Pathogen-induced activation of disease-suppressive functions in the endophytic root microbiome.

Microorganisms living inside plants can promote plant growth and health, but their genomic and functional diversity remain largely elusive. Here, metagenomics and network inference show that fungal infection of plant roots enriched for Chitinophagaceae and Flavobacteriaceae in the root endosphere and for chitinase genes and various unknown biosynthetic gene clusters encoding the production of nonribosomal peptide synthetases (NRPSs) and polyketide synthases (PKSs). After strain-level genome reconstruction, a consortium of Chitinophaga and Flavobacterium was designed that consistently suppressed fungal root disease. Site-directed mutagenesis then revealed that a previously unidentified NRPS-PKS gene cluster from Flavobacterium was essential for disease suppression by the endophytic consortium. Our results highlight that endophytic root microbiomes harbor a wealth of as yet unknown functional traits that, in concert, can protect the plant inside out.

Potential role of rumen microbiota in altering average daily gain and feed efficiency in meat goats fed simple and mixed pastures using bacterial tag-encoded FLX amplicon pyrosequencing1.

Cost-effective and feasible production system of meat goats requires that grazed forages are converted to profitable goat meat product. However, there are studies as how altering forage type influences ruminal fermentation parameters and animal growth performance, and interact with microbiota in meat goats. Our objective for current study was to examine whether the comparative abundance of the Bacteroidetes (B) and Firmicutes (F) bacterial phyla in meat goats fed simple and mixed forages influenced average daily gain (ADG) and rumen fermentation parameters. In the present study, a molecular approach, bacterial tag-encoded FLX amplicon pyrosequencing (bTEFAP) was applied to accomplish diversity analyses of rumen bacterial populations. Thirty-six Kiko-cross growing meat goats (body weight (BW) = 27.7 ± 2.83 kg) at approximately 7 mo of age were used in this study. Animals were randomly allocated to 3 pasture treatment groups (n = 12) as follows: 1) bermudagrass pasture (BG; Cynodon dactylon), 2) sunn hemp forage (SH; Crotalaria juncea), and 3) BG + SH forage combinations. There were 2 replicates per treatment and animals grazed these pastures for 45 d. Results indicated that treatments had similar initial BW, but final BW and ADG were higher (P < 0.01) for SH and BG + SH combinations than for BG alone. Animal ADG and rumen fermentation (acetate to propionate; A/P ratios) were highly correlated with the abundance of various bacterial populations within the rumen microbiome. There were linear decreases in percentage of Bacteroidetes (R2 = -0.84; P < 0.05) associated with decreasing ADG. In contrast, increased ADG was linearly associated with higher percentages of Firmicutes (R2 = 0.79; P < 0.05), F/B ratios (R2 = 0.88; P = 0.07), total VFA (R2 = 0.45; P < 0.05), and lower A/P ratio (R2 = -0.72; P < 0.01). This suggests that the substrates (diets) and bacterial community have the role in adapting host biological parameters in meat goats. The abundance examination of both Bacteroidetes and Firmicutes will be useful for exploring the structure of gut microbiota as an estimate of animal performance.

Gut commensal Parabacteroides goldsteinii plays a predominant role in the anti-obesity effects of polysaccharides isolated from Hirsutella sinensis.

