bluuebunny/crossref_metadata_2025 huggingface dataset:
Genome homology and divergence in the SPβ-related bacteriophages of Bacillus subtilis
Authors: Spancake Gregory A. , Daignault Steven D. , Hemphill H. Ernest
Published: May 2010

Chromosomal organization in related temperate Bacillus subtilis bacteriophages SPβ, [Formula: see text], ρ11, Z, and E was compared. DNA–DNA hybridization studies done in conjunction with available restriction fragment maps of SPβ, [Formula: see text], and ρ11 demonstrated that DNA homology between these three phages extended over most of their respective genomes, although each contained unique chromosomal segments. [Formula: see text], ρ11, Z, and E, but not SPβ, possessed apparently homologous structural genes (thyP) for thymidylate synthetase. DNA from all thyP-containing phages transformed thymine auxotrophs of B. subtilis SPβ lysogens to prototrophy. This transformation commonly involved incorporation of the thyP gene into SPβ prophage within a region corresponding to the middle of the viral chromosome. Chimeric plasmids containing the thyP gene from [Formula: see text] or cloned fragments of SPβ DNA were used in DNA–DNA hybridization studies to locate the thymidylate synthetase gene near the center of the [Formula: see text] chromosome, and to demonstrate that the organization of this region resembled the analogous portion of the SPβ genome. Profiles of virion structural proteins from the five phages were also very similar, further suggesting functional homology between these viruses. However, despite these evidences of relatedness, populations of fragments generated by digesting SPβ, [Formula: see text], ρ11, Z, and E DNA with restriction enzymes were quite dissimilar.
Electron microscopic study of the methylcellulose-mediated detachment of cellulolytic rumen bacteria from cellulose fibers
Authors: Kudo H. , Cheng K.-J. , Costerton J. W.
Published: May 2010

The presence of methylellulose prevents the attachment of cellulolytic rumen bacteria to cellulose fibers. The addition of methylcellulose to pure cultures of these organisms in which the cells are already adherent to cellulose causes their detachment from this insoluble substrate and the inhibition of their growth. Methylcellulose is not used as a carbon source by these organisms and has no effect on their growth when glucose and cellobiose are the carbon sources. Attached cells of Bacteroides succinogenes orient themselves in the plane of the individual cellulose fibers and their methylcellulose-induced detachment, which is complete (almost 100%), leaves grooves where the cellulose has been digested. Attached cells of Ruminococcus albus colonize the cellulose in a looser and less regular pattern and their almost complete methylcellulose-induced detachment leaves less regular pits in the cellulose surface. On the other hand, attached cells of Ruminococcus flavefaciens colonize the cellulose surface in a random orientation by means of a discernible exopolysaccharide network, and their less complete methylcellulose-induced detachment leaves no residual impressions on the cellulose surface. These data support the suggestion that bacterial attachment is necessary for the digestion of highly ordered crystalline cellulose, and that cellulolytic species differ in the nature of their attachment to this insoluble substrate and in the nature of their enzymatic attack. Methylcellulose is an effective agent for detaching major rumen cellulolytic bacteria from their cellulosic substrate.
Effects of glyphosate on Fusarium spp.: its influence on root colonization of weeds, propagule density in the soil, and crop emergence
Authors: Lévesque C. André , Rahe James E. , Eaves David M.
Published: May 2010

Glyphosate is a broad spectrum herbicide that can lead to root rot like damage on crops. This study was undertaken to investigate the effect of glyphosate on the root-colonizing Fusarium spp. The research was conducted at two sites. Site one was densely covered with perennial weeds, and site two with annuals. At site one, spraying the weed cover with glyphosate increased (p < 0.05) the level of colonization by Fusarium spp. in Ranunculus repens and Holcus lanatus, but not in Stellaria media and Plantago lanceolata. At site two, glyphosate enhanced colonization in Spergula arvensis, Stellaria media, Echinochloa crusgalli, and Chenopodium album, but not in Capsella bursa-pastoris and Polygonum persicaria. At both sites, the number of colony-forming units of Fusarium spp. per gram of dried soil was increased by the application of glyphosate. Nevertheless, crops subsequently sown in the field containing the annual weeds were not detrimentally affected by glyphosate treatment of these weeds.
Novel transformations of progesterone by a Mucor sp.
Authors: Madyastha K. Madhava , Srivatsan Jayanthi
Published: May 2010

A Mucor sp. isolated from soil and identified as Mucor piriformis was used to study the mode of transformation of progesterone. Major metabolites isolated and identified were 14α-hydroxyprogesterone, 7β, 14α-dihydroxyprogesterone, 7α, 14α-dihydroxyprogesterone, and 6β, 14α-dihydroxyprogesterone. Among the minor metabolities, 5β, 14α-dihydroxy-pregnane-3, 20-dione has been characterized. Time-course studies of the formation of transformation products showed that hydroxylation at the 14α-position is the first step in the formation of dihydroxyprogesterones. The formation of 7β, 14α-dihydroxyprogesterone and 5β, 14α-dihydroxypregnane-3, 20-dione represents novel transformations by Mucor species.
Polysaccharide-degrading enzymes formed by three species of anaerobic rumen fungi grown on a range of carbohydrate substrates
Authors: Williams Alan G. , Orpin Colin G.
Published: May 2010

