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PubMed2005

Study on EDTA-degrading bacterium Burkholderia cepacia YL-6 for bioaugmentation.

Bioaugmentation production of EDTA-degrading bacterium Burkholderia cepacia YL-6 was carried out in an aerobic fermentor. Three different carbon sources (ferric-ethylenediaminetetraacetate (Fe-EDTA), potassium acetate, and ethylamine) were used. The bacterium cultivated with Fe-EDTA and maintained in the growth phase could reach the maximum cell concentration on the 38th day. Whereas, the bacterium cultivated with potassium acetate and ethylamine reach the maximum cell concentration at the 76th and 100th hour. The viable-cell counts of the augmentation agents made by feeding Fe-EDTA, potassium acetate, and ethylamine were 8.2x10(10), 6.8x10(11), and 4.3x10(11) CFU/g agent, respectively. The EDTA-degradation time required for the afore-mentioned bioaugmentation agents made by feeding various carbon sources lay in the following order: ethylamine<potassium acetate<Fe-EDTA. Especially, the most efficient bioaugmentation agent (made by feeding ethylamine) only required 10 and 13 days for complete degradation of EDTA from the Fe-EDTA and Cu-EDTA complexes, respectively. It shows that ethylamine was the best substrate for augmentation production of EDTA-degrading bacterium B. cepacia YL-6.

Biodegradation, Environmental↗
PubMed2006

Biological control of postharvest spoilage caused by Penicillium expansum and Botrytis cinerea in apple by using the bacterium Rahnella aquatilis.

The epiphytic bacterium Rahnella aquatilis, isolated from fruit and leaves of apples, was tested for antagonistic properties against Penicillium expansum and Botrytis cinerea on Red Delicious apple fruit. In "in vitro" assays, this bacterium inhibited completely the germination of P. expansum and B. cinerea spores, but it needed direct contact with the spores to do it. However the putative mechanism seemed be different for the two pathogens. The bacterium did not produce extracellular antibiotic substances and when the acute toxicity test was performed no mortality, toxicity symptoms or organ alterations of the test animals (Wistar rats) were observed. Assays of biological control of P. expansum and B. cinerea on apple fruit were carried out at different temperatures. At 15 degrees C and 90% RH, the incidence of disease caused by P. expansum on apples stored for 20 days, was reduced by nearly 100% by R. aquatilis (10(6) cells/ml), while in the case of B. cinerea, the reduction of decay severity was nearly 64% but there was no reduction in the incidence of disease. At 4 degrees C and 90% RH the treatment with the bacterium significantly inhibited the development of B. cinerea on apples stored for 40 days and the incidence of disease was reduced by nearly 100%, while the incidence of disease caused by P. expansum at 4 degrees C was 60%. The results obtained show that R. aquatilis would be an interesting microorganism to be used as a biocontrol agent.

Animals↗
PubMed2006

Sedimenticola selenatireducens, gen. nov., sp. nov., an anaerobic selenate-respiring bacterium isolated from estuarine sediment.

The respiration of selenate, as a terminal electron acceptor has been known for over a decade, but the microorganisms involved in this respiration are largely unknown. Here we characterize a novel selenate-respiring bacterium, strain AK4OH1, isolated from an estuarine sediment enrichment culture. Strain AK4OH1 has the unique capability to oxidize aromatic acids, such as benzoate, 4-hydroxybenzoate and 3-hydroxybenzoate, coupled to selenate respiration. This novel respiratory coupling has not been described before. Reduction of selenate is followed by stoichiometric accumulation of selenite. The strain grows in agar shake tubes forming bright red colonies due to precipitation of elemental selenium. Strain AK4OH1 is a strictly anaerobic bacterium, which can also respire nitrate and nitrite via denitrification. Analysis of the 16S rRNA gene sequence shows that this strain clusters with another selenate-reducing bacterium and a (per) chlorate reducing bacterium, within the Gammaproteobacteria, along with symbionts of bivalves and tubeworms. Based on its unique physiological capabilities and its 16S rRNA gene sequence phylogeny, we classify this strain AK4OH1 as a new genus and species with the proposed name Sedimenticola selenatireducens.