OBJECTIVE: The medicinal fungus Ophiocordyceps sinensis and its anamorph Hirsutella sinensis have a long history of use in traditional Chinese medicine for their immunomodulatory properties. Alterations of the gut microbiota have been described in obesity and type 2 diabetes. We examined the possibility that H. sinensis mycelium (HSM) and isolated fractions containing polysaccharides may prevent diet-induced obesity and type 2 diabetes by modulating the composition of the gut microbiota. DESIGN: High-fat diet (HFD)-fed mice were treated with HSM or fractions containing polysaccharides of different molecular weights. The effects of HSM and polysaccharides on the gut microbiota were assessed by horizontal faecal microbiota transplantation (FMT), antibiotic treatment and 16S rDNA-based microbiota analysis. RESULTS: Fraction H1 containing high-molecular weight polysaccharides (>300 kDa) considerably reduced body weight gain (∼50% reduction) and metabolic disorders in HFD-fed mice. These effects were associated with increased expression of thermogenesis protein markers in adipose tissues, enhanced gut integrity, reduced intestinal and systemic inflammation and improved insulin sensitivity and lipid metabolism. Gut microbiota analysis revealed that H1 polysaccharides selectively promoted the growth of Parabacteroides goldsteinii, a commensal bacterium whose level was reduced in HFD-fed mice. FMT combined with antibiotic treatment showed that neomycin-sensitive gut bacteria negatively correlated with obesity traits and were required for H1's anti-obesogenic effects. Notably, oral treatment of HFD-fed mice with live P. goldsteinii reduced obesity and was associated with increased adipose tissue thermogenesis, enhanced intestinal integrity and reduced levels of inflammation and insulin resistance. CONCLUSIONS: HSM polysaccharides and the gut bacterium P. goldsteinii represent novel prebiotics and probiotics that may be used to treat obesity and type 2 diabetes.

Plant growth-promoting bacteria elevate the nutritional and functional properties of black cumin and flaxseed fixed oil.

BACKGROUND: In order to study the influence of plant growth-promoting bacteria (PGPB) belonging to Streptomyces sp., Paenibacillus sp., and Hymenobacter sp. on fixed oil content of flaxseed and black cumin, 2-year field experiments were conducted. PGPB was applied during seedtime of plants. The extraction of oil from seeds was performed using supercritical CO2 . RESULTS: The addition of PGPB significantly increases the content of C18:1 (from 16.06 ± 0.03% to 16.97 ± 0.03%) and C18:3 (from 42.97 ± 0.2% to 45.42 ± 0.5%) in flaxseed oil and C18:2 (from 52.68 ± 0.50% to 57.11 ± 0.40%) and C20:2 (from 4.34 ± 0.02% to 4.54 ± 0.03%) in black cumin seed oil. The contents of total polyphenols, flavonoids, and carotenoids, as well as antioxidant activity measured by ferric-reducing ability of plasma assay, were found to be greater in the oil from the seeds of plants treated with the PGPB, compared with the respective non-treated samples. CONCLUSION: The use of PGPB enhances plant nutritive properties; these represent a great source for obtaining valuable functional food ingredients. © 2017 Society of Chemical Industry.

Shift in bacterioplankton diversity and structure: Influence of anthropogenic disturbances along the Yarlung Tsangpo River on the Tibetan Plateau, China.

River systems have critical roles in the natural water environment and the transportation of nutrients. Anthropogenic activities, including wastewater discharge and river damming, raise adverse impacts on ecosystem and continuum of rivers. An increasing amount of attention has been paid to riverine bacterioplankton as they make vital contributions to biogeochemical nutrient cycle. A comprehensive study was conducted on the bacterioplankton community along the Yarlung Tsangpo River, which is the longest plateau river in China and is suffering from various anthropogenic impacts. The results indicated that nutrient variations corresponded to anthropogenic activities, and silica, nitrogen and phosphorus were retained by the dam. River damming influenced the biomass and diversity of the bacterioplankton, but significant alterations in the community structure were not observed between upstream and downstream of the dam. Moreover, the spatial distribution of the bacterioplankton community changed gradually along the river, and the dominant bacterioplankton in the upstream, midstream and downstream portions of the river were Firmicutes, Bacteroidetes and Proteobacteria, respectively. Soluble reactive phosphorus, elevation, ammonium nitrogen, velocity and turbidity were the main environmental factors that shape the bacterioplankton community. Our study offers the first insights into the variation of a bacterioplankton community of a large river in plateau region.

Comparative Genomics of the Dual-Obligate Symbionts from the Treehopper, Entylia carinata (Hemiptera: Membracidae), Provide Insight into the Origins and Evolution of an Ancient Symbiosis.