The range of polysaccharide-degrading enzymes formed by three anaerobic rumen fungi (Neocallimastix patriciarum, Piromonas communis, and an unidentified isolate (F)) was monitored following growth on seven mono-, di-, and poly-saccharide carbohydrate substrates. Enzymes capable of degrading a variety of α- and β-glucans, β-galactans, galactomannan, and hemicellulosic arabinoxylans were present in all three isolates. Although reducing saccharides were released from pectin, polygalacturonic acid was not degraded by the preparations. Enzyme activity was present in both the zoospore and vegetative stages of the life cycle and was also detected extracellularly in culture supernatants after vegetative growth. The specific activities of the polysaccharidases were affected by the growth substrate, being lowest in preparations grown on mono- and di-saccharides, whereas polysaccharide growth substrates resulted in increased activity of the corresponding polysaccharidases. The enzymes were, however, formed after growth on all substrates. Oligomers and monosaccharides were produced as a result of polysaccharide breakdown by the unfractionated enzyme preparations. Studies on hemicellulose (arabinoxylan) breakdown by unfractionated vegetative preparations of the three isolates indicated that their modes of action, pH optima, substrate affinities, and response to potential inhibitors were similar.
Glycoside hydrolase enzymes present in the zoospore and vegetative growth stages of the rumen fungi Neocallimastix patriciarum, Piromonas communis, and an unidentified isolate, grown on a range of carbohydrates
Authors: Williams Alan G. , Orpin Colin G.
Published: May 2010

The rumen fungi Neocallimastix patriciarum, Piromonas communis, and a morphologically distinct but unidentified isolate were cultivated on the polysaccharides starch, cellulose, xylan, and their principal component monosaccharides and disaccharides, and the range and specific activities of the glycoside hdyrolases formed were monitored using gluco-oligo-saccharide and p-nitrophenyl glycoside substrates. A wide range of enzyme activities was detected in preparations from vegetative growth and zoospores of all three isolates. Enzyme activity was also present in the culture medium. The specific activities were affected by the carbohydrate source available in the growth medium, although the more active hydrolases involved in the degradation of plant structural and storage polysaccharides were formed on all seven carbohydrate sources evaluated. Enzyme activities were increased in the zoospore, vegetative, and extracellular preparations after growth on the appropriate structurally related disaccharide or polysaccharide. The hemicellulolytic glycosidases (α-L-arabinofuranosidase, β-D-xylosidase) were most active after growth on xylan, whereas α-/β-glucosidase activity was increased with the corresponding glucan as growth substrate. However, whereas wide-ranging β-glucosidase activity was detected following growth on maltose or starch, the α-glucosidase activities of P. communis were lower or undetectable in vegetative preparations grown on glucose or the β-glucans cellobiose and cellulose.
Cellular incorporation of poly-β-hydroxybutyrate into plasma membranes of Escherichia coli and Azotobacter vinelandii alters native membrane structure
Authors: Reusch R. , Hiske T. , Sadoff H. , Harris R. , Beveridge T.
Published: May 2010

Under growth-limiting conditions or conditions which mediate genetic transformation, Escherichia coli and Azotobacter vinelandii incorporate poly-β-hydroxybutyrate into their plasma membranes. Genetic transformation competence of both bacteria increased in proportion to the concentration of membrane poly-β-hydroxybutyrate. The effects of this lipid polymer on membrane structure were investigated by freeze-fracture electron microscopy. Before poly-β-hydroxybutyrate incorporation, freeze-fracture revealed a typical mosaic of particles and pits on both concave and convex surfaces of the plasma membrane. As the cells incorporated the lipid polymer into the membrane, transformability developed and small semiregular plaques which possessed shallow particles were seen. These plaques grew in size and frequency as the membrane poly-β-hydroxy-butyrate concentrations and transformability increased.
Actinomycètes parasites de champignons : étude des espèces, spécificité de l'action parasitaire au genre Fusarium et antagonisme dans le sol envers Fusarium oxysporum f.sp. albedinis (Killian et Maire) Gordon
Authors: Sabaou Nasserdine , Bounaga Nicole
Published: May 2010

A study of two actinomycetes which are parasitic on fungi confirmed that one strain belongs to Nocardiopsis dassonvillei and the other to Streptomyces alni. Although both belong to different genera, they are physiologically related. A study of their parasitic action on numerous species in different genera of fungi revealed a specific mode of action on the genus Fusarium. In an autoclaved palm-grove soil, both actinomycetes strongly reduced propagule populations of Fusarium oxysporum f. sp. albedinis, a pathogen of date palm. This action was less pronounced in the same nonautoclaved soil, where the antagonism of actinomycetes was extenuated by the presence of other soil microorganisms. However, both N. dassonvillei and particularly S. alni decrease the population of F. oxysporum f. sp. albedinis without affecting the number of spores from other soil fungi.
Effect of some soybean and bean phytoalexins and related isoflavonoids on growth of Candida albicans
Authors: Stössel Peter
Published: May 2010

The influence of a series of related isoflavonoids on growth of the zoopathogenic yeast, Candida albicans, in liquid media was studied. The order of effectiveness was identical with that previously found for a range of phytopathogenic fungi. Minimum inhibitory concentration of phaseollinisoflavan, the most active test compound, was 250 μM for 3 days after inoculation. However, C. albicans resumed growth thereafter. Phaseollinisoflavan, 500 μM, did not inhibit but only delayed growth of the yeast. Tolerance of C. albicans to phaseollin and phaseollinisoflavan was based on nondegradative mechanism(s), while tolerance to glyceollin appeared to be based on detoxification.
Effects of root colonizing bacteria on nodulation of soybean roots by Bradyrhizobium japonicum
Authors: Polonenko D. R. , Scher F. M. , Kloepper J. W. , Singleton C. A. , Laliberte M. , Zaleska I.
Published: May 2010

