores were produced singly along the mycelia. These morphological characters resembled those of some type strains of species belonging to the family 'Thermoactinomycetaceae', except that aerial mycelia were not formed. Phylogenetic analyses based on 16S rRNA gene sequences indicated that the closest related species to the isolates were members of the family 'Thermoactinomycetaceae', but that the isolates formed an independent phylogenetic lineage. Some chemotaxonomic characters of the isolates, such as DNA G+C contents of 58.7-60.3 mol%, MK-7 as the major menaquinone and cellular fatty acid profiles, differed from those of members of the family 'Thermoactinomycetaceae'. DNA-DNA hybridization showed that the isolates could be divided into two genomic groups, strain H0165(T) and the other three strains. These results indicated that the four isolates should be classified into two species of a novel genus in the family 'Thermoactinomycetaceae', for which the names Planifilum fimeticola gen. nov., sp. nov. (type strain H0165(T)=ATCC BAA-969(T)=JCM 12507(T)) and Planifilum fulgidum sp. nov. (type strain 500275(T)=ATCC BAA-970(T)=JCM 12508(T)) are proposed.