Insect species in the Auchenorrhyncha suborder (Hemiptera) maintain ancient obligate symbioses with bacteria that provide essential amino acids (EAAs) deficient in their plant-sap diets. Molecular studies have revealed that two complementary symbiont lineages, "Candidatus Sulcia muelleri" and a betaproteobacterium ("Ca. Zinderia insecticola" in spittlebugs [Cercopoidea] and "Ca. Nasuia deltocephalinicola" in leafhoppers [Cicadellidae]) may have persisted in the suborder since its origin ∼300 Ma. However, investigation of how this pair has co-evolved on a genomic level is limited to only a few host lineages. We sequenced the complete genomes of Sulcia and a betaproteobacterium from the treehopper, Entylia carinata (Membracidae: ENCA), as the first representative from this species-rich group. It also offers the opportunity to compare symbiont evolution across a major insect group, the Membracoidea (leafhoppers + treehoppers). Genomic analyses show that the betaproteobacteria in ENCA is a member of the Nasuia lineage. Both symbionts have larger genomes (Sulcia = 218 kb and Nasuia = 144 kb) than related lineages in Deltocephalinae leafhoppers, retaining genes involved in basic cellular functions and information processing. Nasuia-ENCA further exhibits few unique gene losses, suggesting that its parent lineage in the common ancestor to the Membracoidea was already highly reduced. Sulcia-ENCA has lost the abilities to synthesize menaquinone cofactor and to complete the synthesis of the branched-chain EAAs. Both capabilities are conserved in other Sulcia lineages sequenced from across the Auchenorrhyncha. Finally, metagenomic sequencing recovered the partial genome of an Arsenophonus symbiont, although it infects only 20% of individuals indicating a facultative role.

Mucilaginibacter ginsenosidivorans sp. nov., Isolated from Soil of Ginseng Field.

A Gram-reaction-negative, aerobic, nonmotile, nonspore-forming, and rod-shaped bacterial strain designated Gsoil 3017T was isolated from soil of ginseng field and investigated by phenotypic and phylogenetic analyses. Strain Gsoil 3017T grew at 10-37 °C (optimal growth at 30 °C) and at pH 5.5-8.0 (optimal growth at pH 7) on R2A and nutrient agar without additional NaCl as a supplement. Strain Gsoil 3017T possessed ß-glucosidase activity, which was responsible for its ability to transform ginsenosides Rb1, Rc, and Rd (the three dominant active components of ginseng) to F2 and C-K, respectively. Based on 16S rRNA gene phylogeny, the novel strain represents a new branch within the genus Mucilaginibacter family Sphingobacteriaceae, and clusters with Mucilaginibacter frigoritolerans FT22T (95.6%) and Mucilaginibacter gotjawali SA3-7T (95.6%). The G+C content of the genomic DNA was 48.7%. The predominant respiratory quinone was MK-7, and the major fatty acids were iso-C15:0, iso-C17:0 3-OH, and summed feature 3 (comprising C16:1 ω6c and/or C16:1 ω7c). The major polar lipid was phosphatidylethanolamine. Strain Gsoil 3017T could be differentiated genotypically and phenotypically from other type strains of the genus Mucilaginibacter. The isolate therefore represents a novel species, for which the name Mucilaginibacter ginsenosidivorans sp. nov. is proposed, with the type strain Gsoil 3017T (=KACC 14954T = JCM 17081T).

Local Environmental Factors Drive Divergent Grassland Soil Bacterial Communities in the Western Swiss Alps.

