"Watching" a Molecular Twist in a Protein by Raman Optical Activity

Light-absorbing chromophores in photoreceptors contain a π-electron system and are intrinsically planar molecules. However, within a protein environment these cofactors often become nonplanar and chiral in a manner that is widely believed to be functionally important. When the same chromophore is out-of-plane distorted in opposite directions in different members of a protein family, such conformers become a set of enantiomers. In techniques using chiral optical spectroscopy such as Raman optical activity (ROA), such proteins are expected to show opposite signs in their spectra. Here we use two microbial rhodopsins, Gloeobacter rhodopsin and sodium ion pump rhodopsin (NaR), to provide the first experimental and theoretical evidence that the twist direction of the retinal chromophore indeed determines the sign of the ROA spectrum. We disrupt the hydrogen bond responsible for the distortion of the retinal in NaR and show that the sign of the ROA signals of this nonfunctional mutant is flipped. The reported ROA spectra are monosignate, a property that has been seen for a variety of photoreceptors, which we attribute to an energetically favorable gradual curvature of the chromophore.

Description of Maribellus sediminis sp. nov., a marine nitrogen-fixing bacterium isolated from sediment of cordgrass and mangrove

Two marine bacterial strains designated Y2-1-60^T and GM1-28 were isolated from sediments of cordgrass and mangrove along the Luoyang estuary in Quanzhou Bay, China, respectively. Both strains were Gram-staining-negative, straight rod-shaped, non-flagellum, facultatively anaerobic, nitrogen-fixing, and did not contain carotenoid pigment. Catalase activities were found to be weak positive and oxidase activities negative. The 16S rRNA gene sequences of the two strains were identical and had maximum similarity of 98.0% with Maribellus luteus XSD2^T, and of <94.5% with other species. ANI value (96.9%) and DDH estimate (71.5%) between the two strains supported that they belonged to the same species. ANI value and DDH estimate between the two strains and M. luteus XSD2^T was 74.3% and 19.4%, respectively, indicating that they represent a novel species. Phylogenetic analysis based on 16S rRNA gene and phylogenomic analysis indicated that strains Y2-1-60^T and GM1-28 formed a monophyletic branch within the genus Maribellus. The respiratory quinone was menaquinone MK-7. The major fatty acid (>10%) consisted of iso-C_15:0, and iso-C_17:0 3-OH. The polar lipids consisted of phosphatidylethanolamine and several unidentified lipids. The genomic G+C contents were 41.9-42.0mol%. Gene annotation revealed that strains Y2-1-60^T and GM1-28 contained a set of nif gene cluster (nifHDKENB) responsible for nitrogen fixation. Based on the above characteristics, strains Y2-1-60^T and GM1-28 represent a novel species within the genus Maribellus. Thus, Maribellus sediminis sp. nov. is proposed with type strain Y2-1-60^T (=MCCC 1K04285^T=KCTC 72884^T), isolated from cordgrass sediment and strain GM1-28 (=MCCC 1K04384=KCTC 72880), isolated from mangrove sediment.

Comparison of microbial source tracking efficacy for detection of cattle fecal contamination by quantitative PCR

Identification of fecal contamination sources in surface water has become heavily dependent on quantitative PCR (qPCR) because this technique allows for the rapid enumeration of fecal indicator bacteria as well as the detection and quantification of fecal source-associated genetic markers in the environment. Identification of contamination sources in impaired waters is a prerequisite for developing best management practices to reduce future pollution. Proper management decisions rely on the quality and interpretation of qPCR data. In this study, we developed a method to determine analytical and process lower limits of detection (LLOD) and quantification (LLOQ) using two cattle-associated genetic markers targeting Bacteroidales. Analytical LLOD (A_LLOD) for both CowM2 and CowM3 genetic markers in the qPCR assay were five gene copies per reaction. Using composite fecal DNA, the analytical LLOQ (A_LLOQ) determined for CowM2 and CowM3 were 78 and 195 gene copies/reaction, respectively. When plasmid DNA was used, the A_LLOQ for CowM2 and CowM3 were 46 and 20 gene copies/reaction, respectively. The process LLOD (P_LLOD) for CowM2 and CowM3 were 0.4 and 0.02 mg feces/filter (wet weight), respectively. Using the standard deviation value of 0.25 as a cut-off point for LLOQ in regression analysis, the process LLOQ (P_LLOQ) for CowM2 and CowM3 were 3.2 and 0.3 mg feces/filter, respectively. These results indicate that CowM3 exhibited superior performance characteristics compared with CowM2 for fecal samples collected from our geographical region. Moreover, the method for calculating LLOD and LLOQ developed here can be applied to other microbial source tracking studies.

Biochemical Characterization and Elucidation of Action Pattern of a Novel Polysaccharide Lyase 6 Family Alginate Lyase from Marine Bacterium Flammeovirga sp. NJ-04

Alginate lyases have been widely used to prepare alginate oligosaccharides in food, agricultural, and medical industries. Therefore, discovering and characterizing novel alginate lyases with excellent properties has drawn increasing attention. Herein, a novel alginate lyase FsAlyPL6 of Polysaccharide Lyase (PL) 6 family is identified and biochemically characterized from Flammeovirga sp. NJ-04. It shows highest activity at 45 °C and could retain 50% of activity after being incubated at 45 °C for 1 h. The Thin-Layer Chromatography (TLC) and Electrospray Ionization Mass Spectrometry (ESI-MS) analysis indicates that FsAlyPL6 endolytically degrades alginate polysaccharide into oligosaccharides ranging from monosaccharides to pentasaccharides. In addition, the action pattern of the enzyme is also elucidated and the result suggests that FsAlyPL6 could recognize tetrasaccharide as the minimal substrate and cleave the glycosidic bonds between the subsites of −1 and +3. The research provides extended insights into the substrate recognition and degradation pattern of PL6 alginate lyases, which may further expand the application of alginate lyases.

Flavihumibacter profundi sp. nov., isolated from eutrophic freshwater sediment

A Gram-stain-positive, aerobic, non-motile, non-spore-forming, and rod-shaped bacterium, designated strain CHu64-6-1^T, was isolated from a 67-cm-long sediment core collected from the Daechung Reservoir at a water depth of 17-m in Daejeon, Republic of Korea. Comparative 16S rRNA gene sequence studies placed the new isolate in the class Sphingobacteriia, and the isolate is notably most closely related to Flavihumibacter sediminis CJ663^T (98.1% similarity), Flavihumibacter solisilvae 3-3^T (97.8%), Flavihumibacter petaseus T41^T (97.5%), Flavihumibacter cheonanensis WS16^T (97.4%), and Flavihumibacter stibioxidans YS-17^T (97.2%). The cells of strain CHu64-6-1^T formed yellow colonies on R2A agar and contained MK-7 as the only menaquinone, phosphatidylethanolamine, an unidentified phospholipid, and two unidentified aminolipids as the major polar lipids, and C_15:0 iso, C_17:0 iso 3-OH, C_15:1 iso G, and C_16:1ω5c as the major fatty acids (> 5%). The DNA G + C content of the genome was determined to be 46.5 mol%. The DNA-DNA hybridization values of strain CHu64-6-1^T with F. sediminis CJ663^T, F. solisilvae 3-3^T, F. petaseus T41^T, F. cheonanensis WS16^T, and F. stibioxidans YS-17^T were 12.4-33.2%. Based on the combined genotypic and phenotypic data, we propose that strain CHu64-6-1^T represents a novel species of the genus Flavihumibacter, for which the name Flavihumibacter profundi sp. nov. is proposed. The type strain is CHu64-6-1^T (= KCTC 62290^T = CCTCC AB 2018060^T).

