Family Flavobacteriaceae Research Articles

Genome analysis of Flaviramulus ichthyoenteri Th78T in the family Flavobacteriaceae: insights into its quorum quenching property and potential roles in fish intestine

BackgroundIntestinal microbes play significant roles in fish and can be possibly used as probiotics in aquaculture. In our previous study, Flaviramulus ichthyoenteri Th78T, a novel species in the family Flavobacteriaceae, was isolated from fish intestine and showed strong quorum quenching (QQ) ability. To identify the QQ enzymes in Th78T and explore the potential roles of Th78T in fish intestine, we sequenced the genome of Th78T and performed extensive genomic analysis.ResultsAn N-acyl homoserine lactonase FiaL belonging to the metallo-β-lactamase superfamily was identified and the QQ activity of heterologously expressed FiaL was confirmed in vitro. FiaL has relatively little similarity to the known lactonases (25.2 ~ 27.9% identity in amino acid sequence). Various digestive enzymes including alginate lyases and lipases can be produced by Th78T, and enzymes essential for production of B vitamins such as biotin, riboflavin and folate are predicted. Genes encoding sialic acid lyases, sialidases, sulfatases and fucosidases, which contribute to utilization of mucus, are present in the genome. In addition, genes related to response to different stresses and gliding motility were also identified. Comparative genome analysis shows that Th78T has more specific genes involved in carbohydrate transport and metabolism compared to other two isolates in Flavobacteriaceae, both isolated from sediments.ConclusionsThe genome of Th78T exhibits evident advantages for this bacterium to survive in the fish intestine, including production of QQ enzyme, utilization of various nutrients available in the intestine as well as the ability to produce digestive enzymes and vitamins, which also provides an application prospect of Th78T to be used as a probiotic in aquaculture.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-015-1275-0) contains supplementary material, which is available to authorized users.

Hanstruepera neustonica gen. nov., sp. nov., a zeaxanthin-producing member of the family Flavobacteriaceae isolated from estuarine water, and emendation of Sediminibacter furfurosus Khan et al. 2007 emend. Kwon et al. 2014, Mangrovimonas yunxiaonensis Li et al. 2013, Antarcticimonas flava Yang et al. 2009 and Hoppeia youngheungensis Kwon et al. 2014.

A Gram-staining-negative, strictly aerobic, yellowish-orange, flexirubin-positive, rod-shaped, non-flagellated, non-spore-forming and non-gliding marine bacterium, designated strain CC-PY-50(T), was isolated from estuarine water off Pingtung, Taiwan. The strain produced zeaxanthin as a major carotenoid pigment, and showed highest pairwise 16S rRNA gene sequence similarity to Bizionia hallyeonensis T-y7(T) (93.9 %) followed by Corallibacter vietnamensis KMM 6217(T) (93.8 %), Geojedonia litorea YCS-16(T) (93.7 %) and other members of the family Flavobacteriaceae (<93.7 %). Strain CC-PY-50(T) established a distinct phyletic lineage associated with Mangrovimonas yunxiaonensis LYYY01(T) (93.1 % sequence similarity) with poor bootstrap support during neighbour-joining and maximum-likelihood phylogenetic analyses (37 % for each). The polar lipid profile of strain CC-PY-50(T) was determined to accommodate large numbers of unknown lipids including major amounts of three unidentified aminolipids and two unidentified lipids, and moderate amounts of an unidentified phospholipid, an unidentified glycolipid and an unidentified lipid. In addition, phosphatidylethanolamine was also detected in significant amounts. The major (>5 % of total) fatty acids were iso-C15 : 0, iso-C15 : 1 G, iso-C17 : 0 3-OH, C16 : 0 and C16 : 1ω6c and/or C16 : 1ω7c. The DNA G+C content was 37.1 mol% and menaquinone-6 (MK-6) was the sole respiratory quinone. Based on the phylogenetic evidence and several distinguishing phenotypic and chemotaxonomic features, strain CC-PY-50(T) is proposed to represent a novel genus and species of the family Flavobacteriaceae, for which the name Hanstruepera neustonica gen. nov., sp. nov. is proposed. The type strain of the type species Hanstruepera neustonica gen. nov., sp. nov. is CC-PY-50(T) ( = JCM 19743(T) = BCRC 80747(T)). Emended descriptions of the species Sediminibacter furfurosus, Mangrovimonas yunxiaonensis, Antarcticimonas flava and Hoppeia youngheungensis are also proposed.

