bluuebunny/crossref_metadata_2025 huggingface dataset:
A simple apparatus for measuring the Eh of anaerobic media
Authors: Patel G. B. , Agnew B. J.
Published: May 2010

A 22-mm outside diameter screw cap test tube was modified for measuring the redox potential (Eh) of samples of anaerobic media. The screw cap was fitted with a grey butyl rubber septum with a hole through which a platinum–calomel combination electrode was inserted. The tube was shortened in length and a small side arm that could be sealed with a serum stopper and an aluminium seal was attached. This device enabled the measurement of Eh of anaerobic media without the need for continuous flushing of the vessel headspace to maintain anaerobiosis.
Thermodynamics of halobacterial environments
Authors: Edgerton Mary E. , Brimblecombe Peter
Published: May 2010

The ranges of the major ion composition of near neutral hypersaline lakes have been described in terms of the charge concentration and the mole fraction of monovalent cations. An ion interactive method was used to establish the thermodynamic activity of the chemical species in these model brines, which were then used in culture media for Halobacterium halobium, H. salinarium, and H. volcanii. The bacteria grew rapidly at water activities of 0.78, 0.79, and 0.925, respectively. The growth areas for these organisms were not easily defined in terms of the Na+ or Cl− activity. The morphology of H. halobium and H. salinarium changes from rod shaped to spherical when the Mg2+ activity drops below 0.15 mol∙kg−1. Niches described by the chemical parameters reflect the marine origin of the environments of H. halobium and H. salinarium, and the more heterogeneous environments of H. volcanii.
An abbreviated scheme for identification of Yersinia enterocolitica isolated from food enrichments on CIN (cefsulodin–irgasan–novobiocin) agar
Authors: Devenish J. A. , Schiemann D. A.
Published: May 2010

An abbreviated procedure for the biochemical identification of Yersinia enterocolitica isolated from food enrichments on CIN (cefsulodin–irgasan–novobiocin) agar was investigated. A total of 170 colonies resembling Y. enterocolitica in colonial morphology and appearance on CIN agar were selected for identification using API strips. Ninety-three of these isolates were examined with the PathoTec ornithine decarboxylase, Voges–Proskauer, and urease test strips. The PathoTec urease strip alone was adequate for identification of all isolates of Y. enterocolitica. Christensen's urea agar was applied to the remaining 77 isolates and found less specific in that 1 isolate of Enterobacter agglomerons was urease positive along with 10 isolates of Y. enterocolitica. CIN agar is a highly specific medium for isolation of Y. enterocolitica, requiring only Kligler iron agar and urea slants for confirmation of presumptive colonies.
Phosphoenolpyruvate-dependent sugar phosphotransferase activity in Megasphaera elsdenii
Authors: Dills Steven S. , Lee Catherine A. , Saier Jr. Milton H.
Published: May 2010

Megasphaera elsdenii was found to possess an inducible phosphoenolpyruvate:sugar phosphotransferase system for glucose and fructose but not for other hexoses, hexosamines, or hexitols. The complexity of the Megasphaera phosphoenolpyruvate:sugar phosphotransferase system lies intermediate to systems found in photoautotrophic bacteria and enteric bacteria. Megasphaera elsdenii phosphotransferase proteins exhibited enzymatic cross-reactivity with those from Escherichia coli; however, differences were found in substrate specificities and the physical characteristics of the proteins from these organisms. Sugar uptake was reduced in M. elsdenii stationary-phase as compared with log-phase cells and this loss correlated with a reduction in enzyme II function.
Activités bactéricides du colorant Erio acide rouge XB 400 vis-à-vis Bacillus thuringiensis
Authors: Smirnoff W. A.
Published: May 2010

Laboratory and field tests revealed that the addition of Erio acid red XB 400 dye (EAR) to Bacillus thuringiensis formulations inhibited spores of the bacillus. In the laboratory, 74% of the spores present in a suspension containing 16 × 109 viable spores/mL, and 0.25 gm/L of EAR, were inhibited after 28 h. Spore inactivation in a physiological solution containing 1 × 107 viable spores/mL was 75% after the same period of exposure to the same EAR concentration. Field tests showed a reduction in the number of viable spores in a suspension exposed to sunlight; a suspension of 75 000 viable spores/mL yielded 2000 and 400 viable spores/mL after 2 and 4 h of exposure to sunlight, while the same suspension added with 2.5 ppm EAR yielded 1000 and 100 viable spores/mL after the same periods of exposure. The photodynamic action of sunlight on the dye provokes a chemical reaction (oxydation) and the inactivation effect of EAR increases with temperature. Consequently, use of EAR is incompatible with B. thuringiensis formulations and methods used for deposit assessment, based on the use of EAR, should be modified accordingly.
Inhibitory effect of molybdenum and vanadium salts on aflatoxin B1 synthesis by Aspergillus flavus
Authors: Rabie C. J. , Meyer C. J. , Heerden Laetitia van , Lübben Annelie
Published: May 2010

