bluuebunny/crossref_metadata_2025 huggingface dataset:
Discriminant analysis of microcalorimetric data of bacterial growth
Authors: Bermúdez J. , López D. , Sanahuja A. , Viñas M. , Lorén J. G.
Published: May 2010

In this work a bacterial classification method based on the discriminant analysis of the microcalorimetric data provided by the growth power–time (p–t) curves is developed. This method is applied to classify several species of Enterobacteria of different origins, and the results are compared with those obtained by conventional techniques. The proposed analysis allows us to classify bacteria into species and discriminate among strains of the same species. The classification is carried out using one run of each isolate after standardization of inocula and growth conditions. The discrimination power of available microcalorimetric data is also discussed, and the most discriminant set of data is proposed as the input variables of the analysis. Finally, the advantages of microcalorimetry as a taxonomical technique are discussed.
Ultrastructural observations on Thrombocytozoons ranarum Tchacarof 1963, an intrathrombocytic yeast of frogs
Authors: Desser S. S. , Barta J. R.
Published: May 2010

Electron microscopic observations were made on Thrombocytozoons ranarum in ranid frogs from Algonquin Park, Ontario. These observations revealed that this bacilliform, intrathrombocytic organism is a yeast which ultrastructurally resembles Candida albicans.
A new marine ammonium-oxidizing bacterium, Nitrosomonas cryotolerans sp. nov.
Authors: Jones Ronald D. , Morita Richard Y. , Koops Hans-Peter , Watson Stanley W.
Published: May 2010

An ammonium-oxidizing chemolithotroph has been isolated from Alaskan waters that is different from any of the previously described species. The cells are 2.0–4.0 μm long and 1.2–2.2 μm wide. The cells contain flattened peripheral membranes that often expand, forming spherical structures near the ends of the cells. The cytomembrane structure is significantly different from any described species. The organism is an obligate halophile. The mol% G + C is 45.8, and DNA–DNA hybridization results indicate that the isolate is a new species; the name Nitrosomonas cryotolerans is proposed.
Selective association and transport of Campylobacter jejuni through M cells of rabbit Peyer's patches
Authors: Walker Richard I. , Schmauder-Chock Elsa A. , Parker Joe L. , Burr Donald
Published: May 2010

M cells in the Peyer's patches may facilitate transport of pathogens such as Campylobacter jejuni from the intestine. We evaluated this hypothesis by using electron microscopy to examine Peyer's patches in ligated adult rabbit ileal loops inoculated with 5-mL suspensions of 109 cfu/mL of Campylobacter jejuni. Peyer's patches taken at intervals from 15 min to 2 h after inoculation of loops in anaesthetized rabbits provided evidence that Campylobacter jejuni selectively adhered to M cells as opposed to absorptive epithelial cells and was transported, apparently intact, into the M cell follicle. Although intercellular organisms were seen within the follicle, many others were phagocytosed by lymphoid cells. The proximity of the lymphatic and blood circulatory systems to the M cell follicle makes this a probable route for systemic spread of Campylobacter jejuni.
Monoclonal antibodies against the capsular K antigen of Escherichia coli (09: K30(A): H12): characterisation and use in analysis of K antigen organisation on the cell surface
Authors: Homonylo Mary K. , Wilmot Sheila J. , Lam Joseph S. , MacDonald Leslie A. , Whitfield Christopher
Published: May 2010

Monoclonal antibodies were produced against the capsular antigen of Escherichia coli serotype K(A)30, using a mouse hybridoma system. The antibodies also recognised the chemically identical capsular polysaccharide produced by Klebsiella K20. Chemical modification of the K30 polysaccharide indicated that the glucuronic acid residues found in the E. coli K30 capsular antigen were important in the epitope recognised by these antibodies. Use of the antibodies as molecular probes revealed the presence of two discrete forms of the K30 antigen. One form was comprised of high molecular weight polysaccharide, present as a surface capsular layer. The second form of the antigen was of low molecular weight and was associated with lipopolysaccharide fractions from cell surface polysaccharide extracts. Separation of lipopolysaccharide fractions using gel chromatography in the presence of detergent showed that the low molecular weight K-antigenic fraction comigrated with a lipopolysaccharide lipid A core fraction present in encapsulated E. coli K30 bacteria but absent in acapsular mutants.
Preliminary ESR study of Mn(II) retention by the yeast Saccharomyces
Authors: Kihn Jean Claude , Dassargues Christine M. , Mestdagh Michèle M.
Published: May 2010

Manganese(II) retention by yeast cells was investigated in the absence of any energy source in the medium. Only a small fraction of the cations retained (2.7 to 9%) was bound by the cell wall; the binding sites were negatively charged groups like phosphodiesters in the phosphomannan and carboxylates in the proteins. ESR spectra of the cations, which entered the cell, indicated that they could be complexed by polyelectrolytes or precipitated with orthophosphate to form MnHPO4(crystal). In both cases, the concentration of free Mn2+ remained low. The entry of cations was thus driven by the concentration gradient, and no metabolic energy was therefore required in our experimental conditions.
Transformation de la matière organique végétale sous l'action du termite Macrotermes mülleri (Sjöstedt) et de son champignon symbiotique
Authors: Garnier-Sillam E. , Toutain F. , Villemin G. , Renoux J.
Published: May 2010

