Search

The phylogenetic positions and G+C contents of most species belonging to the genera Flavobacterium, Cytophaga, and Flexibacter and several related taxa were determined. Most of the strains included in this study belong to rRNA superfamily V, as shown by DNA-rRNA hybridization data, but the three main genera are highly polyphyletic. Several so-called Cytophaga and Flexibacter species isolated from soil and freshwater cluster with the type species of the genus Flavobacterium, Flavobacterium aquatile, and with Flavobacterium branchiophilum. The fatty acid and protein profiles of members of this group of organisms were determined. We provide an emended description of the genus Flavobacterium and propose new combinations for the following 7 of the 10 validly described species included in this genus: Flavobacterium columnare, Flavobacterium flevense, Flavobacterium johnsoniae (we also correct the specific epithet of this taxon), Flavobacterium pectinovarum, Flavobacterium psychrophilum, Flavobacterium saccharophilum, and Flavobacterium succinicans. A new name, Flavobacterium hydatis, is proposed for [Cytophaga] aquatilis Strohl and Tait 1978. The emended genus Flavobacterium contains bacteria that have the following main characteristics: gram-negative rods that are motile by gliding, produce yellow colonies on agar, are chemoorganotrophs and aerobes, decompose several polysaccharides but not cellulose, and are widely distributed in soil and freshwater habitats. Three Flavobacterium species are pathogenic for fish. The G+C contents of Flavobacterium DNAs range from 32 to 37 mol%. An emended description of the family Flavobacteriaceae is also provided.

On the basis of the 16S rRNA sequence data analysis among the closely related species, the specific primers for Flexibacter maritimus, Flavobacterium branchiophilum, and Cytophaga columnaris were constructed. The specificity in amplifying the 16S rDNA of each species was confirmed by using selected strains of related bacteria and principal fish pathogenic bacteria. A primer pair of MAR 1 and MAR2 could differentiate F. maritimus from other species. The PCR performed with a pair of primers specific to F. branchiophilum failed to amplify the 16S rDNA. However, the PCR with a pair of a specific primer BRA1 and a universal primer 1500R succeeded in specifically amplifying 16S rDNA from F. branchiophilum. The Nucleotide Sequence Database (GenBank) contains two different 16S rRNA sequence data for C. columnaris. On the basis of these data, we produced two primer pairs. A pair of COL1 and 1500R amplified the 16S rDNA from 5 of 7 strains of C. columnaris, and a pair of COLa and COLb worked for the rest of the strains. In addition, these two groups within C. columnaris were supported by PCR-RFLP.

Amplification and sequence analysis of the 16S rRNA genes from DNA samples extracted directly from the environment allows the study of microbial diversity in natural ecosystems without the need for cultivation. In this study this methodology has been applied to two coastal lagoons. Activity and numbers of heterotrophic bacteria have indicated that, as expected, Prevost lagoon (located on the French Mediterranean coast) is more eutrophic than that of the Arcachon Bay (French Atlantic coast). Analysis of partial 16S rRNA gene sequences revealed that, in both environments, a relatively large number of clones related to Cytophaga/Flexibacter/Bacteroides as well as to α-Proteobacteria were found. One hundred percent similarity with the sequences of the data bases were not found for any of the more than a hundred clones studied, in fact for most clones maximum similarity was below 95% for the approx. 200 bases sequenced. Similarity was not higher with any of the sequences found for the 14 isolates (pure cultures) obtained from the same samples. Redundancy, i.e. number of identical sequences, was higher in the samples from Arcachon. In addition, sequences related to representatives of ten major phylogenetic branches of Bacteria were obtained from Prevost lagoon; however only five branches were represented by the data from Arcachon. These findings indicated a higher bacterial phylogenetic diversity in the Prevost lagoon.

Production and consumption of nitric oxide (NO) by Flexibacter canadensis cells under anaerobic conditions was investigated using a chemiluminescence NO analyzer. Net NO production from nitrite in the presence of carbonyl cyanide m-chlorophenylhydrazone (CCCP) was pH dependent, increased in the pH range from 4.5 to 6.5, and sharply decreased at pH >6.5. CCCP inhibited NO consumption but only at pH values ≤6.5. This can explain why CCCP stimulation of NO production depends on the pH. Denitrification of nitrite at high concentrations (≥5 mM) also resulted in net NO accumulation. Diethyldithiocarbamate, a copper chelating agent, prevented not only net production of NO during the reduction of nitrite in the presence of CCCP, but also production of nitrous oxide (N2O) from nitrite in the presence of C2H2. This suggests that F. canadensis may possess a copper-type nitrite reductase. However, cytochrome cd1- and copper-containing nitrite reductase DNA probes from Pseudomonas species did not hybridize with the total DNA of F. canadensis, indicating that the nitrite reductase of F. canadensis may possess unique properties. In addition to diethyldithiocarbamate, sulfide, carbon monoxide, azide, cyanide, hydroxylamine and Triton X-100 prevented net NO production from nitrite in the presence of CCCP, and also inhibited NO consumption. C2H2, an inhibitor of N2O reductase, did not affect NO production or consumption.Key words: nitrite reductase, nitric oxide (NO), carbonyl cyanide m-chlorophenylhydrazone (CCCP), Flexibacter canadensis.

Bacteria capable of inhibiting growth of a pathogenic Vibrio sp. were isolated from the gastrointestinal tract of cultured halibut larvae during the first feeding and weaning stages. No such bacteria were found among isolates from the surface of eggs or the gastrointestinal tract of yolk sac larvae. The fraction of pathogen-inhibitors among the total number of isolates ranged between 0–100% (first feeding) and 0–66% (weaning). All pathogen-inhibitors were Gram-negative rods, and 95% were oxidase and catalase positive fermentative isolates, capable of producing acid aerobically from a varying range of carbohydrates. These isolates possessed the characteristics of the Vibrio/Aeromonas-group, but only 19% were sensitive to the vibriostatic agent 0/129. Isolates from eggs and yolk sac larvae were dominated by bacteria belonging to the Cytophaga/Flexibacter/Flavobacterium- group. The high fraction of isolates with the ability to inhibit growth of the pathogenic Vibrio sp. among the total number of isolates indicates that pathogen inhibition may be an important mutualistic role of the intestinal flora of early life stages of halibut.

