Soon-Ja Seok

Spirosoma oryzae sp. nov., isolated from rice soil and emended description of the genus Spirosoma.

A bacterial strain, designated RHs22(T), was isolated from a soil sample cultivated with rice in the Suwon region of South Korea. The cells were aerobic, Gram-stain-negative, non-spore-forming, non-flagellated rods or occasionally filaments. The strain grew at 10-37 °C (optimum, 28-30 °C), at pH 5.0-10.0 (optimum, 7.0) and in the presence of 0-1 % (w/v) NaCl (optimum, 0 %). Phylogenetically, the strain was closely related to members of the genus Spirosoma, as its 16S rRNA gene sequence had similarity of 90.3-92.1 % with respect to those of members of the genus Spirosoma, showing the highest sequence similarity with Spirosoma panaciterrae DSM 21099(T). Strain RHs22(T) revealed relatively low sequence similarities of less than 90 % with all the other species with validly published names. It contained MK-7 as the predominant menaquinone and summed feature 3 (C16 : 1ω6c and/or C16 : 1ω7c), C16 : 1ω5c, iso-C15 : 0 and iso-C17 : 0 3-OH as the main fatty acids. The polar lipids of strain RHs22(T) were phosphatidylethanolamine, one unknown aminolipid, two unknown aminophospholipids, one unknown phospholipid and five unknown lipids. The DNA G+C content was 57.0 mol%. Phylogenetic, phenotypic and chemotaxonomic data obtained in this study indicate that strain RHs22(T) represents a novel species of the genus Spirosoma, for which the name Spirosoma oryzae sp. nov. is proposed. The type strain is RHs22(T) ( = KACC 17324(T) = DSM 28354(T)). An emended description of the genus Spirosoma is also proposed.

Roseomonas aerophila sp. nov., isolated from air.

An aerobic, Gram-stain-negative, motile, mesophilic bacterium, designated strain 7515T-07(T), was isolated from an air sample in the Taean region, Republic of Korea. The strain grew at 4-40 °C (optimum, 30 °C) and pH 5.0-9.0 (optimum, pH 7.0). Phylogenetic analysis based on 16S rRNA gene sequences showed that strain 7515T-07(T) was related to members of the genus Roseomonas and had highest 16S rRNA gene sequence similarity with Roseomonas ludipueritiae 170/96(T) (96.7%). 16S RNA gene sequence similarity between strain 7515T-07(T) and Roseomonas gilardii ATCC 49956(T) (the type species of the genus Roseomonas) was 93.4%. Strain 7515T-07(T) contained Q-10 as the ubiquinone and C18:1ω7c and C19:0 cyclo ω8c as the dominant fatty acids (>10%). The polar lipid profile contained diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine and two unidentified aminolipids. The DNA G+C content was 73.0 mol%. Combined data from phenotypic, phylogenetic and chemotaxonomic studies demonstrated that strain 7515T-07(T) is a representative of a novel species of the genus Roseomonas, for which the name Roseomonas aerophila sp. nov. is proposed. The type strain is 7515T-07(T) (=KACC 16529(T)=NBRC 108923(T)).

Genetic variation and relationships in Laetiporus sulphureus s. lat., as determined by ITS rDNA sequences and in vitro growth rate

The aim of this study was to characterise the genetic variation and molecular relationships of the brown rot polypore, Laetiporus sulphureus s. lat., from Europe, South America, Africa, and Asia, using ITS sequences of the nu-rDNA and by comparing the growth rate in vitro. In a NJ analysis of the sequences of 130 individuals of L. sulphureus s. lat., eight distinct clusters emerged, supported by BS values of 70-100%. Within each cluster, the ITS rDNA sequence variation was below 3%. The sequences were also analysed together with Laetiporus sequences available from GenBank. Results demonstrated the possible presence of L. huroniensis in Europe (invalidly named L. montanus) and L. gilbertsonii in South America, and provided more information on the Pan-American and European distribution of one of the clades, currently known in North America as L. sulphureus. L. conifericola formed a separate distinct clade. Moreover, the analysis revealed two unknown Laetiporus taxa in Korea, one in South Africa, and one in Europe. As L. sulphureus is described from Europe (France), and we show that more than one taxon exist here, it is presently not possible to define L. sulphureus s. str. Certain biological differences between some of the clades (in vitro growth rates, chemical composition, and pigmentation) were demonstrated and discussed.