Base Sequence↗
PubMed2004

A symbiont of the tick Ixodes ricinus invades and consumes mitochondria in a mode similar to that of the parasitic bacterium Bdellovibrio bacteriovorus.

We have recently performed molecular characterisation of an intracellular alpha-proteobacterium, named IricES1, which resides in the ovarian tissue of female Ixodes ricinus ticks from Italy. A unique characteristic of this bacterium is its ability to invade the mitochondria of the cells in which it resides. Although some ultrastructural studies have been performed on close relatives of this bacterium from I. ricinus in England and Switzerland, a number of questions remain about its movement within ovarian tissues and mitochondria. We have performed the first detailed ultrastructural examination of IricES1 in engorged female adult I. ricinus. Among our findings was that the bacterium enters mitochondria in a similar way to that employed by the 'predatory' bacterium Bdellovibro bacteriovorus, that is, between the inner and outer membranes. It then appears to multiply, with the new 'colony' consuming the mitochondrial matrix. Despite having many of their mitochondria consumed, oocytes appear to develop normally, and the bacteria are likely to be vertically transferred to all eggs.

Animals↗
PubMed2003

Direct measurement of interaction forces between a single bacterium and a flat plate.

A technique for precisely measuring the equilibrium and viscous interaction forces between a single bacterium and a flat surface as functions of separation distance is described. A single-beam gradient optical trap was used to micromanipulate the bacterium against a flat surface while evanescent wave light scattering was used to measure separation distances. Calibrating the optical trap far from the surface allowed the trapped bacterium to be used as a force probe. Equilibrium force-distance profiles were determined by measuring the deflection of the cell from the center of the optical trap at various trap positions. Simultaneously, viscous forces were determined by measuring the relaxation time for the fluctuating bacterium. Absolute distances were determined using a best-fit approximation to the theoretical prediction for the hindered mobility of a diffusing sphere near a wall. Using this approach, forces in the range from 0.01 to 4 pN were measured at near-nanometer resolution between Staphylococcus aureus and glass that was bare or coated with adsorbed protein.

Adsorption↗
PubMed2001

Regioselective biotransformation of the dinitrile compounds 2-, 3- and 4-(cyanomethyl) benzonitrile by the soil bacterium Rhodococcus rhodochrous LL100-21.

The cyanomethyl benzonitrile compounds used for this study contain two cyano groups: a -CH(2)CN side chain, plus a cyano group attached to the benzene ring. The ortho, meta and para -CH(2)CN substituted compounds were biotransformed using whole cell suspensions of the bacterium Rhodococcus rhodochrous LL100-21. The bacterium had previously been grown on the mono-nitrile compounds propionitrile, benzonitrile or acetonitrile, inducing the formation of nitrile hydrolyzing enzymes.Suspensions of R. rhodochrous LL100-21 that had been grown on propionitrile or benzonitrile converted the aliphatic group of 2-(cyanomethyl) benzonitrile (a) to the corresponding carboxylic acid, 2-(cyanophenyl) acetic acid (d) with excellent recovery of the product and no evidence for any other products. Conversely, when grown on acetonitrile the bacterium converted 2-(cyanomethyl) benzonitrile (a) to the amide derivatives 2-(cyanophenyl) acetamide (k) and 2-(cyanomethyl) benzamide (l) but only in low yields.Biotransformations of 3-(cyanomethyl) benzonitrile (b) and 4-(cyanomethyl) benzonitrile (c), by suspensions of bacteria that had been grown on benzonitrile or propionitrile, resulted in hydrolysis of the aromatic nitrile to produce 3- and 4-(cyanomethyl) benzoic acid (j) and (m), respectively, both with a high yield. Low concentrations of other products were also detected, for example the diacids 3- and 4-(carboxyphenyl) acetic acid (h) and (i).When the bacterium was grown on acetonitrile it could biotransform 3- and 4-(cyanomethyl) benzonitrile (b) and (c) to different products indicating less regiospecificity by the nitrile hydratase enzyme.Comparison of the initial rates of conversion of the aliphatic cyano side chain of 2-(cyanomethyl) benzonitrile (a) and other substituted benzonitriles indicated that electronic effects did not affect the initial rate of the reaction as they would require transmission through an SP(3) methylene carbon atom.