In the course of our screening for elastase inhibitors from microorganism, we have found two new cyclic-depsipeptides designated YM-47141 and 47142. In this paper, we described the taxonomy of the producing organism and isolation, physico-chemical properties, and biological activities of YM-47141 and 47142.

Tenacibaculum maritimum (formerly Cytophaga marina and Flexibacter marinus ) is an opportunistic bacterial pathogen that causes a disease called ‘flexibacteriosis’ in marine fish. Other names that have been used for flexibacteriosis are ‘gliding bacterial disease’, ‘eroded mouth syndrome’ and ‘black patch necrosis’. The disease is mainly characterised by haemorrhagic skin lesions and this condition is also associated with fin and gill disease. In a few cases, systemic forms have also been reported. Initially, T maritimum was isolated from marine fish cultured in Japan in 1979 (Hikida and others 1979). The first report in Europe was published in 1982, in Dover sole ( Solea solea ) (Campbell and Buswell 1982). Flexibacteriosis is currently widely spread in Europe, the USA and Japan, affecting many marine fish species (Vatsos 2007) Based on phenotypic and biochemical characteristics, T maritimum is generally considered as a homogeneous taxon. Methods for isolation and identification of the pathogen include the following: observation of accumulations of long rods in wet mounts or gram-stained preparations obtained from gills or skin lesions; isolation in various culture media, especially Anacker and Ordal, Marine Agar, Flexibacter maritimus medium (FMM; Pazos and others 1996); and PCR (Toyama and others 1996, Avendano-Herrera and others 2004). Greece is the main producer of sea bream ( Sparus aurata ) and sea bass ( Dicentrachus labrax ) in the Mediterranean area. Flexibacteriosis is considered as one of the main bacterial diseases in these two …

We analyzed methylotrophs in Bina natural vegetation (BNV), and revegetated overburden dump of four (ROBD4) and 12 years (ROBD12), at Bina coal mine in Sonbhadra district. The cultured strains identified as Pseudomonas, Acinetobacter, Stenotrophomonas and Cellvibrio (γ-Proteobacteria), Methylophilus, Ralstonia, Burkholderia (α-Proteobacteria) Methylobacterium and Inquilinus (β-Proteobacteria), Bacillus (Firmicutes) and Flexibacter (Sphingobacteria) in their 16s rRNA gene sequence similarity. The strains differed in citrate, lactose, formate, urea and xylose utilization. Methanol utilization by Stenotrophomonas, Inquilinus, Cellvibrio and Flexibacter is for first time. The preferred N- sources were proline, glutamate and nitrate for most of the strains. All strains tolerated (2.5 % NaCl) and SDS (0.2 %); 16 strains survived in crystal violet (0.01 %) and nine strains in sodium azide (0.02 %. Methylotrophic population trend was BNV > ROBD12 > ROBD4. The presence of majority of strain of BNV at ROBD12 and ROBD4 indicated restoration of soil methylotrophic functional diversity in revegetated dumps.

We studied the sensitivity to oxygen of the reductases involved in denitrification by whole cells and membrane fractions of Flexibacter canadensis. All of the nitrate reductase activity was found in the membrane fraction, suggesting that the nitrate reductase of F. canadensis is largely or entirely a membrane-bound enzyme. Methyl viologen and benzyl viologen were good electron donors to nitrate reductase in both whole cells and membrane fractions, whereas glucose and glycerol were effective in whole cells but, as expected, not in membrane fractions. Oxygen, generated by means of H2O2 plus catalase, inhibited the production of nitrite from nitrate by intact cells but not by membrane fractions, suggesting that O2 exerts its inhibitory effect at the level of nitrate transport rather than nitrate reduction. In intact cells, the rates of nitric oxide accumulation during reduction of nitrite in the presence of 20 μM carbonyl cyanide m-chlorophenylhydrazone, and consumption of nitric oxide and nitrous oxide, decreased as the concentration of H2O2 was increased. The concentrations of H2O2 giving 50% inhibition of reduction of nitrate and nitrite were 0.34 and 0.12 mM, respectively. In contrast, the rates of nitric oxide and nitrous oxide consumption were inhibited by only 36 and 32% at a concentration of H2O2 of 3.99 mM. These results indicate that the reduction of both nitric oxide and nitrous oxide is relatively tolerant to oxygen, and that nitrite reductase is much more sensitive to oxygen than the other reductases.Key words: nitrate reductase, nitrate transport, denitrification, O2 inhibition, Flexibacter canadensis.

Rhodothermus marinus, a gram-negative heterotrophic marine thermophile, has been the subject of several recent studies. Isolation, sequencing, and analyses of a 16S rRNA gene have shown that R. marinus diverges sharply from major bacterial phyla and is most closely allied to the Flexibacter-Cytophaga-Bacteroides group. Further analyses revealed that the R. marinus chromosome contains a single rRNA operon with a 16S-23S intergenic region coding for tRNA(Ile) and tRNA(Ala).

Gliding bacteria of the genera Cytophaga and Flexibacter contain unusual sulfonolipids, capnoids, that may serve as a biochemical marker for these organisms in soil. We examimed recovery of sulfonolipids from cells added to soil and the dynamics of 35 S-labeled sulfonolipids in soil with or without added Aporrectodea turgida . Recovery of sulfonolipids from intact cells added to soil was complete, and sulfonolipids did not persist in soil in an extractable form upon cell death. Application of the biomarker technique to soil influenced by the activities of the endogeic earthworm A. turgida demonstrated three phases of 35 S-labeled sulfonolipid dynamics—accumulation, steady state and loss—and is consistent with the expected pattern for a biomarker sensitive to changes in the biomass of Cytophaga and Flexibacter spp. in soil. The physical rearrangement of the soil fabric by the activities of earthworms did not increase the size or alter the gross composition of the microbial biomass, as indicated by phospholipid-P and analysis of profiles of fatty acids released from phospholipids. Instead, there was a stimulation of subsets of the biomass, as illustrated by the altered dynamics of 35 S-labeled sulfonolipids.