Eighteen strains of soybean root colonizing soil bacteria were tested for interference with nodulation of soybeans (Glycine max (L.) Merrill) grown in a field soil – perlite mix or in a soil-less planting medium. Seventeen of the strains were identified as Pseudomonas fluorescens or Pseudomonas putida and one as Aeromonas hydrophila. All strains colonized soybean roots at levels of log 3.9 to 5.7 cfu/g root. Although nine strains increased significantly the weights of nodules formed by Bradyrhizobium japonicum 110 on soybeans grown in the soil–perlite mix, numbers of nodules increased in only three treatments. Significant increases in nodule numbers were not observed when the soil bacteria were tested with B. japonicum 118, and only two treatments increased nodule weights when compared with the controls. One of the 18 treatments increased and 1 decreased significantly the dry weights of shoots of plants inoculated with B. japonicum 110 and grown in the soil-less mix. Only one treatment reduced the dry weights of roots. Several strains stimulated increases in the dry weights of shoots and roots of plants inoculated with B. japonicum 118, but these effects were not correlated with changes in nodule numbers or weights. The results suggest that root colonizing bacteria generally do not interfere with the ability of B. japonicum to form nodules in soybean roots and that certain strains may actually enhance nodulation and plant growth. The relevance of these results for the development of improved Bradyrhizobium inoculant products by the addition of selected plant growth promoting rhizobacteria is discussed.
Inhibition of methanogenesis in pure cultures by ammonia, fatty acids, and heavy metals, and protection against heavy metal toxicity by sewage sludge
Authors: Jarrell Ken F. , Saulnier Michelle , Ley Art
Published: May 2010

The effect of ammonium chloride, sodium butyrate, sodium propionate, and the heavy metals nickel, zinc, and copper on methanogenesis by pure cultures of Methanospirillum hungatei, Methanosarcina barkeri, Methanobacterium thermoautotrophicum, and Methanobacterium formicicum at pH 6.5 was studied. The latter three strains were resistant to > 60 g/L of the volatile fatty acids and to > 10 g/L of NH3 N. Methanospirillum hungatei was somewhat more sensitive with 50% inhibition of methanogenesis occurring at 4.2 g/L NH3 N, 27 g/L butyrate, and 41 g/L propionate. All strains were very sensitive to both copper (1–5 mg/L) and zinc (1–10 mg/L), but much more resistant to nickel. Zinc and copper concentrations 30 to 270 times higher were required to cause inhibition of Msp. hungatei incubated in sewage sludge compared with buffer, indicating a strong protective environment was afforded the methanogens against heavy metal toxicity in the sludge.
The recovery of high numbers of bdellovibrios from the surface water microlayer
Authors: Williams H. N.
Published: May 2010

Bdellovibrios lytic against the bacterium Vibrio parahaemolyticus have been recovered in the surface water microlayer. The organisms were recovered at numbers several 100-fold higher than the number recovered from subsurface waters, the aquatic area where most quantitative studies for bdellovibrios have been conducted. The number of total cultivable bacteria recovered in the surface water microlayer exceeded by several logs the number of cultivable bacteria recovered from subsurface waters. The results of this study reveal that bdellovibrios can be recovered in the aquatic environment at higher numbers than some previous studies have indicated. The high numbers of bdellovibrios and other bacteria recovered from the surface water microlayer makes this an attractive ecosystem in which to study the ecology of bdellovibrios in the aquatic environment.
Diauxic growth of the fission yeast Schizosaccharomyces pombe in mixtures of D-glucose and ethanol or acetate
Authors: Tsai C. Stan , Aveledo Antonio J. , McDonald Ian J. , Johnson Byron F.
Published: May 2010

The fission yeast Schizosaccharomyces pombe was unable to utilize ethanol or acetate as its sole carbon source for growth. However, ethanol and acetate were utilized in the presence of D-glucose during diauxic growth. No mutants capable of utilizing ethanol or acetate as sole carbon source were isolated from cultures grown in glucose together with ethanol or acetate. Low concentrations of acetate facilitated growth with glucose, whereas high concentrations of ethanol or acetate were inhibitory. Growing cells readily took up [1-14C]ethanol and [1-14C]acetate. The exogenous [1-14C]acetate was initially incorporated into biomacromolecules which were subsequently catabolized.
Effects of ethanol and acetate on glucose-limited chemostat cultures of Schizosaccharomyces pombe, a fission yeast
Authors: McDonald Ian J. , Walker Teena , Johnson Byron F. , Aveledo Antonio J. , Tsai C. Stan
Published: May 2010

Glucose-limited chemostat cultures of Schizosaccharomyces pombe were studied to assess metabolic changes induced by the presence of ethanol and acetate. Both ethanol and acetate were utilized by the chemostat cultures. Ethanol increased the maintenance rate of glucose assimilation. Acetate reduced the maintenance rate of glucose consumption and cell counts without significantly affecting the glucose requirements for growth and cell yield. Ethanol accumulation in the chemostat cultures was facilitated by high dilution rates and noninhibitory concentrations of acetate.
Metabolic changes in a conidia-induced Claviceps paspali strain during submerged fermentation
Authors: Gaberc-Porekar V. , Sočič H. , Pertot E. , Miličić S.
Published: May 2010