Lactarane sesquiterpenoids from Lactarius subvellereus and their cytotoxicity

Subvellerolactones B (1), D (2), and E (3), structurally unusual lactarane sesquiterpenoids, were isolated from the fruiting bodies of Lactarius subvellereus together with four known lactarane sesquiterpenes (4-7). The chemical structures and stereochemistries of compounds 1-3 were determined on the basis of spectroscopic analyses, including 1D and 2D NMR experiments and a convenient Mosher ester procedure. Subvellerolactone B (1) exhibited cytotoxicity against the A549, SK-MEL-2, and HCT-15 cell lines with IC50 values of 26.5, 18.3, and 14.2 microM, respectively, and subvellerolactones D (2) and E (3) showed cytotoxicity against the A549 and HCT-15 cell lines (IC50 (2): 25.1 and 17.8 microM, and IC50 (3): 19.6 and 28.7 microM, respectively).

Phellinstatin, a new inhibitor of enoyl-ACP reductase produced by the medicinal fungus Phellinus linteus.

A new trimeric hispidin derivative, phellinstatin, was isolated from a culture broth of the medicinal fungus Phellinus linteus and its structure was established by various spectral analysis. Phellinstatin strongly inhibited Staphylococcus aureus enoyl-ACP reductase with an IC(50) of 6 μM and also showed antibacterial activity against S. aureus and MRSA.

Spirosoma aerophilum sp. nov., isolated from an air sample.

A rod-shaped, yellow, Gram-stain-negative, non-flagellated, aerobic bacterium, designated 5516J-17T, was isolated from an air sample collected from Jeju Island, Republic of Korea. It grew in the temperature range of 10-37 °C (optimum 28-30 °C), pH 6.0-11.0 (optimum, pH 7.0) and 0-1 % NaCl (w/v). Phylogenetic trees generated using 16S rRNA gene sequences revealed that strain 5516J-17T belongs to the genus Spirosoma, showing 96.9 % sequence similarity to the most closely related species, Spirosoma linguale DSM 74T. The cellular fatty acids comprised large amounts (>10 % of total fatty acids) of summed feature 3 (C16:1ω7c and/or C16:1ω6c) and C16:1ω5c, and moderate amounts (5-10 % of total fatty acids) of iso-C17:0 3-OH, iso-C15:0 and C16:0. The DNA G+C content was 55.7 mol % and MK-7 was the predominant isoprenoid quinone. Polar lipids were phosphatidylethanolamine, two unknown aminophospholipids, one unknown aminolipid and one unknown lipid. On the basis of this phenotypic and polyphasic taxonomy study, it is suggested that strain 5516J-17T represents a novel species within the genus Spirosoma, with the proposed name Spirosoma aerophilum. The type strain is 5516J-17T (= KACC 17323T = DSM 28388T = JCM 19950T).

Daldinan A, a novel isoindolinone antioxidant from the ascomycete Daldinia concentrica

Free radicals have been known to be involved in the pathogenesis of various diseases such as ischemia, arteriosclerosis, diabetes, rheumatoid arthritis, inflammation and in the initiation of cancer.1–3 Freeradical scavengers are considered to be protective agents against these diseases and thus, the demand for antioxidants having free-radical scavenging effect is gradually growing. Mushrooms are ubiquitous in nature and are a good source of food with high nutritional attributes, as well as they produce various classes of structurally unique secondary metabolites with valuable biological activities. During the screening for natural antioxidants from the Korean native ascomycetes,4 we found that the fruiting body of ascomycete Daldinia concentrica, belonging to family Xylariaceae, exhibited significant free-radical scavenging activity. D. concentrica is known to produce diverse bioactive entities including azaphilone derivatives daldinins,5 diaporthin,6 an anti-HIV agent concentricolide,7 squalene-type triterpenoids concentriols,8 aromatic steroids,9 daldinones10 and neuroprotective lignans.11 In this study, we isolated and characterized a novel isoindolinone derivative (daldinan A, Figure 1) responsible for free-radical scavenging effect from the methanolic extract of the fruiting body of D. concentrica. The fruiting body of D. concentrica (B320 g) collected near Muju county, Jeonbuk province, Korea, was ground and extracted with methanol at room temperature. This methanolic extract was concentrated under reduced pressure, and the aqueous resultant was partitioned consecutively between hexane, chloroform, ethyl acetate and butanol and water. The ethyl acetate-soluble portion, exhibiting potent radical-scavenging activity, was concentrated under reduced pressure, subjected to silica gel column chromatography, and eluted stepwise with chloroform:methanol (100:1-1:1, v/v). An antioxidant fraction was further separated by the second silica gel column chromatography eluted with chloroform:methanol (20:1, v/v). Active fractions were combined, concentrated in vacuo and chromatographed on a column of Sephadex LH-20 (Pharmacia, Uppsala, Sweden) eluted with methanol. Active fractions were combined and subjected to a reversed phase (C18) Sep-pak cartridge eluted with 70% aqueous methanol, followed by preparative HPLC equipped with reversed phase column (150 10 mm i.d.; Cosmosil, Nacalai tesque, Japan) and eluted with 35% aqueous methanol/0.04% trifluoroacetic acid to afford daldinan A (20 mg). The molecular weight of daldinan A was determined to be 415 by EI-mass measurement and its molecular formula was established to be C22H25NO7 by high-resolution EI-mass measurement (m/z 415.1634 [M+], D+3.0 m.m.u.) in combination with 1H and 13C NMR data. This molecular formula requires 11 degrees of unsaturation. The UV absorption maxima at 293 and 258 nm suggested the presence of aromatic functions in its structure. The 1H and 13C NMR peaks of daldinan A measured at room temperature was very broad and thus, two-dimensional NMR spectra did not provide enough and critical correlations to determine its chemical structure. At low temperatures such as 273, 253 and 233 K; however, the 1H and 13C NMR peaks were sharpen and well resolved. Therefore, all NMR spectra were obtained at 243 K. The 1H NMR spectrum of daldinan A showed signals due to