Culture of channel catfish, "Ictalurus punctatus," accounts for virtually all catfish production. Recently, however, an increasing number of catfish farmers are growing or are considering the culture of blue catfish, "I. furcatus." Current and past research the compared the culture traits of channel and blue catfish are reviewed. Blue catfish could be potentially advantageous for certain farm environments. Strain effects in both species are important. In general, channel catfish grow faster to market size than do blue catfish. However, some strains of blue catfish grow faster than many strains of channel catfish. Blue catfish are more vulnerable to parasites such as "Icthyophthirius" and to bacterial infections such as those from "Flexibacter columnaris when compared to channel catfish. Blue catfish do not tolerate handling as well as channel catfish, and handling stress often leads to infections in blue catfish. However, blue catfish have high resistance to enteric septicemia of catfish caused by "Edward...

Largemouth bass Micropterus salmoides caught in each of eight tournaments during May-September, then released into cages and held for 4 d afterward, had postrelease mortalities averaging 25.4 ± 4.4% (±SE; N = 660), compared with 2.9 ± 1.8% postrelease mortality for largemouth bass collected by electrofishing (N = 70). On average, 8.2 ± 1.5% of fish died before the weigh-in at the tournament (initial mortality); thus, the total mortality (initial plus postrelease mortalities) of fish caught in tournaments was 33.1 ± 4.3%. In total, 242 tournament fish and 33 control fish were examined for external lesions after the 4-d holding periods. Pathogenic bacteria isolated from caged fish (tournament-caught and control) with external lesions were Aeromonas hydrophila complex, Pseudomonas spp., and Edwardsiella tarda. In addition, Flexibacter (Cytophaga) columnaris was identified in wet mounts ofgills and skin lesions. A bacterial pathogen was found in 42 of 76 tournament fish with skin lesions, but only 4 ...

Channel catfish, Ictalurus punctatus, in a quadruplicate flowthrough aquaria for 15 weeks, were fed a semipurified basal diet containing no folic acid or with folic acid levels ranging from 0.2 to 10.0 mg/kg with or without antibiotic. A second study was conducted for 25 weeks under similar conditions but with semipurified diets containing either 20 or 200 mg/kg ascorbic acid and either 0, 0.4, or 4.O.mg/kg folic acid in a factorial design. Mortalities throughout both experiments were monitored and the etiological causes noted. Fish remaining from the second study were overwintered in circular tanks, kept on the same experimental diets, and challenged with Edwardsiella ictaluri after having been on experimental diets for 50 weeks. In both studies, the addition of folk acid to the basal experimental diet resulted in a decreased incidence of columnaris, Flexibacter columnaris. Folic acid concentration in the diet significantly affected mortalities in fish exmrimentallv challenged with E. ictaluri; however, ...

Gliding bacteria of the genera Cytophaga and Flexibacter contain an unusual sulfonolipid in their outer membrane that may be a potential biochemical marker for these organisms in soil. The precision with which a marker provides information about biomass varies with the range in marker content within the cells of the taxon under study. To evaluate this, Cytophaga and Flexibacter spp. were isolated from earthworm fecal pellets and soil, batch cultured with [35S]sulfate, and extracted for lipids. Sulfonolipid S was measured using isotope dilution techniques and lipid phosphate was determined by colorimetry. Ratios of sulfonolipid S to protein and to phospholipid P were compared among isolates grown under various conditions. Ratios of sulfonolipid S to phospholipid P from 0.22 to 0.98 confirmed sulfonolipids as major cell components of Cytophaga and Flexibacter spp. Two criteria essential to the success of sulfonolipids as a biomarker for these organisms in soil were met: (i) sulfonolipid concentration among the noncellulolytic isolates, with one exception, spanned a narrow range (40–60 μmol S/g cell protein), and (ii) this range in sulfonolipid concentration was maintained under the range of growth conditions studied here. Cellulolytic cytophagas, however, could be clearly differentiated from other Cytophaga and Flexibacter spp. on the basis of sulfonolipid content, 85–164 μmol S/g cell protein. This dichotomy in sulfonolipid content between cellulolytic and noncellulolytic isolates must be considered when interpreting data where sulfonolipids are used as a quantitative biomarker for Cytophaga and Flexibacter spp. in habitats where cellulolytic cytophagas are dominant.Key words: lipid biomarkers, cellulolytic cytophagas, Cytophaga, Flexibacter, sulfonolipids.

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.

A Gram-negative bacterium, designated NS12(T), was previously isolated from duplicate treatments of surface-sterilized Zea mays stems. The plants were grown in synthetic soil under greenhouse conditions and watered with fertilizer containing no nitrogen. Strain NS12(T) was not isolated from plants watered with the standard level or 20% (w/v) of the standard level of nitrogen. Cells were bent rods that formed chains of irregular shapes in R2A broth. Unlike its closest described relative Runella slithyformis, strain NS12(T) fermented glucose and sucrose. The G+C content was 49 mol%. Phylogenetic analysis of the 16S rRNA gene showed that the strain was a member of the domain Bacteria and is most closely related to R. slithyformis, a member of the Flexibacter group within the Cytophaga-Flexibacter-Bacteroides phylum. Phenotypic and genotypic analyses indicated that strain NS12(T) could not be assigned to any recognized species; therefore a new species designated Runella zeae sp. nov. is proposed, for which NS12(T) ( = ATCC BAA-293(T) = LMG 21438(T)) is the type strain.