Chemical changes in the mycelium of the conidial Claviceps paspali mutant strain, isolated after γ irradiation, were followed during the course of submerged fermentation and compared with the mycelial parent strain; both strains are capable of producing simple lysergic acid derivatives. The syntheses of lipids, carbohydrates, phosphates, nucleic acids, proteins, and alkaloids, as well as nutrient uptake, were determined. It was found that conidiation induced by mutagenic treatment was accompanied by a set of changes in the metabolic pattern. In the conidial mutant, the primary and secondary metabolic activities were repressed and the protein to nonprotein compound ratio of the cells was changed in favour of protein compounds.
Antigenic variability of the outer membrane antigens of Legionella pneumophila serogroups 1 to 8
Authors: Boissinot Maurice , Ramsay Danielle , Barthe Christine , Joly Jean R.
Published: May 2010

The outer membrane proteins of Legionella pneumophila serogroups 1 to 8 were prepared from broken cells by selective solubilization using sodium lauryl sarcosinate. The isolated proteins were separated by sodium dodecyl sulfate – polyacrylamide gel electrophoresis and transferred to nitrocellulose sheets. Rabbit antisera against each of the eight serogroups of L. pneumophila were obtained by immunizing each animal with live bacteria. The transferred proteins were revealed using these antisera and peroxidase-labeled swine anti-rabbit immunoglobulins. Antigenic determinants common to all eight serogroups were found in at least three outer membrane antigens (19, 29, and 45 kilodaltons (kDa)). However, cross-absorption experiments revealed that these three antigens were immunologically related, but not identical among serogroups. The antigenic relationships observed with two of these three antigens correlated well with cross-reactions observed in immunofluorescence. When a monoclonal antibody directed against L. pneumophila serogroup 1 lipopolysaccharide was used to reveal a blot of serogroup 1 outer membrane antigens, the 29- and 45-kDa bands appeared. This demonstrates a strong association between lipopolysaccharide and outer membrane proteins.
Isolation of various hyperactive mutants of phenylalanine ammonia-lyase containing yeasts
Authors: Evans Christopher T. , Payne Cheryl , Conrad Dayle , Hanna Kim , Misawa Masanaru
Published: May 2010

Various strains of phenylalanine ammonia-lyase (PAL) containing yeasts were mutagenised using ultraviolet (UV) irradiation. Two of the yeast, SPA 1 and SPA 17, produced UV kill curves with a distinct shoulder reflecting their diploid nature. Of the analogues used, p-fluoro-D,L-phenylalanine and β-2-thienyl-D,L-alanine selected the greatest frequency of mutants with the highest PAL activities: one such mutant, FP10M6, exhibited five times the PAL activity of the parent SPA 10. Mutants constitutive for PAL synthesis could not be isolated using any selection regime, including resistance to relatively high concentrations of 2-deoxyglucose. Three of the hyperactive PAL mutants examined were not impaired for growth and their PAL-induction profiles were not different from the respective parents. Inactivation of PAL shortly after peak synthesis was found with all mutants examined, although this was not extensively investigated. Of the 21 strains mutagenised, mutants from three of the wild-type yeasts were found to exhibit moderate growth at 37 °C, while growth of the parent strains was greatly impaired. The latter temperature-resistant mutants exhibited a twofold increase in PAL activity as compared with the parent strains at either 30 or 37 °C. Under biotransformation reaction conditions, several of the mutants were capable of producing more than 15 g L-phenylalanine∙L−1. Although the stability of the PAL catalyst varied markedly among different mutants, some of the most productive mutants did exhibit good reuseability under sequentially repeated batch reaction conditions.
α-Santonin 1,2-reductase and its role in the formation of dihydrosantonin and lumisantonin by Pseudomonas cichorii S
Authors: Naik Ulhas , Mavuinkurve Suneela
Published: May 2010

1,2-Dihydrosantonin is the first stable product in the degradative pathway of α-santonin by Pseudomonas cichorii S. Its formation is catalyzed by an oxidoreductase, which is NADH or NADPH dependent and has an apparent Km value of 66.66 μM for santonin and 44.33 μM for NADH. The enzyme activity is stable at pH 6.0, 7.0, and 8.0, and is not affected by EDTA and divalent metal ions. It is postulated that the enzymic reduction of santonin occurs via formation of a transient zwitterionic intermediate, which undergoes nonenzymatic 1,4-sigmatropic rearrangement to yield lumisantonin during the solvent extraction process. Lumisantonin is, thus, not a true metabolic intermediate but an artifact.
Modulating action of cyclic AMP on the expression of two SOS genes in Escherichia coli K-12
Authors: Barbé Jordi , Gibert Isidre , Guerrero Ricardo
Published: May 2010

Ultraviolet irradiation and cyclic AMP treatment produce a synergistic effect on the induction of the clel gene (coding for bacteriocin ColE1) in wild-type strains of Escherichia coli. On the other hand, cyclic AMP does not affect the uv-mediated induction of the recA, sfiA, and umuDC genes. Growth in the presence of glucose or glycerol does not affect the factor of amplification of the expression of the clel gene in uv-irradiated cells of the wild-type strain. Although, in cultures not treated with uv, the basal level of clel induction is about twice as high in cells grown with glycerol as in those using glucose as carbon source. In recA mutants neither simultaneous nor separate treatments with either cyclic AMP or uv irradiation induced transcription of the clel gene. Moreover, cyclic AMP induced a slight increase in clel gene expression in uv-irradiated cya strains, but not in the crp mutants. Nevertheless, the pattern of the uv-mediated induction of other SOS genes, such as umuDC, was the same in the cya and crp mutants, as in their parental wild-type strains. Furthermore, the uv-mediated induction of lambda prophage was decreased after either addition of cyclic AMP or growth in cultural conditions where the level of this nucleotide was low.
Septation and filament splitting in Methanospirillum hungatei
Authors: Beveridge Terry J. , Harris Bob J. , Sprott G. Dennis
Published: May 2010