Mountain ecosystems are characterized by a diverse range of climatic and topographic conditions over short distances and are known to shelter a high biodiversity. Despite important progress, still little is known on bacterial diversity in mountain areas. Here, we investigated soil bacterial biogeography at more than 100 sampling sites randomly stratified across a 700-km2 area with 2,200-m elevation gradient in the western Swiss Alps. Bacterial grassland communities were highly diverse, with 12,741 total operational taxonomic units (OTUs) across 100 sites and an average of 2,918 OTUs per site. Bacterial community structure was correlated with local climatic, topographic, and soil physicochemical parameters with high statistical significance. We found pH (correlated with % CaO and % mineral carbon), hydrogen index (correlated with bulk gravimetric water content), and annual average number of frost days during the growing season to be among the groups of the most important environmental drivers of bacterial community structure. In contrast, bacterial community structure was only weakly stratified as a function of elevation. Contrasting patterns were discovered for individual bacterial taxa. Acidobacteria responded both positively and negatively to pH extremes. Various families within the Bacteroidetes responded to available phosphorus levels. Different verrucomicrobial groups responded to electrical conductivity, total organic carbon, water content, and mineral carbon contents. Alpine grassland bacterial communities are thus highly diverse, which is likely due to the large variety of different environmental conditions. These results shed new light on the biodiversity of mountain ecosystems, which were already identified as potentially fragile to anthropogenic influences and climate change. IMPORTANCE: This article addresses the question of how microbial communities in alpine regions are dependent on local climatic and soil physicochemical variables. We benefit from a unique 700-km2 study region in the western Swiss Alps region, which has been exhaustively studied for macro-organismal and fungal ecology, and for topoclimatic modeling of future ecological trends, but without taking into account soil bacterial diversity. Here, we present an in-depth biogeographical characterization of the bacterial community diversity in this alpine region across 100 randomly stratified sites, using 56 environmental variables. Our exhaustive sampling ensured the detection of ecological trends with high statistical robustness. Our data both confirm previously observed general trends and show many new detailed trends for a wide range of bacterial taxonomic groups and environmental parameters.

Negadavirga shengliensis gen. nov., sp. nov., a novel member of the family Cyclobacteriaceae isolated from oil-contaminated saline soil.

Four novel Gram-stain-negative, rod-shaped, and non-motile bacterial strains, SLG210-21(T), SLG210-4, SLG210-5 and SLG210-14, were isolated from oil-contaminated saline soil in Shengli Oilfield, China. Growth were observed at 25-42 °C (optimum 37 °C), in the presence of 0-10 % (w/v) NaCl (optimum 0-1 %) and at pH 4.0-10.0 (optimum pH 7.6-8.6). All the strains were positive for catalase and α, ß-galactosidase activities and nitrogen reduction, and negative for oxidase activity, glucose fermentation and hydrolysis of agar, starch, gelatin, Tween 40, 60 and 80. The DNA G+C contents of the four strains were 41.3-43.0 mol% and the predominant respiratory quinones were all menaquinone-7. The major fatty acids were iso-C15:0, anteiso-C15:0, summed feature 3 (C16:1 ω7c and/or C16:1 ω6c), C16:1 ω5c and summed feature 9 (iso-C17:1 ω9c and/or 10-methyl C16:0), while the polar lipids consisted of phosphatidylcholine, phosphatidylethanolamine, glycolipid, two unidentified phospholipids and two unidentified amino lipids. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the four strains clustered together to form a stable branch in the family Cyclobacteriaceae, and were most closely related to the genera Cyclobacterium and Echinicola with the 16S rRNA gene sequence similarities being 88.6-90.3 and 89.6-91.4 %, respectively. DNA-DNA hybridization between SLG210-21(T) and the other three strains showed the relatedness of 93.8 ± 4.5, 96.2 ± 4.2 and 82.3 ± 4.8 %, respectively. Based on the polyphasic analysis, a novel species in a new genus, Negadavirga Shengliensis gen. nov., sp. nov., is proposed with SLG210-21(T) (=LMG 27737(T) = CGMCC1.12768(T)) [corrected] as the type strain.

Anaerocella delicata gen. nov., sp. nov., a strictly anaerobic bacterium in the phylum Bacteroidetes isolated from a methanogenic reactor of cattle farms.

