bluuebunny/crossref_metadata_2025 huggingface dataset:
Isolation and characterization of bacteriophages specific for Rhizobium leguminosarum biovar phaseoli
Authors: Dhar B. , Upadhyay K. K. , Singh R. M.
Published: May 2010

Two lytic phages, designated as H3V and R2V, specific for Rhizobium leguminosarum biovar phaseoli, were isolated and characterized. Phage H3V was active against four indigenous isolates (HURR-3, HURR-21, HURR-35, and HURR-56) and two standard strains (RCR-3605 and USDA-2669) whereas R2V was specific to one indigenous (Raj-2) and one standard (USDA-2676) strain; there was no cross infectivity. Both phages had distinct morphology; phage H3V had an oblate polyhedral head (58 × 76 nm) and a flexible noncontractile tail (120 × 10 nm), while phage R2V had a hexagonal head (56 nm wide) and a very short tail (11 × 10 nm). The lytic cycle of phage R2V requires Ca2+ ions (1 mM), which considerably reduce its latent period and burst size. Adsorption and one-step growth experiments of phages revealed that H3V had a slower adsorption rate (0.56 × 10−9 cm3/min), a longer latent period (255 min), and a higher burst size (240 plaque-forming units/cell) than R2V, which had an adsorption rate of 0.94 × 10−9 cm3/min, a 210-min latent period, and a burst size of 200 plaque-forming units/cell. Inactivation of these phages by heat, osmotic shock, and uv irradiation showed that phage H3V was comparatively more sensitive than R2V. These phages were frequently detected in healthy nodules of French beans (Phaseolus vulgaris) at two different field locations and no correlation between phage titer and nodule size or colour was observed. Phage titer varied from 2.8 × 102 to 1.2 × 106 plaque-forming units/nodule.Key words: Rhizobium, phages, morphology.
Digestion of cell-wall monosaccharides of ryegrass and alfalfa hays by the ruminal bacteria Fibrobacter succinogenes and Butyrivibrio fibrisolvens
Authors: Miron Joshua , Ben-Ghedalia Daniel
Published: May 2010

The ruminal bacteria Fibrobacter succinogenes strains S85 and BL2 were grown in monocultures or in coculture with strain D1 of Butyrivibrio fibrisolvens, and the solubilization of ryegrass and alfalfa cell walls (CW) and digestion of CW monosaccharides were measured. Fibrobacter succinogenes monocultures and cocultures with B. fibrisolvens D1 degraded 58–69% of ryegrass CW, solubilizing 67–78% of CW glucose, 65–71% of CW xylose, 69–75% of hemicellulose, and 68–77% of total CW monosaccharides. When grown on alfalfa CW, those cultures degraded 28–39% of alfalfa CW, solubilizing 42–58% of CW glucose, 30–36% of CW xylose, and 37–45% of hemicellulose. With respect to both substrates, F. succinogenes strains solubilized CW carbohydrates better than did B. fibrisolvens D1. Complementary interaction between B. fibrisolvens D1 and the F. succinogenes strains was identified with respect to the utilization of some solubilized carbohydrates, but not with respect to the extent of CW solubilization, which was determined mainly by the F. succinogenes strains. For both substrates, utilization of solubilized cellulose by F. succinogenes monocultures was high (96–98%), whereas that of hemicellulose was lower (24–26% in ryegrass and 49–50% in alfalfa). Under scanning electron microscopy, F. succinogenes bacterial cells attached to and colonized on CW particles were characterized by the appearance of protuberant surface structures that we have identified as "polycellulosome complexes." Key words: cell wall monosaccharides, ryegrass, alfalfa, ruminal bacteria, Fibrobacter succinogenes, Butyrivibrio fibrisolvens.
Comparison of amylolytic and proteolytic activities of ruminal fungi grown on cereal grains
Authors: Yanke L. J. , Dong Y. , McAllister T. A. , Bae H. D. , Cheng K.-J.
Published: May 2010

Strains of the ruminal fungi Neocallimastixpatriciarum, Orpinomyces joyonii, and Piromyces communis were grown on cellobiose and on cereal grains and then examined for proteolytic and amylolytic activities. On cellobiose all three fungi displayed similar activities, with the exception of little amylolytic activity in the cell-associated fraction of N. patriciarum. Growth on the cereal grains barley, corn, and wheat showed differences in proteolytic and amylolytic activities amongst the ruminal fungi and between the cereal grains. The data suggest that while these fungi are capable of fermenting the cereal grains the mode of enzymatic attack varies both with the particular fungus and the type of cereal grain.Key words: Neocallimastix, Orpinomyces, Piromyces, cereal grain, amylolytic, proteolytic.
Use of 5-bromo-4-chloro-3-indolyl-β-D-galactopyranoside for the isolation of β-galactosidase-positive bacteria from municipal water supplies
Authors: Ley Arthur , Barr Susanne , Fredenburgh Diane , Taylor Michael , Walker Nina
Published: May 2010

A new medium, mX-Gal, has been developed for the membrane filter enumeration of β-galactosidase-positive bacteria in municipal water supplies. mX-Gal medium contains the chromogenic β-galactosidase substrate 5-bromo-4-chloro-3-indolyl-β-D-galactopyranoside (X-Gal). All Aeromonas, Citrobacter, and Enterobacter strains isolated from raw water on mX-Gal medium were β-galactosidase positive. In contrast, only 10 to 20% of these strains produced a red colony with a metallic sheen on m-Endo agar LES medium. Of 674 chlorinated water samples analyzed for total coliforms on m-Endo agar LES medium and for β-galactosidase-positive bacteria on mX-Gal medium, 18 that were negative for coliforms on m-Endo agar LES showed β-galactosidase-positive bacteria on mX-Gal. Of a total of 50 β-galactosidase-positive bacteria isolated from these samples, 76% were identified as Aeromonas hydrophila.Key words: β-galactosidase, 5-bromo-4-chloro-3-indolyl-β-D-galactopyranoside, total coliforms, Aeromonas.
Purification and characterization of NADH dehydrogenase from Bacillus megaterium
Authors: Thiagalingam Sam , Yang Tsanyen
Published: May 2010