Methanospirillum hungatei GP1 consists of chains of rod-shaped cells separated from one another by "cell spacers" comprised of two spacer plugs sandwiching a loose, amorphous material. The chain is encased within a highly ordered sheath to form a cylindrical, multicelled filament about 5 to 10 cells long under our growth conditions. Cells within the filament divide by septation in a manner similar to gram-positive eubacteria; the plasma membrane and wall grow inward to partition the cell in two. Yet, unlike gram-positive eubacteria, the wall is flexible, since cells round up when extruded from the sheath; the shape-maintaining structures are the sheath and spacer plugs. After septation and daughter cell separation, the cell spacer grows between the new cells. Initially, the growth of a spacer plug is detected by electron microscopy as the addition of electron-dense layers, exhibiting an 18.0-nm periodicity, at the surface of one new cell pole. Usually three layers develop at this pole before plug assembly is initiated at the opposite pole. As assembly proceeds, the two newly formed plugs separate from each other to form the loose, amorphous central zone of the spacer. Presumably, cell and cell spacer elongation requires sheath extension, since filament growth is observed. The amorphous cell spacer zone continues to expand as the spacer grows larger until lesions appear in the sheath near the zone's midpoint. Usually, the largest spacer zones are found towards each filament's centre and the lesions split the chain in two. Consequently, M. hungatei requires two separate events for filament division: cell replication which is a septation process and filament splitting which is a "cell spacer" breakage.
Protection against Pseudomonas aeruginosa infection by passive transfer of anti-flagellar serum
Authors: Drake David , Montie Thomas C.
Published: May 2010

The specificity of adsorbed flagellar antisera for H-antigen was demonstrated in vitro by cross-agglutination assays, motility inhibition, and an ELISA. The specific flagellar antibody was determined to be an IgG. Complete protection against burn wound sepsis was achieved with flagellar antisera. Cross-protection experiments revealed that protection was not only H-antigen dependent, but specific for the flagella antigen type. Antiserum raised against b-type flagella would only protect against homologous bacterial challenge and not against a-type flagellated strains. Results using a-type antisera were consistent, giving protection only against the homologous strain. In contrast, protective capacity was selectively removed from antisera by adsorbing with Fla+ cells. Bacteria colonized the burn wounds of passively protected mice to similar levels as seen in nonprotected animals, but the colonization remained localized and did not result in systemic infection, a pattern similar to infections with motility mutants observed in other studies. Animals rendered neutropenic prior to burning were not protected with flagellar antisera. These data suggested a role for phagocytic cells in protection. Immobilization by flagellar antiserum was observed both by microscopic studies and by inhibition of colony spreading. Antiflagellar antibody is hypothesized as exerting its protective capacity possibly in two ways; first by inhibiting the motility of invading bacteria by binding to the flagellum and immobilizing the bacteria, and secondly by acting as an opsonin, targeting either immobilized or mobile cells for phagocytosis.
The use of T1 oligonucleotide mapping to determine that the emergence of Canadian 1973-like and 1974-like H3N2 strains in 1984 was the result of laboratory contamination
Authors: Brown E. G.
Published: May 2010

Influenza undergoes extensive antigenic variation in nature. These new antigenic variants invariably supplant the preceding antigenic type that then disappears. In apparent contrast to this, two H3N2 strains that were forwarded to the Laboratory Centre for Disease Control, Ottawa, in 1984 from a Canadian public health laboratory for reference analysis were shown to be most closely related to 1973 and 1974 strains. Laboratory contamination on isolation by the regional public health laboratory was the most likely explanation for the occurrence of these strains, since one of the isolates (RV/76/84) was identical by T1 mapping to an A/Eng-like isolate being grown in the laboratory of isolation. The two isolates, RV/74/84 and RV/76/84, were shown to be distinct from each other and from prototype H3N2 strains by RNase T1 oligonucleotide mapping, SDS–PAGE, peptide mapping of hemagglutinin, and hemagglutination inhibition assay. RV/74 and RV/76 appeared to have been genetically stable for the 10 to 11 years preceding 1984; this is consistent with laboratory frozen storage for this period of time. This paper demonstrates the utility of RNase T1 mapping for the characterization of novel or spurious influenza isolates.
Effect of a pesticide pentachlorophenol on soil microflora. III. Growth rates as an index of pesticide resistance of bacterial groups isolated from soil
Authors: Sato Kyo
Published: May 2010

Pentachlorophenol resistance was investigated in bacteria isolated from glycine- or water-percolated soils where the bacterial flora was modified by the addition of pentachloropenol. The strains isolated from the water-percolated soil amended with PCP had the highest resistance, and the addition of glycine to the percolated soil weakened the resistance. The strains from the glycine-percolated soil without pentachlorophenol had a medium degree of resistance, and the resistance of the strains from the water-percolated soil without PCP was the lowest. The bacterial groups were sorted taxonomically; differences in pentachloropenol resistance were correlated with taxonomic groupings. Relative growth rate in the presence of pentachlorophenol was proposed as a useful means to distinguish among the bacterial species.
Actinopolyspora halophila does not contain mycolic acids
Authors: Kates M. , Porter Suzanne , Kushner D. J.
Published: May 2010