Intestinal microbiota and immune related genes in sea cucumber (Apostichopus japonicus) response to dietary β-glucan supplementation

β-glucan is a prebiotic well known for its beneficial outcomes on sea cucumber health through modifying the host intestinal microbiota. High-throughput sequencing techniques provide an opportunity for the identification and characterization of microbes. In this study, we investigated the intestinal microbial community composition, interaction among species, and intestinal immune genes in sea cucumber fed with diet supplemented with or without β-glucan supplementation. The results show that the intestinal dominant classes in the control group are Flavobacteriia, Gammaproteobacteria, and Alphaproteobacteria, whereas Alphaproteobacteria, Flavobacteriia, and Verrucomicrobiae are enriched in the β-glucan group. Dietary β-glucan supplementation promoted the proliferation of the family Rhodobacteraceae of the Alphaproteobacteria class and the family Verrucomicrobiaceae of the Verrucomicrobiae class and reduced the relative abundance of the family Flavobacteriaceae of Flavobacteria class. The ecological network analysis suggests that dietary β-glucan supplementation can alter the network interactions among different microbial functional groups by changing the microbial community composition and topological roles of the OTUs in the ecological network. Dietary β-glucan supplementation has a positive impact on immune responses of the intestine of sea cucumber by activating NF-κB signaling pathway, probably through modulating the balance of intestinal microbiota.

Chryseobacterium profundimaris sp. nov., a new member of the family Flavobacteriaceae isolated from deep-sea sediment.

A Gram-stain negative, strictly aerobic, rod-shaped, non-motile bacterium, designated strain DY46(T), was isolated from Atlantic Ocean sediment. The isolate was found to grow in medium containing 0-3.0% (w/v) NaCl (optimally at 0-1.0%), at 4-37°C and pH 5.0-8.0. Chemotaxonomic analysis detected MK-6 as the sole isoprenoid quinone. The major fatty acids were identified iso-C15:0, iso-C17:0 3-OH, iso-C17:1 ω9c and summed feature 3 (comprising iso-C15:0 2-OH and/or C16:1 ω7c). The DNA G+C content was determined to be 40.7mol%. Phylogenetic analyses based on the 16S rRNA gene sequence indicated that strain DY46(T) falls within the cluster comprising Chryseobacterium species. The levels of 16S rRNA gene sequence similarity between strain DY46(T) and the type strains of the Chryseobacterium species with validly published names ranged from 92.4 to 99.1%, the high values (>97%) being with Chryseobacterium takakiae A1-2(T) (99.1%), C. taiwanense BCRC 17412(T) (98.0%), C. taeanense PHA3-4(T) (97.3%), C. hispalense DSM 25574(T) (97.3%), C. camelliae THG C4-1(T) (97.2%), C. gregarium DSM 19109(T) (97.1%) and C. wanjuense R2A10-2(T) (97.0%). The DNA-DNA relatedness values between strain DY46(T) and the type strains of the above closely related species were 47, 57, 24, 34, 6, 40 and 21%, respectively. On the basis of phenotypic and genotypic characteristics, strain DY46(T) represents a novel member within the genus Chryseobacterium, for which the name Chryseobacterium profundimaris is proposed. The type strain is DY46(T) (=CGMCC 1.12663(T)=JCM 19801(T)).

Hyunsoonleella pacifica sp. nov., isolated from seawater of South Pacific Gyre.

A Gram-stain-negative, strictly aerobic, non-flagellated, non-gliding, oxidase- and catalase-positive and rod-shaped yellow-pigmented bacterium, designated strain SW033(T) was isolated from a surface seawater sample collected from the South Pacific Gyre (GPS position: 26° 29' S 137° 56' W) during the Integrated Ocean Drilling Program, expedition 329. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain SW033(T) belonged to the genus Hyunsoonleella and showed the highest 16S rRNA gene sequence similarity with Hyunsoonleella jejuensis CNU004(T) (96.8%). It showed 94.7-95.8% 16S rRNA gene sequence similarity with respect to members of the genera Jejuia , Arenitalea and Algibacter in the family Flavobacteriaceae . Optimal growth occurred in the presence of 2-3% (w/v) NaCl, at pH 8.0 and at 28 °C. The genomic DNA G+C content of strain SW033(T) was 36.1 mol%. The major fatty acids were iso-C(15 : 1) G, iso-C(15 : 0), iso-C(17 : 0) 3-OH, iso-C(15 : 0) 3-OH and summed feature 3 (comprising C(16 : 1)ω7c and/or C(16 : 1)ω6c). The major respiratory quinone was menaquinone-6. The major polar lipids were phosphatidylethanolamine, two unidentified aminolipids and four unidentified lipids. On the basis of the polyphasic analyses, strain SW033(T) is considered to represent a member of a novel species in the genus Hyunsoonleella , for which the name Hyunsoonleella pacifica sp. nov. is proposed. The type strain is SW033(T) ( = CGMCC 1.11009(T) = JCM 17860(T)).