Bacterial community structure and prevalence of Pusillimonas-like bacteria in aged landfill leachate

Although several works have been performed from an engineering point of view, a limited number of studies have focused on microbial communities involved in the humification of aged landfill leachates. In this work, cultivation techniques, next-generation sequencing, and phospholipid fatty acid analysis were adopted to decrypt the diversity and the ecophysiological properties of the dominant microbiota in aged landfill leachate. Based on Illumina sequencing, Betaproteobacteria, Bacteroidetes, Actinobacteria, and Alphaproteobacteria dominated the aged landfill leachate. The main taxa identified at genus level were Pusillimonas-like bacteria and Leucobacter (41.46% of total reads), with all of them being also isolated through cultivation. The presence of Pusillimonas-like bacteria was also verified by the detection of cyclo17:0 and iso-19:0 fatty acids in aged landfill leachate microbiota. Despite that almost all bacterial isolates exhibited extracellular lipolytic ability, no particular specificity was observed in the type of substrate utilized. The prevalence of effective degraders, such as Pusillimonas-like bacteria, makes the aged landfill leachate an ideal source for isolation of novel microorganisms with potential in situ bioremediation uses.

Illumina MiSeq sequencing reveals the key microorganisms involved in partial nitritation followed by simultaneous sludge fermentation, denitrification and anammox process

A combined process including a partial nitritation SBR (PN-SBR) followed by a simultaneous sludge fermentation, denitrification and anammox reactor (SFDA) was established to treat low C/N domestic wastewater in this study. An average nitrite accumulation rate of 97.8% and total nitrogen of 9.4mg/L in the effluent was achieved during 140days' operation. The underlying mechanisms were investigated by using Illumina MiSeq sequencing to analyze the microbial community structures in the PN-SBR and SFDA. Results showed that the predominant bacterial phylum was Proteobacteria in the external waste activated sludge (WAS, added to the SFDA) and SFDA while Bacteroidetes in the PN-SBR. Further study indicated that in the PN-SBR, the dominant nitrobacteria, Nitrosomonas genus, facilitated nitritation and little nitrate was generated in the PN-SBR effluent. In the SFDA, the co-existence of functional microorganisms Thauera, Candidatus Anammoximicrobium and Pseudomonas were found to contribute to simultaneous sludge fermentation, denitrification and anammox.

An Aquatic Microbial Metaproteomics Workflow: From Cells to Tryptic Peptides Suitable for Tandem Mass Spectrometry-based Analysis

Meta-omic technologies such as metagenomics, metatranscriptomics and metaproteomics can aid in the understanding of microbial community structure and metabolism. Although powerful, metagenomics alone can only elucidate functional potential. On the other hand, metaproteomics enables the description of the expressed in situ metabolism and function of a community. Here we describe a protocol for cell lysis, protein and DNA isolation, as well as peptide digestion and extraction from marine microbial cells collected on a cartridge filter unit (such as the Sterivex filter unit) and preserved in an RNA stabilization solution (like RNAlater). In mass spectrometry-based proteomics studies, the identification of peptides and proteins is performed by comparing peptide tandem mass spectra to a database of translated nucleotide sequences. Including the metagenome of a sample in the search database increases the number of peptides and proteins that can be identified from the mass spectra. Hence, in this protocol DNA is isolated from the same filter, which can be used subsequently for metagenomic analysis.

Phylogenetic and Morphological Diversity ofBacteroidalesMembers Associated with the Gut Wall of Termites

The microbial community adherent directly or indirectly to the gut wall of termites is distinct from that of the other habitats in the gut. The bacterial 16S rRNA genes were identified from the fractionated gut walls of two termite species, Hodotermopsis sjoestedti and Neotermes koshunensis, and compared with those previously identified from Reticulitermes speratus. Surprisingly, the bacterial constituents were almost entirely different among the termites at the phylotype level (the criterion of the phylotype was >97% nucleotide identity). Bacteria in the order Bacteroidales, which were commonly abundant symbionts on gut walls, were phylogenetically analyzed. They were dispersed in a number of clusters formed by phylotypes from the guts of various termites. In situ hybridization with probes specific for some phylotypes and a phylogenetic cluster detected the cells of several Bacteroidales members with a significant variety of cell morphology in the gut wall fractions, which reflects the phylogenetic diversity of this order.

A new antibacterial amino phenyl pyrrolidone derivative from a novel marine gliding bacterium Rapidithrix thailandica

A recently described marine gliding bacterium Rapidithrix thailandica strain TISTR 1741 was isolated from biofilm specimen collected from the Andaman Sea in Thailand. Four liters fermentation broth of R. thailandica TISTR 1741 cultivated in VY/2 medium were extracted with methanol to yield a novel amino phenyl pyrrolidone derivative compound (1) with antibacterial activities. The chemical structure and physico-chemical properties of 1 were investigated by spectrometry techniques. Compound 1 exhibited selective inhibition against vancomycin-resistant Enterococcus faecalis (VRE) with the MIC of 5.97 mM.

Bacterioruberin and salinixanthin carotenoids of extremely halophilic Archaea and Bacteria: a Raman spectroscopic study

Laboratory cultures of a number of red extremely halophilic Archaea (Halobacterium salinarum strains NRC-1 and R1, Halorubrum sodomense, Haloarcula valismortis) and of Salinibacter ruber, a red extremely halophilic member of the Bacteria, have been investigated by Raman spectroscopy using 514.5nm excitation to characterize their carotenoids. The 50-carbon carotenoid α-bacterioruberin was detected as the major carotenoid in all archaeal strains. Raman spectroscopy also detected bacterioruberin as the main pigment in a red pellet of cells collected from a saltern crystallizer pond. Salinibacter contains the C40-carotenoid acyl glycoside salinixanthin (all-E, 2'S)-2'-hydroxy-1'-[6-O-(methyltetradecanoyl)-β-d-glycopyranosyloxy]-3',4'-didehydro-1',2'-dihydro-β,ψ-carotene-4-one), for which the Raman bands assignments of are given here for the first time.

Marinoquinolines A-F, pyrroloquinolines from Ohtaekwangia kribbensis (Bacteroidetes)

Marinoquinoline A (1) was isolated from the gliding bacterium Ohtaekwangia kribbensis together with the novel marinoquinolines B-F (2-6). Their structures were elucidated from NMR and HRESIMS data. The pyrroloquinolines showed weak antibacterial and antifungal activities and moderate cytotoxicity against four growing mammalian cell lines with IC(50) values ranging from 0.3 to 8.0 μg/mL. In a screening against tropical parasites marinoquinolines A-F (1-6) showed activity against Plasmodium falciparum K1 with IC(50) values between 1.7 and 15 μM.

Acetylcholinesterase-inhibiting activity of pyrrole derivatives from a novel marine gliding bacterium, Rapidithrix thailandica

Acetylcholinesterase-inhibiting activity of marinoquinoline A (1), a new pyrroloquinoline from a novel species of a marine gliding bacterium Rapidithrix thailandica, was assessed (IC₅₀ 4.9 μM). Two related pyrrole derivatives, 3-(2′-aminophenyl)-pyrrole (3) and 2,2-dimethyl-pyrrolo-1,2-dihydroquinoline (4), were also isolated from two other strains of R. thailandica. The isolation of 3 from a natural source is reported here for the first time. Compound 4 was proposed to be an isolation artifact derived from 3. The two isolated compounds were virtually inactive in the acetylcholinesterase-inhibitory assay (enzyme inhibition < 30% at 0.1 g L⁻¹).