A strictly anaerobic bacterial strain (WN081(T)) was isolated from rice-straw residue in a methanogenic reactor treating waste from cattle farms in Japan. Cells were Gram-staining negative, non-motile, non-spore-forming straight rods. The strain grew rather well on PY agar slants supplemented with a B-vitamin mixture as well as sugars (PYV4S medium) and made translucent and glossy colonies. Growth in liquid medium with the same composition, however, was scanty, and growth was not improved in spite of various additives to the medium. Strain WN081(T) produced small amounts of acetate, propionate, isobutyrate, butyrate, isovalerate and H(2) from PYV liquid medium. The strain did not use carbohydrates or organic acids. The pH range for growth was narrow (pH 6.8-8.2), having a pH optimum at 6.8-7.5. The temperature range for growth was 10-37°C, the optimum being 25-30°C. The strain was sensitive to bile, and did not have catalase or oxidase activities. Hydrogen sulfide was produced from L-cysteine and L-methionine as well as peptone. Indole was produced from L-tryptophan and peptone. The strain had iso-C(15:0) as the exclusively predominant cellular fatty acid (70%) together with some branched chain components (such as iso-C(15:0) DMA, iso-C(17:0) 3-OH and iso-C(15:0) aldehyde) as minor components. The genomic DNA G+C content was 32.3 mol%. Phylogenetic analysis based on the 16S rRNA gene sequence placed strain WN081(T) in the phylum Bacteroidetes with rather low sequence similarities with the related species such as Rikenella microfusus (85.7% sequence similarity), Alistipes putredinis (85.5%) and Alistipes finegoldii (85.5%) in the family Rikenellaceae. Based on the phylogenetic, physiological and chemotaxonomic analyses, the novel genus and species Anaerocella delicata gen. nov., sp. nov. is proposed to accommodate the strain. The type strain is WN081(T) (= JCM 17049(T) = DSM 23595(T)).

Application of molecular techniques to elucidate the influence of cellulosic waste on the bacterial community structure at a simulated low-level-radioactive-waste site.

Low-level-radioactive-waste (low-level-waste) sites, including those at various U.S. Department of Energy sites, frequently contain cellulosic waste in the form of paper towels, cardboard boxes, or wood contaminated with heavy metals and radionuclides such as chromium and uranium. To understand how the soil microbial community is influenced by the presence of cellulosic waste products, multiple soil samples were obtained from a nonradioactive model low-level-waste test pit at the Idaho National Laboratory. Samples were analyzed using 16S rRNA gene clone libraries and 16S rRNA gene microarray (PhyloChip) analyses. Both methods revealed changes in the bacterial community structure with depth. In all samples, the PhyloChip detected significantly more operational taxonomic units, and therefore relative diversity, than the clone libraries. Diversity indices suggest that diversity is lowest in the fill and fill-waste interface (FW) layers and greater in the wood waste and waste-clay interface layers. Principal-coordinate analysis and lineage-specific analysis determined that the Bacteroidetes and Actinobacteria phyla account for most of the significant differences observed between the layers. The decreased diversity in the FW layer and increased members of families containing known cellulose-degrading microorganisms suggest that the FW layer is an enrichment environment for these organisms. These results suggest that the presence of the cellulosic material significantly influences the bacterial community structure in a stratified soil system.

Niabella ginsengisoli sp. nov., isolated from soil cultivated with Korean ginseng.

The taxonomic status of a yellow- to light orange-coloured strain isolated from soil of a Korean ginseng field was established based on a polyphasic investigation. The novel isolate, strain GR10-1(T), was an obligately aerobic, Gram-staining-negative, non-motile, flexirubin-pigment-producing, short rod-shaped bacterium. The strain grew optimally at 28-30 degrees C, at pH 7.0 and in the presence of 0-1 % NaCl. Phylogenetic analyses based on 16S rRNA gene sequences demonstrated that the new isolate showed the highest sequence similarities with Niabella aurantiaca R2A15-11(T) (95.1 %) and Niabella soli JS13-8(T) (94.6 %). The DNA G+C content of strain GR10-1(T) was 43 mol%. It contained iso-C(15 : 1) G (36.4 %) and iso-C(15 : 0) (32.8 %) as the major fatty acids (>10 %) and MK-7 as the major isoprenoid quinone. On the basis of evidence from our polyphasic taxonomic study, it was concluded that strain GR10-1(T) should be classified within a novel species of the genus Niabella, for which the name Niabella ginsengisoli sp. nov. is proposed. The type strain is GR10-1(T) (=KACC 13021(T) =JCM 15444(T)).