Characterizing the internal structure of laboratory ice samples with nuclear magnetic resonance

AbstractDue to solute impurities and freezing-point depression in polycrystalline ice, a complicated and dynamic network of liquid water forms within the solid ice matrix at the boundaries between ice crystal grains. Impurity concentrations, temperature and pressure influence this network structure and impact physical, transport and rheological properties of ice. However, the nature of this internal network structure is not fully understood. Here we utilize nuclear magnetic resonance (NMR) measurements of diffusion and magnetic relaxation to study the geometry and interconnectivity of the liquid-filled network in laboratory ice, formed from a 7 g L−1NaCl solution, and its evolution due to recrystallization processes. Additionally, we apply these NMR measurements to observe the impact on ice microstructure of an ice-binding protein (IBP) excreted by the V3519-10 organism (Flavobacteriaceae family) isolated from the Vostok ice core in Antarctica. Recrystallization inhibition was observed as a function of IBP concentration. This work demonstrates the utility of advanced NMR techniques for applications to ice microstructure and has broader implications for understanding geophysical properties of cryospheric systems.

Wenyingzhuangia heitensis sp. nov., a new species of the family Flavobacteriaceae within the phylum Bacteroidetes isolated from seawater.

A Gram-negative, strictly aerobic, beige-pigmented, non-motile, rod-shaped strain designated H-MN17(T) was isolated from seawater in Japan. Phylogenetic analyses based on the 16S rRNA gene sequence revealed that the novel isolate was affiliated with the family Flavobacteriaceae within the phylum Bacteroidetes and that it showed highest sequence similarity (97.5%) to Wenyingzhuangia marina D1(T). The hybridization values for DNA-DNA relatedness between the strains of H-MN17(T) and W. marina D1(T) were lower than 70%, which is accepted as the phylogenetic definition of a novel species. The DNA G+C content of strain H-MN17(T) was 31.8mol%; MK-6 was the major menaquinone; and anteiso-C15:0, anteiso-C17:0 and anteiso-C19:0 were identified as the major (>10%) cellular fatty acids. A complex polar lipid profile was present consisting of phosphatidylethanolamine, three unidentified lipids, three unidentified glycolipids and three unidentified aminolipids. From the distinct phylogenetic position and combination of genotypic and phenotypic characteristics, the strain is considered to represent a novel species of the genus Wenyingzhuangia for which the name Wenyingzhuangia heitensis sp. nov. is proposed. The type strain of W. heitensis sp. nov. is H-MN17(T) (=KCTC 42245(T)=NBRC 110601(T)).

Flavicella marina gen. nov., sp. nov., a carotenoid-producing bacterium from surface seawater.

A Gram-stain-negative, non-motile, mesophilic, aerobic, rod-shaped or spherical bacterium, strain 2A-7(T), was isolated from surface seawater at Muroto city, Kochi prefecture, Japan. The strain produced a pigment(s), the absorption spectrum of which closely resembled that of β-carotene. Phylogenetic analyses based on 16S rRNA gene sequences showed that the strain fell within the family Flavobacteriaceae and clustered distantly with the type strains of species of the genus Lutibacter (up to 93.9 % similarity). The DNA G+C content was 34.1 mol%. The major fatty acids were summed feature 3 (iso-C15 : 0 2-OH and/or C16 : 1ω7c), iso-C17 : 0 3-OH and iso-C15 : 0 3-OH. The major polar lipids were phosphatidylethanolamine and three unidentified lipids. Menaquinone 6 was detected as the sole isoprenoid quinone. On the basis of phenotypic, genotypic and chemotaxonomic data, strain 2A-7(T) represents a novel genus and species, for which the name Flavicella marina gen. nov., sp. nov. is proposed. The type strain of Flavicella marina is 2A-7(T) ( = NBRC 110145(T) = KCTC 42197(T)).

