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At least 199 records · Page 11Linked to original sources
PubMed2001

Pleomorphism of the marine bacterium Teredinobacter turnirae.

AIMS: A morphology transition for the marine bacterium, Teredinobacter turnirae is reported. METHODS AND RESULTS: When grown in the rod-shaped morphology, the cells require high concentrations of NaCl (0.3 mol x l(-1)) and secrete extracellular protease and endoglucanase activity. When this bacterium is grown in a medium containing casein as a sole carbon and nitrogen source, a major change in morphology to a stable aggregated form is obtained. CONCLUSION: In the aggregated morphology, much higher protease production rates (170 Units x ml(-1) x d-1 for aggregates vs. 15 Units x ml(-1) x d(-1) for rods, for the same initial biomass) and negligible endoglucanase titres are obtained. In addition, the aggregated morphology does not require sodium chloride for growth. SIGNIFICANCE AND IMPACT OF THE STUDY: The phenomenon reported here describes a novel relationship between the cell morphology and the biochemical characteristics of the bacterium.

Bacterial Proteins↗
PubMed2000

Use of polymerase chain reaction (PCR) and DNA probe hybridization to determine the Gram reaction of the infecting bacterium in the intraocular fluids of patients with endophthalmitis.

OBJECTIVES: To evaluate polymerase chain reaction (PCR) combined with DNA probe hybridization to determine the Gram reaction of the bacterium in intraocular specimens from patients with infectious endophthalmitis. METHODS: Fifty-seven intraocular specimens - 17 aqueous humor (AH) and 40 vitreous fluid (VF) - from 55 patients with clinically diagnosed infectious endophthalmitis and 25 control intraocular specimens from non-infectious ocular disorders (10 AH and 15 VF) were evaluated by microscopy, culture and PCR-DNA probe hybridization to detect the Gram reaction of the bacterium. RESULTS: PCR-DNA probe hybridization was specific and sensitive to detect 30 fg of both gram-positive and gram-negative bacterial DNA. None of the controls showed bacteria by microscopy, culture or PCR. Of the 57 intraocular specimens, conventional microbiological methods could detect a bacterial aetiology in 32 (56.1%), while PCR-DNA probe hybridization could detect 52 (91.2%) specimens. This difference was statistically significant (P= 0.003). In bacteriologically positive specimens, there was absolute correlation of the Gram reaction between the results of smear and culture methods and PCR-DNA probe hybridization. Of the 25 bacteriologically negative specimens, 20 (80%) were positive by PCR-DNA probe hybridization, of which seven (35%) were gram-positive, 12 (60%) gram-negative and one (5%) positive by both. Results of PCR on AH and VF were not significantly different. CONCLUSION: PCR and DNA probe hybridization to determine the Gram reaction of the bacterium in intraocular fluids is a specific and sensitive method in the diagnosis of bacterial endophthalmitis. AH is an ideal specimen for PCR, since its collection is a simple and safe office procedure.

Aqueous Humor↗
PubMed2001

A newly discovered bacterium associated with parthenogenesis and a change in host selection behavior in parasitoid wasps.

The symbiotic bacterium Wolbachia pipientis has been considered unique in its ability to cause multiple reproductive anomalies in its arthropod hosts. Here we report that an undescribed bacterium is vertically transmitted and associated with thelytokous parthenogenetic reproduction in Encarsia, a genus of parasitoid wasps. Although Wolbachia was found in only one of seven parthenogenetic Encarsia populations examined, the "Encarsia bacterium" (EB) was found in the other six. Among seven sexually reproducing populations screened, EB was present in one, and none harbored Wolbachia. Antibiotic treatment did not induce male production in Encarsia pergandiella but changed the oviposition behavior of females. Cured females accepted one host type at the same rate as control females but parasitized significantly fewer of the other host type. Phylogenetic analysis based on the 16S rDNA gene sequence places the EB in a unique clade within the Cytophaga-Flexibacter-Bacteroid group and shows EB is unrelated to the Proteobacteria, where Wolbachia and most other insect symbionts are found. These results imply evolution of the induction of parthenogenesis in a lineage other than Wolbachia. Importantly, these results also suggest that EB may modify the behavior of its wasp carrier in a way that enhances its transmission.