NADH dehydrogenase of Bacillus megaterium was isolated from the sonicate soluble fraction. The enzyme was purified approximately 61-fold by a combination of ammonium sulfate fractionation and column chromatography on DEAE-Sephadex and hydroxyapatite. The purified enzyme has an apparent molecular weight of 42 000 as determined by SDS-polyacrylamide gel electrophoresis and activity staining for NADH-MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide) oxidoreductase. The enzyme is specific for NADH and has a pH optimum of 7.5–7.8. The apparent Km values for NADH are 15.7, 34.8, and 69.2 μM as determined for NADH-DCIP (dichlorophenol–indophenol), NADH-ferricyanide, and NADH-MTT oxidoreductases. FAD is the prosthetic group of the enzyme. NAD+ acts as a competitive inhibitor. The inhibition studies suggest that NADH dehydrogenase is the primary electron donor of the NADH oxidase system. Localization studies and inhibition studies together indicate that the NADH oxidase is a complex of membrane-bound enzymes and coenzymes.Key words: NADH dehydrogenase, NADH oxidase, Bacillus megaterium, purification, characterization.
Production of a cloned xylanase in Bacillus cereus and its performance in kraft pulp prebleaching
Authors: Tremblay L. , Archibald F.
Published: May 2010

Xylanase production from a Bacillus subtilis gene cloned into a strain of Escherichia coli was monitored. Although this gene was expressed in E. coli at several temperatures, efficient xylanase secretion did not occur; the observed protein release apparently depended on cell leakage or lysis. Screening for a better microbial protein secretor free of cellulase selected Bacillus cereus No. 518. A bidirectional vector plasmid (pMK3) was employed to carry the cloned gene into this B. cereus strain. Transformation was carried out by electroporation. Total xylanase production by the new pMK3-borne gene in B. cereus was similar to that from E. coli but the xylanase was shown to be normally secreted. The xylanase gene products from the E. coli and B. cereus hosts were shown to function identically. Both xylanases improved the delignification of unbleached softwood and hardwood kraft pulps, thus reducing the Cl2 required to achieve a given degree of bleaching, without altering the physical properties of the fibers. Using a target kappa number (lignin content) of 5, xylanase pretreatment of aspen kraft (chemical) pulp led to a 22% savings of chlorine. Adsorbable organic halogens in the bleachery effluent were also lowered by more than 50%.Key words: Bacillus subtilis, endoxylanase gene, bleaching, kraft pulp properties.
The production of polyclonal antibodies against the mycotoxin derivative patulin hemiglutarate
Authors: McElroy L. J. , Weiss C. M.
Published: May 2010

The mycotoxin patulin is a toxic, carcinogenic, unsaturated lactone produced by a number of molds. Polyclonal antibodies against patulin hemiglutarate were produced. Specific antibodies against patulin alone, however, were not clearly demonstrated. Because of its low molecular weight, patulin required conjugation to bovine serum albumin (BSA) to increase its immunogenicity. Anti-patulin-hemiglutarate-BSA antibody titer and specificity were determined using indirect and indirect competitive ELISA, respectively. Immunoassays would facilitate detection and quantitation of patulin.Key words: patulin, mycotoxin, antibodies.
Abiotic conversion of dihydrophloroglucinol to resorcinol
Authors: Armstrong S. M. , Patel T. R.
Published: May 2010

Chemical conversion of a dihydrophloroglucinol preparation (a mixture of the tautomers 1,3,5-trihydroxy-1,3-cyclohexadiene, 1,3-dioxo-5-hydroxycyclohexane, and 3,5-dihydroxy-3-cyclohexene-1-one) to resorcinol occurred during a 24-h extraction of an acidic (pH 2.0) aqueous dihydrophloroglucinol preparation into ethyl acetate. This conversion did not occur at neutral pH, nor did phloroglucinol (1,3,5-trihydroxybenzene)-induced or succinate-induced Penicillium simplicissimum enzyme extracts convert the dihydrophloroglucinol preparation to resorcinol at pH values of 5.5–8.0. The chemical structure of the dihydrophloroglucinol preparation was determined by gas chromatography - mass spectrometry, high resolution 13C and 1H nuclear magnetic resonance, Fourier-transformed infrared spectrometry, and ultraviolet spectrophotometry. Resorcinol (1,2-dihydroxybenzene) was detected by gas chromatography - mass spectrometry or thin-layer chromatography and ultraviolet spectrophotometry. A chemical mechanism for the conversion of the dihydrophloroglucinol preparation to resorcinol is proposed.Key words: dihydrophloroglucinol, chemical conversion, resorcinol.
Effect of different environmental conditions on bacterial chemotaxis toward fungal spores
Authors: Arora Dilip K. , Gupta Sushma
Published: May 2010