Studies using the techniques of thin-layer chromatography, mass spectrometry, gas–liquid chromatography, and pyrolysis gas chromatography have shown conclusively that the extreme halophilic actinomycete Actinopolyspora halophila does not contain any detectable mycolic acids. This finding is consistent with the grouping of A. halophila with other wall chemotype IV actinomycetes.
Environmental pH as a factor in the competition between strains of the oral streptococci Streptococcus mutans, S. sanguis, and "S. mitior" growing in continuous culture
Authors: Bowden G. H. , Hamilton I. R.
Published: May 2010

Strains of Streptococcus mutans (biotype 1), Streptococcus sanguis, and Streptococcus mitior have been grown in mixed continuous culture in a semidefined medium under glucose limitation at a growth rate of D = 0.1 h−1. The effect of varying the environmental pH on the proportions of the different populations within the community has been determined. Initially the populations were allowed to reach steady state at pH 7.0 when S. sanguis was dominant with S. mutans and "S. mitior" maintaining similar populations. The medium pH was then lowered in steps of 0.5 pH units from pH 7.0 to 4.5, and the community was grown at each step for at least 15 generations. Viable counts of each species were made at 24-h intervals. The population ratios established at pH 7.0 remained relatively stable when the environmental pH was set at pH 6.5. However, after the medium pH was lowered to 6.0 (days 18–27), the population of S. mutans began to increase and the S. mitior population began to decline. A further change was seen at pH 5.5 (days 27–34) when S. mutans became dominant, S. sanguis declined, and S. mitior was not detectable. At pH 4.5, both S. mutans and S. sanguis were reduced in numbers, but survived until the experimental run was terminated (44 days). Samples of culture fluid were taken throughout the experiment and analyzed for the presence of the acid products of glucose metabolism. The amounts of lactic acid produced by the community increased as the environmental pH was lowered. The results show that there was variation in the ability of Streptococcus species to compete in acidic environments. Streptococcus mutans is most favoured by an environment below pH 6.0, while "S. mitior" is relatively sensitive to low pH, therefore a low environmental pH can be selective for S. mutans. Comparison of these results to two similar studies carried out recently suggests that there is variation in the ability of given strains of S. sanguis and "S. mitior" to compete with S. mutans in acid environments. Therefore, it is not valid to take data from studies of a single strain and interpret it as applicable to the species as they are presently defined.
The nucleotide sequence of herpes simplex virus type 2 (333) glycoprotein gB2 and analysis of predicted antigenic sites
Authors: Zwaagstra John C. , Leung Wai-Choi
Published: May 2010

The gene coding for glycoprotein B2 (gB2) of herpes simplex virus type 2 (HSV-2) strain 333 was mapped and its nucleotide sequence determined. Open reading frame analysis deduced a polypeptide consisting of 902 amino acids and having close homology to gB1 of HSV type 1. Several predicted features of gB2 are consistent with a membrane-bound glycoprotein, i.e., a signal peptide sequence, a hydrophilic extracellular domain containing possible N-linked glycosylation sites, a hydrophobic membrane spanning sequence, and a cytoplasmic domain. Computer analysis on hydrophilicity, accessibility, and flexibility of the gB2 amino acid sequence, produced a composite surface value plot. At least nine major antigenic regions were predicted on the extracellular domain. The amino acids between residues 59–74, 127–139, 199–205, 460–476, and 580–594 exhibited the highest surface values. Comparison of the primary sequence with gB1 revealed localized regions showing amino acid diversity. Several of these locations correspond to major antigenic regions. Chou and Fasman analyses indicated that the amino acid substitutions, between positions 57–66, 461–472, and 473–481, induced changes in the secondary structure of gB. These sites could represent site-specific epitopes in the gB polypeptide.
Properties of the particulate enzyme F420-reducing hydrogenase isolated from Methanospirillum hungatei
Authors: Sprott G. Dennis , Shaw Kathleen M. , Beveridge Terry J.
Published: May 2010

F420-reducing hydrogenase was isolated from spheroplast lysates of Methanospirillum hungatei by sedimentation, followed by sucrose gradient centrifugations and gel filtration. These procedures resulted in a preparation free of methyl reductase and cytoplasmic membranes. The hydrogenase was a brown protein with an absorption spectrum characteristic for a nonheme iron protein. In electron micrographs it was a coin-shaped, multisubunit protein complex of 15.9 nm diameter with a central depression on one surface. On phenyl Sepharose chromatography the hydrogenase exhibited hydrophobic properties. The holoenzyme was about 720 kilodaltons (kDa), composed of 50.7 and 30.7 kDa subunits in a ratio of 1:3. Each enzyme particle contained 6 or 7 Ni2+ atoms. H2-dependent reduction of F420 activity was readily, but transiently, reactivated by anaerobic conditions following exposure of the enzyme to air. Mg2+ or Ca2+ were stimulatory, but added FAD was not required. Antibody raised against the purified hydrogenase of strain GP1 gave a negative reaction with extracts of nine other methanogens and a reaction of identity with strain JF1 and Methanosarcina barkeri MS. Direct comparisons with the hyrogenase from Methanobacterium thermoautotrophicum ΔH revealed striking differences in subunit composition and in the acidity of the holoenzyme.
Frequency of Escherichia coli 0157:H7 isolation from stool specimens
Authors: Cahoon Frederic E. , Thompson J. Stephen
Published: May 2010