The effects of the elements zinc, manganese, iron, copper, molybdenum, and vanadium, added in various salt forms, on mycelial weights and aflatoxin B1 accumulation in the mycelium of Aspergillus flavus were investigated in liquid shake cultures. Ammonium heptamolybdate, when added to a complete medium at concentrations of 50–100 mg/L, appreciably reduced aflatoxin B1 accumulation without affecting growth of the fungus. Sodium molybdate and sodium monovanadate also reduced aflatoxin B1 yields without affecting mycelial growth, but to a lesser extent.The addition of zinc sulphate stimulated aflatoxin B1 production in all media used. The influence of the other trace elements on aflatoxin production depended on the level of trace elements present in the basal medium. In general, manganese chloride had a stimulatory effect, whereas copper sulphate depressed yields.Mycelial levels of aflatoxin had peaked and then declined before mycelial dry weights had reached maximum.High yields of aflatoxin B1 were obtained in media having a final pH as low as pH 2.8.
Salt extends the upper temperature limit for growth of food-poisoning bacteria
Authors: Tesone S. , Hughes A. , Hurst A.
Published: May 2010

Inclusion of NaCl into the growth medium raised the upper temperature limit of growth of the following organisms: Staphylococcus aureus (two strains), Salmonella senftenberg, S. typhimurium, Escherichia coli, Streptococcus faecalis, Bacillus cereus, Clostridium sporogenes, C. perfringens (two strains). The magnitude of the response varied with the culture, the largest being 3.5 °with B. cereus cells. The spores of B. cereus were not protected by salt but clostridial spores behaved as the vegetative cells (response of 2.5°). The optimal salt concentration for the protective effect varied with the organism ranging from 0.2 M for the Gram-negative organisms to 1.0 M for S. aureus.
The effect of magnesium on transfection and transformation in Bacillus subtilis
Authors: López Paloma , Ureña M. Teresa Pérez , Espinosa Manolo
Published: May 2010

The influence of Mg2+ on phage SPP1 DNA-mediated transfection as compared with chromosomal transformation was studied.A differential influence of this cation in both processes was detectable by analyzing the competence development and the kinetics of appearance of transformants and transfectants. Binding and uptake of DNA and release of acid-soluble products by competent cells in high- and low-Mg2+ media was measured for 3H-labelled SPP1 and 3H-labelled Bacillus subtilis DNAs. Phage SPP1 DNA was shown to be subjected to endonucleolytic cleavage after exposure to competent cells.
The electrochemical diminution of surface bacterial concentration
Authors: Dhar Hari P. , Lewis Donald H. , Bockris John O'M.
Published: May 2010

An investigation of the electrodic effects on bactericidal activity is presented while applying electrode potentials. Dark-field and phase-contrast microscopy were used to examine regions adjacent to surfaces of SnO2 glass electrodes for bactericidal activity, while scanning electron microscopy (SEM) was used to visualize microbicidal effects on the surfaces of SnO2 electrodes.As the cathode potential approached −0.3 V (normal hydrogen electrode) the bacterial concentration near the cathode was reduced by 99%. The SEM results showed bacterial concentration on cathode to be reduced to 0.1–1% of the original value. Anodes showed reduction of 0.01–1%. The application of the same potential in pulses resulted in enhanced cleaning of the surfaces. The off periods using the pulses could be more than 10 times the on ones.Models considered to explain the observed results involved effects due to change of surface energy with potential, the depletion of O2 in the solution, the production of bactericides (e.g., H2O2), and the change of pH near the surface. Results are inconsistent with the first two models. Many of them are consistent with both the latter two. Diagnostic experiments are suggested.
The effect of inorganic phosphate on cyclic adenosine 3′, 5′-monophosphate in streptomycin-producing cultures of Streptomyces griseus
Authors: Terry J. , Springham D. G.
Published: May 2010

Intracellular and extracellular cyclic adenosine 3′, 5′-monophosphate (cyclic AMP) levels were measured during the growth of a streptomycin-producing strain of Streptomyces griseus. Increasing the inorganic phosphate concentration of the defined media resulted in a decreased streptomycin titre and alterations in the magnitude and timing of changes in cyclic AMP concentration. Addition of excess inorganic phosphate after 24 h of growth reduced steptomycin production but had no effect on the intracellular cyclic AMP concentration. The results do not suggest that the effect of inorganic phosphate on streptomycin biosynthesis is mediated by cyclic AMP.
Cytochemical and enzymatic characterization of the sporulation septum of Streptomyces antibioticus
Authors: Braña Alfredo F. , Manzanal Manuel B. , Hardisson Carlos
Published: May 2010