Non-contiguous finished genome sequence of Ornithobacterium rhinotracheale strain H06-030791.

The Gram-negative, pleomorphic, rod-shaped bacterium Ornithobacterium rhinotracheale is a cause of pneumonia and airsacculitis in poultry. It is a member of the family Flavobacteriaceae of the phylum “Bacteroidetes”. O. rhinotracheale strain H06-030791 was isolated from the lung of a turkey in North Carolina in 2006. Its genome consists of a circular chromosome of 2,319,034 bp in length with a total of 2243 protein-coding genes and nine RNA genes. Genome sequences are available for two additional strains of O. rhinotracheale, isolated in 1988 and 1995, the latter described in a companion genome report in this issue of SIGS. The genome sequence of O. rhinotracheale strain H06-030791, a more contemporary isolate, will be of value in establishing core and pan-genomes for O. rhinotracheale and elucidating its evolutionary history.

Complete genome sequence of Ornithobacterium rhinotracheale strain ORT-UMN 88.

Ornithobacterium rhinotracheale strain ORT-UMN 88 is a Gram-negative, pleomorphic, rod-shaped bacterium and an etiologic agent of pneumonia and airsacculitis in poultry. It is a member of the family Flavobacteriaceae of the phylum Bacteroidetes. O. rhinotracheale strain ORT-UMN 88 was isolated from the pneumonic lung of a turkey in 1995. It was the isolate first used to experimentally reproduce disease in turkeys and has since been the focus of investigations characterizing potential virulence factors of the bacterium. The genome of O. rhinotracheale strain ORT-UMN 88 consists of a circular chromosome of 2,397,867 bp with a total of 2300 protein-coding genes, nine RNA genes, and one noncoding RNA gene. A companion paper in this issue of SIGS reports the non-contiguous finished genome sequence of an additional strain of O. rhinotracheale, isolated in 2006.

Description of Lacinutrix venerupis sp. nov.: A novel bacterium associated with reared clams

A group of five Gram-negative strains isolated from clams (Venerupis decussata and Venerupis philippinarum) in Galicia (NW Spain) were analyzed using a polyphasic taxonomic approach. The strains were non-motile, strictly aerobic rods, and formed yellow-pigmented colonies. Based on 16S rRNA gene sequence similarity, the clam isolates belonged to the Lacinutrix genus, within the Flavobacteriaceae family, and showed the highest sequence similarities with Lacinutrix mariniflava (97.0%) and Lacinutrix algicola (96.9%). The DNA G+C content of the designated type strain Cmf 20.8T was 34.1%, which was within the range of the other species in the genus (29.0–37.0%). The main cellular fatty acids of the type strain Cmf 20.8T were iso-C15:0 3-OH, iso-C15:1 G, iso-C15:0 and iso-C17:0 3-OH. The DNA–DNA analysis value of strain Cmf 20.8T with L. mariniflava AKS292T was 51% and with L. algicola AKS293T it was 56%. Phenotypic data showed that the isolates could be differentiated easily from the other species of the genus. On the basis of these results, the strains represent a novel species of the genus Lacinutrix, for which the name Lacinutrix venerupis sp. nov. is proposed, with Cmf 20.8T (=CECT 8573T=DSM 28755T) as the designated type strain.

Isolation and classification of a novel marine Bacteroidetes as Frondibacter aureus gen. nov., sp. nov.

A facultatively anaerobic, Gram-stain negative, golden-yellow pigmented, non-motile and rod-shaped bacterium, designated strain A5Q-67(T) was isolated from leaf litter collected at the mangrove estuary of Nakama River, Japan. Phylogenetic analysis based on the 16S rRNA gene sequence revealed the novel isolate was affiliated with the family Flavobacteriaceae of the phylum Bacteroidetes and that it showed highest sequence similarity (94.2 %) to Imtechella halotolerans K1(T). The strain could be differentiated phenotypically from recognized members of the family Flavobacteriaceae. The major fatty acids of strain A5Q-67(T) were identified as iso-C17:0 3-OH, summed feature 1 (iso-C15:1 H and/or C13:0 3-OH) and iso-C15:0 as defined by the MIDI system. The DNA G+C content was determined to be 36.7 mol%, the major respiratory quinone was identified as menaquinone 6 (MK-6) and a polar lipid profile was present consisting of phosphatidylethanolamine, two unidentified aminolipids and an unidentified lipid. From the distinct phylogenetic position and combination of genotypic and phenotypic characteristics, the strain is considered to represent a novel genus for which the name Frondibacter aureus gen. nov., sp. nov. is proposed. The type strain of F. aureus is A5Q-67(T) (=KCTC 32991(T) = NBRC 110021(T)).