During a 6-month period, 7252 faeces specimens were examined for Escherichia coli serotype0157:H7. Forty-nine specimens (0.7%) from 19 patients yielded this organism. Escherichia coli 0157:H7 was the third most frequently isolated bacterial pathogen, following Campylobacter jejuni and (or) Salmonella sp. Although regional variation between laboratories determined whether Campylobacter jejuni or Salmonella was the primary bacterial pathogen isolated, E. coli 0157:H7 was consistently isolated more frequently than either Shigella or Yersinia enterocolitica.
Effect of oxygen on continuous cultures of Azospirillum spp. and diazotrophic rods closely associated with Kallar grass
Authors: Hurek Thomas , Reinhold Barbara , Niemann Ernst-Georg
Published: May 2010

The effect of oxygen on [Formula: see text] growth of two Azospirillum strains and two diazotrophic rods closely associated with roots of Kallar grass (Leptochloa fusca) and one Azospirillum brasilense soil isolate as reference was studied. To enable precise comparison, bacteria were grown in dissolved oxygen controlled continuous cultures at a constant dilution rate. Similar O2 responses for all strains were found. Steady states were achieved from about 1 to 190 μM dissolved O2, all of them carbon limited. The response of all steady-state cultures to increasing O2 concentrations suggested that neither oxygen limitation nor oxygen toxicity occurred within the range of O2 concentrations applied. Growth of the plant-associated diazotrophs on combined nitrogen did not explain the colonization pattern of the different root zones of Kallar grass.
Degradation of lignocellulosics by unique tunnel-forming bacteria
Authors: Daniel Geoffrey F. , Nilsson T. , Singh A. P.
Published: May 2010

Transmission electron microscopic observations on a wide range of decaying wood samples obtained from both field situations and laboratory exposure tests have confirmed bacteria to have a capacity to degrade intact highly lignified substrates including preservative-treated and naturally durable woody tissues. Studies have shown a number of bacterial forms to be involved and have provided morphological evidence for in situ lignin degradation confirming 14C-labelled experiments with synthetic and natural lignins. A unique type of bacterial attack (tunnelling) characterized by the development of tunnels containing peculiar cross-tunnel wall secretions has been recognized. Cytochemical studies have shown the extracellular tunnel secretions to contain negatively charged constituents, while transmission electron microscopic energy-dispersive X-ray spectroscopy has shown these tunnels to bind heavy metals during decay of timbers treated with metal-containing preservatives. The tunnelling bacteria are motile nonflagellated Gram-negative rods. These bacteria have highly plastic cell envelopes which can produce vesicles. Our studies provide evidence that tunnelling bacteria can remove total cell wall material, including lignin, and show a relationship between their motility and the unique tunnels they produce.
Micromolar sulfide concentrations alleviate acetylene blockage of nitrous oxide reduction by denitrifying Pseudomonas fluorescens
Authors: Sørensen Jan , Rasmussen Lone K. , Koike Isao
Published: May 2010

The influence of low sulfide concentrations on nitrous oxide (N2O) reduction by resting cells of denitrifying Pseudomonas fluorescens was studied. Nitrous oxide reduction was inhibited by sulfide with an apparent Ki value of 1 μM. The inhibition was immediate and was readily alleviated by a short treatment of the cells with O2. In the absence of sulfide, addition of acetylene (0.2 kPa C2H2 or more) caused an immediate and complete inhibition of N2O reduction. However, when the sulfide concentration was higher than 2 μM, addition of C2H2 (range of 0.7–13 kPa tested) gave incomplete inhibition of the N2O reduction. Complete inhibition was in this case only obtained after prolonged exposure to the C2H2. The transition period with incomplete C2H2 blockage was shortest (about 20 min) for relatively high C2H2 applications (about 10 kPa). Incomplete C2H2 blockage was seen only when sulfide was added to the cell suspensions before C2H2. The data may relate to the low efficacy of the "acetylene blockage technique" when the assay is applied to [Formula: see text]-deficient and reducing environments.
Metabolism of hexoses and pentoses by Cellulomonas uda under aerobic conditions and during fermentation
Authors: Marschoun S. , Rapp P. , Wagner F.
Published: May 2010

Cellulomonas uda utilized the constituent carbohydrates of cellulose and hemicellulose under aerobic conditions and during fermentation. Balances of fermentation of cellobiose, glucose, xylose, L-arabinose, mannose, galactose, fructose, and sucrose were determined. Products formed were ethanol, L-lactic acid, acetic acid, formic acid, and succinic acid. In contrast to acetic acid, a small amount of succinic acid was utilized under aerobic conditions but only together with glucose. Ethanol was not consumed either under aerobic conditions or during fermentation. The rate of both glucose uptake and lactic acid excretion during fermentation increased with increasing initial pH values of 7 to 9. The intracellular concentration of ethanol at the end of glucose fermentation was 20 times higher than that in the culture supernatant. Switching from aerobic to fermentation conditions increased specific activities of fructose-6-phosphate kinase and fructose-1,6-bisphosphate aldolase, both key enzymes of the fructose-1,6-bisphosphate pathway, whereas those of glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase, key enzymes of the pentose phosphate cycle, were not affected significantly. Of the enzymes involved in pyruvic acid metabolism, pyruvate formate lyase, L-lactate dehydrogenase, and alcohol dehydrogenase were demonstrated in cell-free extracts. Fructose-1,6-bisphosphate had an activating effect on L-lactate dehydrogenase. Alcohol dehydrogenase was inhibited competitively by high concentrations of ethanol and noncompetitively by NAD.
Strain-dependent inhibition of nitrous oxide reduction in denitrifiers by yeast extract
Authors: Chan Yiu-Kwok , Marshall Peter R.
Published: May 2010