The fungus Termitomyces sp., an exosymbiont of the termite Macrotermes mülleri, can perforate the pectin–cellulose walls of the vegetative cells present in the fungal comb in such a way as to get near the dark pigments (polyphenol proteins). This fungus, through cellulolytic, pectinolytic, and perhaps ligninolytic activities, extensively degraded these brown substances. Subsequently bacterial and enzymatic degradation of the different plant materials continued in the digestive tract of the termite and its endosymbionts. The faeces deposited in the nest and on the ground were essentially composed of organic granules and organo–mineral microaggregates. These microaggregates were produced during intestinal transit by the adsorption of clay particles onto the biodegraded organic matter. The weak organo–mineral bonds suggest that the organic residue will be easily mineralized.
Isolation and regeneration of protoplasts from Termitomyces clypeatus
Authors: Mukherjee M. , Sengupta S.
Published: May 2010

A method for the efficient release of protoplasts from the mycelia of Termitomyces clypeatus and the conditions necessary for the regeneration of the protoplasts are described. It was possible to obtain T. clypeatus protoplasts, to a concentration of 2 × 108/mL of incubation mixture, by digesting the mycelia with a mixture of cellulase, chitinase, and Novozym 234 for 3 h. Mycelial regeneration of the protoplasts was not detected in liquid regenerating medium, whereas more than 50% of the protoplasts developed into colonies on the same solid medium. Both direct hyphal growth and budding of the protoplasts without any hyphal development were observed on solid medium. However, budding of the protoplasts was only observed in the liquid regenerating medium.
Properties and characteristics of a bacteriocin-like substance produced by Propionibacterium acnes isolated from dental plaque
Authors: Paul Greg E. , Booth S. James
Published: May 2010

A cell-associated bacteriocinlike substance with an approximate molecular weight of 78 000 was isolated from an oral isolate of Propionibacterium acnes. The substance was bacteriostatic and was active against both gram-positive and gram-negative anaerobes. Lysozyme inhibited the activity of the bacteriocinlike substance at low ionic strength.
Glycoconjugates on the surface of spores of the pathogenic fungus Phytophthora cinnamomi studied using fluorescence and electron microscopy and flow cytometry
Authors: Hardham A. R. , Suzaki E.
Published: May 2010

Glycoconjugates on the surface of zoospores and cysts of the pathogenic fungus Phytophthora cinnamomi have been studied using fluorescein isothiocyanate labelled lectins for fluorescence microscopy and flow cytometry, and ferritin- and gold-labelled lectins for ultrastructural analysis. Of the five lectins used, only concanavalin A (ConA) binds to the surface of the zoospores, including the flagella and water expulsion vacuole. This suggests that of accessible saccharides, glucosyl or mannosyl residues predominate on the outer surface of the zoospore plasma membrane. Early in encystment, a system of flat disc-like cisternae, which underlie the zoospore plasma membrane, vesiculate. These and other small peripheral vesicles quickly disappear. After the induction of encystment, ConA is no longer localised close to the plasma membrane but binds to material loosely associated with the cell surface. Quantitative measurements by flow cytometry indicate that the ConA-binding material is gradually lost from the cell surface. The cyst wall is weakly labelled, but the site of germ tube emergence stains intensely. During the first 2 min after the induction of encystment, material that binds soybean agglutinin, Helix pommatia agglutinin, and peanut agglutinin appears on the surface of the fungal cells. The distribution of this material, rich in galactosyl or N-acetyl-D-galactosaminosyl residues, is initially patchy, but by 5 min the material evenly coats most of the cell surface. Labelling of zoospores in which intracellular sites are accessible indicates that the soybean agglutinin binding material is stored in vesicles that lie beneath the plasma membrane. Quantitation of soybean agglutinin labelling shows that maximum binding occurs 2–3 min after the induction of encystment. Key words: cell surface, flow cytometry, lectins, pathogenic fungi, Phytophthora cinnamomi.
Stimulation of α-glucosidases from fast-growing rhizobia and Agrobacterium tumefaciens by K+, NH+4, and Rb+
Authors: Hoelzle Inger , Streeter John G.
Published: May 2010

Extracts from cultured fast-growing rhizobia and Agrobacterium tumefaciens contain enzymes for hydrolysis of the α-glucosides maltose, sucrose, and α,α-trehalose. The hydrolysis of all three sugars was stimulated by the presence of K+, Rb+, or [Formula: see text]. This stimulation varied from less than 2-fold to more than 12-fold, depending on the bacterial species, culture conditions, and experimental conditions, such as type of enzyme, buffer, and ion concentration. Eight other ions tested, including several divalent cations, did not have any stimulatory effect. Other sources of enzyme (Escherichia coli, Saccharomyces cerevisiae, Oryza sativa, porcine kidney, and Medicago sativa and Glycine max nodule cytosol) contained α-glucosidases that differed in both substrate specificity and pH optima and were not affected by K+, Rb+ or [Formula: see text] ions. Bacteroids from G. max and Phaseolus vulgaris nodules did not have detectable α-glucosidase activity. Growth of Rhizobium leguminosarum biovar phaseoli USDA 2667 with one of the α-glucosides as carbon source increased Vm and substrate affinity for all three disaccharidase activities. The pH optimum for all three enzyme activities in R. leguminosarum bv. phaseoli USDA 2667 was 6.6. Stimulation by specific monovalent cations appears to be a novel property of α-glucosidases in the bacterial family Rhizobiaceae. Key words: maltose, sucrose, trehalose, disaccharidases, Rhizobiaceae.
Detection of papillomavirus DNA in human prostatic tissue by Southern blot analysis
Authors: McNicol Patricia J. , Dodd Janice G.
Published: May 2010