Phylogenetic analysis of epibacterial communities on the surfaces of four red macroalgae

Macroalgal surfaces are prone to being attached by bacteria. Epibacterial community structures on marine macroalgae are host-specific but temporally and spatially variable. In this study, we investigated the structure of epibacterial communities on the surfaces of four red macroalgae, Gracilaria lemaneiformis, Gloiopeltis furcata, Mazzaella sp. and Porphyra yezoensis, by analyzing the sequences of 16S rRNA gene libraries. Healthy individuals of all macroalgae species were collected in winter from a farm at Dalian, China. The results showed that the epibacterial communities were mainly dominated by α-Proteobacteria, γ-Proteobacteria and Bacteroidetes. Deinococcus-Thermus, Spirochaetes and ɛ-Proteobacteria were also found. The majority of cloned sequences shared the greatest similarity to those of culturable organisms. A large portion of sequences from the α-Proteobacteria homed in Roseobacter clade, i.e., genera Ahrensia, Roseovarius, Litoreibacter, Octadecabacter, Thaiassobacter and Sulfitobacter, while members of Bacteroidetes mainly belonged to family Flavobacteriaceae. The cloned sequences could be separated into 66 OTUs at 0.01 distance value, and rare common OTUs were found among libraries. At genus level, Pseudoalteromonas dominated Gr. lemaneiformis and Gl. furcata libraries, accounting for 72.2% and 47.3%, respectively. Sulfitobacter dominated P. yezoensis library, accounting for 35.4%. A previously undefined cluster within Deinococcus-Thermus dominated Mazzaella sp. library, accounting for 24.6% of the all. These results indicated that a broad range of bacteria inhabited the surfaces of these macroalgae.

Actibacter haliotis sp. nov., isolated from the gut of an abalone, Haliotis discus hannai, and emended description of the genus Actibacter.

A novel strain, designated strain W113(T), was isolated from the gut of an abalone, Haliotis discus hannai, which was collected from the northern coast of Jeju in Korea. The isolate was a Gram-staining-negative, facultatively anaerobic, non-motile, rod-shaped bacterium producing yellow-to-orange carotenoid-type pigments. 16S rRNA gene sequence analysis showed that the isolate belonged to the genus Actibacter in the family Flavobacteriaceae and it shared the highest sequence similarity with the type strain of Actibacter sediminis (98.8 % similarity). Optimal growth occurred at 25 °C, at pH 7 and with 2 % (w/v) NaCl. The major cellular fatty acids were iso-C15:0, anteiso-C15:0 and iso-C15:1 G. Menaquinone-6 was the main respiratory quinone. The polar lipids of the isolate were phosphatidylethanolamine, three unidentified amino lipids, and three unidentified lipids. The genomic DNA G+C content was 42.6 mol% and DNA-DNA hybridization values indicated that the strain shared <18 % genomic relatedness with the most closely related species. The results of the phylogenetic, phenotypic and genotypic analyses indicated that strain W113(T) represents a novel species in the genus Actibacter, for which the name Actibacter haliotis sp. nov. is proposed. The type strain is W113(T) ( = KACC 17209(T) = JCM 18868(T)).

Polaribacter marinivivus sp. nov., a member of the family Flavobacteriaceae isolated from seawater.