Bacterial infection among the most common cultured mudfish Clarias gariepinus in Africa, has become a cause of concern, because it constitutes the largest economic loss in fish farms. In order to provide useful biological data of the pathogens for good management practices, samples were collected monthly between January 2008 and December 2009 in three monoculture nursery ponds, located in three different positions: upriver (A, grassland), mid-river (B, mixed forest and grassland) and downriver (C, rainforest) along 200km length of Cross River floodplains, Nigeria. A total of 720 fingerlings between 15.1 and 20.7g were analyzed to determine the degree of infection. The bacterial pathogens were taken from their external surfaces, and were isolated and identified by standard methods. The caudal fins of fingerlings from pond A had the highest bacterial load (5.8x10³cfu/g), while the least counts (1.2x103cfu/g) were identified on the head of fish from pond C, with Flexibacter columnaris as the major etiological agent. Pseudomonas fluorescens, Aeromonas hydrophila, Escherichia coli, Staphylococcus aureus and Micrococcus luteus were identified as co-isolates with P. fluorescens as dominant (0.7x10²cfu/mL) co-isolates in pond water. Clinical signs of five white spots with red periphery appeared on the external surface of infected fish. All the fish sampled, died after 4 to 9 days. There was no significant difference in the bacterial counts between different ponds, but the difference between fish organs/parts examined was significant. Fish from these ponds are therefore potentially dangerous to consumers and highly devalued, with the economic impact to producers. Preventive methods to avoid these infections are recommended. Rev. Biol. Trop. 59 (2): 751-759. Epub 2011 June 01.Las infeccines bacterianas son comunes en el pez de cultivo Clarias gariepinus, el cual es el más cultivado en Africa y se han convertido en una causa de preocupación, ya que constituye la mayor pérdida económica en las granjas piscícolas. Se proporcionan datos biológicos de los agentes patógenos con el fin de proporcionar información útil para buenas prácticas de gestión en las granjas. Las muestras fueron recolectadas mensualmente entre Enero 2008 y Diciembre 2009 en tres viveros de estanques de monocultivo, situados en tres posiciones diferentes: río arriba (A, pastizales), mitad del río (B, bosque mixto y pastos) y aguas abajo (C, bosque) a lo largo de 200km de longitud en las llanuras de inundación del río Cross, Nigeria. Un total de 720 alevines de entre 15.1 y 20.7g fueron analizados para determinar el grado de infección. Los patógenos bacteriales fueron tomados de las superficies externas, y fueron aislados e identificados por métodos estándar. Las aletas caudales de los alevines del estanque A tuvieron la mayor carga bacteriana (5.8x10³cfu/g), mientras el menor conteo de bacterias (1.2x103cfu/g) fue identificado en la cabeza de los peces del estanque C, con Flexibacter columnaris como el agente etiológico más importante. Pseudomonas fluorescens, Aeromonas hydrophila, Escherichia coli, Staphylococcus aureus y Micrococcus luteus se identificaron como co-aislamientos con P. fluorescens, como dominantes (0.7x102cfu/mL) co-aislados en el agua del estanque. Los signos clínicos fueron cinco puntos blancos con la periferia roja y aparecieron en la superficie externa de los peces infectados. Todos los peces de la muestra, murieron después de 4 a 9 días. No hubo diferencia significativa en los recuentos bacterianos entre los diferentes estanques, pero la diferencia entre los órganos y las partes de los peces examinados fue significativa. Los peces de estos estanques son potencialmente peligrosos para los consumidores y con alta devaluación, con un impacto económico para los productores. Se recomiendan métodos de prevención para evitar estas infecciones

In an analysis of 47 aerobic myxobacterial strains, representing 19 genera in suborders Cystobacterineae , Nannocystineae , Sorangiineae , and a novel isolate, “ Aetherobacter ” SBSr008, an enormously diverse array of fatty acids (FAs) was found. The distribution of straight-chain fatty acids (SCFAs) and branched-chain fatty acids (BCFAs) supports the reported clustering of strains in the phylogenetic tree based on 16S rRNA genes. This finding additionally allows the prediction and assignment of the novel isolate SBSr008 into its corresponding taxon. Sorangiineae predominantly contains larger amounts of SCFA (57 to 84%) than BCFA. On the other hand, Cystobacterineae exhibit significant BCFA content (53 to 90%), with the exception of the genus Stigmatella . In Nannocystineae , the ratio of BCFA and SCFA seems dependent on the taxonomic clade. Myxobacteria could also be identified and classified by using their specific and predominant FAs as biomarkers. Nannocystineae is remarkably unique among the suborders for its absence of hydroxy FAs. After the identification of arachidonic (AA) FA in Phaselicystidaceae , eight additional polyunsaturated fatty acids (PUFAs) belonging to the omega-6 and omega-3 families were discovered. Here we present a comprehensive report of FAs found in aerobic myxobacteria. Gliding bacteria belonging to Flexibacter and Herpetosiphon were chosen for comparative analysis to determine their FA profiles in relation to the myxobacteria.

The phylogenetic position of the causative agent of septicemia anserum exsudativa, now most often referred to as [Moraxella] anatipestifer (brackets indicate a generically misnamed taxon) or ''[Pasteurella] anatipestifer,'' was established by performing rRNA cistron similarity studies. [Moraxella] anatipestifer belongs to rRNA superfamily V, together with the genera Flavobacterium, Cytophaga, Flexibacter, Weeksella, Capnocytophaga, and Sphingobacterium. The detailed structure of rRNA superfamily V, which now contains five major rRNA homology groups, is described. An analysis of various phenotypic parameters, including new data (cellular proteins and fatty acids) and previously published data (respiratory quinones, enzyme activities, and classical phenotypic features), revealed that [Moraxella] anatipestifer differs in many aspects from its closest relatives, Flavobacterium indologenes, Flavobacterium gleum, Flavobacterium indoltheticum, Flavobacterium balustinum, Flavobacterium meningosepticum, and Weeksella zoohelcum. The combined genotypic and phenotypic data indicate that this organism should be placed in a separate genus; the name Riemerella anatipestifer gen. nov., comb. nov. is proposed for this bacterium. The specific epithet anatipestifer is kept in order to avoid nomenclatural confusion. However, it should be emphasized that the illness caused by this organism is a septicemic disease which is not restricted to ducks.