Human papillomavirus deoxyribonucleic acid was detected in prostate tissue from patients with benign prostatic hyperplasia or prostatic carcinoma. Radiolabelled genomic probes, specific for the sexually transmitted human papillomavirus types 16 and 18, were used to detect viral genomic sequences in prostate DNA samples analyzed by the Southern blot technique. Viral sequences were identified in DNA from 7 of 16 prostate samples including both hyperplastic and carcinoma tissues and including tissues obtained by transurethral resection or suprapubic prostatectomy. These data indicate that the prostate gland can be infected with human papillomavirus and imply that the prostate may act as a reservoir for the sexual transmission of papillomavirus via seminal fluid. The detection of both episomal and integrated viral DNA sequences in prostate tissue may have important implications for the etiology of prostate disease. Key words: human papillomavirus, prostate, hyperplasia, carcinoma, Southern blot.
A kinetic analysis of a step-up photosensory response of the ciliate Stentor coeruleus
Authors: Doughty Michael J.
Published: May 2010

Suspensions of Stentor coeruleus were illuminated with a white light (tungsten) source after prior adaptation to cool-white fluorescent light. The cells, with such overall illumination, exhibited a marked step-up response characterized by periodic interruptions of the forward left spiral swimming motion pattern. The interrupted motion type was persistent and the result of a light-dependent reversal of the membranellar ciliary system of the cell. The overall frequency of responses and the duration of the responses increased (from threshold effects at 14 W/m2) as a function of fluence rate (tested up to 158 W/m2; 300–1100 nm). The response frequency changed from 5 to 8 responses/s, while the overall response duration increased from 0.81 to 2.9 s. Key words: Stentor coeruleus, photosensory response, ciliate.
Pathogenicity of Staphylococcus lugdunensis, Staphylococcus schleiferi, and three other coagulase-negative staphylococci in a mouse model and possible virulence factors
Authors: Lambe Jr. D. W. , Ferguson K. P. , Keplinger J. L. , Gemmell C. G. , Kalbfleisch J. H.
Published: May 2010

Staphylococcus lugdunensis and Staphylococcus schleiferi, two newly described species, have been isolated from numerous types of human infections. We compared the pathogenicity of 30 strains of S. lugdunensis, S. schleiferi, Staphylococcus epidermidis, Staphylococcus warneri, and Staphylococcus hominis, using a mouse model in which a foreign body preadhered with the test strain was implanted subcutaneously, followed by injection of the test strain. All five species of staphylococci produced abscesses. Staphylococcus epidermidis, S. schleiferi, and S. lugdunensis yielded species means of 76–91% abscess formation; 80–100% of the infected foreign bodies and tissues were culture positive. These three species were more virulent than S. warneri or S. hominis, which produced abscesses in 54 and 65% of mice, respectively; only 10–48% of the infected samples were culture positive. Transmission electron microscopy of pure cultures of selected strains showed that all species possessed glycocalyx. All species produced a variety of possible virulence factors, such as α and δ hemolysins, as well as the aggressins lipase and esterase. The production of exoenzymes did not always correlate with virulence as demonstrated by abscess formation in mice. Key words: coagulase-negative staphylococci, Staphylococcus lugdunensis, Staphylococcus schleiferi.
Selenium as a nutrient for freshwater bacterioplankton and its interactions with phosphorus
Authors: Eriksson Cecilia , Pedrós-Alió Carlos
Published: May 2010

The influence of selenite on the growth of bacterioplankton present in samples of three lakes was analyzed; these samples were collected in sulfate-rich, oligotrophic Lake Banyoles, moderately eutrophic Lake Erken, and hypereutrophic Lake Vallentunasjön. Experiments were set up in a completely randomized factorial design to analyze the effect of selenite alone and, in the same experiment, the effect of selenite in the presence of phosphate. Cultures of bacterioplankton, free of algae and zooplankton, diluted with filtered natural water, were used in the bioassays. The addition of 100 μg P∙L−1 to samples from Lake Banyoles, collected during the winter, enhanced cell yield 2.7 times; the addition of 10 μg P∙L−1 to samples from Lake Erken, collected during the spring, doubled the yield. Strong effects of phosphate on growth rates were found in samples from lakes Banyoles and Vallentunasjön. When bacteria from Lake Banyoles were exposed to 100 μg P∙L−1, the specific growth rate was 0.08 h−1 (log units), compared with 0.03 h−1 in the control. In spring, Lake Vallentunasjôn contained water with a considerable amount of dissolved organic phosphorus (18 μg P∙L−1); the addition of 100 μg P∙L−1, in the form of phosphate, resulted in a shorter lag phase of at least 48 h and reduced the specific growth rate to about half that in the control. Selenite had a significant positive effect on cell yield in samples from lakes Banyoles (p = 0.0001) and Vallentunasjön (p = 0.020), whereas the effect on cell yield in samples from Lake Erken was slightly negative (p = 0.110). The addition of selenite alone (550 ng Se∙L−1) to samples from Lake Banyoles, collected during the summer, doubled the biovolume of bacterioplankton within 37 h. Among winter bacteria from Lake Banyoles, selenite, at concentrations of 55 and 550 ng Se∙L−1, increased the number of bacteria twofold and threefold, respectively, but only when the phosphate level was high (100 μg P∙L−1). A high inorganic phosphorus level of 100 μg P∙L−1 was also necessary to stimulate the effect of selenite on bacterial growth in samples from Lake Vallentunasjön; 550 ng Se∙L−1 enhanced cell yield 24%. The negative effect of selenite on samples from Lake Erken was most obvious when phosphate (10 or 100 μg P∙L−1) had been added simultaneously (p = 0.030 for selenium and phosphorus interaction). Cell yields were always greater at the highest temperature. With samples from Lake Vallentunasjön, selenite stimulated bacterial growth at 25 °C but had no effect at 10 °C. With samples from Lake Banyoles, the simultaneous addition of phosphate and selenite increased cell yield threefold at 15 °C and only twofold at 30 °C. Key words: phosphorus, sulfate, Lake Erken, Lake Vallentunasjön, Lake Banyoles.
Mineralization of 3-phenoxybenzoate by a two-membered bacterial co-culture
Authors: Topp Edward , Akhtar M. Humayoun
Published: May 2010