Rapidithrix thailandica gen. nov., sp. nov., a marine gliding bacterium isolated from samples collected from the Andaman sea, along the southern coastline of Thailand

The taxonomic positions of three strains of marine gliding bacteria, TISTR 1736, TISTR 1741 and TISTR 1750(T), isolated from the southern coastline of Thailand were evaluated by using a polyphasic approach. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the three isolates formed a distinct lineage within the family 'Flammeovirgaceae', phylum Bacteroidetes, and were related to the genus Flexithrix. The DNA G+C contents of the isolates were in the range 40-43 mol%. The major respiratory quinone was MK-7. The major cellular fatty acids were 16 : 1omega5c (cis-5-hexadecenoic acid) and 15 : 0 (pentadecanoic acid). The major hydroxyl fatty acids were 3-OH 17 : 0 (3-hydroxyheptadecanoic acid), 3-OH 15 : 0 (3-hydroxypentadecanoic acid) and 3-OH 16 : 0 (3-hydroxyhexadecanoic acid). On the basis of phenotypic, chemotaxonomic, genotypic and phylogenetic data, these marine bacteria are considered to represent a novel species of a new genus, for which the name Rapidithrix thailandica gen. nov., sp. nov. is proposed. The type strain of Rapidithrix thailandica is TISTR 1750(T) (=IAM 15448(T)).

Chitinophaga terrae sp. nov., isolated from soil

A novel strain, designated KP01(T), belonging to the class Sphingobacteria (phylum Bacteroidetes) was isolated from soil in South Korea and was characterized taxonomically using a polyphasic approach. The strain was found to comprise Gram-negative, aerobic, non-motile, non-spore-forming rods. A phylogenetic analysis based on 16S rRNA gene sequences indicated that the strain belonged to the genus Chitinophaga but was clearly separated from established Chitinophaga species. The 16S rRNA gene sequence similarities between KP01(T) and type strains of established Chitinophaga species ranged from 90.3 to 95.7 %. Phenotypic and chemotaxonomic data (major menaquinone, MK-7; major fatty acids, iso-C(15 : 0) and C(16 : 1) omega 5c; major hydroxy fatty acid, C(17 : 0) iso 3-OH) supported the affiliation of strain KP01(T) with the genus Chitinophaga. Therefore strain KP01(T) represents a novel species, for which the name Chitinophaga terrae sp. nov. is proposed. The type strain is KP01(T) (=KCTC 12836(T) =LMG 24015(T)).

Pedobacter duraquae sp. nov., Pedobacter westerhofensis sp. nov., Pedobacter metabolipauper sp. nov., Pedobacter hartonius sp. nov. and Pedobacter steynii sp. nov., isolated from a hard-water rivulet

Five isolates that were related phylogenetically to members of the genus Pedobacter were isolated from freshwater of the hard-water creek Westerhöfer Bach, North Germany. The five strains (WB 2.1-25T, WB 2.3-71T, WB 3.3-3T, WB 3.3-22T and WB 2.3-45T) were Gram-negative and chemoheterotrophic, with rod-shaped cells. Most of their metabolic properties matched those given in the description of the genus Pedobacter. Consistent with the genus description, their fatty acids included mainly iso-C15 : 0 and summed feature 3 (C16 : 1 ω7c, iso-C15 : 0 2-OH or both); C16 : 1 ω5c, C16 : 0, iso-C15 : 0 3-OH, C16 : 0 3-OH and iso-C17 : 0 3-OH were present in smaller amounts. The major isoprenoid quinone was menaquinone 7. With one exception, binary similarity values of the almost complete 16S rRNA gene sequences determined among the isolates as well as between the isolates and type strains of Pedobacter species were lower than 98.5 %. The only exception was the close relationship between Pedobacter caeni DSM 16990T and strain WB 2.3-45T (99.2 % similarity). DNA–DNA reassociation values determined for this pair of strains was 29.8 %, indicating that strain WB 2.3-45T represents a unique genospecies. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strains WB 2.1-25T and WB 2.3-71T form a group that is moderately related to P. caeni and strain WB 2.3-45T (98.5 % similarity). Strains WB 3.3-3T and WB 3.3-22T (98.5 % similarity) branched separately from these four organisms. The five phylogenetically isolated strains differed from each other as well as from the type strain of the type species (Pedobacter heparinus DSM 2366T) and some related representatives of the genus in several metabolic reactions and cultural parameters. On the basis of phenotypic and phylogenetic distinctiveness, five novel species are proposed: Pedobacter duraquae sp. nov., with WB 2.1-25T (=DSM 19034T=CIP 109481T) as the type strain; Pedobacter westerhofensis sp. nov., with WB 3.3-22T (=DSM 19036T=CIP 109479T) as the type strain; Pedobacter metabolipauper sp. nov., with WB 2.3-71T (=DSM 19035T=CIP 109480T) as the type strain; Pedobacter hartonius sp. nov., with WB 3.3-3T (=DSM 19033T=CIP 109468T) as the type strain; and Pedobacter steynii sp. nov., with WB 2.3-45T (=DSM 19110T=CIP 109507T) as the type strain.

Pseudosphingobacterium domesticum gen. nov., sp. nov., isolated from home-made compost

A bacterial strain, DC-186(T), isolated from home-made compost, was characterized for its phenotypic and phylogenetic properties. The isolate was a Gram-negative rod that was able to grow at 15-36 degrees C and pH 5.5-8.0. Strain DC-186(T) was positive in tests for catalase, oxidase and beta-galactosidase activities and aesculin hydrolysis. The predominant fatty acids were the summed feature C(16 : 1)/iso-C(15 : 0) 2-OH (42 %) and iso-C(15 : 0) (26 %), the major respiratory quinone was menaquinone-7 and the genomic DNA G+C content was 42 mol%. 16S rRNA gene sequence analysis and phenetic characterization indicated that this organism belongs to the phylum Bacteroidetes and revealed its affiliation to the family Sphingobacteriaceae. Of recognized taxa, strain DC-186(T) was most closely related to Sphingobacterium daejeonense (90 % sequence similarity) based on 16S rRNA gene sequence analysis. The low 16S rRNA gene sequence similarity with other recognized taxa and the identification of distinctive phenetic features for this isolate support the definition of a new genus within the family Sphingobacteriaceae. The name Pseudosphingobacterium domesticum gen. nov., sp. nov. is proposed, with strain DC-186(T) (=CCUG 54353(T)=LMG 23837(T)) as the type strain.