Diagnostic records of the Southeastern Cooperative Fish Disease Project were used to determine the incidence of bacterial and parasitic diseases in cagecultured channel catfish Ictalurus punctatus. Laboratory submissions increased moderately from 1987 through 1990 and decreased in 1991. The proportion of diagnosed epizootics attributable to Edwardsiella ictaluri (enteric septicemia of catfish) decreased during this period, from 32% in 1987 to 10% in 1990 and 21% in 1991. Incidence of motile Aeromonas septicemia decreased from a high of 22% in 1987 to approximately 12% in 1991. Flexibacter (Cytophaga) columnaris was the cause of 12–23% of the diagnosed epizootics. Incidence of parasitic infestations of Ichthyobodo (Costia) necatrix decreased from 21 and 23% in 1988 and 1989, respectively, to 8% in 1991. Incidence of Henneguya infestations fluctuated between 7 and 14%, and Ichthyophthirius multifiliis outbreaks occurred only during 1987 and 1990. Severe anemia was diagnosed in 4% of the submitted c...

Summary Four strains of agarolytic bacteria were isolated from a tar-ball that drifted ashore. Their gliding motility, cyclic morphological change and NaCl requirement for growth suggested that they belong to the genus Microscilla, which is the marine counterpart of Flexibacter. The growth of the isolates were generally mesophilic, moderately halophilic and neutrophilic with the optimum conditions of 24–37 °C, 0.5–0.7 M NaCl and pH 6–8. Agarases were partially purified from the culture supernatant of the isolates. The agarase activities were commonly mesophilic, moderately halophilic and neutrophilic in nature, with optimum conditions of 27–37°C, 0.3–0.6 M NaCl and pH 6.8–6.9. The Michaelis constants of the enzyme activity ranged from 49 to 391 agar mg/l.

Artemia sp. were grown to pre-adult on diets consisting of bacteria, bacteria plus algae, and algae alone. There was little difference in survival among Artemia grown on these diets, but significant differences in length and dry weight were observed. Artemia fed with Flexibacter strain Inp3 plus 50 cells/ μ l of algae resulted in best growth and biomass (7.33 mm, 29.67 mg/l, respectively). However, highest concentration of PUFAs per dry weight of Artemia was obtained by feeding the 100 cells/ μ l of algae diet. The results of this study suggest that the bacteria acted not only as a food for the Artemia , but also assisted in the digestion of the algae.

The chemical structure of a new dipeptide antibiotic, TAN-1057 A, isolated from the broth filtrate of Flexibacter sp. PK-74 was determined to be (3′S, 5S)-5-[N-methyl-N-(3′-amino-6′-guanidinohexanoyl)amino]5,6-dihydro-2-ureido-4(1H)-pyrimidone. The antibiotic was specifically active against staphylococcus species including methicillin-resistant strains.

Understandably, most fish pathologists feel that arguments among specialists about the classification and names of bacteria are very far from their concern and that the resulting changes in bacteri...

Oceanic bacteria perform many environmental functions, including biogeochemical cycling of many elements, metabolizing of greenhouse gases, functioning in oceanic food webs (microbial loop), and producing valuable natural products and viruses. We demonstrate that the widespread capability of marine bacteria to participate in horizontal gene transfer (HGT) in coastal and oceanic environments may be the result of gene transfer agents (GTAs), viral-like particles produced by α-Proteobacteria. We documented GTA-mediated gene transfer frequencies a thousand to a hundred million times higher than prior estimates of HGT in the oceans, with as high as 47% of the culturable natural microbial community confirmed as gene recipients. These findings suggest a plausible mechanism by which marine bacteria acquire novel traits, thus ensuring resilience in the face of environmental change.

The structures of topostins, a novel type of mammalian DNA topoisomerase I inhibitors isolated from the bacterium Flexibacter topostinus sp. nov., have remained unknown. Reexamination of the production of topostins resulted in the isolation of original topostins B (B553 (1) and B567 (2)) and new related compounds named topostins D (D640 (3) and D654 (4)). Their structures, including the absolute stereochemistry, were determined by spectroscopic analyses and chemical degradations. These substances are lipid-containing amino acids and peptides.

We investigated the community structure of endophytic bacteria in narrowleaf cattail (Typha angustifolia L.) roots growing in the Beijing Cuihu Wetland, China, using the 16S rDNA library technique. In total, 184 individual sequences were used to assess the diversity of endophytic bacteria. Phylogenetic analysis revealed that 161 clones (87.5%) were affiliated with Proteobacteria, other clones grouped into Cytophaga/Flexibacter/Bacteroids (3.3%), Fusobacteria (3.8%), and nearly 5% were uncultured bacteria. In Proteobacteria, the beta and gamma subgroups were the most abundant, accounting for approximately 46% and 36.6% of all Proteobacteria, respectively. The dominant genera included Rhodoferax, Pelomonas, Uliginosibacterium, Pseudomonas, Aeromonas, Rhizobium, Sulfurospirillum, Ilyobacter and Bacteroides. While some of these endophytic bacteria are capable of fixing nitrogen and can therefore improve plant growth, other endophytes may play important biological roles by removing nitrogen, phosphorus and/or organic matter from the water body and thus have the potential to enhance the phytoremediation of eutrophic water bodies. These bacteria have the potential to degrade xenobiota such as methane, methanol, methylated amines, catechol, oxochlorate, urea, cyanide, and 2,4-dichlorophenol. Hence, the use of certain endophytic bacteria in the process of phytoremediation could be a powerful approach for the restoration of eutrophic systems.