3-Phenoxybenzoic acid is an intermediate in the degradation of several pyrethroid insecticides in soil. Two pseudomonads were isolated together on vitamin-supplemented nutrient agar from 3-phenoxybenzoate enrichment of an agricultural soil. One isolate, designated 13b, grew on 3-phenoxybenzoate in mineral salts medium producing stoichiometric amounts of phenol. It degraded 3-[phenoxy-14C(U)]phenoxybenzoate to [14C(U)]phenol and did not assimilate any 14C from this molecule. It metabolized [carboxyl-14C]3-phenoxybenzoate but not [14C(U)]phenol. It also produced 4-chlorophenol and p-cresol from 3-(4-chlorophenoxy)benzoate and 3-(4-methylphenoxy)benzoate, respectively. This indicated that isolate 13b transformed the benzoate but not the phenoxy moiety of 3-phenoxybenzoate. The second isolate, designated 13a, did not metabolize 3-phenoxybenzoate but grew on and mineralized phenol. Incubation of 3-phenoxybenzoate with isolates 13a and 13b together resulted in the degradation of both aromatic nuclei. Key words: 3-phenoxybenzoate, bacterial degradation, mineralization, pyrethroid.
Induction of protein synthesis in response to cold shock in the psychrotrophic yeast Trichosporon pullulans
Authors: Julseth Craig R. , Inniss William E.
Published: May 2010

The synthesis of proteins in response to a cold shock in the psychrotrophic yeast Trichosporon pullulans was examined. Two-dimensional electrophoretic analysis of a 21 to 5 °C cold shock revealed the induction of 26 cold-shock proteins (csps) at the maximum induction time of 12 h. The induction of only 10 csps after a 24 to 5 °C cold shock suggested that the growth of cells above their optimum growth temperature reduced their ability to induce csps. Comparison of the csp profile obtained after a 15 to a 5 °C cold shock with the profile for the 21 to 5 °C cold shock suggested that the range of the cold shock influences which proteins are induced. Key words: cold-shock proteins, psychrotrophic yeast.
Purification and properties of extracellular proteases produced by the nematophagous fungus Verticillium suchlasporium
Authors: Lopez-Llorca L. V.
Published: May 2010

The fungal parasite of eggs of cyst nematodes, Verticillium suchlasporium, produced extracellular proteases when grown in semiliquid culture with gelatin as the only source of nitrogen and carbon. The proteolytic activity of culture filtrates was maximum 12–14 days after inoculation. Gel filtration chromatography in Sephadex G-100 resolved two peaks of proteolytic activity. The peak accounting for most of the activity was further purified by ion-exchange chromatography in SP-Sephadex C-25 as a single peak. This protease had a molecular mass of 32 kDa calculated by sodium dodecyl sulfate – polyacrylamide gel electrophoresis. The enzyme was an endopeptidase that degraded fibrinogen in zymograms and had an optimum pH of 8.5 using fluorescein isothiocyanate – casein as the substrate. It was inhibited by phenylmethylsulfonyl fluoride, indicating that it was a serine protease. The purified protease was able to degrade certain cyst nematode proteins suggesting the involvement and specificity of the 32-kDa protease during nematode egg penetration by Verticillium suchlasporium. Key words: nematophagous fungi, Verticillium suchlasporium, extracellular enzymes, serine proteases.
Response of attached bacteria to zinc in artificial streams
Authors: Dean-Ross Deborah
Published: May 2010

To study the response of natural communities of attached bacteria to Zn, artificial streams were dosed with Zn at levels of 0, 0.01,0.1,0.5, 1.0, and 10.0 mg/L in duplicate treatment groups. Changes in total biomass, chlorophyll a content, total bacterial numbers, and heterotrophic activity were measured over a 5-week exposure period. The adaptation of the culturable bacterial community to Zn was assessed by comparing viable counts on unsupplemented medium with counts on media supplemented with several concentrations of Zn. The structure of that portion of the bacterial community capable of growth on nutrient agar was assessed by characterizing randomly selected colonies with respect to 20 nutritional capabilities and grouping the strains by numerical taxonomy. Streams receiving 0.5, 1.0, and 10.0 mg Zn/L were significantly inhibited with respect to all variables studied when compared with streams receiving 0, 0.01, or 0.1 mg Zn/L. Bacteria developed tolerance to the exposure concentration of Zn but were resistant to higher Zn concentrations. Increasing concentrations of Zn produced alterations in the structure of the culturable bacterial community, resulting in differing assemblages of bacterial groups and a decrease in diversity as measured by the Shannon–Wiener index and rarefaction. These results suggest that streams receiving 0.5 mg Zn/L or more may be adversely impacted. Key words: attached bacteria, zinc, heavy-metal resistance, species diversity.
NMR study of 13CO2 incorporation into short-chain fatty acids by pig large-intestinal flora
Authors: Graeve K. G. De , Grivet J. P. , Durand M. , Beaumatin P. , Demeyer D.
Published: May 2010