Pseudomonas sp. type strain H8 (ATCC 35402) was shown to be capable of denitrification but unable to reduce N2O in a complex medium containing 0.15% yeast extract. When added to a defined medium, autoclaved or filter-sterilized yeast extract from various suppliers was confirmed to inhibit N2O reduction by H8. The inhibition increased to 90% when the yeast extract concentration was increased to 0.5% in the medium. Only one of seven other denitrifying pseudomonads tested was similarly inhibited. Fractionation of yeast extract on a Sephadex G-10 column showed that the component responsible was a small molecule (molecular weight <700) that eluted with the first uv absorption peak. The inhibition was reversible by the addition of 10 μM Cu2+. Reduced glutathione was assayed in the first fraction of the Sephadex eluate and was found to mimic the effect of yeast extract. It is proposed that yeast extract inhibits N2O reduction by certain denitrifiers through glutathione complexing of Cu2+ which is a cofactor of N2O reductase.
Fermentation of wheat straw xylan by the white-rot fungus Dichomitus squalens
Authors: Agosin Eduardo , Rouau Xavier , Brillouet Jean Marc
Published: May 2010

The pattern of degradation of purified wheat straw xylan by submerged cultures of the ligninolytic white-rot fungus Dichomitus squalens has been determined. After a 22-h lag period, extracellular xylanase and protease activities developed during the first phase of secretion, the exponential growth phase. A rapid drop in the degree of polymerization of the soluble xylan was observed, corresponding to the release of xylobiose, followed by the release of xylotriose and xylose. After 70 h cultivation, soluble sugars were almost exhausted; laminarinase activities were secreted, followed by endoxylanases, β-xylosidases, CM-cellulases, and an α-L-arabinofuranosidase. All the endoxylanases exhibited β-xylosidase activity. No α-D-glucuronidase could be determined. Accumulation of an undegradable soluble polymer, highly substituted by glucuronic acid residues, was observed. Since no free arabinose or free glucuronic acid could be detected in the culture medium, it is suggested that a progressive increase of unsubstituted xylose units arises from preferential attack on the more highly substituted regions of the xylan backbone by endoxylanases.
Investigation of a Providencia rettgeri strain that has enterobacterial common antigen in the immunogenic state
Authors: Quigley Robert C. , Penner John L.
Published: May 2010

Antigenic material obtained by phenol–water extraction from Providencia rettgeri strains, Escherichia coli O:14 strains, and mutants of the E. coli O:14 strain were examined by the passive (indirect) hemagglutination technique, by sodium dodecyl sulphate – polyacrylamide gel electrophoresis, and by immune blotting (lipopolysaccharide (LPS) blotting). Providencia rettgeri 965, like E. coli O;14, was demonstrated to have an enterobacterial common antigen (ECA) in the immunogenic form but, unlike E. coli O:14, it possessed characteristics of a smooth strain. Two populations of molecules were observed to occur in P. rettgeri 965 phenol–water extracts: one consisting of LPS identifiable with specific O antisera and the other of ECA molecules identifiable with E. coli O:14 antiserum or with a monoclonal antibody against ECA.
Determining vesicular–arbuscular mycorrhizal effectiveness by monitoring P status of leaf disks
Authors: Aziz Taufiqul , Habte Mitiku
Published: May 2010

A greenhouse experiment was conducted to monitor the development of symbiotic interaction between the vesicular–arbuscular mycorrhizal (VAM) fungus Glomus aggregatum and Vigna unguiculata grown in a typical Oxisol before and after the soil was subjected to simulated erosion and at various levels of phosphorus in the soil solution. VAM development monitored in terms of P status of cowpea leaf disks revealed that VAM activity was not detected in the eroded soil unless the soil was amended with P. When P was not limiting, VAM activity (effectiveness) was detected as early as 17 days from planting, the activity peaking 5–10 days thereafter. Peak VAM activity was observed at a soil solution P level of 0.026 μg/mL and the peak values were similar in the eroded and uneroded soil samples. Maximum mycorrhizal inoculation effect was also observed at this level of soil solution P. Our results illustrate the usefulness of the leaf-disk technique for monitoring the development of the VAM symbiosis and the significance of soil solution P in regulating host response to VAM inoculation.
Bacterial flora in bottled uncarbonated mineral drinking water
Authors: González Carmen , Gutiérrez Carmen , Grande Teresa
Published: May 2010

A quantitative study of bacterial populations in mineral water was carried out. Samples were stored at 6 and 20 °C, and the colony counts were determined on tryptone agar plates incubated at 22 and 37 °C. Samples were collected from the spring source in sterile glass flasks and from the bottling factory in conventional plastic and glass containers. In both cases, the initial population (101–102 cfu/mL water) increased to 105–106 cfu/mL after 3 days storage as determined from plate counts incubated at 22 °C. The levels reached by this population were similar to those of samples of mineral water obtained at the market stage. Results from plate counts incubated at 37 °C showed that populations in samples collected at the bottling factory reached 102–103 cfu/mL. No growth was observed in water collected from spring source. Bacterial multiplication was not stopped even when water was stored at 6 °C. Caulobacter was the genus found most frequently in both types of samples, followed by Sphaerotilus-Leptothrix. Acinetobacter calcoaceticus and Pseudomonas fluorescens were frequently found in only two springs, and Pseudomonas putida, Arthrobacter, Aeromonas hydrophila, and Corynebacterium were isolated less frequently. Janthinobacterium was recovered only once from a single spring. A giant bacterium closely resembling Hyphomicrobium and a budding one similar to Pasteuria were recovered from all samples of a single spring and from some of the commercial samples.