Journal Article↗
PubMed1999

Growth and enumeration of the meat spoilage bacterium Brochothrix thermosphacta.

Brochothrix thermosphacta is a common meat spoilage bacterium. The morphology of this bacterium changes from coccobacilli and short rods to chains during growth, which may give a false estimation in numbers using some enumeration techniques. Methods for the quantification of this bacterium have been compared. Turbidimetric readings showed good agreement with cell dry weight indicating that the former provides a good measure of the change in cell mass during growth. The turbidimetric method also correlated well with bacterial numbers determined by plate counts, flow cytometry and manual counts (by microscope) over a limited range of 10(7)-10(9) cells/ml. Flow cytometry and manual counts gave a linear relationship over a wider range of 10(5)-10(9) cells/ml. The sensitivity of analysis, growth rates and lag time attained using these methods were also compared. As a consequence of changes in bacterial cell size during growth, turbidimetry over-estimated the growth rate. The plate count method proved unable to detect the difference between bacteria existing as chains or single cells. The sensitivity of analysis and the calculated growth related parameters were similar for flow cytometry and manual counts. This suggests that flow cytometry is capable of counting individual cells in a chain. Further investigation showed that passage of B. thermosphacta cells through the flow cytometer resulted in the breakage of chains into single cells. The reliability, low error and rapidity of this technique make it attractive for bacterial enumeration, something which has been demonstrated using B. thermosphacta, a bacterium which exhibits complex morphologies.

Animals↗
PubMed1979

Human infection from an unidentified erythrocyte-associated bacterium.

A 49-year-old splenectomized man had an infection from an unidentified, gram-positive, rod-shaped bacterium that adhered to the majority of his peripheral-blood erythrocytes. On transmission electron microscopy, the bacterium was seen to be extra-erythrocytic and was 0.2 micrometer wide by 1.0 to 1.7 micrometer long. It possessed a thick, granular cell wall, a trilamellar membrane external to the cell wall and prominent mesosomes. Attempts to cultivate the organism in vitro or to duplicate the patient's disease in splenectomized animals were unsuccessful. The patient's response suggested that the bacterium was susceptible to cell-wall-active antibiotics and to chloramphenicol but not to tetracycline. This bacterium may be the cause of other chronic, fever-producing, multisystem diseases of unknown origin.

Animals↗
PubMed1980

Legionnaires' disease bacterium: a non-endospore-former.

This investigation was done to determine whether dipicolinic acid was present in the Legionnaires' disease bacterium. A colorimetric assay for dipicolinic acid was done and the results for the bacterium were compared with those obtained for Escherichia coli and Bacillus subtilis. Dipicolinic acid was not detected in the Legionnaires' disease bacterium. This demonstrated that the bacterium was unable to produce typical bacterial endospores under the experimental conditions examined.

Bacteria↗
PubMed1980

ESR studies on the membrane properties of a moderately halophilic bacterium. I. Physical properties of lipid bilayers in whole cells.

The lipid membrane properties of a moderately halophilic gram-negative bacterium, Pseudomonas halosaccharolytica ATCC 29423, were studied by the use of stearate spin labels, 5NS, 12NS, and 16NS, changing the temperature of ESR measurement from 15 to 50 degrees C. The order parameter and the rotational correlation time of the spin labels incorporated into intact cell membranes of this bacterium grown at various temperatures in media containing different NaCl concentrations were calculated. The activation energy of rotational microviscosity was obtained from Andrade plots. At low growth temperature and low NaCl concentration in the medium, extractable lipids of this bacterium contained comparatively large amounts of unsaturated fatty acids, but as the growth temperature and NaCl concentration in the medium increased, the contents of saturated and cyclopropanoic fatty acids increased to more than half of the total fatty acids. 5NS gave the highest order parameters for the intact cells of this bacterium, while 12NS gave lower and 16NS gave the lowest results. The order parameters of 5NS, 12NS, and 16NS were completely separated, and all order parameters decreased gradually as the measuring temperature was increased. In contrast, the rotational correlation times of the intact cells with 12NS were as large as those with 5NS, while those with 16NS were distinctly smaller. Increasing NaCl concentrations in the growth medium caused an increase of the rotational correlation times, that is, stiffened the lipid bilayers. The Andrade plot for 16NS was approximately a straight line, whereas 5NS and 12NS gave two straight lines crossing at a temperature near the growth temperature, indicating phase transition from solid to liquid. The microviscosity activation energies were 5--10 kcal/mol in the liquid phase and 15--25 kcal/mol in the solid phase.