Pedobacter lentus sp. nov. and Pedobacter terricola sp. nov., isolated from soil

Two Gram-negative, non-motile, pleomorphic bacterial strains, DS-40T and DS-45T, were isolated from a soil sample collected from Dokdo, Korea, and their exact taxonomic positions were investigated by using a polyphasic approach. Strains DS-40T and DS-45T grew optimally at 25 °C and pH 6.5–7.5 in the presence of 0–1.0 % (w/v) NaCl. They contained MK-7 as the predominant menaquinone and possessed iso-C15 : 0, iso-C17 : 0 3-OH and summed feature 3 (C16 : 1 ω7c and/or iso-C15 : 0 2-OH) as the major fatty acids. The DNA G+C contents of strains DS-40T and DS-45T were 36.0 and 36.8 mol%, respectively. Strains DS-40T and DS-45T shared a 16S rRNA gene sequence similarity of 96.7 % and demonstrated a mean DNA–DNA relatedness level of 12 %. Phylogenetic analyses based on 16S rRNA gene sequences revealed that strains DS-40T and DS-45T were most closely phylogenetically affiliated with the genus Pedobacter of the family Sphingobacteriaceae. Strains DS-40T and DS-45T exhibited 16S rRNA gene sequence similarity values of 91.4–93.7 and 89.9–91.6 % with respect to the type strains of Pedobacter and Sphingobacterium species, respectively. Phenotypic and chemotaxonomic properties, together with the phylogenetic data, support the assignment of strains DS-40T and DS-45T as two distinct species within the genus Pedobacter. On the basis of phenotypic, phylogenetic and genetic data, strains DS-40T and DS-45T represent two novel species of the genus Pedobacter, for which the names Pedobacter lentus sp. nov. and Pedobacter terricola sp. nov. are proposed, respectively. The respective type strains are DS-40T (=KCTC 12875T=JCM 14593T) and DS-45T (=KCTC 12876T=JCM 14594T).

Pedobacter insulae sp. nov., isolated from soil

A Gram-negative, non-motile, rod-shaped bacterium, DS-139T, was isolated from a soil sample collected from Dokdo, Korea, and subjected to a polyphasic taxonomic analysis. Strain DS-139T grew optimally at 25 °C and pH 6.5–7.5 in the presence of 0–0.5 % (w/v) NaCl. It contained MK-7 as the predominant menaquinone and iso-C15 : 0, C16 : 1 ω7c and/or iso-C15 : 0 2-OH and iso-C17 : 0 3-OH as the major fatty acids. The DNA G+C content was 39.4 mol%. Phylogenetic analyses based on 16S rRNA gene sequences revealed that strain DS-39T belongs to the genus Pedobacter in the family Sphingobacteriaceae. The similarity values between the 16S rRNA gene sequence of strain DS-139T and those of the type strains of recognized Pedobacter species, except Pedobacter saltans, were in the range 93.9–96.7 %. The differential phenotypic properties, together with the phylogenetic distinctiveness, were sufficient to assign strain DS-139T to a species that is separate from recognized Pedobacter species. On the basis of the phenotypic and phylogenetic data, therefore, strain DS-139T represents a novel species of the genus Pedobacter, for which the name Pedobacter insulae sp. nov. is proposed. The type strain is DS-139T (=KCTC 12820T =DSM 18684T).

The motility symbiont of the termite gut flagellate Caduceia versatilis is a member of the "Synergistes" group

The flagellate Caduceia versatilis in the gut of the termite Cryptotermes cavifrons reportedly propels itself not by its own flagella but solely by the flagella of ectosymbiotic bacteria. Previous microscopic observations have revealed that the motility symbionts are flagellated rods partially embedded in the host cell surface and that, together with a fusiform type of ectosymbiotic bacteria without flagella, they cover almost the entire surface. To identify these ectosymbionts, we conducted 16S rRNA clone analyses of bacteria physically associated with the Caduceia cells. Two phylotypes were found to predominate in the clone library and were phylogenetically affiliated with the "Synergistes" phylum and the order Bacteroidales in the Bacteroidetes phylum. Probes specifically targeting 16S rRNAs of the respective phylotypes were designed, and fluorescence in situ hybridization (FISH) was performed. As a result, the "Synergistes" phylotype was identified as the motility symbiont; the Bacteroidales phylotype was the fusiform ectobiont. The "Synergistes" phylotype was a member of a cluster comprising exclusively uncultured clones from the guts of various termite species. Interestingly, four other phylotypes in this cluster, including the one sharing 95% sequence identity with the motility symbiont, were identified as nonectosymbiotic, or free-living, gut bacteria by FISH. We thus suggest that the motility ectosymbiont has evolved from a free-living gut bacterium within this termite-specific cluster. Based on these molecular and previous morphological data, we here propose a novel genus and species, "Candidatus Tammella caduceiae," for this unique motility ectosymbiont of Caducaia versatilis.

Flavisolibacter ginsengiterrae gen. nov., sp. nov. and Flavisolibacter ginsengisoli sp. nov., isolated from ginseng cultivating soil

Two strains (Gsoil 492T and Gsoil 643T) isolated in Pocheon Province, South Korea, from soil used for ginseng cultivation were characterized using a polyphasic approach. Both isolates comprised Gram-negative, aerobic, non-motile, rod-shaped bacteria. They had similar chemotaxonomic characteristics, e.g. containing MK-7 as the major quinone, having a DNA G+C content in the range 42.5–43.3 mol% and possessing iso-C15 : 0 and iso-C17 : 0 3-OH as the major fatty acids. A phylogenetic analysis based on 16S rRNA gene sequences indicated that the two isolates formed a tight cluster with several uncultured bacterial clones and with the established genera Terrimonas, Niastella and Chitinophaga in the phylum Bacteroidetes but were clearly separate from these genera. The levels of 16S rRNA gene sequence similarity between the isolates and type strains of related genera ranged from 87.5 to 92.4 %. Furthermore, the results of physiological and biochemical tests allowed phenotypic differentiation of the isolates from phylogenetically closely related species with validly published names. The level of 16S rRNA gene sequence similarity between the two strains was 99.5 %, whereas the DNA–DNA relatedness value was 44 %, indicating that they represent separate species. On the basis of the polyphasic evidence, a novel genus, Flavisolibacter gen. nov., and two novel species, Flavisolibacter ginsengiterrae sp. nov. (type strain Gsoil 492T=KCTC 12656T=DSM 18136T) and Flavisolibacter ginsengisoli sp. nov. (type strain Gsoil 643T=KCTC 12657T=DSM 18119T), are proposed. Flavisolibacter ginsengiterrae is the type species of the genus.

Sediminitomix flava gen. nov., sp. nov., of the phylum Bacteroidetes, isolated from marine sediment

A novel bacterium designated Mok-1-85T was isolated from a marine sediment sample collected from Okinawa Island, Japan. Cells of strain Mok-1-85T stained Gram-negative, were catalase- and oxidase-positive and were non-motile. In a neighbour-joining tree based on 16S rRNA gene sequences, the novel strain clustered with the genus Flammeovirga, a member of the family ‘Flammeovirgaceae’. The novel isolate shared low 16S rRNA gene sequence similarities (≤86 %) with the members of the genus Flammeovirga and other related taxa. The major isoprenoid quinone was MK-7 and the predominant fatty acids of this organism were iso-C15 : 0, C16 : 1 ω5c and C16 : 0 3-OH. The G+C content of the DNA was 38 mol%. Combined phylogenetic and physiological data showed that strain Mok-1-85T represents a novel genus and species for which the name Sediminitomix flava gen. nov., sp. nov. is proposed. The type strain is Mok-1-85T (=NBRC 101625T=KCTC 12970T=CIP 109411T).