The chemotactic response of four common soil bacteria, Agrobacterium radiobacter, Bacillus subtilis, Pseudomonas fluorescens, and Xanthomonas malvacearum, was observed in natural soil to conidia of Cochliobolus sativus, chlamydospores of Fusarium oxysporum f.sp. ciceri, sclerotia of Macrophomina phaseolina, and oospores of Phytophthora drechsleri f.sp. cajani. All bacteria migrated through soil toward fungal spores. Chemical analysis of fungal exudates demonstrated the presence of various amino acids and sugars that served as chemoattractants. The effect of temperature, pH, soil water matric potential, and soil texture on bacterial chemotaxis toward fungal spores was also investigated. In general, the response of bacteria to different types of fungal spores was significantly greater (P = 0.05) at higher water matric potential (0 and −5 kPa) than at lower soil water potential (−10 and −20 kPa). The chemotactic response was greatest in sandy soil, followed by sandy loam and clay loam soil. High temperature (40 °C) was not favourable for bacterial chemotaxis. The chemotactic response decreased by 4 to 28 times when soil pH decreased from 7 to 5 or increased from 7 to 9. The relative concentration response of the exudate of fungal spores and the motility or chemotaxis of bacteria were assessed. A significant positive correlation (P = 0.05; r = 0.89–0.92) was recorded between motility and relative concentrations of exudate. The swimming speed and tumbling frequency of Pseudomonas fluorescens cells was observed at different pH values and temperatures. The swimming speed of bacteria increased with increasing temperature, but decreased with an increase in pH from 5 to 7. The tumbling frequency had a sharp peak at 30 °C and pH 7. Bacteria were able to stimulate the release of exudate from the fungal spores. The amount of exudation was also affected by temperature, pH, and soil texture. A positive significant correlation (P = 0.05; r = 0.79–0.85) was recorded between exudation and a progressive increase in temperature. The amount of exudation also increased with an increase in soil pH from 5 to 8, but further increases in pH decreased the rate of exudation. In general, fungal spores exuded the greatest amounts of carbon compounds in sandy soil, followed by sandy loam and clay loam soil. Exudation in sandy soil was often greatest in the presence of A. radiobacter cells, while the greatest exudation in sandy loam and clay loam soils was induced by B. subtilis cells.Key words: chemotaxis, chemoattractants, fungal spores, motility.
Infection of Spodoptera frugiperda and Choristoneura fumiferana cell lines with the baculovirus Choristoneura fumiferana nuclear polyhedrosis virus
Authors: Liu J. Jian , Carstens Eric B.
Published: May 2010

The growth properties of cell lines derived from Spodoptera frugiperda (alfalfa looper) and Choristoneura fumiferana (spruce budworm) were investigated. The data demonstrated that the spruce bud worm cell line grew more slowly than the alfalfa looper cell line, and this reduced growth rate appeared to affect the rate of baculovirus replication in infected cells. Trypsinizing the spruce budworm cells or varying the multiplicity of infection did not greatly influence the rate of viral replication. Autographa californica nuclear polyhedrosis virus was able to replicate its DNA and synthesize late and very late proteins in both cell lines but did not produce infectious extracellular virus in the spruce budworm cell line. The replication cycle of C. fumiferana nuclear polyhedrosis virus did not produce late proteins or infectious extracellular virus in the alfalfa looper cells. The results indicate that S. frugiperda cells are nonpermissive for the C. fumiferana nuclear polyhedrosis virus but C. fumiferana cells are semipermissive for the A. californica nuclear polyhedrosis virus, resulting in an abortive infection.Key words: baculovirus, host specificity, AcMNPV, CfMNPV, spruce budworm.
Stimulation de la croissance du maïs et de la laitue romaine par des microorganismes dissolvant le phosphore inorganique
Authors: Chabot Rock , Antoun Hani , Cescas Michel P.
Published: May 2010

Phosphorus solubilizing microorganisms constituted 26 to 46% of the microbial population of the four Quebec soils studied. Among the microorganisms isolated 10 bacteria and 3 fungi were selected for their ability to form a large clarification zone on solid media containing different insoluble P salts. In a glasshouse assay, the inoculation of maize seeds with the 13 organisms selected did not significantly influence maize growth or P content, after 3 weeks of growth. In field trials, the Enterobacter sp. isolates 22a and 22c and the Pseudomonas sp. isolate 24 significantly increased (7–9%) plant height after 60 days of growth. After 108 days of growth, only isolate 22c caused a significant increase (23%) of shoots fresh mass. Field trials with Paris Island Cos lettuce seeds inoculated with the bacterial isolates 22a and 24 resulted in 14 and 18% increase in shoots fresh mass yields, respectively. Isolate 68 of Rhizopus sp. also increased lettuce yield by 11% over the control. The growth improvement observed in maize and lettuce probably did not result only from P solubilization activity but also, in part, from the ability of the four organisms inoculated to produce siderophores and auxins.Key words: microbial solubilization, phosphorus, corn, lettuce.
Analysis of ploidy and sexual characteristics of natural isolates of Cryptococcus neoformans
Authors: Takeo K. , Tanaka R. , Taguchi H. , Nishimura K.
Published: May 2010

We report here an extensive examination of the ploidy of a basidiomycetous yeast. The ploidy of 34 strains of Cryptococcus neoformans var. neoformans, isolated mostly from Japanese patients, was determined by means of quantitative fluorescence microscopy after DNA staining with propidium iodide. The sexual characteristics of the strains including the two tester strains were as follows. Twenty-four strains were of the heterothallic α type, 1 was of the heterothallic a type, and 2 were self fertile; the remaining 7 showed no sexual response. The following strains were found to be haploid: the heterothallic a strain, 20 of the 24 heterothallic α strains, and 3 of the 7 asexual strains. Thus, the C. neoformans strains were mostly haploid, as the sexual response of this organism suggests. Both of the self-fertile strains and four of the seven asexual strains were diploid. Unexpectedly, 4 of the 24 heterothallic α strains were diploid.Key words: ploidy, heterothallic diploid, Cryptococcus neoformans, basidiomycetous yeast, mating.
Catabolic activity on humic acids of Streptomyces viridosporus grown under oxygen
Authors: Kontchou C. Yanze , Béchet Max , Blondeau Roland
Published: May 2010

When Streptomyces viridosporus was grown in batch culture on mineral salts – glucose medium and under oxygen, aerial mycelium formation and sporulation were suppressed. Under these conditions, biodegradation of soil or synthetic humic acids (expressed as the rate of decolorization of growth medium and the loss of radioactivity of labeled melanoidin, respectively) increased. Concurrently, both the catabolic activity of cells (expressed as peroxidase production, measured by the oxidation of N,N,N′,N′-tetramethyl-1,4-phenylenediamine as substrate) and the excretion of siderophores were stimulated.Key words: humic acid biodegradation, melanoidin mineralization, Streptomyces viridosporus, peroxidase, siderophore.
Two-dimensional electrophoresis method used for determination of plasmid profiles of Escherichia coli isolated from a sewage treatment plant
Authors: Arturo M. , Tamanai-Shacoori Z. , Mamez C. , Pommepuy M. , Cormier M.
Published: May 2010