Animals↗
PubMed2003

Comparative analysis of pyruvate kinases from the hyperthermophilic archaea Archaeoglobus fulgidus, Aeropyrum pernix, and Pyrobaculum aerophilum and the hyperthermophilic bacterium Thermotoga maritima: unusual regulatory properties in hyperthermophilic archaea.

Pyruvate kinases (PK, EC 2.7.1.40) from three hyperthermophilic archaea (Archaeoglobus fulgidus strain 7324, Aeropyrum pernix, and Pyrobaculum aerophilum) and from the hyperthermophilic bacterium Thermotoga maritima were compared with respect to their thermophilic, kinetic, and regulatory properties. PKs from the archaea are 200-kDa homotetramers composed of 50-kDa subunits. The enzymes required divalent cations, Mg2+ and Mn2+ being most effective, but were independent of K+. Temperature optima for activity were 85 degrees C (A. fulgidus) and above 98 degrees C (A. pernix and P. aerophilum). The PKs were highly thermostable up to 110 degrees C (A. pernix) and showed melting temperatures for thermal unfolding at 93 degrees C (A. fulgidus) or above 98 degrees C (A. pernix and P. aerophilum). All archaeal PKs exhibited sigmoidal saturation kinetics with phosphoenolpyruvate (PEP) and ADP indicating positive homotropic cooperative response with both substrates. Classic heterotropic allosteric regulators of PKs from eukarya and bacteria, e.g. fructose 1,6-bisphosphate or AMP, did not affect PK activity of hyperthermophilic archaea, suggesting the absence of heterotropic allosteric regulation. PK from the bacterium T. maritima is also a homotetramer of 50-kDa subunits. The enzyme was independent of K+ ions, had a temperature optimum of 80 degrees C, was highly thermostable up to 90 degrees C, and had a melting temperature above 98 degrees C. The enzyme showed cooperative response to PEP and ADP. In contrast to its archaeal counterparts, the T. maritima enzyme exhibited the classic allosteric response to the activator AMP and to the inhibitor ATP. Sequences of hyperthermophilic PKs showed significant similarity to characterized PKs from bacteria and eukarya. Phylogenetic analysis of PK sequences of all three domains indicates a distinct archaeal cluster that includes the PK from the hyperthermophilic bacterium T. maritima.

Adenosine Diphosphate↗
PubMed2005

A membrane-bound multienzyme, hydrogen-oxidizing, and sulfur-reducing complex from the hyperthermophilic bacterium Aquifex aeolicus.

Aquifex aeolicus is a hyperthermophilic, chemolithoautotrophic, hydrogen-oxidizing, and microaerophilic bacterium growing at 85 degrees C. We have shown that it can grow on an H2/S degrees medium and produce H2S from sulfur in the later exponential phase. The complex carrying the sulfur reducing activity (electron transport from H2 to S degrees ) has been purified and characterized. It is a membrane-bound multiprotein complex containing a [NiFe] hydrogenase and a sulfur reductase connected via quinones. The sulfur reductase is encoded by an operon annotated dms (dimethyl sulfoxide reductase) that we have renamed sre and is composed of three subunits. Sequence analysis showed that it belongs to the Me2SO reductase molybdoenzyme family and is similar to the sulfur/polysulfide/thiosulfate/tetrathionate reductases. The study of catalytic properties clearly demonstrated that it can reduce tetrathionate, sulfur, and polysulfide, but cannot reduce Me2SO and thiosulfate, and that NADPH increases the sulfur reducing activity. To date, this is the first characterization of a supercomplex from a bacterium that couples hydrogen oxidation and sulfur reduction. The distinctive feature in A. aeolicus is the cytoplasmic localization of the sulfur reduction, which is in accordance with the presence of sulfur globules in the cytoplasm. Association of this sulfur-reducing complex with a hydrogen-oxygen pathway complex (hydrogenase I, bc1 complex) in the membrane suggests that subcomplexes involved in respiratory chains in this bacterium are part of supramolecular organization.

Amino Acid Sequence↗
PubMed2001

Alcaligenes faecalis subsp. parafaecalis subsp. nov., a bacterium accumulating poly-beta-hydroxybutyrate from acetone-butanol bioprocess residues.