Cell Membrane↗
PubMed1993

Ileal symbiont intracellularis, an obligate intracellular bacterium of porcine intestines showing a relationship to Desulfovibrio species.

A new genus and species of obligate intracellular-bacteria found in porcine intestines are described. Growth on any bacteriological medium deprived of living cells has not been demonstrated. The organism has been grown intracellularly in cell culture. The 16S rRNA gene sequence data, DNA probe results, and microscopic observations provide evidence that these bacteria differ from those in other described genera and that they belong to the delta subdivision of the class Proteobacteria. We have amplified and sequenced the 16S ribosomal DNA of four preparations of the intracellular bacterium from pigs. For this, intracellular organisms were released and purified from the infected cells without culture techniques. After DNA purification, the polymerase chain reaction with primers complementary to highly conserved eubacterial sequences was used to amplify regions of 16S ribosomal DNA which were subsequently cloned (in some cases) and sequenced directly by standard techniques. The sequences obtained from each preparation were identical and were most similar to that of a sulfate-reducing proteobacterium, Desulfovibrio desulfuricans ATCC 27774 (91% similarity). An oligonucleotide probe complementary to a hypervariable region of the 16S rRNA sequence of the bacterium hybridized with intracellular organisms obtained from porcine intestines. The bacterium is a gram-negative, curved rod with tapered ends. It multiplies intracellularly in the cytoplasm of ileal epithelial cells by septation. The vernacular name Ileal symbiont (IS) intracellularis is proposed for this bacterium. The type strain of IS intracellularis is strain 1482/89 grown in cell culture from a pig affected by proliferative enteropathy. It is deposited in the National Collection of Type Cultures, Colindale, London, as NCTC 12656.

Animals↗
PubMed1996

Isolation and characterization of Desulfitobacterium frappieri sp. nov., an anaerobic bacterium which reductively dechlorinates pentachlorophenol to 3-chlorophenol.

An anaerobic bacterium, strain PCP-1T (T = type strain), which dechlorinates pentachlorophenol (PCP) to 3-chlorophenol, was isolated from a methanogenic consortium. This organism is a spore-forming rod-shaped bacterium that is nonmotile, asaccharolytic, and Gram stain negative but Gram type positive as determined by electron microscopic observations. Inorganic electron acceptors, such as sulfite, thiosulfate, and nitrate (but not sulfate), stimulate growth in the presence of pyruvate and yeast extract. The optimum pH and optimum temperature for growth are 7.5 and 38 degrees C, respectively. The dechlorination pathway is: PCP-->2,3,4,5-tetrachlorophenol -->3,4,5-trichlorophenol-->3,5-dichlorophenol-->3-chlorophenol. This bacterium dechlorinates several different chlorophenols at ortho, meta, and para positions; exceptions to this are 2,3-dichlorophenol, 2,5-dichlorophenol, 3,4-dichlorophenol, and the monochlorophenols. The time course of PCP dechlorination suggests that two enzyme systems are involved in dehalogenation in strain PCP-1T. One system is inducible for ortho dechlorination, and the second system is inducible for meta and para dechlorinations. A 16S rRNA analysis revealed that strain PCP-1T exhibits 95% homology with Desulfitobacterium dehalogenans JW/IU-DC1, an anaerobic bacterium which can dehalogenate chlorophenols only in ortho positions. These results suggest that strain PCP-1T is a member of a new species and belongs to the recently proposed genus Desulfitobacterium. Strain PCP-1T differs from D. dehalogenans JW/IU-DC1 by its broader range of chlorophenol dechlorination. Strain PCP-1 is the type strain of the new species, Desulfitobacterium frappieri.