The plasmid contents of 306 strains of Escherichia coli isolated from raw and treated sewage from a treatment plant as well as from the water 1 km downstream were determined. The number and molecular weight of plasmids isolated from a representative sample of these strains were also measured. It was observed that biological treatment did not significantly alter these parameters. In contrast, statistically significant differences in plasmid number and size were observed when strains from sewage (raw and treated) were compared with strains isolated from brackish water. In raw and treated sewage, more than 96% of the strains contained plasmids, compared with 85% in brackish water. Nine to 13% of the strains from sewage contained plasmids with more than 56 kilobases, while only 5% of the strains from brackish water reached this size.Key words: Escherichia coli, plasmids, two-dimensional electrophoresis, sewage treatment, brackish water.
Long-term storage of bradyrhizobia in sterile water
Authors: Wagner Stephen C. , Skipper Horace D.
Published: May 2010

Preservation of strains of bradyrhizobia is an important aspect of legume research and development. Storage of strains of bradyrhizobia in sterile water is an inexpensive and simple method of preservation. This study was conducted to determine if bradyrhizobia strains remained viable after being stored in water for 66 months. Twenty-three bradyrhizobia strains were viable and pure after 66 months of storage in water. Nine Bradyrhizobium japonicum strains that were resistant to antibiotics remained viable and pure after 60 months of storage in water. However, three of the nine antibiotic-resistant strains lost antibiotic resistance after storage as assessed by failure to grow on yeast extract mannitol agar plates containing antibiotics. Maintenance in water should be limited to 48 months, at which time bradyrhizobia strains can be revived in media containing appropriate antibiotics and resuspended in water. These results demonstrated that bradyrhizobia strains can remain viable for at least 66 months of storage in water, but these bacteria may lose traits such as antibiotic resistance if stored too long in sterile water.Key words: bradyrhizobia, storage, water.
Source of soil protease in paddy fields
Authors: Watanabe Katsuji , Hayano Koichi
Published: May 2010

Properties of soil proteases and proteases from Bacillus spp. obtained from water-logged paddy fields treated with organic manure or chemical fertilizer or not treated with fertilizer were compared to elucidate the sources of soil proteases. The major extractable soil proteases were metal chelator sensitive neutral proteases that were active in hydrolyzing benzyloxycarbonyl-L-phenylalanyl-L-leucine and benzyloxycarbonyl-L-phenylalanyl-L-tyrosyl-L-leucine. In this respect they resembled extracellular proteases from Bacillus subtilis (six isolates), Bacillus cereus (four isolates), and Bacillus mycoides (three isolates) isolated from the same fields. The major extractable soil protease from the manured field was a serine neutral protease that was active in hydrolyzing casein. It resembled an extracellular protease from B. subtilis (eight isolates) isolated from the same field. Extractable soil proteases accounted for 18–96% of the total soil protease in the aforementioned soil. We concluded that a major source of soil protease in water-logged paddy fields is proteolytic Bacillus spp.Key words: soil protease, metal chelator sensitive neutral protease, serine neutral protease, proteolytic Bacillus spp.
Fate of the fish pathogen Aeromonas salmonicida in the peritoneal cavity of rainbow trout
Authors: Garduño Rafael A. , Thornton Julian C. , Kay William W.
Published: May 2010

A model was developed to study the fate of the fish pathogen Aeromonas salmonicida in vivo, inside a specialized intraperitoneal chamber implanted in rainbow trout, Oncorhynchus mykiss. Although normally recalcitrant to lytic agents in vitro, owing to the presence of its regular surface array (S layer), A. salmonicida was rapidly killed in the peritoneal cavity by a host-derived, soluble lytic activity present in peritoneal fluid. Peritoneal fluid was also found to kill other bacteria and lyse various types of erythrocytes, but was particularly lytic to A. salmonicida. Intraperitoneal survival of injected (free) A. salmonicida cells was several orders of magnitude higher than survival of implanted (restrained) cells. Injected free cells could evade the lytic activity of peritoneal fluid because they readily spread, initiating lethal infections. One evasion strategy was envisioned to be the penetration of peritoneal and (or) tissue macrophages. In spite of the killing mechanisms of these phagocytic cells, A. salmonicida was still able to survive and even replicate inside head kidney macrophages, thereby supporting the notion of A. salmonicida as a facultatively intracellular pathogen. Intraperitoneal chambers in rainbow trout may constitute a valuable experimental tool for studying the in vivo fate of A. salmonicida, and perhaps of other fish pathogens as well.Key words: Aeromonas salmonicida, intraperitoneal chambers, rainbow trout, complement-mediated cell lysis.
Use of the cytomegalovirus antigenemia (CMV-Ag) assay for the detection of CMV in the blood of AIDS patients
Authors: Lipson Steven M. , Kaplan Mark H. , Tseng Ling-Fang , Mandel Francine S.
Published: May 2010