The community structure and diversity of endophytic bacteria in reed (Phragmites australis) roots growing in the Beijing Cuihu Wetland, China was investigated using the 16S rRNA library technique. Primers 799f and 1492r were used to amplify the specific bacterial 16S rRNA fragments successfully and construct the clone library. In total, 166 individual sequences were verified by colony PCR and used to assess the diversity of endophytic bacteria in reed roots. Phylogenetic analysis revealed that 78.9% of the clones were affiliated with Proteobacteria and included all five classes. Other clones belonged to Firmicutes (9.0%), Cytophaga/Flexibacter/Bacteroids (6.6%), Fusobacteria (2.4%), and nearly 3.0% were unidentified bacteria. In Proteobacteria, the Alpha and Gamma subgroups were the most abundant, accounting for approximately 34.4% and 31.3% of all Proteobacteria, respectively, and the dominant genera included Pleomorphomonas, Azospirillum, and Aeromonas. In addition, nearly 13.6% of the Proteobacteria were very similar to some genera of sulfate-reducing bacteria (SRB) such as Dechloromonas, Desulfovibrio, and Sulfurospirillum. The bacteria in these genera are considered to play important roles in the metabolism of nitrogen, phosphorus, sulfur, and some organic compounds in wetland systems. Hence, this study demonstrates that within the diverse bacterial communities found in reed roots, endophytic strains might have a strong potential to enhance phytoremediation by reed wetlands.

Laboratory breeding conditions of the model organism C. elegans do not correspond with the conditions in its natural soil habitat. To assess the consequences of the differences in environmental conditions, the effects of air composition, medium and bacterial food on reproductive fitness and/or dietary-choice behavior of C. elegans were investigated. The reproductive fitness of C. elegans was maximal under oxygen deficiency and not influenced by a high fractional share of carbon dioxide. In media approximating natural soil structure, reproductive fitness was much lower than in s tandard laboratory media. I n seminatural media, the reproductive fitness of C. elegans was low with the standard laboratory food bacterium E. coli (γ-Proteobacteria), but significantly higher with C. arvensicola (Bacteroidetes) and B. tropica (β-Proteobacteria) as food. Dietary-choice experiments in semi-natural media revealed a low preference of C. elegans for E. coli but significantly higher preferences for C. arvensicola and B. tropica (among other bacteria). Dietary-choice experiments under quasi-natural conditions, which were feasible by fluorescence in situ hybridization (FISH) of bacteria, showed a high preference of C. elegans for Cytophaga-Flexibacter-Bacteroides, Firmicutes, and β-Proteobacteria, but a low preference for γ-Proteobacteria. The results show that data on C. elegans under standard laboratory conditions have to be carefully interpreted with respect to their biological significance.

On the basis of small subunit rRNA sequence analyses five major subgroups within the flavobacteria-bacteroides phylum have been defined. These are tentatively designated the cytophaga subgroup (comprising largely Cytophaga species), the flavobacter subgroup (comprising the true flavobacteria and the polyphyletic genus Weeksella), the bacteroides subgroup (comprising the bacteroides and certain cytophaga-like bacteria), the sphingobacter subgroup (which contains the known sphingolipid-producing members of the phylum), and the saprospira subgroup (comprising particular species of Flexibacter, Flavobacterium, Haliscomenobacter, and, of course, the genus Saprospira). These groupings are given not only by evolutionary distance analysis, but can be defined and distinguished on the basis of a simple small subunit rRNA signatures.

Scanning electron micrographs of halibut eggs with an epiflora dominated by Flexibacter sp., showed ulcerations colonized by large numbers of bacteria. The chorion was dissolved in most ulcerations and the zona radiata was severely damaged. Infection experiments showed that exposure to these bacteria caused high mortalities at the late egg stage, hatching and the early yolk sac stage. Eggs exposed to three different Vibrio spp. showed different mortality patterns, with low mortality at hatching, followed by a continuous high mortality throughout the yolk sac stage. Mortality in the uninfected control group was low throughout the experiment. Transmission electron microscopy of the Vibrio-infected larvae showed bacteria present in the gill, heart and frontal yolk sac regions.

The subcellular distribution of nitrous oxide reductase was studied in the gliding soil bacterium Flexibacter canadensis. Nitrous oxide reductase activity, as measured by the methyl viologen-nitrous oxide oxidoreductase assay, was associated entirely with the membrane fraction of cell-free extracts. The enzyme was liberated from the membranes with use of detergents but not by high-salt concentrations, thus implying that nitrous oxide reductase is an integral membrane protein. The nitrous oxide reductase of F. canadensis is the first reported example of a membrane-bound form of this respiratory enzyme.

Summary: The mechanism of unsaturated fatty acid biosynthesis in two estuarine strains of Flexibacter was investigated. Addition of cyclic AMP (cAMP) inhibited the incorporation of radiolabeled acetate into fatty acids of lateexponential phase cultures of strain Inp2. Cerulenin selectively inhibited the incorporation of radioactive acetate into the major fatty acid, 16:1. When Flexibacter strain Inp3 was grown in a medium of high osmotic strength, polyunsaturated fatty acids were present, but they were absent from cultures grown in media with an osmotic strength close to that of sea water. Addition of cAMP to cultures growing at high osmotic strength suppressed the formation of polyunsaturated fatty acids; the uncoupler 2,4-dinitrophenol had a similar effect. The findings are discussed in the context of the suggestion made by Intriago and Floodgate (Journal of General Microbiology 137, 1503–1509, 1991) that Flexibacter strains possess both the anaerobic and aerobic pathways for unsaturated fatty acid biosynthesis, the activity of the latter being modulated by the intracellular concentration of cAMP.

The taxonomic position of the misclassified strains [Flexibacter] tractuosus KCTC 2958T and ‘[Microscilla] sericea’ LMG 13021 was studied using a polyphasic approach. The two strains shared 99.1 % 16S rRNA gene sequence similarity and 28 % DNA–DNA relatedness. On the basis of the phylogenetic evidence supported by genotypic and phenotypic data [Flexibacter] tractuosus KCTC 2958T and ‘[Microscilla] sericea’ LMG 13021 are classified as two distinct species in a novel genus, Marivirga, in the family ‘Flammeovirgaceae’, as Marivirga tractuosa comb. nov. and Marivirga sericea nom. rev., comb. nov., with strains KCTC 2958T (=ATCC 23168T =CIP 106410T =DSM 4126T =NBRC 15989T =NCIMB 1408T =VKM B-1430T) and LMG 13021T (=ATCC 23182T =NBRC 15983T =NCIMB 1403T), respectively, as the type strains. The type species is Marivirga tractuosa.