The authors have previously isolated a solvent tolerant bacterium, strain G(T), (T = type strain) capable to convert acetone-butanol bioprocess residues into poly-beta-hydroxybutyrate. Strain G(T) was initially identified as Alcaligenes spp by standard bacteriological tests. In this study the taxonomic position of the bacterium was investigated in detail. The 165 rDNA sequence analysis, the G + C content of DNA (56 mol%) and the presence of ubiquinone Q-8 confirmed strain G(T) as a representative of the genus Alcaligenes. In the polyamine pattern of the bacterium putrescine and cadaverine were detected, but only trace amounts of 2-hydroxyputrescine. The extremely low content of 2-hydroxyputrescine is remarkable, since this unique diamine is a common marker for beta-proteobacteria. Phylogenetic analyses of 16S rDNA demonstrated that Alcaligenes sp. G(T) is most closely related to the species Alcaligenes faecalis (99.6% sequence similarity to A. faecalis HR4 and 98.7% sequence similarity to A. faecalis [ATCC 8750T = DSM 30030T]. On the basis of DNA-DNA relatedness (56% similarity), the unique polyamine pattern, the physiological and biochemical differences strain G(T) could be distinguished from the species A. faecalis. Therefore, a new subspecies for the species Alcaligenes faecalis is proposed; Alcaligenes faecalis subsp. parafaecalis subsp. nov.

Acetone↗
PubMed2006

Biodegradation of endosulfan by a soil bacterium.

A bacterium capable of metabolizing endosulfan (6,7,8,9,10,10-hexachloro-1,5,5a,6,9,9a-hexahydro-6,9-methano-2,4,3-benzodioxathiepine3-oxide) was isolated from cotton-growing soil and effectively shown to degrade endosulfan into endosulfan sulfate. The bacterium degraded 50% of the compound within 3 days of incubation. Endosulfan sulfate was the only terminal product and no other metabolites were formed during the incubation. Endosulfan and its metabolites were analyzed by gas chromatography. The metabolites formed indicated that the organism follows an oxidative pathway for metabolism of this pesticide. Therefore, the present study, microbial degradation of endosulfan by a soil bacterium, may provide a basis for the development of bioremediation strategies to remediate the pollutants in the environment.

Bacillus↗
PubMed2004

Characterization of an indigenous iron-oxidizing bacterium and its effectiveness in bioleaching heavy metals from anaerobically digested sewage sludge.

The objective of the present study was to isolate the indigenous iron-oxidizing bacterium and compare its effectiveness in bioleaching of heavy metals from fresh anaerobically digested sludge and aged sludge which had undergone a storage period in a sludge holding tank. An acidophilic iron-oxidizing bacterium Acidithiobacillus ferrooxidans strain ANYL-1 was successfully isolated from the sludge collected from a wastewater treatment plant at Yuen Long district in Hong Kong. It was a Gram negative, non-motile rod shaped bacterium which used ferrous iron, elemental sulfur or thiosulfate as energy source, but did not utilize tetrathionate or glucose as energy source. The optimal temperature and pH for its growth and iron oxidation were 30-35 degrees C and pH 2.0-2.5, respectively. When it was used in the bioleaching of anaerobically digested sewage sludge, an inhibition on metal solubilization was observed in fresh sludge except for Zn whose dissolution was solely a chemical process. Compared to the 3 and 4 days required for solubilization of Cu and Cr respectively from the sludge sample collected after the sludge holding tank (Sludge SHT), 6 days were required to bioleach Cu and Cr from fresh sludge (Sludge AD). The fresh sewage sludge posed an unfavorable condition for bioleaching of heavy metals from anaerobically digested sludge as reflected by the prolonged bioleaching time. Therefore, further studies were needed to understand the inhibitory effects in the fresh anaerobically digested sludge and develop measures to remove it in order to improve the heavy metal bioleaching efficiency.

Acidithiobacillus↗
PubMed1999

Isolation and characterization of a mutant defective in the production of methanol dehydrogenase from a new restricted facultative methanol-oxidizing bacterium.