Direct specimen testing was performed on 186 peripheral blood specimens to identify the presence of antigen to cytomegalovirus (viz., the cytomegalovirus antigenemia (CMV-Ag) assay). Confirmatory testing was performed using the shell vial indirect immunofluorescence assay (SVA-IFA), the indirect immunoperoxidase assay (TC-IPA), and conventional tube culture isolation (TC-CPE). The primary reagent for the CMV-Ag assay consisted of anti-CMV monoclonal antibody directed against the internal matrix structural phosphoprotein (1C3; Clonatec-Biosoft, France). The 72-kDa early nuclear antigen (Dupont) was utilized in the SVA-IFA and the TC-IPA. All test systems received an equal number of polymorphonuclear leukocytes in the inoculum. CMV was detected and isolated from 30% (55/186) of the specimens evaluated by either one or a combination of the tests. Detection and (or) isolation of CMV from blood by the CMV-Ag assay, SV-IFA, TC-IPA, and TC-CPE occurred at a rate of 17 (31/186), 12 (22/186), 16 (29/186), and 26% (49/186). Three of 55 positive specimens were identified only by the CMV-Ag assay; each patient in question, however, had at least one previous CMV isolate. No significant differences in sensitivity occurred between the CMV-Ag assay, the SVA-IFA, or the TC-IPA. However, TC-CPE including the blind passage of all negative tube cultures yielded a significantly larger number of positive blood specimens than either of the rapid detection methodologies. The CMV-Ag assay encompasses the benefits of a nonculture system, is simple to perform and easy to read, permits a same-day diagnosis, and requires less reagents than the routinely used SVA-IFA or TC-IPA. The CMV-Ag assay and TC-CPE including a blind passage are recommended assays for the rapid and then long-term identification, respectively, of CMV in the blood of AIDS patients.Key words: cytomegalovirus, antigenemia, blood, AIDS.
Pseudomonas aeruginosa UG2 rhamnolipid biosurfactants: structural characterization and their use in removing hydrophobic compounds from soil
Authors: Dyke M. I. Van , Couture P. , Brauer M. , Lee H. , Trevors J. T.
Published: May 2010

The structure of two rhamnolipid biosurfactants produced by Pseudomonas aeruginosa UG2 was studied. Analyses by gas chromatography - mass spectrometry and nuclear magnetic resonance spectroscopy showed these two rhamnolipids to be α-L-rhamnopyranosyl-β-hydroxydecanoyl-β-hydroxydecanoate and 2-O-α-L-rhamnopyranosyl-α-L-rhamnopyranosyl-β-hydroxydecanoyl-β-hydroxydecanoate. The ability of UG2 rhamnolipid biosurfactants to enhance removal of naphthalene, anthracene, phenanthrene, fluorene, 2,2′,5,5′-tetrachlorobiphenyl, and 3,3′,4,4′,5,5′-hexachlorobiphenyl into the aqueous phase was affected by soil type, hydrocarbon equilibration time, and biosurfactant adsorption to soil. Partially purified UG2 biosurfactants at a concentration of 5 g/L removed approximately 10% more hydrocarbon from a sandy loam soil than silt loam soil. High levels of UG2 rhamnolipids adsorbed to soil. In 18% (w/v) soil slurries 74, 49, 38, and 20% of 0.5, 1, 2, and 5 g UG2 rhamnolipids/L, respectively, were bound to the soil phase. Sodium dodecyl sulphate recovered lower levels and Witconol SN70 higher levels of phenanthrene and 2,2′,5,5′-tetrachlorobiphenyl than UG2 biosurfactants.Key words: biosurfactant, hydrocarbon, Pseudomonas aeruginosa, remediation.
Cloning of a recA-like gene from the diazotroph Herbaspirillum seropedicae strain Z78
Authors: Steffens M. B. R. , Rigo L. U. , Funayama S. , Souza E. M. , Machado H. B. , Pedrosa F. O.
Published: May 2010

A recombinant plasmid, pBMR5, carrying a recA-like gene of Herbaspirillum seropedicae, was isolated from a H. seropedicae genomic library by intergeneric complementation of Escherichia coli recA mutant strain HB101. Quantitative survival experiments showed that pBMR5 restored the ultraviolet radiation and methyl methanesulfonate resistances and recombinational proficiency of this strain. Hybridization studies showed that there is DNA sequence homology between the recA gene of E. coli K12 and that of H. seropedicae. Restriction sites for EcoRI, HindIII, BamHI, and BglII were found in the DNA insert derived from H. seropedicae in pBMR5. A Tn5 insertional mutant of pBMR5, called pBMR26.2, failed to restore recombination proficiency and methyl methanesulfonate and ultraviolet resistance to recA mutants of E. coli.Key words: Herbaspirillum seropedicae, nitrogen fixation, recA-like gene, Tn5 mutagenesis.
Quantitative extraction and determination of elemental sulfur and stoichiometric oxidation of sulfide to elemental sulfur by Thiobacillus thiooxidans
Authors: Chan C. W. , Suzuki Isamu
Published: May 2010

A sensitive and quantitative analytical method for determining elemental sulfur in a biological system was developed. Elemental sulfur was determined after extraction with petroleum ether by cyanolysis and ferric thiocyanate color formation in acetone. The method was successfully applied to show that sulfide was oxidized by Thiobacillus thiooxidans to elemental sulfur nearly stoichiometrically when further oxidation of elemental sulfur was inhibited by N-ethylmaleimide.Key words: elemental sulfur, quantitative analysis, sulfide oxidation, Thiobacillus thiooxidans.
The effect of chromic oxide (Cr2O3) on aerobic bacterial populations associated with the intestinal epithelial mucosa of Arctic charr, Salvelinus alpinus (L.)
Authors: Ringø Einar
Published: May 2010