The aim of this work was to study the influence of bacterial epiflora on egg hatching of the sardine (Sardina pilchardus) obtained from a natural environment (Ría de Vigo, Spain) during the spawning season of the sardine (from January to June). Total bacteria, viable bacteria or the presence of specific potential pathogens for eggs, such as Pseudoalteromonas piscicida and Tenacibaculum (Flexibacter) ovolyticus, did not affect the viability of sardine eggs. Additionally, no relationship was observed between the presence of Vibrio spp., pathogenic for fish larvae, and the egg hatching. This was probably because the amount of bacteria associated with the eggs were between 10(2) and 10(4) orders lower than those found so far on the eggs of different fish species in rearing systems. Therefore, epiphytic bacteria did not affect the wild sardine eggs and, hence, in the area studied, it is probably not an important factor affecting annual recruitment success of this pelagic fish species.

Endophytic bacteria are ubiquitous in most plants and colonise plants without exhibiting pathogenicity. Studies on the diversity of bacterial endophytes have been mainly approached by characterisation of isolates obtained from internal tissues. Despite the broad application of culture-independent techniques for the analysis of microbial communities in a wide range of natural habitats, little information is available on the species diversity of endophytes. In this study, microbial communities inhabiting stems, roots and tubers of three potato varieties were analysed by 16S rRNA-based techniques such as terminal restriction fragment length polymorphism analysis, denaturing gradient gel electrophoresis as well as 16S rDNA cloning and sequencing. Two individual plant experiments were conducted. In the first experiment plants suffered from light deficiency, whereas healthy and robust plants were obtained in the second experiment. Plants obtained from both experiments showed comparable endophytic populations, but healthy potato plants possessed a significantly higher diversity of endophytes than stressed plants. In addition, plant tissue and variety specific endophytes were detected. Sequence analysis of 16S rRNA genes indicated that a broad phylogenetic spectrum of bacteria is able to colonise plants internally including alpha-, beta-, and gamma-Proteobacteria, high-GC Gram-positives, microbes belonging to the Flexibacter/Cytophaga/Bacteroides group and Planctomycetales. Group-specific analysis of Actinomycetes indicated a higher abundance and diversity of Streptomyces scabiei-related species in the variety Mehlige Mühlviertler, which is known for its resistance against potato common scab caused by S. scabiei.

Although Mar Piccolo of Taranto (Ionian Sea, Italy) is one of the most important Mytilus galloprovincialis farming areas, data concerning the natural bacterial microbiota of these mussels and their surrounding environment are still scant. This study was carried out seasonally, throughout a year, to determine culturable heterotrophic bacteria both in the water and mussels samples collected at three sampling sites in the Northern Ionian Sea: S. Vito, Lido Gandoli and Lido Silvana. Culturable heterotrophic bacteria abundance was determined by spread plate on Marine Agar. Heterotrophic bacteria were identified by several morphological, culture and biochemical methods. Bacterial concentrations were higher in the mussel samples compared to the corresponding seawater throughout the year. Among Gram negative heterotrophic bacteria, Aeromonas prevailed both in the water (18%) and mussel samples (40%). Other genera such as Moraxella, Pseudomonas, Alcaligenes, Acinetobacter, Flavobacterium, Chromobacterium, Photobacterium and Flexibacter were present with different percentages of isolation. Bacilli were predominant among Gram positive bacteria. Some genera (Lucibacterium and Vibrio) were present only in mussel samples. The results obtained contribute to improve the knowledge on both the bacterial abundance and diversity in mussels and the surrounding seawater in the Northern Ionian Sea.

Summary: The total fatty acid content of the estuarine Flexibacter sp. strain Inp and the relative proportions of its constituent fatty acids were affected by growth temperature and salinity. Whilst both the proportion and concentration of the polyunsaturates were markedly stimulated by increases in salinity, the total amount of fatty acid per mg cell protein decreased. The highest concentration of fatty acid per mg cell protein did not coincide with the highest percentage of polyunsaturated fatty acids, which occurred when the bacterium was grown on glucose. The presence of an inverse relationship between C16: 1w5 and C18: 1w9 are regarded as evidence that two different pathways exist for the biosynthesis of unsaturated fatty acids in Flexibacter strain Inp.

Columnaris disease, Flexibacter columnaris infection, was first described in North America. Recent publications indicate that its distribution is worldwide. Both warmwater and coldwater fish are infected with F. columnaris. All freshwater fish are probably susceptible to the disease under environmental conditions favourable to the bacterium and stressful to the fish. Flexibacter columnaris cannot tolerate sea water. Generally, outbreaks occur when the average water temperatures reach 15°C. The bacterium apparently enters the fish through the skin and gills. The swarms of bacteria involved give the lesions a characteristic yellow pigmentation. The external lesions destroy the skin, muscle and gill tissues. It is relatively easy to isolate the bacteria from the internal organs of the diseased fish, but there is no evidence of internal tissue damage. In this short review, emphasis is placed on several factors relative to water environment which play a role in the development of outbreaks of columnaris disease: 1 The optimum temperature for an outbreak of F. columnaris infection is thought to be between 20 and 30°C. Mortalities seldom occur at temperatures below 15°C, although highly virulent strains can kill fish at lower temperatures. 2 Flexibacter columnaris can survive longer in water of normal to high hardness, as well as in water containing small amounts of sodium, potassium, calcium or magnesium salts, but it cannot live in sea water. 3 Flexibacter columnaris grows well on paniculate fish feeds so that such deposits in the water may act as reservoirs of infection. 4 An important source of infection is feral fish. In the Columbia River or the Fraser River, resident coarse fish such as suckers, Catostomus spp., are thought to transmit the infection to returning adult salmon. 5 Flexibacter columnaris fails to invade fish in the presence of competitive bacteria like Citrobacter freundii when its initial numbers are approximately one in a 100 less than those of the competitors. 6 Crowding seems to be not only a stressor for fish, but also a factor that increases the chance of adhesion of F. columnaris to the external tissues of fish.