The nuclear magnetic resonance technique was used to study carbon dioxide reduction by the pig large-intestinal flora. Washed bacterial cell suspensions were incubated for 6 and 15 h under 13CO2 and H2 as the gas phase and with a buffer containing NaH13CO3 and cellobiose and amino acids (casein hydrolysate) as substrates. Methane was produced in all incubation media. Significant amounts of single- as well as multiple-labelled acetate and butyrate were formed, demonstrating synthesis of acetate from H2 + CO2. Propionate was labelled mainly on the carboxyl group, which was attributed to an enzymatic exchange of the carboxyl group of propionate with 13CO2. These results indicate that the reduction of CO2 to acetate may be an important pathway for microbial production of acetate in the pig large intestine even in the presence of methanogenesis. Key words: 13C NMR, acetogenesis, hydrogen, hindgut microbe.
Studies on cytokine activation of listericidal activity in murine macrophages
Authors: Denis Michel , Gregg Evan O.
Published: May 2010

The ability of a variety of soluble factors, alone or in combination, to endow murine resident peritoneal macrophages with listericidal activity was assessed. Inhibition of growth and (or) killing of Listeria in infected macrophages was determined by the uptake of [3H]uracil following lysis of the infected macrophage monolayers. Interferon-γ was shown to induce modest listericidal activity in murine resident macrophages as compared with untreated monolayers. Treatment with tumour necrosis factor alpha also induced significant listericidal activity in this system. Among other cytokines tested, IL-4 induced an ability to inhibit growth of Listeria in resident macrophages. The ability of cytokines to act in an additive or synergistic fashion with IFN-γ was also investigated. Combinations of IFN-γ and IL-4 and IFN-γ and IL-2 induced listericidal activity not greater than that seen with IFN-γ alone. IFN-γ and TNF-α were shown to increase bactericidal activity in an additive fashion. However, elicited macrophages were shown to spontaneously exert a significant listericidal activity that was not enhanced by cytokine treatment. Collectively, these findings show that cytokine treatment induced rather modest enhancement in listericidal activity in murine resident peritoneal macrophages and no enhancement whatsoever in elicited macrophages. Thus, in in vivo situations where Listeria organisms are completely cleared from the infected organs, mechanisms other than lymphokine-induced listericidal activity of resident macrophages would seem to be operating. Key words: Listeria, macrophages, cytokines.
Identification of a denitrifying gliding bacterium, isolated from soil and able to reduce nitrous oxide in the presence of sulfide and acetylene, as Flexibacter canadensis
Authors: Jones Alison M. , Adkins Anne M. , Knowles Roger , Rayat Gina R.
Published: May 2010

We have reexamined the properties of a gliding bacterium, Is-11, which was previously isolated from soil because of its ability to denitrify and to reduce nitrous oxide in the presence of sulfide and normally inhibitory concentrations of acetylene. Occurrence of such an organism may have important implications for the use of the acetylene inhibition assay for measuring denitrification rates in reduced, sulfidic environments. Although originally tentatively identified as a Cytophaga sp., extensive morphological, physiological, and biochemical tests as well as G+C analysis and DNA hybridization studies now indicate that the soil isolate Is-11 is a strain of Flexibacter canadensis. Key words: gliding bacteria, Flexibacter canadensis, denitrification, acetylene, sulfide, nitrous oxide.
Involvement of cell surface sugars in recognition, attachment, and appressorium formation by a mycoparasite
Authors: Manocha M. S. , Chen Y. , Rao N.
Published: May 2010

Fluorescein isothiocyanate labeled lectin binding techniques have revealed differences in the distribution pattern of glycosyl residues at the cell wall level between fungi that are hosts and those that are nonhosts of the mycoparasite Piptocephalis virginiana, and at the protoplast level between compatible and incompatible hosts. The cell wall of the compatible hosts (Choanephora cucurbitarum and Mortierella pusilla) and an incompatible host (Phascolomyces articulosus), as well as that of the mycoparasite itself, contains glucose and N-acetylglucosamine. However, the cell wall of a nonhost (Mortierella candelabrum) tested positive with lectins specific for various sugars, including not only glucose and N-acetylglucosamine, but also fucose, N-acetylgalactosamine, and galactose. These latter sugars could also be exposed at the surfaces of hosts and of the mycoparasite, but only after mild treatment with proteinase or when grown in a liquid culture. Pretreatment of the mycoparasite with glucose and N-acetylglucosamine inhibited its attachment to the host cell surface, but had no obvious effect on appressorium formation. On the other hand, appressorium formation was inhibited by heat treatment of host cell wall fragments which still permitted attachment, thus indicating that the factors responsible for attachment and for appressorium formation are different. The protoplast surfaces of compatible hosts contained all the sugars listed above and these protoplasts could attach to the germ tube of the mycoparasite. Only lectins specific for N-acetylglucosamine and for glucose were bound at the protoplast surface of the incompatible host; these protoplasts did not attach to the mycoparasite germ tube. Key words: mycoparasite, appressorium formation, lectins, host cell surface, attachment, protoplast surface.
Nitrate reduction to ammonia: a dissimilatory process in Enterobacter amnigenus
Authors: Fazzolari E. , Mariotti A. , Germon J. C.
Published: May 2010