Olivibacter soli sp. nov., Olivibacter ginsengisoli sp. nov. and Olivibacter terrae sp. nov., from soil of a ginseng field and compost in South Korea.

Three novel strains, designated Gsoil 034T, Gsoil 060T and Jip13T, isolated from soil from a ginseng field and compost in South Korea, were characterized using a polyphasic approach to clarify their taxonomic positions. These isolates were found to be Gram-negative, aerobic and heterotrophic, non-spore-forming, non-motile and rod-shaped. Phylogenetic analysis based on 16S rRNA gene sequences indicated that these three isolates formed a cluster with the monospecific genus Olivibacter within the family Sphingobacteriaceae but were clearly separated from Olivibacter sitiensis. The 16S rRNA gene sequence similarities between these isolates and the type strain of O. sitiensis were in the range 88.5-90.1 %. Phenotypic and chemotaxonomic data (MK-7 as the major isoprenoid quinone and iso-C15 : 0 2-OH and/or C16 : 1omega7c, iso-C15 : 0 and iso-C17 : 0 3-OH as the major fatty acids) supported the affiliation of these strains to the genus Olivibacter. However, the results of physiological and biochemical tests allowed phenotypic differentiation of the isolates from Olivibacter species with validly published names. Therefore strains Gsoil 034T, Gsoil 060T and Jip13T represent three novel species of the genus Olivibacter, for which the names Olivibacter soli sp. nov. (type strain Gsoil 034T =KCTC 12645T =LMG 23492T), Olivibacter ginsengisoli sp. nov. (type strain Gsoil 060T =KCTC 12646T =LMG 23491T) and Olivibacter terrae sp. nov. (type strain Jip13T =KCTC 12644T =LMG 23494T) are proposed.

Population biology of cytoplasmic incompatibility: maintenance and spread of Cardinium symbionts in a parasitic wasp.

Bacteria that cause cytoplasmic incompatibility (CI) are perhaps the most widespread parasites of arthropods. CI symbionts cause reproductive failure when infected males mate with females that are either uninfected or infected with a different, incompatible strain. Until recently, CI was known to be caused only by the alpha-proteobacterium Wolbachia. Here we present the first study of the population biology of Cardinium, a recently discovered symbiont in the Bacteroidetes that causes CI in the parasitic wasp Encarsia pergandiella (Hymenoptera: Aphelinidae). Cardinium occurs at high frequency ( approximately 92%) in the field. Using wasps that were recently collected in the field, we measured parameters that are crucial for understanding how CI spreads and is maintained in its host. CI Cardinium exhibits near-perfect rates of maternal transmission, causes a strong reduction in viable offspring in incompatible crosses, and induces a high fecundity cost, with infected females producing 18% fewer offspring in the first 4 days of reproduction. We found no evidence for paternal transmission or horizontal transmission of CI Cardinium through parasitism of an infected conspecific. No evidence for cryptic parthenogenesis in infected females was found, nor was sex allocation influenced by infection. We incorporated our laboratory estimates into a model of CI dynamics. The model predicts a high stable equilibrium, similar to what we observed in the field. Interestingly, our model also predicts a high threshold frequency of CI invasion (20% for males and 24% for females), below which the infection is expected to be lost. We consider how this threshold may be overcome, focusing in particular on the sensitivity of CI models to fecundity costs. Overall our results suggest that the factors governing the dynamics of CI Wolbachia and Cardinium are strikingly similar.

Parapedobacter soli sp. nov., isolated from soil of a ginseng field.