Infectivity of Flexibator columnaris to loach, Misgurnus anguillicaudatus (Blecker, Gunther), was studied with variation conditions and the presence of other bacteria in the water medium. Invasion of fish by the poathogen varied with different water conditions. The highest prevalence of infection was observed in an experimentally formulated water containing 0·03% NaCl 0·01% KCl, 0·002% CaCl22H2O and 0·004% MgCI2 6H2O. The percentage of infection in tap water was similar to that of the formulated water. The infeetion rate was low in the individual salt solutions, and no infection occurred in distilled water. Even in the formulated water, the pathogen failed to infect the fish when Citrobacter freundii, Aeromonas hydrophila or Pseudomonas fluorescens were present at densities 100 times that of F. columnaris. However, in such cases, the numbers of F. columnaris in the mucus of the fish body surface did not increase much throughout the experimental period. In contrast, F. columnaris suceessfully invaded the fish in the presence of either Streptococcus sp., Flavobacterium flavescens or Flavobacterium fuscum, even when the numbers of these bacteria were 1000 times that of F. columnaris. In this ease, F. columnaris gradually increased its numbers on the fish body surface.

En el presente trabajo se reporta la presencia de Flavobacterium psychrophilum, como agente causante de la patología “enfermedad bacteriana del agua fría” en alevines de Onchorhynchus mykiss “trucha arco iris” del Centro Piscícola El Ingenio, Junín (3250 m de altitud). La lesión macroscópica externa más frecuente fue la ulceración profunda de la región dorsal del pez acompañado de un ennegrecimiento localizado de la piel. Internamente se observó una marcada esplenomegalia, palidez del hígado, riñón y branquias, inflamación del intestino y acumulación de líquido ascítico en el peritoneo. No se detectó hemorragia interna. En Agar Cytophaga Modificado (ACM) según Anaker & Ordal (1959) fueron aisladas inicialmente 29 Gram negativas, de las cuales según la caracterización fenotípica y pruebas bioquímicas 9 fueron consideradas como F. psychrophilum. Pruebas de susceptibilidad antibiótica mostraron alta sensibilidad de las cepas a Gentamicina, Ceftazidina, oxitetraciclina, Norfloxacina, furazolidona, Ciprofloxacina y Cefoxitina., The present paper reports the presence of Flavobacterium psychrophilum such as pathological agent of "bacterial disease of cold water" on juvenile Onchorhynchus mykiss "rainbow trout" from El Ingenio fish farm, Junín (3250 m). The ulceration of the dorsal area was the most frequent macroscopic external injury as well the localized blackening of the skin. Internally there was a marked splenomegaly, pallor of the liver, kidney and gills, inflammation of the intestine and ascitic fluid in the peritoneum. Internal hemorrhage was not detected. 29 strain Gram negative were isolated in Modified Cytophaga Agar (MCA) (Anaker & Ordal, 1959), which according to the phenotypic characterization and the biochemical tests 9 were considered as F. psychrophilum. Tests of antibiotic susceptibility showed high sensitivity of this strains to Gentamicin, Ceftazidine, oxytetracycline, Norfloxacine, furazolidone, Ciprofloxacine and Cefoxitine

The present paper reports the presence of Flavobacterium psychrophilum such as pathological agent of "bacterial disease of cold water" on juvenile Onchorhynchus mykiss "rainbow trout" from El Ingenio fish farm, Junín (3250 m). The ulceration of the dorsal area was the most frequent macroscopic external injury as well the localized blackening of the skin. Internally there was a marked splenomegaly, pallor of the liver, kidney and gills, inflammation of the intestine and ascitic fluid in the peritoneum. Internal hemorrhage was not detected. 29 strain Gram negative were isolated in Modified Cytophaga Agar (MCA) (Anaker & Ordal, 1959), which according to the phenotypic characterization and the biochemical tests 9 were considered as F. psychrophilum. Tests of antibiotic susceptibility showed high sensitivity of this strains to Gentamicin, Ceftazidine, oxytetracycline, Norfloxacine, furazolidone, Ciprofloxacine and Cefoxitine En el presente trabajo se reporta la presencia de Flavobacterium psychrophilum, como agente causante de la patología “enfermedad bacteriana del agua fría” en alevines de Onchorhynchus mykiss “trucha arco iris” del Centro Piscícola El Ingenio, Junín (3250 m de altitud). La lesión macroscópica externa más frecuente fue la ulceración profunda de la región dorsal del pez acompañado de un ennegrecimiento localizado de la piel. Internamente se observó una marcada esplenomegalia, palidez del hígado, riñón y branquias, inflamación del intestino y acumulación de líquido ascítico en el peritoneo. No se detectó hemorragia interna. En Agar Cytophaga Modificado (ACM) según Anaker & Ordal (1959) fueron aisladas inicialmente 29 Gram negativas, de las cuales según la caracterización fenotípica y pruebas bioquímicas 9 fueron consideradas como F. psychrophilum. Pruebas de susceptibilidad antibiótica mostraron alta sensibilidad de las cepas a Gentamicina, Ceftazidina, oxitetraciclina, Norfloxacina, furazolidona, Ciprofloxacina y Cefoxitina.

Analysis of many proteins produced during the transition into the stationary phase and under stress conditions (including starvation stress) demonstrated that a number of novel proteins were induced in common to each stress and could be the reason for cross-protection in bacterial cells. It is necessary to investigate the synthesis of these proteins during different stress conditions.The changes in protein profile of Flexibacter chinensis at various stages of the starvation process and the other stresses were investigated using two-dimensional gel electrophoresis which has proven to be a powerful tool for investigation of the changes in protein profiles under such conditions.Most starvation proteins were synthesized during the early stationary phase and many of these proteins remained during long-term starvation. Some of these proteins were transiently synthesized. The sequencing result of one of the proteins showed that there was a 62.5% identity in 8 amino acids overlapped with the 5' residue of a 10 kDa chaperon protein which is known to be involved in the starvation stress response in other organisms.There are many proteins synthesized in common with many stresses in Flexibacter chinensis. Some of these proteins must play a major role in the stability of the cell under different stresses.