A new restricted facultative methanol-oxidizing bacterium Methylobacillus sp. strain SK1 (DSM 8269) was subjected to insertion mutagenesis studies with the transposon Tn5 to generate mutants deficient in the production of methanol dehydrogenase (MDH). The transposon was conjugally transferred into the methylotroph by using the triparental mating procedure. The mutants induced by Tn5 were selected directly from a plate containing succinate by using the allyl alcohol selection procedure. The transposition of Tn5 to the bacterium showed a moderate transposition frequency (10(-5) - 10(-6)). Southern hybridization analysis confirmed that the transposon Tn5 was inserted into the chromosomal DNA of the mutants. In addition, the mutants had no RNA transcripts produced from the mdh gene, as judged by Northern blot analysis. The mutants could neither grow on methanol nor produce MDH protein, as determined by Western blot analysis with anti-MDH antibody. These results suggest that Tn5 mutagenesis maybe a useful tool for the molecular analysis of a facultative methanol-oxidizing bacterium.

Alcohol Oxidoreductases↗
PubMed1978

Amino acid sequence of a ferredoxin from Chlorobium thiosulfatophilum strain Tassajara, a photosynthetic green sulfur bacterium.

We have determined the amino acid sequence of a ferredoxin from a photosynthetic green sulfur bacterium, Chlorobium thiosulfatophilum strain Tassajara. It contains 61 amino acid residues with 9 cysteines, and 8 of the 9 were located at positions corresponding to those in clostridial-type ferredoxins. Other structural features were closer to those of ferredoxins from another photosynthetic bacterium, C. limicola, than to those of non-photosynthetic bacteria. Compared with ferredoxin from Chromatium, a photosynthetic purple sulfur bacterium, all photosynthetic bacterial ferredoxins have a common region in the carboxyl-terminal half with several extra residues and a unique cysteine residue. We compared all the photosynthetic bacterial ferredoxins that have been sequenced and concluded that C. thiosulfatophilum ferredoxin is most closely related to C. limicola ferredoxin I.

Amino Acid Sequence↗
PubMed2001

Absence of carotenes and presence of a tertiary methoxy group in a carotenoid from a thermophilic filamentous photosynthetic bacterium Roseiflexus castenholzii.

We identified pigments in a thermophilic filamentous photosynthetic bacterium Roseiflexus castenholzii strain HL08. We detected neither bacteriochlorophyll (BChl) c nor carotenes in this bacterium cultured under the aerobic dark and the anaerobic light conditions, which may correspond to its lack of chlorosomes. In the cells cultured under the aerobic dark conditions, the carotenoids were derivatives of keto-gamma-carotene, and the major ones were methoxy-keto-myxocoxanthin and keto-myxocoxanthin glucoside fatty acid ester. Although the tertiary methoxy group at C-1' and the double bond at C-3',4' in the psi end group of carotenoid, such as spirilloxanthin, have only been found in purple bacteria, this was the first such report in other bacterial groups. The fatty acid moiety was composed of iso fatty acids, which were rare in the cellular lipids. In the cells cultured under the anaerobic light conditions, in addition to these keto-carotenoids, we also found non-oxidized carotenoids (derivatives of gamma-carotene). Concerning the esterifying alcohol of BChl a, we found a substantial amount of geranylgeraniol, although the major component was phytol. The existence of these pigments makes this bacterium unique among the known species in CHLOROFLEXACEAE.

Aerobiosis↗
PubMed2001

Selection of a plant-bacterium pair as a novel tool for rhizostimulation of polycyclic aromatic hydrocarbon-degrading bacteria.

We developed a novel procedure for the selection of a microbe-plant pair for the stable and efficient degradation of naphthalene. Based on the rationale that root exudate is the best nutrient source available in soil, the grass (Lolium multiflorum) cultivar Barmultra was selected because of its abilities to produce a highly branched root system, root deeply, and carry a high population of Pseudomonas spp. bacteria on its roots. Starting with a mixture of total rhizobacteria from grass-like vegetation collected from a heavily polluted site and selecting for stable naphthalene degradation as well as for efficient root colonization, Pseudomonas putida strain PCL1444 was isolated. The strain's ability to degrade naphthalene was shown to be stable in the rhizosphere. Moreover, it had superior root-colonizing properties because, after the inoculation of grass seedlings, it appeared to colonize the root tip up to 100-fold better than the efficient root colonizer Pseudomonas fluorescens WCS365. Strain PCL1444 uses root exudate as the dominant nutrient source because the presence of grass seedlings in soil results in up to a 10-fold increase of PCL1444 cells. Moreover, the root colonized by strain PCL1444 was able to penetrate through an agar layer, resulting in the degradation of naphthalene underneath this layer. In addition, the inoculation of grass seeds or seedlings with PCL1444 protected them against naphthalene phytotoxicity. Finally, this plant-microbe combination appeared able to degrade naphthalene from soil that was heavily polluted with a complex mixture of polycyclic aromatic hydrocarbons. To our knowledge, this is the first time that a naturally occurring bacterium has been selected for the combination of the abilities to degrade a pollutant and colonize plant roots. We suggest that the principle described here, to select a bacterium which combines efficient root colonization with a beneficial activity, also can be used to improve the selection of other more efficient plant-bacterium pairs for beneficial purposes such as biocontrol, biofertilization, and phytostimulation.