Chitinophaga ginsengisegetis sp. nov. and Chitinophaga ginsengisoli sp. nov., isolated from soil of a ginseng field in South Korea

Two novel strains belonging to the phylum Bacteroidetes [formerly the Cytophaga–Flexibacter–Bacteroides (CFB) group], designated Gsoil 040T and Gsoil 052T, were isolated from the soil of a ginseng field in Pocheon province, South Korea. A polyphasic approach was used to characterize the taxonomic position of the novel strains. Both strains were Gram-negative, aerobic, non-motile, non-spore-forming and rod-shaped. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the novel isolates belong to the genus Chitinophaga but are clearly separated from the recognized species of this genus; gene sequence similarities between the novel isolates and type strains of recognized species ranged from 91.2 to 96.5 %. One exception was found; strain Gsoil 052T and the type strain of Chitinophaga filiformis had a gene sequence similarity of 99.6 % but had a DNA–DNA relatedness value of 38 %. Phenotypic and chemotaxonomic data (major menaquinone, MK-7; major fatty acids, iso-C15 : 0 and C16 : 1 ω5c; major hydroxy fatty acid, iso-C17 : 0 3-OH and major polyamine, homospermidine) supported the affiliation of both strains Gsoil 040T and Gsoil 052T to the genus Chitinophaga. The results of physiological and biochemical tests enabled the genotypic and phenotypic differentiation of the novel strains from the other recognized species of the genus Chitinophaga. Therefore, it is suggested that the new isolates represent two novel species, for which the names Chitinophaga ginsengisegetis sp. nov. [type strain Gsoil 040T (=KCTC 12654T=DSM 18108T)] and Chitinophaga ginsengisoli sp. nov. [type strain Gsoil 052T (=KCTC 12592T=DSM 18017T)] are proposed.

Parapedobacter koreensis gen. nov., sp. nov

Strain Jip14T, a Gram-negative, non-spore-forming, rod-shaped, non-motile bacterium, was isolated from dried rice straw and characterized in order to determine its taxonomic position. 16S rRNA gene sequence analysis revealed that strain Jip14T belongs to the family Sphingobacteriaceae, and the highest degree of sequence similarity was determined to be to Pedobacter saltans DSM 12145T (88.5 %), Pedobacter africanus DSM 12126T (87.6 %), Pedobacter heparinus DSM 2366T (87.1 %) and Pedobacter caeni LMG 22862T (86.9 %). Chemotaxonomic data revealed that strain Jip14T possesses menaquinone MK-7 and the predominant fatty acids C15 : 0 iso, C16 : 0, C16 : 0 10-methyl, C17 : 0 iso 3-OH and summed feature 3 (C15 : 0 iso 2-OH/C16 : 1 ω7c). The results of physiological and biochemical tests clearly demonstrated that strain Jip14T represents a distinct species. Based on these data, Jip14T should be classified within a novel genus and species, for which the name Parapedobacter koreensis gen. nov., sp. nov. is proposed. The type strain of Parapedobacter koreensis is Jip14T (=KCTC 12643T=LMG 23493T).

Perexilibacter aurantiacus gen. nov., sp. nov., a novel member of the family ‘Flammeovirgaceae’ isolated from sediment

A strictly aerobic, Gram-negative, gliding, dull-orange-pigmented, rod-shaped bacterium, designated strain Shu-F-UV2-2T, was isolated from sediment (Carp Island, Republic of Palau) and was the focus of a polyphasic taxonomic study. Phylogenetic analyses based on the 16S rRNA gene sequence revealed that the novel isolate was affiliated to the family ‘Flammeovirgaceae’ of the phylum Bacteroidetes and that it showed highest sequence similarity (85.5 %) to Flammeovirga yaeyamensis NBRC 100898T. The novel isolate could be differentiated phenotypically and physiologically from recognized members of the family ‘Flammeovirgaceae’. The G+C content of the DNA was 43.0 mol%, MK-7 was the major menaquinone and iso-C15 : 0, C16 : 1 ω7c and C16 : 1 ω5c were the major fatty acids. On the basis of this polyphasic evidence, it was concluded that strain Shu-F-UV2-2T represents a novel species in a new genus of the family ‘Flammeovirgaceae’, for which the name Perexilibacter aurantiacus gen. nov., sp. nov. is proposed. The type strain is Shu-F-UV2-2T (=MBIC06993T=IAM 15413T=KCTC 12867T).

Chitinophaga soli sp. nov. and Chitinophaga terrae sp. nov., isolated from soil of a ginseng field in Pocheon Province, Korea

Two novel strains of the Cytophaga-Flexibacter-Bacteroides (CFB) group, designated Gsoil 219" and Gsoil 2381, were isolated from soil of a ginseng field of Pocheon Province in Korea. Both strains were Gram-negative, aerobic, nonmotile, nonspore-forming, and rod-shaped. Phylogenetic analysis based on 16S rRNA gene sequences indicated that both isolates belong to the genus Chitinophaga but were clearly separated from established species of this genus. The sequence similarities between strain Gsoil 219T and type strains of the established species and between strain Gsoil 238T and type strains of the established species ranged from 91.4 to 94.7% and 91.6 to 94.2%, respectively. Phenotypic and chemotaxonomic data (major menaquinone, MK-7; major fatty acids, iso-C15:0 and C(16:1) omega5c; major hydroxy fatty acid, iso-C(17:0) 3-OH; major polyamine, homospermidine) supported the affiliation of both strains Gsoil 219T and Gsoil 238T to the genus Chitinophaga. Furthermore, the results of physiological and biochemical tests allowed genotypic and phenotypic differentiation of both strains from the other validated Chitinophaga species. Therefore, the two isolates represent two novel species, for which the name Chitinophaga soli sp. nov. (type strain, Gsoil 219T=KCTC 12650T=DSM 18093T) and Chitinophaga terrae sp. nov. (type strain, Gsoil 238T=KCTC 12651T=DSM 18078T) are proposed.

Fulvivirga kasyanovii gen. nov., sp. nov., a novel member of the phylum Bacteroidetes isolated from seawater in a mussel farm

A novel, strictly aerobic, heterotrophic, gliding, Gram-negative, oxidase-, catalase-, β-galactosidase- and alkaline phosphatase-positive marine bacterium, designated strain KMM 6220T, was isolated from seawater and studied by using a polyphasic taxonomic approach. The DNA G+C content of strain KMM 6220T was 59.9 mol%. The predominant fatty acids were iso-C15 : 1, iso-C15 : 0, iso-C15 : 0 3-OH, iso-C17 : 0 3-OH and C16 : 1 ω7/iso-C15 : 0 2-OH. Phylogenetic analysis based on 16S rRNA gene sequencing revealed that strain KMM 6220T formed a cluster with the misclassified strains [Flexibacter] aggregans NBRC 15974 and [Flexibacter] tractuosus NBRC 16035 and with the type strains of Reichenbachiella agariperforans and Roseivirga ehrenbergii with levels of similarity of 95.9, 94.4, 92.0 and 91.8 %, respectively. On the basis of its phenotypic, chemotaxonomic, genotypic and phylogenetic characteristics, strain KMM 6220T is considered to represent a novel species of a new genus in the phylum Bacteroidetes, for which the name Fulvivirga kasyanovii gen. nov., sp. nov. is proposed. The type strain of the type species is KMM 6220T (=CCTCC AB 206119T=KCTC 12832T).

Probing the Importance of Selected Phylum-specific Amino Acids in σA of Bacteroides fragilis, a Primary σ Factor Naturally Devoid of an N-terminal Acidic Region 1.1

The sigmaA factor of Bacteroides fragilis is the prototype of a novel subgroup of primary sigma factors that are essential for growth and ensure the initiation of transcription of the housekeeping genes. This subgroup is confined to the phyla Bacteroidetes and Chlorobi. Its members carry a specific amino acid signature and are notably characterized by a short, basic N-terminal segment instead of the typical acidic region 1.1. Using in vitro mutagenesis, we investigated the importance of this basic segment and of several residues of the signature for the function of sigmaA. We have shown that the conserved residues Phe-61 and Lys-265, located in the core binding and DNA binding subregions 2.1 and 4.2, respectively, are critical for full function of the B. fragilis holoenzyme. With respect to the unusual subregion composition of sigmaA, we have shown that truncation of the basic N-terminal segment, or reversion of its charge, strongly affects the overall transcriptional activity of B. fragilis RNA polymerase in vitro. Our results indicate that the presence of the intact basic segment is required for the formation of RNA polymerase (RNAP)-promoter open complexes, the correct architecture of the transcription bubble, and efficient promoter clearance.