A Gram-stain negative, non-flagellated, non-gliding, aerobic and rod-shaped bacterium, designated GYSW-15(T), was isolated from a seawater of Geoje island on the South Sea, South Korea, and subjected to a polyphasic taxonomic approach. Strain GYSW-15(T) was found to grow optimally at 30 °C, at pH 7.0-8.0 and in the presence of approximately 2.0 % (w/v) NaCl. Neighbour-joining phylogenetic tree based on 16S rRNA gene sequences showed that strain GYSW-15(T) belongs to the genus Polaribacter, clustering coherently with the type strain of Polaribacter porphyrae showing sequence similarity value of 97.0 %. Strain GYSW-15(T) exhibited 16S rRNA gene sequence similarity values of 94.3-96.4 % to the type strains of the other Polaribacter species. Strain GYSW-15(T) was found to contain MK-6 as the predominant menaquinone and iso-C15:0, iso-C15:1 G, iso-C16:0 3-OH and summed feature 3 (C16:1 ω7c and/or C16:1 ω6c) as the major fatty acids. The polar lipid profile of strain GYSW-15(T) containing phosphatidylethanolamine and an unidentified lipid as major components was similar to that of the type strain of P. porphyrae. The DNA G + C content of strain GYSW-15(T) was determined to be 31.2 mol% and its mean DNA-DNA relatedness with P. porphyrae LMG 26671(T) was 17 %. Differential phenotypic properties, together with its phylogenetic and genetic distinctiveness, revealed that strain GYSW-15(T) is separated from recognized Polaribacter species. On the basis of the data presented, strain GYSW-15(T) is considered to represent a novel species of the genus Polaribacter, for which the name Polaribacter marinivivus sp. nov. is proposed. The type strain is GYSW-15(T) ( = KCTC 42156(T) = CECT 8655(T)).

Spongiivirga citrea gen. nov., sp. nov., a new marine bacterium of the family Flavobacteriaceae isolated from a marine sponge.

A Gram-negative, strictly aerobic, lemon-yellow pigmented, non-motile, rod-shaped strain designated A7G-39(T) was isolated from a yellow coloured marine sponge (Tethya sp.). Phylogenetic analyses based on the 16S rRNA gene sequence indicated that the new strain represented a member of the family Flavobacteriaceae of the phylum Bacteroidetes and that it showed highest sequence similarity (94.1 %) to Algibacter wandonensis WS-MY22(T). The strain could be differentiated phenotypically from recognised members of the family Flavobacteriaceae. The major fatty acids of strain A7G-39(T) were identified as iso-C15:0 3-OH and summed feature 1 (iso-C15:1 H and/or C13:0 3-OH) as defined by the MIDI system. The DNA G+C content was determined to be 32.6 mol%, the major respiratory quinone was identified as menaquinone 7 (MK-7) and a polar lipid profile was present consisting of phosphatidylethanolamine, an unidentified aminolipid and an unidentified lipid. From the distinct phylogenetic position and combination of genotypic and phenotypic characteristics, the strain is considered to represent a novel genus for which the name Spongiivirga citrea gen. nov., sp. nov. is proposed. The type strain of S. citrea is A7G-39(T) (=KCTC 32990(T) = NBRC 110022(T)).

Evaluation of the effects of probiotics in controlling bacterial necrosis symptoms in larvae of the mud crab Scylla serrata during mass seed production

We aimed to evaluate the practicability of probiotics in controlling larval necrosis symptoms and mass mortality occurred during seed production of the mud crab Scylla serrata. We targeted a bacterium in the family Flavobacteriaceae that causes necrosis symptoms of mud crab larvae. Five candidate probiotic bacterial strains, which showed inhibitory effects against the causative bacterium but were innocuous to larvae, were screened from the seed production environment. Sterile culture medium supernatants of the candidate strains inhibited the causative bacterium through the secretion of extracellular factors. These inhibitory effects were largely reduced when the strains were inoculated into sea water, suggesting medium-dependent production of inhibitory factors. The strain that exhibited the highest inhibitory effect on larval necrosis in 7-day larval rearing experiments was selected as a probiotic strain. In large-scale larval rearing experiments, the probiotic treatment significantly suppressed larval necrosis symptoms and improved larval survival in the early rearing period until the fourth zoeal stage. However, the effect disappeared after the fifth (last) zoeal stage, corresponding to a decrease in inoculated probiotic bacterial counts in the larval rearing water. Almost all larvae had died by the first crab stage. The effectiveness of probiotics developed in vitro has not yet proved practical in commercial-scale seed production. The continuous proliferation of probiotic bacteria and extracellular production as inhibitory factors in larval rearing water are the key factors in developing probiotics for commercial-scale seed production.

Flavobacterium ahnfeltiae sp. nov., a new marine polysaccharide-degrading bacterium isolated from a Pacific red alga.