Thirty-four bacterial isolates from an agricultural soil anaerobically preincubated in the presence of glucose were tested for their ability to reduce nitrate to ammonia or to denitrify in two different media: nitrate broth and a minimal medium enriched with glucose. Ten isolates were considered denitrifying bacteria and 7 were dissimilatory ammonia producers. Ammonia production by the isolate identified as Enterobacter amnigenus was quantified and attained 50% of 138 mg∙L−1 of added NO3− N. The dissimilatory character of this reduction was clearly confirmed by culturing this 15N-labeled bacterium in the presence of unlabeled nitrite. Nitrous oxide was produced at the same time as nitrite was reduced to ammonia. Increasing nitrate N levels from 48 to 553 mg∙L−1 in culture medium resulted in an increase in the level of nitrite produced and simultaneously a decrease in ammonia and nitrous oxide production. Key words: dissimilatory nitrate reduction, dissimilatory ammonia production, denitrification, Enterobacter amnigenus, 15N.
Population dynamics of pseudomonads after iodination
Authors: Pyle Barry H. , McFeters Gordon A.
Published: May 2010

The population dynamics of pseudomonads grown under rich or low nutrient conditions were examined following iodination. Iodinated and untreated controls of Pseudomonas aeruginosa or Pseudomonas cepacia were resuspended in phosphate buffer and incubated at room temperature. Viable populations of iodine-treated cultures increased faster in phosphate-buffered water than uniodinated controls. Thus, bacteria in iodinated water systems may recover or multiply during storage and distribution after disinfection and may pose a significant health risk. Key words: iodine, disinfection, pseudomonads.
Utilization by yeasts of D-glucarate, galactarate, and L-tartarate is uncommon and occurs in strains of Cryptococcus and Trichosporon
Authors: Schneider H. , Biely P. , Latta R. , Lee H. , Dorscheid D. , Levy-Rick S.
Published: May 2010

In 38 yeast genera tested, utilization of D-glucarate was uncommon, occurring with only 10 strains out of 373. The ability was prominent among Cryptococcus strains, with 8 out of 8 tested being positive, including the pathogen Cryptococcus neoformans. The ability was present also in Trichosporon where 2 out of the 4 strains tested were positive. There was a correlation between ability to utilize D-glucarate, galactarate, L-tartarate, and D-glucuronate. Use of L-ascorbate occurred in more genera than use of D-glucarate, but all strains that grew on D-glucarate grew on L-ascorbate. The utilization of certain hydroxylated carboxylates by strains, mainly found in two genera, is of interest in identifying the catabolic pathways involved, in taxonomic studies, and in developing rapid methods of yeast identification. Key words: Cryptococcus, Trichosporon, glucarate, galactarate, tartarate.
A correlation of phylogenetic diversity in the Proteobacteria with the influences of ecological forces
Authors: Zavarzin G. A. , Stackebrandt E. , Murray R. G. E.
Published: May 2010

The Proteobacteria are physiologically and morphologically diverse, although they form a coherent set of four main lineages on phylogenetic analysis of ribosomal RNA. A rational and consistent taxonomic arrangement bringing today's phenotypic and phylogenetic conclusions about them into register is not yet possible. It is also difficult to understand the selective forces involved in their evolution that fostered such diversity. This latter problem is addressed in this essay and is based on the assumption that bacterial evolution could only have occurred in ecological consortia whose products of metabolism modified the environment, provided nutrition, and have a basis for selection of new capabilities. Key words: Proteobacteria, bacterial diversity, bacterial evolution, ecological selection.
Serological characterization of surface proteins of Spiroplasma citri
Authors: Fletcher Jacqueline , Wijetunga Chandi
Published: May 2010

Four surface proteins of the phytopathogenic Mollicute Spiroplasma citri were characterized using monospecific polyclonal antisera. Antiserum specific for P29 (spiralin) caused growth inhibition, spiral deformation, and metabolism inhibition, while anti-P89, anti-P77, anti-P58, and preimmune sera did not. In Triton X-114 phase partitioning, P29, P89, and one of two P77 bands were hydrophobic, indicating the probability that they are integral membrane proteins. P58 partitioned into the hydrophilic phase and may be an extrinsic membrane protein. A second band which reacts with anti-P77 serum was also hydrophilic. Treatment of the two P77 components with trypsin and chymotrypsin resulted in very different polypeptide patterns, suggesting that the two bands represent unrelated proteins. These results demonstrate the variability in hydrophobicity among surface-exposed proteins in S. citri and describe procedures that should prove useful for characterizing and separating other proteins of interest in spiroplasmas. Key words: Spiroplasma, mollicute, surface proteins, serology, Triton X-114.
Cellobiose uptake by the cellulolytic ruminai anaerobe Fibrobacter (Bacteroides) succinogenes
Authors: Maas Lori K. , Glass Thomas L.
Published: May 2010

Cellobiose transport by the cellulolytic ruminal anaerobe Fibrobacter (Bacteroides) succinogenes was measured using randomly tritiated cellobiose. When assayed at the same concentration (1 mM), total cellobiose uptake was one-fourth to one-third that of total glucose uptake. The abilities of F. succinogenes to transport cellobiose or glucose were not affected by the sugar on which the cells were grown. Aspects of the simultaneous transport of [14C(U)]glucose and [3H(G)]cellobiose, the failure of high concentrations of cold glucose to compete with hypothetical [3H(G)] glucose (derived externally from [3H(G)]cellobiose), and differential metal-ion stimulation of cellobiose transport indicate a cellobiose permease, rather than cellobiase plus glucose permease, was responsible for cellobiose transport. Glucose (10-fold molar excess) partially inhibited cellobiose transport. This was enhanced by prior incubation of the cells with glucose, suggesting subsequent metabolism of the glucose was responsible for the inhibition. Compounds interfering with electron transport or maintenance of transmembrane ion gradients inhibited cellobiose uptake, indicating that active transport rather than a phosphoenolpyruvate:phosphotransferase system catalyzed cellobiose transport. Na+, but not Li+, stimulated cellobiose transport. Key words: Fibrobacter (Bacteroides) succinogenes, cellobiose transport, rumen bacteria.
Ammonium assimilation by Candida albicans and other yeasts: a 13N isotope study
Authors: Holmes Ann R. , McNaughton Graeme S. , More Ray D. , Shepherd Maxwell G.
Published: May 2010