Alistipes onderdonkii sp. nov. and Alistipes shahii sp. nov., of human origin

Two groups of previously unknown Gram-negative, strictly anaerobic, pigment-producing, rod-shaped bacteria, which phenotypically and phylogenetically displayed a close association with the recently described species Alistipes finegoldii, were characterized using phenotypic and molecular taxonomic methods. A 16S rRNA gene sequence divergence of approximately 3 % between the two unknown bacteria and A. finegoldii, as well as distinguishable biochemical characteristics, demonstrates that these organisms are genotypically and phenotypically distinct and that each group represents a previously unknown subline within the genus Alistipes. Chromosomal DNA-DNA reassociation studies further confirmed the separateness of the unidentified bacteria and A. finegoldii. On the basis of the phenotypic and phylogenetic findings, two novel species, Alistipes onderdonkii sp. nov. and Alistipes shahii sp. nov., are proposed. The type strains of A. onderdonkii and A. shahii are WAL 8169(T) (=CCUG 48946(T)=ATCC BAA-1178(T)) and WAL 8301(T) (=CCUG 48947(T)=ATCC BAA-1179(T)), respectively; their DNA G+C contents are 58 and 56 mol%, respectively.

Lishizhenia caseinilytica gen. nov., sp. nov., a marine bacterium of the phylum Bacteroidetes

A light-orange, aerobic bacterium, strain UST040201-001T, that degrades casein, gelatin and Tween 20, was isolated in February 2004 from a sand-filtered seawater sample from Port Shelter, Hong Kong SAR, China. The strain possessed menaquinone-6 and its 16S rRNA gene sequence shared only 90.1 % similarity with that of Brumimicrobium glaciale IC156T. Phylogenetic analysis showed that UST040201-001T formed a distinct lineage within the family Cryomorphaceae. Its ecophysiological and biochemical characteristics suggest that this strain represents a novel genus and species within the phylum Bacteroidetes. The name Lishizhenia caseinilytica gen. nov., sp. nov. is proposed. The type strain of Lishizhenia caseinilytica is UST040201-001T (=NRRL B-41434T=JCM 13821T).

Niastella koreensis gen. nov., sp. nov. and Niastella yeongjuensis sp. nov., novel members of the phylum Bacteroidetes, isolated from soil cultivated with Korean ginseng

Two novel strains, GR20-10T and GR20-13T, were isolated from soil using R2A medium. The soil sample was collected from a field in the Yeongju region of Korea that was cultivated with Korean ginseng. Phylogenetic analysis based on 16S rRNA gene sequences indicated that these strains formed a cluster with several uncultured bacterial clones and with Flexibacter filiformis, Flexibacter sancti, Flexibacter japonensis, Cytophaga arvensicola and Flavobacterium ferrugineum (recently reclassified as Terrimonas ferruginea) in the phylum Bacteroidetes. The level of 16S rRNA gene sequence similarity between the two novel strains was 98.9 %. Isolates GR20-10T and GR20-13T showed the highest sequence similarities to Flexibacter japonensis IFO 16041T (91.8 and 91.9 %, respectively) and T. ferruginea ATCC 13524T (90.4 and 90.6 %, respectively). The whole-cell fatty acid profiles of the two isolates were similar and their major fatty acids were 15 : 0 iso, 17 : 0 iso 3-OH and 15 : 1 iso G. The major isoprenoid quinone of both strains was MK-7. The G+C contents of GR20-10T and GR20-13T were 45.8 and 44.3 mol%, respectively. DNA–DNA hybridization (57 % DNA–DNA hybridization value) and phenotypic data indicated that strains GR20-10T and GR20-13T each belong to a separate species. On the basis of phenotypic and phylogenetic data and genomic distinctiveness, strains GR20-10T and GR20-13T represent two novel species in a novel genus in the phylum Bacteroidetes; the names Niastella koreensis gen. nov., sp. nov. (the type species; type strain GR20-10T=KACC 11465T=DSM 17620T) and Niastella yeongjuensis sp. nov. (type strain GR20-13T=KACC 11466T=DSM 17621T) are proposed.

Myroides pelagicus sp. nov., isolated from seawater in Thailand

An aerobic, Gram-negative, non-motile, yellow-to-orange pigmented and rod-shaped bacterium, designated strain SM1T, was isolated from seawater in Thailand and subjected to a polyphasic taxonomic study. Phylogenetic analyses based on 16S rRNA gene sequences revealed that the novel isolate shared 93–95 % sequence similarity with species of the genus Myroides. The DNA–DNA relatedness values of strain SM1T with Myroides odoratimimus JCM 7460T and Myroides odoratus JCM 7458T were below 70 %. The DNA G+C content of strain SM1T was 33.6 mol%, the major menaquinone was MK-6 and the major fatty acids were C15 : 0 iso, C17 : 1 ω9c iso and C17 : 0 iso 3-OH. Based on its phenotypic and chemotaxonomic characteristics, strain SM1T was classified as representing a novel species of the genus Myroides, for which the name Myroides pelagicus sp. nov. is proposed. The type strain is SM1T (=IAM 15337T=KCTC 12661T).

Pedobacter aquatilis sp. nov., isolated from drinking water, and emended description of the genus Pedobacter

A Gram-negative, rod-shaped, non-spore-forming bacterium (strain AR107T) was isolated from the drinking water distribution system of Seville (Spain). A polyphasic taxonomic study of the isolate resulted in its identification as a member of the genus Pedobacter. On the basis of 16S rRNA gene sequence comparisons, strain AR107T was shown to belong to the phylum Bacteroidetes, being related to members of the genus Pedobacter. It showed 95.2 % sequence similarity with respect to the type strains of Pedobacter heparinus and Pedobacter piscium, and 94.1 % similarity with respect to the type strain of Pedobacter himalayensis. The predominant fatty acids were iso-C15 : 0, iso-C17 : 0 3-OH and summed feature 3 (iso-C15 : 0 2-OH and/or C16 : 1 ω7c), which supports the affiliation of strain AR107T to the genus Pedobacter. The DNA G+C content of this strain was 38 mol%. On the basis of the phenotypic, phylogenetic and genotypic results, strain AR107T represents a novel species, for which the name Pedobacter aquatilis sp. nov. is proposed. The type strain is AR107T (=CCM 7347T=CECT 7114T=JCM 13454T).