Populations of aerobic heterotrophic bacteria present in the gastrointestinal tract of healthy Arctic charr, Salvelinus alpinus (L.), were estimated using the dilution plate technique. The gastrointestinal bacterial flora of fish fed an unsupplemented diet was dominated by Gram-negative bacteria of the genera Acinetobacter, Aeromonas, Agrobacterium, Alcaligenes, Cytophaga, Flavobacterium, Pseudomonas, and Vibrio, and Gram-positive bacteria of the genera Arthrobacter, Brevibacterium, Corynebacterium, Kurthia, Lactobacillus, Microbacterium, Micrococcus, Staphylococcus, and Streptococcus. The composition of the indigenous aerobic bacterial flora in the digestive tract, and especially the microorganisms isolated from the midgut and hindgut regions, was affected by inclusion of 1% chromic oxide (Cr2O3) in the diet. Many of the Gram-negative bacterial genera and some of the Gram-positive bacterial genera were not detectable in the Cr2O3-fed fish. The midgut and hindgut regions in the Cr2O3-fed fish were dominated by Gram-positive microorganisms of the genera Lactobacillus and Streptococcus. It is suggested that the increased accumulation of Cr2O3 in the alimentary tract, as dietary compounds are removed, affects the attachment sites for the gastrointestinal microflora or affects the gut epithelium directly.Key words: chromic oxide, aerobic bacterial flora, Arctic charr.
Myocardial expression of PDECGF is associated with extracellular matrix remodeling in experimental myocardial infarction in rats
Authors: Hemalatha Thiagarajan , Balachandran Chidambaram , Manohar Bhakthavatsalam Murali , Nayeem Mohammed , Subramaniam Samu , Sharma Hari S. , Puvanakrishnan Rengarajulu
Published: May 2010

Platelet-derived endothelial cell growth factor (PDECGF) is a potent angiogenic peptide with anti-apoptotic activity expressed widely in tumours. However, its expression in myocardial infarction (MI) is not yet established. This study aimed to assess the myocardial expression of PDECGF in rats after MI. Extracellular matrix (ECM) remodeling plays an important role in angiogenesis; hence, changes in the ECM components were investigated in the myocardium after MI, which was induced in rats by coronary artery ligation (CAL) and verified using biochemical markers and histopathology. Immunohistochemistry, RT-PCR, and activity assays identified the expression pattern of PDECGF on days 1, 2, 4, 8, 16, and 32 after CAL. The levels of TNF-α, MMP-2, collagen, and glycosaminoglycans in the ECM were assessed. Studies on immunohistochemistry, RT-PCR, and PDECGF activity demonstrated elevated levels of PDECGF expression from day 2 after CAL. Macrophages, endothelial cells, fibroblasts, and cardiomyocytes, especially at the border region of the lesion, showed an enhanced expression for PDECGF. Remodeling of the ECM was depicted by changes in the levels of TNF-α, MMP-2, collagen, and GAG. Hence, this study clearly indicated PDECGF as an important angiogenic molecule expressed during MI and the alterations in ECM components facilitated the process of angiogenesis.
Recombinant truncated and microsomal heme oxygenase-1 and -2: differential sensitivity to inhibitors
Authors: Vukomanovic Dragic , McLaughlin Brian , Rahman Mona N. , Vlahakis Jason Z. , Roman Gheorghe , Dercho Ryan A. , Kinobe Robert T. , Hum Maaike , Brien James F. , Jia Zongchao , Szarek Walter A. , Nakatsu Kanji
Published: May 2010

Recombinant truncated forms of heme oxygenase-1 and -2 (HO-1 and HO-2) were compared with their crude microsomal counterparts from brain and spleen tissue of adult male rats with respect to their inhibition by azole-based, nonporphyrin HO inhibitors. The drugs tested were an imidazole–alcohol, an imidazole–dioxolane, and a triazole–ketone. Both the recombinant and crude forms of HO-2 were similarly inhibited by the 3 drugs. The crude microsomal spleen form of HO-1 was more susceptible to inhibition than was the truncated recombinant form. This difference is attributed to the extra amino acids in the full-length enzyme. These observations may be relevant in the design of drugs as inhibitors of HO and other membrane proteins.
Acute treatment with polyphenol quercetin improves postischemic recovery of isolated perfused rat hearts after global ischemia
Authors: Barteková Monika , Čarnická Slávka , Pancza Dezider , Ondrejčáková Mária , Breier Albert , Ravingerová Táňa
Published: May 2010

Quercetin is a plant-derived bioflavonoid with potentially beneficial effects on the cardiovascular system. Studies focused on the efficiency of flavonoids against ischemia–reperfusion (I/R) injury have demonstrated that quercetin exerts robust protective effects in renal, cerebral, and hepatic I/R models. However, there is only limited evidence about the effect of quercetin on myocardial I/R injury. Therefore, the aim of the current study was to examine the effect of quercetin on isolated rat heart during ischemia and reperfusion. Rat hearts perfused according to Langendorff at 37 °C were examined during 25 min global ischemia followed by 120 min reperfusion. Quercetin (15 µmol/L) was administered either 15 min before ischemia (group Q1), or during the entire reperfusion period (group Q2). Changes in functional parameters of the hearts were measured during the initial 40 min of reperfusion. At the end of the experiment, the hearts were stained with tetrazolium to estimate the size of infarction (IS). Our study showed that quercetin improved postischemic recovery of functional parameters of isolated hearts in both treated groups. This improvement was manifested by significantly higher values of left ventricular developed pressure (LVDP) and the maximal rates of pressure development and fall (+(dP/dt)maxand –(dP/dt)max) and by significantly lower increase of end-diastolic pressure. Coronary flow was not significantly changed during reperfusion in the group treated before ischemia, but was significantly increased in the group treated during reperfusion. Quercetin also significantly reduced IS in both groups, more markedly in postischemically treated group. We conclude that acute quercetin treatment exerts significant positive effects on isolated hearts during I/R injury. These results are consistent with the beneficial effects of quercetin and other flavonoids on the cardiovascular system.
IMPLEMENTING MEMRISTOR BASED CHAOTIC CIRCUITS
Authors: MUTHUSWAMY BHARATHWAJ
Published: May 2010

This paper provides a practical implementation of a memristor based chaotic circuit. We realize a memristor using off-the-shelf components and then construct the memristor along with the associated chaotic circuit on a breadboard. The goal is to construct a physical chaotic circuit that employs the four fundamental circuit elements — the resistor, capacitor, inductor and the memristor. The central concept behind the memristor circuit is to use an analog integrator to obtain the electric flux across the memristor and then use the flux to obtain the memristor's characterstic function.
BIFURCATION OF LIMIT CYCLES BY PERTURBING PIECEWISE HAMILTONIAN SYSTEMS
Authors: LIU XIA , HAN MAOAN
Published: May 2010