Biodegradation, Environmental↗
PubMed1994

Haloanaerobium salsugo sp. nov., a moderately halophilic, anaerobic bacterium from a subterranean brine.

A strictly anaerobic, moderately halophilic, gram-negative bacterium was isolated from a highly saline oil field brine. The bacterium was a non-spore-forming, nonmotile rod, appearing singly, in pairs, or occasionally as long chains, and measured 0.3 to 0.4 by 2.6 to 4 microns. The bacterium had a specific requirement for NaCl and grew at NaCl concentrations of between 6 and 24%, with optimal growth at 9% NaCl. The isolate grew at temperatures of between 22 and 51 degrees C and pH values of between 5.6 and 8.0. The doubling time in a complex medium containing 10% NaCl was 9 h. Growth was inhibited by chloramphenicol, tetracycline, and penicillin but not by cycloheximide or azide. Fermentable substrates were predominantly carbohydrates. The end products of glucose fermentation were acetate, ethanol, CO2, and H2. The major components of the cellular fatty acids were C14:0, C16:0, C16:1, and C17:0 cyc acids. The DNA base composition of the isolate was 34 mol% G+C. Oligonucleotide catalog and sequence analyses of the 16S rRNA showed that strain VS-752T was most closely related to Haloanaerobium praevalens GSLT (ATCC 33744), the sole member of the genus Haloanaerobium. We propose that strain VS-752 (ATCC 51327) be established as the type strain of a new species, Haloanaerobium salsugo, in the genus Haloanaerobium.

Carbohydrate Metabolism↗
PubMed1996

Analysis of the phylogenetic relationships of strains of Burkholderia solanacearum, Pseudomonas syzygii, and the blood disease bacterium of banana based on 16S rRNA gene sequences.

We determined nearly complete 16S rRNA gene sequences for 19 isolates of Burkholderia solanacearum, three isolates of the blood disease bacterium of bananas, and two isolates of Pseudomonas syzygii, the cause of Sumatra disease of cloves. The dendrogram produced by comparing all of these sequences revealed that there were two divisions, which corresponded to the results obtained previously in a restriction fragment length polymorphism analysis (D. Cook, E. Barlow, and L. Sequeira, Mol. Plant Microbe Interact. 2:113-121, 1989) and a total 16S ribosomal DNA (rDNA) sequence analysis of four isolates representing four biovars of B. solanacearum (X. Li, M. Dorsch, T. Del Dot, L. I. Sly, E. Stackebrandt, and A. C. Hayward, J. Appl. Bacteriol. 74:324-329, 1993). Division 1 comprised biovars 3, 4, and 5 and an aberrant biovar 2 isolate (strain ACH0732), and division 2 included biovars 1, 2, and N2, the blood disease bacterium, and P. syzygii. Specific nucleotides at positions 458 to 460 (UUC) and 474 (A) characterized division 2, whereas in division 1 the nucleotides at these positions were ACU and U, respectively. However, strain ACH0732 had a U at position 458, as did division 2 isolates, and G instead of U at position 474. Division 2 consisted of two subdivisions; one subdivision contained two B. solanacearum isolates that originated from Indonesia, P. syzygii strains, and blood disease bacterium strains, and the other subdivision contained all of the other division 2 isolates. Within division 1, the level of 16S rDNA sequence similarity ranged from 99.8 to 100%, and within division 2, the levels of 16S rDNA sequence similarity ranged from 99.1 to 100%. The division 1 isolates exhibited an average level of 16S rDNA sequence similarity to division 2 isolates of 99.3% (range, 99.1 to 99.5%). The occurrence of consistent polymorphisms in the 16S rDNA sequences of B. solanacearum strains, in particular unique 16S rDNA sequence differences in aberrant biovar 2 isolate ACH0732, and the occurrence of the Indonesian subdivision of division 2 suggest that this group is a rapidly evolving (tachytelic) group.