Bacteria, Anaerobic↗
PubMed1996

Reassessment of the phylogenetic position of the bacterium associated with Whipple's disease and determination of the 16S-23S ribosomal intergenic spacer sequence.

Whipple's disease is a rare chronic illness associated with an unculturable bacterium that is constantly present in affected tissues. This bacterium was previously characterized at the molecular level by PCR and sequencing of the 16S rRNA gene. On the basis of 1,321 nucleotides of the sequence of its gene coding for 16S rRNA (16S rDNA), a phylogenetic relationship to the actinomycetes was established. In this study, we determined an almost complete 16S rDNA sequence (1,495 nucleotides), the 16S-23S ribosomal intergenic spacer sequence, and 200 nucleotides of the 23S rRNA gene. The 16S rDNA sequence was compared with the large number of actinomycete sequences that have been added to the database since the original study. Phylogenetic analysis revealed a branching position as the deepest branch of the cluster comprising the actinomycetes with group B peptidoglycan between this group and the family Cellulomonadaceae. This provides additional information on the phylogenetic position of this bacterium and some clues as to its characteristics. The spacer region between the 16S and 23S rRNA genes is 294 nucleotides long and does not contain tRNA genes. As has been shown in other instances, the increased variability of the ribosomal intergenic spacer compared with the 16S rRNA gene makes it a potential target for use in the differentiation of strains of the bacterium associated with Whipple's disease.

Actinomycetales↗
PubMed1997

In vitro culture and phylogenetic analysis of "Candidatus Arsenophonus triatominarum," an intracellular bacterium from the triatomine bug, Triatoma infestans.

An intracellular symbiotic bacterium was isolated from the hemolymph of Triatoma infestans and cultured in an Aedes albopictus cell line. 16S ribosomal DNA sequence analysis revealed that the bacterium was a member of the gamma-3 subgroup of the class Proteobacteria, having 96.2% sequence identity with the most closely related bacterium, Arsenophonus nasoniae, the causative agent of the son-killer trait in the parasitoid wasp Nasonia vitripennis. These bacteria share morphological features and a common tissue distribution and transmission mode. The A. nasoniae-T. infestans symbiont branch represents a lineage of insect symbionts which may be capable of horizontal transmission between phylogenetically distant host insects. We propose that the intracellular symbiont from T. infestans be classified as "Candidatus Arsenophonus triatominarum." The bacterium found in the hemocytes of T. infestans is designated the type strain of this species.

Animals↗
PubMed1999

Thiorhodospira sibirica gen. nov., sp. nov., a new alkaliphilic purple sulfur bacterium from a Siberian soda lake.

A new purple sulfur bacterium was isolated from microbial films on decaying plant mass in the near-shore area of the soda lake Malyi Kasytui (pH 9.5, 0.2% salinity) located in the steppe of the Chita region of south-east Siberia. Single cells were vibrioid- or spiral-shaped (3-4 microns wide and 7-20 microns long) and motile by means of a polar tuft of flagella. Internal photosynthetic membranes were of the lamellar type. Lamellae almost filled the whole cell, forming strands and coils. Photosynthetic pigments were bacteriochlorophyll a and carotenoids of the spirilloxanthin group. The new bacterium was strictly anaerobic. Under anoxic conditions, hydrogen sulfide and elemental sulfur were used as photosynthetic electron donors. During growth on sulfide, sulfur globules were formed as intermediate oxidation products. They were deposited outside the cytoplasm of the cells, in the peripheral periplasmic space and extracellularly. Thiosulfate was not used. Carbon dioxide, acetate, pyruvate, propionate, succinate, fumarate and malate were utilized as carbon sources. Optimum growth rates were obtained at pH 9.0 and optimum temperature was 30 degrees C. Good growth was observed in a mineral salts medium containing 5 g sodium bicarbonate l-1 without sodium chloride. The new bacterium tolerated up to 60 g sodium chloride l-1 and up to 80 g sodium carbonates l-1. Growth factors were not required. The DNA G + C composition was 56.0-57.4 mol%. Based on physiological, biochemical and genetic characteristics, the newly isolated bacterium is recognized as a new species of a new genus with the proposed name Thiorhodospira sibirica.