Nuclear magnetic resonance spectra of cultures of Candida albicans incubated in the presence of 15N-labelled ammonium demonstrated that glutamine and glutamate were the only initial products of ammonium assimilation. The nature of the route of assimilation in the yeasts Candida albicans, Saccharomyces cerevisiae, and Candida tropicalis was further examined by the use of the short-lived isotope 13N. [13N]ammonium was generated in the reaction 16O(p,α)13N, induced by proton bombardment of water in a tandem accelerator. High-pressure liquid chromatography was used to separate and identify the products of assimilation, and radioactivity was detected and corrected for decay, using a computer-linked Nal scintillation detector. In the three yeasts studied, the labelled ammonium was assimilated into the acid-extractable fraction of cell suspensions within 1 min, and over 75% was converted to glutamine and glutamate. Subsequent to exhaustion of the labelled ammonium, the stoichiometry of the distribution of radiolabel was consistent with a net transfer of radiolabel from glutamine to glutamate, confirming the operation of glutamate synthase (EC 1.4.1.14) in these yeasts. Initial assimilation of label was mostly into glutamine (at a maximal rate within 10 s in C. albicans), whereas accumulation in glutamate did not occur at maximal rate until more than 70% of the labelled ammonium had been assimilated (between 30 and 60 s in C. albicans). We conclude that the glutamine synthetase – glutamate synthase pathway is the major route of ammonium assimilation in C. albicans and also in nitrogen-starved cultures of S. cerevisiae and C. tropicalis. Key words: Candida albicans, ammonium assimilation, nitrogen.
Inhibition of influenza A virus hemagglutinin and induction of interferon by synthetic sialylated glycoconjugates
Authors: Gamian Andrzej , Chomik Maria , Laferrière Craig A. , Roy René
Published: May 2010

Multivalent forms of neoglycoproteins and polyacrylamides containing sialic acid were prepared and shown to be potent inhibitors of influenza A virus (H3N2) hemagglutinin with chick red blood cells. The synthetic sialylated glycoconjugates, although they were neuraminidase substrates, did not suppress viral neuraminidase and did not reduce infectivities in chick embryos. The copolyacrylamide conjugate containing a spacer group of ~11 Å (1 Å = 0.1 nm) between the polymer backbone and the sialic acid residues was the best hemagglutinin inhibitor. Moreover, it exhibited promising interferon-inducing properties. Key words: Influenza A virus, sialic acid, inhibitor, hemagglutinin, interferon.
Succession of moist hay mycoflora during storage
Authors: Breton André , Zwaenepoel Philippe
Published: May 2010

A moist fescue forage in round bales showed a heating process with two peaks of temperature. The first peak, reached after 8 h, was not related to the development of thermophilic fungi but was accompanied by the rapid elimination of the thermosensitive field flora. The second phase of heating took place during several weeks while thermophilic or thermotolerant storage fungi developed. Key words: mycoflora, hay, heating.
Growth of Listeria monocytogenes in murine macrophages and its modulation by cytokines; activation of bactericidal activity by interleukin-4 and interleukin-6
Authors: Denis Michel
Published: May 2010

Bone marrow derived macrophages were infected with a virulent strain of Listeria monocytogenes, and the ability of selected cytokines to modify the intracellular growth was assessed. Macrophage monolayers pretreated with either interferon-γ or tumour necrosis factor were shown to exert a significant listericidal activity. Treatment of monolayers with granulocyte–macrophage colony stimulating factor led to no significant difference in the ability of Listeria to invade and multiply within these cells. Moreover, pulsing of macrophage monolayers with interleukin-6 (IL-6) led to a slight enhancement of Listeria growth in the macrophages, whereas interleukin-4 (IL-4) did not modify Listeria growth. In other sets of experiments, macrophage monolayers were treated with cytokines after phagocytosis of the bacteria. In these conditions, interferon-γ endowed macrophages with only a modest ability to kill Listeria. Conversely, treatment of monolayers with IL-6 or IL-4 at the time of infection led to expression of high bactericidal activity. Collectively, these results suggest that macrophages may respond to different signals, which enhance their antimicrobial activity before or after infection. Furthermore, B-cell stimulatory factors (IL-4 and IL-6) are potent macrophage-activating molecules. Key words: Listeria monocytogenes, cytokines, macrophages.
Manitoba virus, a new rhabdovirus isolated from Culex tarsalis mosquitoes collected in Manitoba, Canada
Authors: Artsob H. , Doane F. , Sekla L. , Stackiw W. , Brust R.
Published: May 2010