Base Sequence↗
PubMed1996

"Candidatus comitans," a bacterium living in coculture with Chondromyces crocatus (myxobacteria).

We describe the phylogenetic position and some taxonomically relevant characteristics of a small pleomorphic gram-negative bacterium that was cocultured with some strains of the myxobacterium Chondromyces crocatus that were isolated from the same geographic and ecological habitat. A 16S ribosomal DNA analysis revealed that the companion was a member of the "Cytophaga-Flavobacterium-Bacteroides" complex and was most closely related to members of the genus Sphingobacterium. The results of a fatty acid analysis, an isoprenoid composition analysis, and a DNA G+C content analysis and the presence of sphingolipids confirmed that this bacterium is affiliated with the genus Sphingobacterium. As the companion bacterium survived for only a few generations on solid media and could not be maintained in pure culture, we assign to this novel taxon that lives in close association with the myxobacterium C. crocatus Candidatus status as "Candidatus comitans."

Bacteroidetes↗
PubMed1997

Porphyrobacter tepidarius sp. nov., a moderately thermophilic aerobic photosynthetic bacterium isolated from a hot spring.

A new thermophilic bacterium, strain OT3T (T = type strain), was isolated from a brackish hot spring. Strain OT3T is an obligate aerobe that synthesizes bacteriochlorophyll a and has a photosynthetic apparatus. This isolate is a thermophilic bacterium with an optimal growth temperature of 40 to 48 degrees C. The cells are nonmotile, ovoid to short rods. An analysis of 16S rRNA sequences revealed that the new strain forms a coherent cluster with members of the alpha-4 group of the alpha subclass of the Proteobacteria, which contains the genera Erythrobacter, Erythromicrobium, and Porphyrobacter. The closest relative is Porphyrobacter neustonensis, with a 16S rRNA sequence similarity of 96.8%. The in vivo absorption spectrum has maxima at 460, 494, 596, 800, and 870 nm. The main carotenoids are OH-beta-carotene sulfate derivatives, nostoxanthin, and bacteriorubixanthinal. Growth occurs with glucose, acetate, glutamate, butyrate, Casamino Acids, and yeast extract as sole energy sources. The pigment composition and nutritional profile of the new isolate are similar to the pigment composition and nutritional profile of P. neustonensis. Although there are marked differences in cell morphology between the new isolate and the budding bacterium P. neustonensis, the results of phenotypic and genetic comparisons suggest that the new isolate is closely related to P. neustonensis. Consequently, we assign the new isolate to the genus Porphyrobacter and propose the name Porphyrobacter tepidarius sp. nov. for it; the type strain of P. tepidarius is strain OT3 (= DSM 10595).

Bacteria, Aerobic↗
PubMed1998

Phylogenetic characterization of the bacterium-like organism associated with marginal chlorosis of strawberry and proposition of a Candidatus taxon for the organism, 'Candidatus phlomobacter fragariae'.

Marginal chlorosis is a new disease of strawberry which was first seen in France in 1988. A phloem-restricted bacterium-like organism was found associated with the disease. Even though the organism could not be cultured and resembles in this way most other phloem-restricted pathogens, characterization was achieved from the sequence of its PCR-generated 16S rDNA, and comparison with other organisms. From these studies, the strawberry agent was found to be a new bacterium within group 3 of the gamma subclass of Proteobacteria, a group of Gram-negative bacteria including, in particular, insect symbionts or parasites as well as enterobacteria. Its closest relative, Arsenophonus nasoniae, is the causal agent of the son-killer trait in wasps. The two bacteria share 92% 16S rDNA sequence identity. We propose a Candidatus taxon for the marginal-chlorosis-associated bacterium, 'Candidatus Phlomobacter fragariae'.

Fruit↗