Bacteria↗
PubMed1999

Phylogenetic status of Anaerobacter polyendosporus, an anaerobic, polysporogenic bacterium.

The almost complete sequence of the 16S rRNA gene of the Gram-positive polysporogenic bacterium Anaerobacter polyendosporus was determined. This allowed phylogenetic analysis of A. polyendosporus by comparing sequences of the 16S rRNA gene of this bacterium to similar genes of other Gram-positive bacteria. It was shown that this polysporogenic bacterium belongs to the Clostridium cluster I, subcluster A. Phylogenetically, A. polyendosporus is distantly related to another polysporogenic, but non-cultivatable, bacterium, 'Metabacterium polyspora' and can be satisfactorily clustered within the saccharolytic clostridia with a low DNA G+C content grouped in subcluster A. A. polyendosporus was most closely related to Clostridium intestinale (94.8% identity of 16S rRNA genes) and Clostridium fallax (93.1%). Like other members of the Clostridium cluster I, subcluster A, A. polyendosporus possesses such common phenotypic features as a Gram-positive cell wall structure, anaerobiosis, derivation of energy from carbohydrate fermentation yielding butyric acid among other organic acids and the capacity for endogenous spore-formation. However, the scale of evolutionary change in the 16S rRNA gene between A. polyendosporus and phylogenetically related Clostridium species does not correspond to the profound changes in the phenotype of A. polyendosporus. Distinctive phenotypic features of the latter are large cell size, polysporogenesis (up to seven spores per cell), alternative modes of development and an unusual membrane ultrastructure.

Anaerobiosis↗
PubMed2001

Thioflavicoccus mobilis gen. nov., sp. nov., a novel purple sulfur bacterium with bacteriochlorophyll b.

A novel phototrophic purple sulfur bacterium was isolated from a flat, laminated microbial mat in a salt marsh near Woods Hole, Massachusetts, USA. The cells were monotrichously flagellated motile cocci with internal photosynthetic membranes of the tubular type. The main photosynthetic pigments were bacteriochlorophyll b and the carotenoid 3,4,3',4'-tetrahydrospirilloxanthin. The marine bacterium showed optimal growth in the presence of 2% salts. It was obligately phototrophic and strictly anaerobic. It grew photoautotrophically and photoassimilated acetate, pyruvate and ascorbate as the only organic substrates. In the presence of sulfide, elemental sulfur globules were formed inside the cells. Elemental sulfur was further oxidized to sulfate. The DNA base composition of the new bacterium was 66.5 mol% G+C. The 16S rDNA nucleotide sequence was most similar to strains of Thiococcus pfennigii, there being approximately 92-93% sequence similarity. The new bacterium is described as a new species and a new genus, and the name Thioflavicoccus mobilis is proposed; the type strain is 8321T (= ATCC 700959T).

Bacteriochlorophylls↗
PubMed2001

Filobacillus milensis gen. nov., sp. nov., a new halophilic spore-forming bacterium with Orn-D-Glu-type peptidoglycan.

A spore-forming, halophilic bacterium was isolated from surface sediment located on the beach of Palaeochori Bay near to a shallow water hydrothermal vent area, Milos, Greece. The bacterium, designated SH 714T, consisted of motile, strictly aerobic rods which contained an Orn-D-Glu type murein and a G+C content of 35 mol%. Thin sections showed a cell wall typical for Gram-positive bacteria; the peptidoglycan layer, however, was very thin. The Gram-reaction of the organism was negative. Comparative 16S rRNA gene sequencing demonstrated that the isolate represents a new line of descent within the spore-forming rods branching at the periphery of the rRNA group 1 Bacillus (Bacillus sensu stricto). The nearest phylogenetic neighbours of the unknown bacterium were Bacillus haloalkaliphilus, Marinococcus albus and Halobacillus species. Based on phylogenetic and phenotypic evidence it is proposed that the unknown bacterium be classified as Filobacillus milensis gen. nov., sp. nov. The type strain is SH 714T (= DSM 13259T = ATCC 700960T).

Bacillus↗