Dyadobacter ginsengisoli sp. nov., isolated from soil of a ginseng field

A Gram-negative, aerobic, non-motile, non-spore-forming and rod-shaped bacterium, strain Gsoil 043T, was isolated from soil from a ginseng field in Pocheon province, South Korea. The novel isolate was characterized in order to determine its taxonomic position. On the basis of 16S rRNA gene sequence similarity, strain Gsoil 043T was shown to belong to the family ‘Flexibacteraceae’ and was related to Dyadobacter fermentans (96.7 %), Dyadobacter crusticola (96.3 %) and Dyadobacter hamtensis (95.8 %). The 16S rRNA gene sequence similarity of the novel strain to other recognized species within the family ‘Flexibacteraceae’ was less than 87.0 %. The G+C content of genomic DNA was 48 mol%. Phenotypic and chemotaxonomic data (major menaquinone, MK-7; major fatty acids, C16 : 1 ω7c, iso-C15 : 0 and C16 : 0) supported the affiliation of strain Gsoil 043T to the genus Dyadobacter. The results of physiological and biochemical tests enabled strain Gsoil 043T to be differentiated genotypically and phenotypically from the three Dyadobacter species with validly published names. The novel isolate therefore represents a novel species for which the name Dyadobacter ginsengisoli sp. nov. is proposed, with the type strain Gsoil 043T (=KCTC 12589T=LMG 23409T).

Reclassification of Bacteroides distasonis, Bacteroides goldsteinii and Bacteroides merdae as Parabacteroides distasonis gen. nov., comb. nov., Parabacteroides goldsteinii comb. nov. and Parabacteroides merdae comb. nov

The characteristics of three Bacteroides species, Bacteroides distasonis, Bacteroides goldsteinii and Bacteroides merdae, were examined. 16S rRNA gene sequence analysis showed that B. distasonis, B. goldsteinii and B. merdae should not be classified as species within the genus Bacteroides. Although B. distasonis, B. goldsteinii and B. merdae were phylogenetically related to Tannerella forsythensis, the ratios of anteiso-C15 : 0 to iso-C15 : 0 in whole-cell methanolysates of the three species were different from that of T. forsythensis. In addition, whereas the major menaquinones of T. forsythensis were MK-10 and MK-11, the major menaquinones of B. distasonis, B. goldsteinii and B. merdae were MK-9 and MK-10. The three species were phenotypically similar to Bacteroides sensu stricto, but phylogenetically distinct. Furthermore, B. distasonis, B. goldsteinii and B. merdae could be differentiated from Bacteroides sensu stricto (predominant menaquinones: MK-10 and MK-11) by the menaquinone composition. This is an important chemotaxonomic characteristic of the three species. On the basis of these data, a novel genus, Parabacteroides gen. nov., is proposed for B. distasonis, B. goldsteinii and B. merdae, with three species, Parabacteroides distasonis gen. nov., comb. nov. (the type species), Parabacteroides goldsteinii comb. nov. and Parabacteroides merdae comb. nov. The type strains of P. distasonis, P. goldsteinii and P. merdae are JCM 5825T (=CCUG 4941T=DSM 20701T=ATCC 8503T), JCM 13446T (=CCUG 48944T) and JCM 9497T (=CCUG 38734T=ATCC 43184T), respectively.

Fluviicola taffensis gen. nov., sp. nov., a novel freshwater bacterium of the family Cryomorphaceae in the phylum 'Bacteroidetes'

A novel, strictly aerobic, Gram-negative, yellow-orange-pigmented, motile, catalase-positive, oxidase-negative bacterium, RW262(T), was isolated from water of the River Taff, Cardiff, UK, during January 2000. Phylogenetic analysis of the 16S rRNA gene indicated that strain RW262(T) was a member of the family Cryomorphaceae within the phylum 'Bacteroidetes'. The DNA G+C content of strain RW262(T) was 37.2 mol%. The predominant fatty acid was the branched-chain saturated fatty acid i15:0 (44.2%). On the basis of polyphasic analysis of phenotypic, chemotaxonomic, genotypic and phylogenetic characteristics, it is proposed that this freshwater bacterium represents a novel genus and species within the family Cryomorphaceae, Fluviicola taffensis gen. nov., sp. nov. The type strain is RW262(T) (=NCIMB 13979(T)=DSM 16823(T)).

Pontibacter actiniarum gen. nov., sp. nov., a novel member of the phylum ‘Bacteroidetes’, and proposal of Reichenbachiella gen. nov. as a replacement for the illegitimate prokaryotic generic name Reichenbachia Nedashkovskaya et al. 2003

The taxonomic position of a marine, gliding, pink-pigmented, aerobic, heterotrophic and Gram-negative bacterium was established using a polyphasic approach. 16S rRNA gene sequence analysis indicated that the strain was a member of the phylum ‘Bacteroidetes’ in which it occupied a separate lineage. The predominant cellular fatty acids were C15 : 0 iso, C17 : 0 iso 3-OH, summed feature 3 and summed feature 4. The DNA G+C content was 48·7 mol%. Phylogenetic evidence and the results of phenotypic, genotypic and chemotaxonomic analyses strongly support the assignment of the newly isolated bacterium as a member of a novel genus and species, for which the name Pontibacter actiniarum gen. nov., sp. nov. is proposed. The type strain is KMM 6156T (=KCTC 12367T=LMG 23027T). It is also proposed that the illegitimate names Reichenbachia and Reichenbachia agariperforans are replaced with Reichenbachiella and Reichenbachiella agariperforans, respectively.

Xanthorhodopsin: a proton pump with a light-harvesting carotenoid antenna

Energy transfer from light-harvesting carotenoids to chlorophyll is common in photosynthesis, but such antenna pigments have not been observed in retinal-based ion pumps and photoreceptors. Here we describe xanthorhodopsin, a proton-pumping retinal protein/carotenoid complex in the eubacterium Salinibacter ruber. The wavelength dependence of the rate of pumping and difference absorption spectra measured under a variety of conditions indicate that this protein contains two chromophores, retinal and the carotenoid salinixanthin, in a molar ratio of about 1:1. The two chromophores interact strongly, and light energy absorbed by the carotenoid is transferred to the retinal with a quantum efficiency of approximately 40%. The antenna carotenoid extends the wavelength range of the collection of light for uphill transmembrane proton transport.

Chemical characterization of exopolysaccharides from Antarctic marine bacteria

Exopolysaccharides (EPS) may have an important role in the Antarctic marine environment, possibly acting as ligands for trace metal nutrients such as iron or providing cryoprotection for growth at low temperature and high salinity. Ten bacterial strains, isolated from Southern Ocean particulate material or from sea ice, were characterized. Whole cell fatty acid profiles and 16S rRNA gene sequences showed that the isolates included representatives of the genera Pseudoalteromonas, Shewanella, Polaribacter, and Flavobacterium as well as one strain, which constituted a new bacterial genus in the family Flavobacteriaceae. The isolates are, therefore, members of the "Gammaproteobacteria" and Cytophaga-Flexibacter-Bacteroides, the taxonomic groups that have been shown to dominate polar sea ice and seawater microbial communities. Exopolysaccharides produced by Antarctic isolates were characterized. Chemical composition and molecular weight data revealed that these EPS were very diverse, even among six closely related Pseudoalteromonas isolates. Most of the EPS contained charged uronic acid residues; several also contained sulfate groups. Some strain produced unusually large polymers (molecular weight up to 5.7 MDa) including one strain in which EPS synthesis is stimulated by low temperature. This study represents a first step in the understanding of the role of bacterial EPS in the Antarctic marine environment.

Isolation of an Algal Morphogenesis Inducer from a Marine Bacterium

Ulva and Enteromorpha are cosmopolitan and familiar marine algal genera. It is well known that these green macroalgae lose their natural morphology during short-term cultivation under aseptic conditions and during long-term cultivation in nutrient-added seawater and adopt an unusual form instead. These phenomena led to the belief that undefined morphogenetic factors that were indispensable to the foliaceous morphology of macroalgae exist throughout the oceans. We characterize a causative factor, named thallusin, isolated from an epiphytic marine bacterium. Thallusin induces normal germination and morphogenesis of green macroalgae.