A rhabdovirus, Mn 936-77, was isolated from a pool of two Culex tarsalis collected on August 16, 1977, from Morris, Manitoba. Isolate Mn 936-77 was not pathogenic for suckling Swiss white mice inoculated by the intracerebral route. The virus propagated in three vertebrate cell lines (Vero, primary chick embryo, mouse neuroblastoma), but apparently not in Aedes albopictus C6/36 cells. Isolate Mn 936-77 did not react by amplified enzyme-linked immunosorbant assay with 230 viruses of proven or possible arbovirus etiology or by immunofluorescence with 88 members of the family Rhabdoviridae. Isolate Mn 936-77 appears to be a newly discovered virus for which the name Manitoba virus is proposed. Key words: arbovirus, Culex tarsalis, rhabdovirus, Manitoba virus.
The stability of outer-membrane protein and antigen profiles of a strain of Bacteroides intermedius grown in continuous culture at different pH and growth rates
Authors: Bowden G. H. , Nolette N. , McKee A. S. , Hamilton I. R.
Published: May 2010

The stability of the outer-membrane proteins and antigens of a strain of Bacteroides intermedius (VP1 8944 group genotype II) grown in contious culture at varying pH and growth rates (D = 0.025–0.2 h−1, pH 6.0–7.3) has been measured. The membranes showed nine major proteins (> 67–19.55 kilodaltons) and six major antigens (65–28 kilodaltons). Membrane proteins and antigens were stable under the conditions tested; the major proteins were detected in all membranes, and the antigen profiles tested with different antisera showed maximum similarities of 82–95%. Differences did occur in the amounts of membrane proteins synthesized; cells at high growth rates and those growing on the surfaces in the chemostat showed increased amounts of two proteins (40 and 32 kilodaltons) and possibly novel proteins of 24 and 25 kilodaltons. In addition, these membranes reflected increased synthesis or a change to increased reactivity of antigens between 20.5 and 24 kilodaltons. The results indicate stability of the expression of outer-membrane proteins and antigens in environments of differing pH and under different growth rates. However, the amount of these molecules synthesized can vary, and increases in certain proteins and antigens occur as the growth rate increases and the organisms grow on surfaces. Key words: Bacteroides intermedius, outer-membrane antigens, antigenic stability, chemostat culture, outer-membrane profiles.
Role of cations in the flocculation of Saccharomyces cerevisiae and discrimination of the corresponding proteins
Authors: Kuriyama Hiroshi , Umeda Itaru , Kobayashi Harumi
Published: May 2010

Asexual yeast flocculation was studied using strong flocculents of Saccharomyces cerevisiae. The inhibitory effect of cations on flocculation is considered to be caused by competition between those cations and Ca2+ at the binding site of the Ca2+-requiring protein that is involved in flocculation. Inhibition of flocculation by various cations occurred in the following order: La3+, Sr2+, Ba2+, Mn2+, Al3+, and Na+. Cations such as Mg2+, Co2+, and K+ promoted flocculation. This promoting effect may be based on the reduction of electrostatic repulsive force between cells caused by binding of these cations anionic groups present on the cell surface. In flocculation induced by these cations, trace amounts of Ca2+ excreted on the cell surface may activate the corresponding protein. The ratio of Sr2+/Ca2+ below which cells flocculated varied among strains: for strains having the FLO5 gene, it was 400 to 500; for strains having the FLO1 gene, about 150; and for two alcohol yeast strains, 40 to 50. This suggests that there are several different types of cell surface proteins involved in flocculation in different yeast strains. Key words: yeast, flocculation, protein, cation, calcium.
Comparison of colony and stool blots for detection of enteropathogens by DNA probes
Authors: Vieira Mônica A. M. , Guth Beatriz E. C. , Gomes Tânia A. T.
Published: May 2010

DNA probes that identify genes coding for heat-labile type I (LT-I) and heat-stable type 1 (ST-I) enterotoxins, enteropathogenic Escherichia coli adherence factor (EAF), and Shigella-like, invasiveness (INV) are used to evaluate the sensitivity and specificity of stool blots in comparison with the sensitivity and specificity of colony blots in detecting enteropathoghens. The sensitivities of the probes in stool blots are 91.7% for the LT-I probe, 76.9% for the ST-I probes, 78.9% for the EAF probe, and 45.5% for the INV probe. The specificity of all probes is higher than 95%. In general, the stool blot method identifies as many if not more LT-I-, ST-I-, and EAF-producing E. coli infections than the colony blots. Key words: DNA probes, stool blots, enteropathogens, diagnosis.
Competition between strains of Escherichia coli with and without plasmid RP4 during chemostat growth
Authors: Numan Zuhair , Venables W. A. , Wimpenny J. W. T.
Published: May 2010

Escherichia coli strains J53(nal) and J53(RP4) were grown together in glucose-limited continuous cultures. Based on the measured growth kinetic constants of the two strains, take-over of the cultures by J53(RP4) was predicted. However, in practice, an initial period of predominance by J53(RP4) was always followed by a prolonged period in which relative numerical proportions of the two strains oscillated widely. This period of oscillation was removed or greatly reduced when the difference between the predicted growth-rate potentials of the two strains was increased by selection of a chemostat-adapted variant of J53(RP4). Key words: competition, chemostat, plasmid, Escherichia coli.
Comparison of the survival of Campylobacter jejuni and Campylobacter coli in culturable form in surface water
Authors: Korhonen L. K. , Martikainen P. J.
Published: May 2010

Six Campylobacter jejuni and six Campylobacter coli strains were isolated from cows and pigs, and their survival in lake water was compared by viable counts. Campylobacter jejuni survived longer in culturable form than C. coli in untreated and membrane-filtered water both at 4 and 20 °C. This difference in survival time may be a reason why C. jejuni is generally isolated from surface waters more frequently than C. coli. Both species survived better in filtered than in untreated water. This suggests that predation and competition for nutrients affect the survival of both Campylobacter species in the aquatic environment. Key words: Campylobacter jejuni, Campylobacter coli, predation, competition, survival, water.