In this paper, the general perturbation of piecewise Hamiltonian systems on the plane is considered. When the unperturbed system has a family of periodic orbits, similar to the perturbations of smooth system, an expression of the first order Melnikov function is derived, which can be used to study the number of limit cycles bifurcated from the periodic orbits. As applications, the number of bifurcated limit cycles of several concrete piecewise systems are presented.
LOWEST STABILITY BOUNDARY ON FLOW OF CONCENTRIC ROTATING CYLINDERS
Authors: LIN H. C. , YANG W. M.
Published: May 2010

In this study, we numerically investigate the lowest instability boundary of nonaxisymmetric Taylor vortex flow (TVF) for different axial wavenumbers. The variation in the axial wavenumber of a supercritical TVF can affect the instability of the flow, because the wavelength of a Taylor vortex is constant only when the flow is axisymmetrical. When the nonaxisymmetric TVF is transformed to a wavy vortex flow (WVF), the instability boundary is changed with the variation in the axial wavenumber. We carry out an instability analysis of the nonaxisymmetric TVF between two concentric rotating cylinders, which have a radius ratio of 0.88.
PERIODIC WAVE SOLUTIONS TO MODIFIED NONLINEAR SCHRÖDINGER EQUATION PERTAINING TO NEGATIVE INDEX MATERIALS
Authors: JOSEPH ANCEMMA , PORSEZIAN K.
Published: May 2010

In this paper, we intend to determine periodic wave solutions for the modified nonlinear Schrödinger equation pertaining to negative index materials. We have treated the propagation equation possessing higher order linear and nonlinear dispersion terms with Jacobian elliptic function expansion method and arrived at the Jacobian elliptic periodic wave solutions. When the module of the Jacobian elliptic function m → 1, these solutions degenerate to the solitary wave solutions of the governing system.
INCOHERENTLY COUPLED SCREENING-PHOTOVOLTAIC SPATIAL SOLITON PAIRS IN BIASED TWO-PHOTON PHOTOVOLTAIC PHOTOREFRACTIVE CRYSTALS
Authors: JI XUANMANG , JIANG QICHANG , LIU JINSONG
Published: May 2010

The incoherently coupled dark–dark, bright–bright, bright–dark screening-photovoltaic spatial soliton pairs are predicted in biased two-photon photovoltaic-photorefractive crystals under steady-state conditions. The result shows that these soliton pairs are established by the solitary beams which have the same polarization, wavelength, and are mutually incoherent. The screening-photovoltaic soliton pairs can be considered as the united form of screening soliton pairs and open or closed-circuit photovoltaic soliton pairs. They reduce to screening soliton pairs in the absence of photovoltaic effect, whereas they become photovoltaic soliton pairs under the open or closed-circuit conditions when the bias field is not applied. Moreover, the stability of these solitons has been investigated.
A COMPLETELY INTEGRABLE SYSTEM OF COUPLED MODIFIED KdV EQUATIONS
Authors: WAZWAZ ABDUL-MAJID
Published: May 2010

In this work, we study a system of coupled modified KdV (mKdV) equations. Multiple soliton solutions and multiple singular soliton solutions are derived by using the Hirota's bilinear method and the Hietarinta approach. The resonance phenomenon is examined.
NONLINEAR OPTICAL PROPERTIES OF mSTRAWBERRY AND mCHERRY FOR SECOND HARMONIC IMAGING
Authors: DE MEULENAERE EVELIEN , DE WERGIFOSSE MARC , BOTEK EDITH , SPAEPEN STIJN , CHAMPAGNE BENOÎT , VANDERLEYDEN JOS , CLAYS KOEN
Published: May 2010

The second-order nonlinear optical properties of two monomeric red fluorescent proteins, mStrawberry and mCherry, have been experimentally determined by frequency-resolved femtosecond hyper-Rayleigh scattering. These proteins were found to exhibit a stronger nonlinear response than the previously described eGFP, eYFP and DsRed,1 confirming the trend that fluorophores with a more extended conjugated system, or a lower-energy band gap between ground and excited state, exhibit a larger static hyperpolarizability (β0). Furthermore, these experimental data were complemented with quantum chemical calculations. A discrepancy was observed between experimental and theoretical results, but this could be explained by the chromophore model extracted from the available X-ray diffraction data. While eGFP showed a larger dynamic experimental response (βHRS) due to the highest resonance enhancement, we measured an even higher signal for mCherry. Furthermore, mCherry also shows a better separation of the second harmonic signal and two-photon excited fluorescent signal, making this the preferred fluorescent protein for second harmonic imaging at 800 nm so far.
DYNAMIC ORIENTATIONAL PHOTO-REFRACTIVE GRATINGS OBSERVED IN CdSe/CdS NANORODS DOPED NEMATIC LIQUID CRYSTAL CELLS
Authors: PETTI LUCIA , RIPPA MASSIMO , FIORE ANGELA , MANNA LIBERATO , MORMILE PASQUALE
Published: May 2010

We observed an orientational photo-refractive effect in semiconductor CdSe/CdS nanorods-doped nematic liquid crystal cells homeotropically aligned. In order to study the photo-refractive and the orientational responses of this cell, we employed both asymmetric two-beam coupling (TBC) to measure two beam coupling gain under the influence of an applied electric field and forced light scattering technique. An optical index grating was written in the device in a holographic tilted configuration by overlapping two laser beams at 514 nm. Self diffraction of the writing beams and diffraction of a probe beam at 633 nm were measured. A high TBC gain coefficient of 270 cm-1 was achieved at a DC field applied of 3.4 V/μm. First-order diffraction efficiencies were evaluated with a maximum efficiency of 7% in the dynamic grating with a nonlinear refractive index, n2, 4 × 10-2 cm2/W for E0 = 3 V /μ m .
OPTICAL CHARACTERIZATIONS OF A RAMAN GENERATOR BASED ON A HOLLOW CORE PHOTONIC CRYSTAL FIBER FILLED WITH A LIQUID
Authors: LEBRUN SYLVIE , BUY CHRISTELLE , DELAYE PHILIPPE , FREY ROBERT , PAULIAT GILLES , ROOSEN GÉRALD
Published: May 2010