Novel sulfonolipid in the extremely halophilic bacterium Salinibacter ruber

Salinibacter ruber is an extremely halophilic bacterium, phylogenetically affiliated with the Flavobacterium/Cytophaga branch of the domain Bacteria. Electrospray mass analyses (negative ion) of the total lipid extract of a pure culture of S. ruber shows a characteristic peak at m/z 660 as the most prominent peak in the high-mass range of the spectrum. A novel sulfonolipid, giving rise to the molecular ion [M-H]- of m/z 660, has been identified. The sulfonolipid isolated and purified by thin-layer chromatography was shown by chemical degradation, mass spectrometry, infrared spectroscopy, and nuclear magnetic resonance analysis to have the structure 2-carboxy-2-amino-3-O-(13'-methyltetradecanoyl)-4-hydroxy-18-methylnonadec-5-ene-1-sulfonic acid. This lipid represents about 10% of total cellular lipids, and it appears to be a structural variant of the sulfonolipids found as main components of the cell envelope of gliding bacteria of the genus Cytophaga and closely related genera (W. Godchaux and E. R. Leadbetter, J. Bacteriol. 153:1238-1246, 1983) and of diatoms (R. Anderson, M. Kates, and B. E. Volcani, Biochim. Biophys. Acta 528:89-106, 1978). Since this sulfonolipid has never been observed in any other extreme halophilic microorganism, we consider the peak at m/z 660 the lipid signature of Salinibacter. This study suggests that this novel sulfonolipid may be used as a chemotaxonomic marker for the detection of Salinibacter within the halophilic microbial community in saltern crystallizer ponds and other hypersaline environments.

Distribution of two triamines, spermidine and homospermidine, and an aromatic amine, 2-phenylethylamine, within the phylum Bacteroidetes

Cellular polyamines of the newly additional 19 species belonging to the class Bacteroides of the phylum Bacteroidetes were analyzed by HPLC to display polyamine distribution as a chemotaxonomic marker within the total 41 species. Three profiles, the presence of spermidine, the presence of homospermidine and the absence of both triamines, corresponded to their phylogenetical positions within the four families of the class. The occurrence of an aromatic amine, 2-phenylethylamine, extracted into cellular polyamine fraction, was also determined within the 121 species distributed within the phylum. This aromatic amine was found in Cellulophaga lytica, Cytophaga latercula, Tenacibaculum amylolyticum, Tenacibaculum martimum, Tenacibaculum mesophilum and Psychroflexus torquis belonging to the family Flavobacteriaceae of the class Flavobacteria, and Flexibacter flexilis and Microscilla marina belonging to the family Flexibacteraceae of the class Sphingobacteria.

Intracellular ion and organic solute concentrations of the extremely halophilic bacterium Salinibacter ruber

Salinibacter ruber is a red obligatory aerobic chemoorganotrophic extremely halophilic Bacterium, related to the order Cytophagales. It was isolated from saltern crystallizer ponds, and requires at least 150 g l(-1) salt for growth. The cells have an extremely high potassium content, the ratio K(+)/protein being in the same range as in halophilic Archaea of the order Halobacteriales. X-ray microanalysis in the electron microscope of cells grown in medium of 250 g l(-1) salt confirmed the high intracellular K(+)concentrations, and showed intracellular chloride to be about as high as the cation concentrations within the cells. A search for intracellular organic osmotic solutes, using (13)C-NMR and HPLC techniques, showed glutamate, glycine betaine, and N-alpha-acetyllysine to be present in low concentrations only, contributing very little to the overall osmotic balance. The results presented suggest that the extremely halophilic Bacterium Salinibacteruses a similar mode of haloadaptation to that of the Archaea of the order Halobacteriales, and does not accumulate organic osmotic solutes such as are used by all other known halophilic and halotolerant aerobic Bacteria.

Description of Cellulophaga algicola sp. nov., isolated from the surfaces of Antarctic algae, and reclassification of Cytophaga uliginosa (ZoBell and Upham 1944) Reichenbach 1989 as Cellulophaga uliginosa comb. nov

A group of strains with potent extracellular enzymic activity were isolated from the surfaces of the chain-forming sea-ice diatom Melosira and from an unidentified macrophyte collected from the Eastern Antarctic coastal zone. 16S rDNA sequence analysis indicated that the strains belonged to the genus Cellulophaga and showed greatest similarity to the species Cellulophaga baltica (sequence similarity 97%). Phenotypic characteristics, DNA base composition and DNA-DNA hybridization values clearly separate the Antarctic strains from Cellulophaga baltica and other Cellulophaga species. Thus, the strains form a distinct and novel species and have the proposed name Cellulophaga algicola sp. nov. (type strain IC166T = ACAM 630T). In addition, it was recognized that the species Cytophaga uliginosa (ZoBell and Upham 1944) Reichenbach 1989, a species phylogenetically remote from the type species of the genus Cytophaga, possessed 16S rDNA sequences and phenotypic and chemotaxonomic traits similar to those of other Cellulophaga species. Thus, it was proposed that the species Cytophaga uliginosa be renamed as Cellulophaga uliginosa comb. nov.

FR901451, a novel inhibitor of human leukocyte elastase from Flexibacter sp. I. Producing organism, fermentation, isolation, physico-chemical and biological properties

A novel human leukocyte elastase (HLE) inhibitor, FR901451 was discovered in the fermentation broth of a bacteria. The bacteria was identified as Flexibacter sp. No. 758. FR901451 has a molecular weight of 1269 and a molecular formula of C60H79N13O18. The mode of inhibition against HLE is competitive, with a Ki value of 9.8 x 10(-9) M.

FR901451, a novel inhibitor of human leukocyte elastase from Flexibacter sp. II. Pharmacological effect of FR901451

Intratracheal (i.t.) or intravenous (i.v.) administration of FR901451, a potent inhibitor of human leukocyte elastase (HLE) prevented HLE-induced lung hemorrhage in hamsters with ED50 values of 10.5 micrograms/site and 8.1 mg/kg, respectively. alpha 1-Antitrypsin (alpha 1-AT) also showed inhibitory effect in this model. However, the ED50 value by i.t. injection of FR901451 was 20-fold lower than that of alpha 1-AT. Moreover, FR901451 i.t. significantly modulated porcine pancreas elastase (PPE)-induced changes of the respiratory mechanics in hamsters. The ED50 values were 529 micrograms/site and 244 micrograms/site, which were expressed by static lung compliance (Cst) and vital capacity (VC) of the lungs, respectively. These results suggest that FR901451 could be clinically useful agent for the treatment of the destructive lung disease such as pulmonary emphysema.

Phylogeny and lipid composition of Thermonema lapsum, a thermophilic gliding bacterium

1,490 nucleotides of the 16S rRNA gene of a Gram-negative, thermophilic and gliding bacterium, Thermonema lapsum, have been sequenced. Phylogenetic analysis indicates that T. lapsum is related to cytophaga-flavobacteria-bacteroides (CFB) and is confirmed by the identification signature nucleotides that define this group. Further phylogenetic analysis indicates that T. lapsum forms the deepest branch in the CFB group; this observation was confirmed by the identification of unique nucleotide and nucleotide pairs which separate T. lapsum from all other members of this group. The phospholipid fatty acid (PLFA) profile also confirmed that T. lapsum is related to the cytophaga-flavobacteria-bacteroides group and also to selected members of the genus Flexibacter; the PLFA profile is unique to T. lapsum.