Strain DCY14(T), a Gram-negative, non-spore-forming, rod-shaped, non-motile bacterium, was isolated from soil from a ginseng field in Korea and was characterized in order to determine its taxonomic position. 16S rRNA gene sequence analysis revealed that strain DCY14(T) belongs to the family Sphingobacteriaceae, the highest degree of sequence similarity being found with respect to Parapedobacter koreensis Jip14(T) (95.8 %). Chemotaxonomic data revealed that strain DCY14(T) possesses MK-7 as the major menaquinone. The major fatty acids present were anteiso-C(13 : 0), iso-C(15 : 0), iso-C(17 : 0) 3-OH and summed feature 4 (C(16 : 1)omega7c/iso-C(15 : 0) 2-OH). The results of physiological and biochemical tests clearly demonstrated that strain DCY14(T) represents a distinct species. On the basis of these data, DCY14(T) represents a novel species of the genus Parapedobacter, for which the name Parapedobacter soli sp. nov. is proposed. The type strain is DCY14(T) (=KCTC 12984(T) =LMG 24069(T)).

Mucilaginibacter paludis gen. nov., sp. nov. and Mucilaginibacter gracilis sp. nov., pectin-, xylan- and laminarin-degrading members of the family Sphingobacteriaceae from acidic Sphagnum peat bog.

Two facultatively aerobic, heterotrophic bacteria capable of degrading pectin, xylan, laminarin and some other polysaccharides were obtained from the acidic Sphagnum peat bog Bakchar, in western Siberia, Russia, and were designated strains TPT18(T) and TPT56(T). Cells of these isolates are Gram-negative, non-motile, long rods that are covered by large capsules. On ageing, they transform into spherical L-forms. Strains TPT18(T) and TPT56(T) are acido- and psychrotolerant organisms capable of growth at pH 4.2-8.2 (with an optimum at pH 6.0-6.5) and at 2-33 degrees C (with an optimum at 20 degrees C). The major fatty acids are iso-C(15 : 0), anteiso-C(15 : 0), iso-C(17 : 0) 3-OH and summed feature 3 (iso-C(15 : 0) 2-OH and/or C(16 : 1)omega7c); the quinones are MK-7 and MK-6. Comparative 16S rRNA gene sequence analysis revealed that the novel strains share 97 % sequence similarity and belong to the family Sphingobacteriaceae; however, they are related only distantly to members of the genera Pedobacter (91.8-93.3 % similarity) and Sphingobacterium (89.6-91.2 % similarity). The DNA G+C content of strains TPT18(T) and TPT56(T) is 42.4 and 46.1 mol%, respectively. The low DNA-DNA hybridization value (42 %) and a number of phenotypic differences between strains TPT18(T) and TPT56(T) indicated that they represent two separate species. Since the two isolates are clearly distinct from all currently described members of the family Sphingobacteriaceae, we propose a novel genus, Mucilaginibacter gen. nov., containing two novel species, Mucilaginibacter gracilis sp. nov. and Mucilaginibacter paludis sp. nov. The type strains of Mucilaginibacter gracilis and Mucilaginibacter paludis are respectively TPT18(T) (=ATCC BAA-1391(T) =VKM B-2447(T)) and TPT56(T) (=ATCC BAA-1394(T) =VKM B-2446(T)).

Olivibacter sitiensis gen. nov., sp. nov., isolated from alkaline olive-oil mill wastes in the region of Sitia, Crete.

A novel, Gram-negative, non-motile, non-sporulating, rod-shaped bacterium isolated from a viscous two-phase olive-oil mill waste ('alpeorujo') is described. The strain, designated AW-6T, is an obligate aerobe, forming irregular, pigmented creamy white colonies. The pH and temperature ranges for growth were pH 5-8 and 5-45 degrees C, with optimal pH and temperature for growth of pH 6-7 and 28-32 degrees C, respectively. Strain AW-6T was chemo-organotrophic and utilized mostly D+ -glucose, protocatechuate and D+ -xylose, followed by L-cysteine, D- -fructose, D+ -galactose, L-histidine, lactose, sorbitol and sucrose. Menaquinone-7 was detected in the respiratory chain of strain AW-6T. The major fatty acids of strain AW-6T were C(16 : 1)omega7c and/or iso-C(15 : 0) 2-OH, iso-C(15 : 0), iso-C(17 : 0) 3-OH and C(16 : 0). The closest phylogenetic relative of strain AW-6T was clone BIti35 (89.7 % 16S rRNA gene sequence similarity), while Sphingobacterium thalpophilum DSM 11723T was the closest recognized relative within the Sphingobacteriaceae (88.2 % similarity). Strain AW-6T showed a low level of DNA-DNA relatedness to S. thalpophilum DSM 11723T (33.8-37.0 %). The DNA G+C content of strain AW-6T was 45.6 mol%. Physiological and chemotaxonomic data further confirmed the distinctiveness of strain AW-6T from members of the genera Sphingobacterium and Pedobacter. Thus, strain AW-6T is considered to represent a novel species of a new genus within the family Sphingobacteriaceae, for which the name Olivibacter sitiensis gen. nov., sp. nov. is proposed. The type strain is AW-6T =DSM 17696T=CECT 7133T).