We present a Raman generator based on a 35 cm long hollow core photonic crystal fiber entirely filled with ethanol emitting on a nearly-Gaussian beam. The power conversion efficiency from the pump at 532 nm to the first Stokes order of ethanol at 630 nm is 67%. Temporal profiles, mode patterns and power stability are also analyzed.
SUPPRESSION OF CHROMOPHORE AGGREGATION IN AMORPHOUS POLYMERIC MATERIALS: TOWARDS MORE EFFICIENT PHOTORESPONSIVE BEHAVIOR
Authors: PRIIMAGI ARRI , KAIVOLA MATTI , VIRKKI MATTI , RODRÍGUEZ FRANCISCO J. , KAURANEN MARTTI
Published: May 2010

We give an overview of our recent work on improving the optical performance of polymeric materials via supramolecular concepts, i.e., by making use of spontaneous non-covalent interactions between the chromophores and the polymer backbone. More precisely, we show that the aggregation of dipolar chromophores in amorphous polymeric materials can be controlled by simply choosing a proper polymer matrix. This approach has a potential impact in a wide range of optical phenomena where chromophore aggregation or phase separation sets a limit to the system performance.
AN INTEGRATED MODEL FOR PROCESS SELECTION AND QUALITY IMPROVEMENT IN MULTI-STAGE PROCESSES
Authors: MUSTAJIB M. IMRON , IRIANTO DRADJAD
Published: May 2010

All production processes produce variance around the desired target value of quality characteristic. This variance affects the product quality level. Accordingly variance reduction needs to be done as the main goal of quality improvement programs. However effort to improve quality of each product unit must take into account to improvement costs.

This paper proposes an optimization model for quality improvement in multi-stage processes using a non linear programming model by selecting alternatives process and determining unit of production of each stage to maximize profit as the difference between total income and total relevant cost. Total cost includes manufacturing cost, quality loss cost, rework and scrap cost, and quality improvement implementation cost. This optimization model is implemented in make-to-order manufacturer that produces crimper (a parts of joining plastic packages in packaging machine) which consist of five main stage manufacturing processes. Sensitivity analysis shows that the optimal solution is not sensitive if little changes occur in the constraints scenario. Thus, adding the value constraint on the quality specification, stage capacity, and quality improvement budget will not improve the objective function.
EXPERIMENTAL STUDIES ON THRUST FORCE AND TORQUE DURING DRILLING OF GLASS FIBER REINFORCED PLASTIC WITH SIC FILLERS
Authors: KUMAR M. SENTHIL
Published: May 2010

The paper discusses the study on thrust force and torque while drilling GFRP composites with SiC fillers. The input parameters such as cutting speed, feed rate and point angle were varied and influencing parameters such as thrust force and torque were studied. The experimental investigation was made during the drilling of GFRP with SiC fillers using four standard twist drills of point angles 90°, 100°, 110° and 120°.
Extremely High Peak Current Densities of over 1×106 A/cm2 in InP-Based InGaAs/AlAs Resonant Tunneling Diodes Grown by Metal–Organic Vapor-Phase Epitaxy
Authors: Sugiyama Hiroki , Yokoyama Haruki , Teranishi Atsushi , Suzuki Safumi , Asada Masahiro
Published: May 2010

InP-based InGaAs/AlAs resonant tunneling diodes (RTDs) with extremely high peak current density ( j
P) were grown by metal–organic vapor-phase epitaxy. High-temperature growth at 660 °C provides high-quality heterointerfaces and excellent current–voltage (I–V) characteristics. To obtain extremely high j
P, the structural parameter dependence of I–V characteristics on barrier and spacer thicknesses and emitter-doping concentration were examined. Clear exponential dependence of j
P on barrier thickness was obtained in the barrier-thickness range from 1.2 to 2.8 nm. The reduction of spacer thickness to 2 nm increased j
P without deteriorating the peak-to-valley current ratio (PVR). An investigation of Si dopant diffusion into double-barrier regions at the growth temperature supports the validity of reducing spacer thickness. The j
P increased as Si doping concentration was increased from 1×1018 to 6×1018 cm-3 in InGaAs emitters. The highest j
P reached 1.29×106 A/cm2 with a PVR of 1.5 in a RTD at room temperature with barrier and spacer thicknesses of 1.4 and 2 nm and Si doping concentration in the emitter of 6×1018 cm-3.
Vacancy-Boron Complexes in Plasma Immersion Ion-Implanted Si Probed by a Monoenergetic Positron Beam
Authors: Uedono Akira , Tsutsui Kazuo , Ishibashi Shoji , Watanabe Hiromichi , Kubota Shoji , Nakagawa Yasumasa , Mizuno Bunji , Hattori Takeo , Iwai Hiroshi
Published: May 2010

Vacancy-type defects in plasma immersion B-implanted Si were probed by a monoenergetic positron beam. Doppler broadening spectra of the annihilation radiation were measured and compared with spectra calculated using the projector augmented-wave method. For the as-doped sample, the vacancy-rich region was found to be localized at a depth of 0–10 nm, and the major defect species were determined to be divacancy–B complexes. After spike rapid thermal annealing at 1075 °C, the lineshape parameter S of Doppler broadening spectra corresponding to the high-B-concentration region (4–30 nm) was found to be smaller than the characteristic S value obtained for defect-free Si. From a detailed analysis of the Doppler broadening spectra, the origin of the decrease in the S value was attributed to the trapping of positrons by negatively charged B clusters such as icosahedral B12.