A Gram-negative, aerobic, rod-shaped, motile by gliding and yellow-pigmented bacterium, designated strain 10Alg 130(T), that displayed the ability to destroy polysaccharides of red and brown algae, was isolated from the red alga Ahnfeltia tobuchiensis. The phylogenetic analysis based on 16S rRNA gene sequence placed the novel strain within the genus Flavobacterium, the type genus of the family Flavobacteriaceae, the phylum Bacteroidetes, with sequence similarities of 96.2 and 95.7 % to Flavobacterium jumunjiense KCTC 23618(T) and Flavobacterium ponti CCUG 58402(T), and 95.3-92.5 % to other recognized Flavobacterium species. The prevalent fatty acids of strain 10Alg 130(T) were iso-C15:0, iso-C15:0 3-OH, iso-C17:0 3-OH, C15:0 and iso-C17:1ω9c. The polar lipid profile consisted of phosphatidylethanolamine, two unknown aminolipids and three unknown lipids. The DNA G+C content of the type strain was 34.3 mol%. The new isolate and the type strains of recognized species of the genus Flavobacterium could strongly be distinguished by a number of phenotypic characteristics. A combination of the genotypic and phenotypic data showed that the algal isolate represents a novel species of the genus Flavobacterium, for which the name Flavobacterium ahnfeltiae sp. nov. is proposed. The type strain is 10Alg 130(T) (=KCTC 32467(T) = KMM 6686(T)).

Mariniflexile ostreae sp. nov., a member of the family Flavobacteriaceae isolated from an oyster.

A Gram-negative, aerobic, non-flagellated and rod-shaped bacterial strain able to move by gliding, designated TYO-10(T), was isolated from an oyster collected at Tongyoung on the South Sea, South Korea. Strain TYO-10(T) was found to grow optimally at 30 °C, at pH 7.0-8.0 and in the presence of 2.0 % (w/v) NaCl. Phylogenetic trees based on 16S rRNA gene sequences revealed that strain TYO-10(T) joined the cluster comprising the type strains of Mariniflexile species. Strain TYO-10(T) exhibited 16S rRNA gene sequence similarity values of 95.4-95.7 % to the type strains of Mariniflexile species and of less than 95.4 % to the type strains of other recognized species. Strain TYO-10(T) was found to contain MK-6 as the predominant menaquinone and iso-C15:0, iso-C15:1 G, anteiso-C15:0, iso-C17:0 3-OH and iso-C15:0 3-OH as the major fatty acids. The major polar lipids of strain TYO-10(T) were identified as phosphatidylethanolamine and an unidentified lipid, which is similar to those of the type strains of Mariniflexile species, but different from those of other phylogenetically related species. The DNA G+C content of strain TYO-10(T) was determined to be 35.9 mol%. The differential phenotypic properties, together with the phylogenetic distinctiveness, revealed that strain TYO-10(T) is separated from other Mariniflexile species. On the basis of the data presented, strain TYO-10(T) is considered to represent a novel species of the genus Mariniflexile, for which the name Mariniflexile ostreae sp. nov. is proposed. The type strain is TYO-10(T) (= KCTC 42113(T) = CECT 8622(T)).

Multilocus sequence analysis of the marine bacterial genus Tenacibaculum suggests parallel evolution of fish pathogenicity and endemic colonization of aquaculture systems.

The genus Tenacibaculum, a member of the family Flavobacteriaceae, is an abundant component of marine bacterial ecosystems that also hosts several fish pathogens, some of which are of serious concern for marine aquaculture. Here, we applied multilocus sequence analysis (MLSA) to 114 representatives of most known species in the genus and of the worldwide diversity of the major fish pathogen Tenacibaculum maritimum. Recombination hampers precise phylogenetic reconstruction, but the data indicate intertwined environmental and pathogenic lineages, which suggests that pathogenicity evolved independently in several species. At lower phylogenetic levels recombination is also important, and the species T. maritimum constitutes a cohesive group of isolates. Importantly, the data reveal no trace of long-distance dissemination that could be linked to international fish movements. Instead, the high number of distinct genotypes suggests an endemic distribution of strains. The MLSA scheme and the data described in this study will help in monitoring Tenacibaculum infections in marine aquaculture; we show, for instance, that isolates from tenacibaculosis outbreaks in Norwegian salmon farms are related to T. dicentrarchi, a recently described species.