Pedobacter ginsengisoli sp. nov., a DNase-producing bacterium isolated from soil of a ginseng field in South Korea.

A Gram-negative, strictly aerobic, rod-shaped, non-motile, non-spore-forming bacterial strain, designated Gsoil 104T, was isolated from a soil sample from a ginseng field in Pocheon Province (South Korea) and was characterized taxonomically by using a polyphasic approach. On the basis of 16S rRNA gene sequence similarities, strain Gsoil 104T was shown to belong to the family Sphingobacteriaceae, being related to Pedobacter africanus DSM 12126T (97.0%), Pedobacter caeni LMG 22862T (96.9%), Pedobacter cryoconitis DSM 14825T (96.8%) and Pedobacter heparinus DSM 2366T (96.6%). The phylogenetic distance from any other Pedobacter species with a validly published name was greater than 3.4% (i.e.<96.6% 16S rRNA gene sequence similarity). DNA-DNA hybridization experiments showed that values for DNA-DNA relatedness between strain Gsoil 104T and its phylogenetically closest neighbours were below 37%. The G+C content of the genomic DNA was 43.6 mol%. The predominant respiratory quinone was MK-7. The major fatty acids were C16:1omega7c, iso-C15:0, C16:0, iso-C17:0 3-OH and iso-C15:0 2-OH. These chemotaxonomic data support the affiliation of strain Gsoil 104T to the genus Pedobacter. On the basis of its phenotypic properties and phylogenetic distinctiveness, strain Gsoil 104T represents a novel species in the genus Pedobacter, for which the name Pedobacter ginsengisoli sp. nov. is proposed. The type strain is Gsoil 104T (=KCTC 12576T=LMG 23399T).

Identification and characterization of bacteria in a selenium-contaminated hypersaline evaporation pond.

Solar evaporation ponds are commonly used to reduce the volume of seleniferous agricultural drainage water in the San Joaquin Valley, Calif. These hypersaline ponds pose an environmental health hazard because they are heavily contaminated with selenium (Se), mainly in the form of selenate. Se in the ponds may be removed by microbial Se volatilization, a bioremediation process whereby toxic, bioavailable selenate is converted to relatively nontoxic dimethylselenide gas. In order to identify microbes that may be used for Se bioremediation, a 16S ribosomal DNA phylogenetic analysis of an aerobic hypersaline pond in the San Joaquin Valley showed that a previously unaffiliated group of uncultured bacteria (belonging to the order Cytophagales) was dominant, followed by a group of cultured gamma-Proteobacteria which was closely related to Halomonas species. Se K-edge X-ray absorption spectroscopy of selenate-treated bacterial isolates showed that they accumulated a mixture of predominantly selenate and a selenomethionine-like species, consistent with the idea that selenate was assimilated via the S assimilation pathway. One of these bacterial isolates (Halomonas-like strain MPD-51) was the best candidate for the bioremediation of hypersaline evaporation ponds contaminated with high Se concentrations because it tolerated 2 M selenate and 32.5% NaCl, grew rapidly in media containing selenate, and accumulated and volatilized Se at high rates (1.65 microg of Se g of protein(-1) x h(-1)), compared to other cultured bacterial isolates.