Undibacterium jejuense sp. nov. and Undibacterium seohonense sp. nov., isolated from soil and freshwater, respectively

Two bacterial strains, designated JS4-4(T) and SHS5-24(T), were isolated from forest soil of Jeju Island and fresh water of Seoho lake in Suwon city, respectively, South Korea. Both strains were Gram-stain-negative, aerobic, motile rods. Strains JS4-4(T) and SHS5-24(T) showed high sequence similarities (97.6-95.8 %) and (96.5-95.6 %), respectively, to the members of the genus Undibacterium. The sequence similarity between strains JS4-4(T) and SHS5-24(T) was 97.0 %. A phylogenetic tree showed that these strains fell within the radius of the genus Undibacterium. The main fatty acids of strains JS4-4(T) and SHS5-24(T) were summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c) (50.1 and 58.7 %, respectively) and C16 : 0 (28.3 and 24.5 %, respectively). Both strains had ubiquinone 8 as the only respiratory quinone, and phosphatidylethanolamine, phosphatidylglycerol and diphosphatidylglycerol as the major polar lipids. Strain JS4-4(T) showed <70 % DNA-DNA hybridization with members of the genus Undibacterium. Thus, based on the evidence of a polyphasic study, it is proposed that strains JS4-4(T) and SHS5-24(T) represent two novel species, for which the names Undibacterium jejuense sp. nov. (type strain JS4-4(T) = KACC 12607(T) = NBRC 108922(T)) and Undibacterium seohonense sp. nov. (type strain SHS5-24(T) = KACC 16656(T) = NBRC 108929(T)) are proposed.

Parasegetibacter terrae sp. nov., isolated from paddy soil and emended description of the genus Parasegetibacter.

A Gram-stain-negative, variably shaped, non-flagellated, yellow-pigmented, aerobic bacterium, designated strain SGM2-10(T), was isolated from a paddy soil sample from the Suwon region, South Korea. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the isolate was related most closely to Parasegetibacter luojiensis RHYL-37(T). Strain SGM2-10(T) showed highest 16S rRNA gene sequence similarity to P. luojiensis RHYL-37(T) (95.1 %), Flavitalea populi HY-50R(T) (95.0 %) and Flavitalea gansuensis JCN-23(T) (94.4 %). No other species in the family Chitinophagaceae shared more than 94.1 % 16S rRNA gene sequence similarity with strain SGM2-10(T). The major fatty acids of strain SGM2-10(T) were iso-C15 : 0, iso-C15 : 1 G and iso-C17 : 0 3-OH. The only menaquinone was MK-7. The polar lipids comprised phosphatidylethanolamine, seven unknown lipids and ten unknown aminolipids. The G+C content of the DNA of strain SGM2-10(T) was 46.7 mol%. On the basis of the results of the polyphasic characterization presented in this study, it is concluded that strain SGM2-10(T) represents a novel species of the genus Parasegetibacter, for which the name Parasegetibacter terrae sp. nov. is proposed. The type strain is SGM2-10(T) ( = KACC 17341(T) = JCM 19942(T)). The description of the genus Parasegetibacter has also been emended.

A New Antioxidant, Clitocybin A, from the Culture Broth of Clitocybe aurantiaca

Clitocybin A (1), a new antioxidant, was isolated from the culture broth of Clitocybe aurantiaca. This compound was purified by solvent extraction, silica gel column chromatography, Sephadex LH-20 column chromatography and preparative HPLC. Its structure was determined as 4,6-dihydroxy-2-ρ-hydroxyphenyl-isoindol-1-one on the basis of the UV, NMR, and MS spectroscopic analysis. The compound 1 showed potent free radical scavenging activity against superoxide, ABTS, and DPPH radicals, and protective effect against cellular DNA damage induced by oxidative stress.