The sporulation septum in Streptomyces antibioticus is formed by two thin electron-dense layers which constitute the annuli, separated by a thick and moderately electron-dense matrix which forms the deposits. By means of cytochemical techniques and enzymatic digestion with lysozyme, we have shown that deposits and annuli have a different chemical composition. Deposits are formed by peptidoglycan and are highly sensitive to lysozyme, whereas annuli, probably due to localized chemical modifications of the peptidoglycan or high degrees of peptide cross-linking, are lysozyme resistant. Our results suggest that the deposits, unlike the annuli, are only temporary assisting structures which are degraded during spore maturation.
Extracellular nucleases of Lysobacter enzymogenes: purification and characterization of a ribonuclease
Authors: vonTigerstrom R. G.
Published: May 2010

The ribonuclease of Lysobacter enzymogenes is one of two major extracellular nucleolytic enzymes produced by the organism. The enzyme was purified 560-fold and appeared to be free of contaminating proteins and interfering enzymes. The Lysobacter RNAase consists of one polypeptide chain with a molecular weight of 46 000 – 47 000. The enzyme was most active at pH 8.0–8.5 and in the presence of Mg2+. Approximately 45% of the maximum activity was obtained in the presence of Ca2+, whereas little or no activity was obtained in the presence of Mn2+ or without divalent metal ions. RNA, poly(A), and poly(C) served as substrates but DNA was not hydrolysed. High molecular weight RNA was degraded by the RNAase to short oligonucleotides with 5′-phosphate ends and there was no apparent base specificity.
Molecular architecture of the hyphal wall of Achlya ambisexualis Raper. I. Chemical analyses
Authors: Reiskind Julia B. , Mullins J. T.
Published: May 2010

Chemical analyses of the hyphal wall of Achlya ambisexualis Raper were done in an attempt to provide a basis for understanding the molecular architecture of the wall. Walls were isolated, purified, and fractionated by differential solubility. The wall and its fractions were then hydrolyzed by acid or enzymes. The resulting hydrolysates were analyzed by paper and gas–liquid chromatography for their neutral sugar content and type of glycosidic linkages. The degree of branching was estimated by periodate oxidation. The only monosaccharide detected was glucose. Three disaccharides, laminaribiose gentiobiose, and cellobiose, were detected, thus indicating β-1,3, β-1,6, and β-1,4 linkages. Acid-soluble β-1,3-glucan with single β-1,6-linked residues represented 40% of the wall. Alkali-soluble glucan, a linear polymer of β-1,3 and β-1,4 linkage with occasional β-1,6 side chains, represented 7% of the wall. Cellulose, as determined by solubility and X-ray diffraction represented 21% of the wall. The insoluble residuum (6%) which remained after these solubilizations had a linkage pattern similar to the alkali-soluble fraction. An insoluble component consisting of glucosamine represented 3% of the wall. Protein comprised 10% of the wall and on hydrolysis gave the full spectrum of amino acids including hydroxyproline. Small amounts of phosphorus were detected.
Infection of canine mononuclear leucocytes by measles virus: possible mechanism of protection from canine distemper
Authors: Ho C. K. , Babiuk L. A.
Published: May 2010

Measles virus was shown to be infectious to canine lymphocytes from peripheral blood as well as from different lymphoid tissues, and the same held true for canine macrophage cultures prepared from peripheral blood. The susceptibility of these leucocytes to measles virus was comparable with that of canine distemper virus. These observations supported the suggestion that interference with canine distemper virus by measles virus could be a possible mechanism of the heterotypic immunity observed in dogs.
The ultrastructure of Candida albicans infections
Authors: Marrie Thomas J. , Costerton J. William
Published: May 2010

Scrapings of Candida albicans plaques from the tongue and buccal mucosa of patients with oral candidiasis were examined electron microscopy. In addition, urine sediment from patients with infection of their catheterized urinary tracts was similar examined. Three types of C. albicans – oral epithelial cell interactions were noted: a loose adherence apparently mediated by ruthenium red positive matrix, a "tight" adherence where no space could be seen between the host and yeast cell, and invasions host cells by yeast hyphal elements. Adhesion of Candida blastospores to hyphal elements and adhesion of bacteria to Candida cells was also frequently observed.Urine sediments from patients with mixed bacteria–yeast infections demonstrated adhesion of the bacteria to the yeast cells. This phenomenon was also demonstrated in in vitro experiments and fibrous ruthenium red material invariably occupied the zo*** of adhesion.Phagocytosis of yeast by polymorphonuclear leukocytes was found in urinary, but not in oral, candidiasis. Our in vivo and vitro observations indicate that a ruthenium red positive matrix covers the surfaces involved in the yeast to yeast, yeast to ho and yeast to bacteria adhesion.
Comparison of numerical taxonomy and DNA–DNA hybridization in diurnal studies of river bacteria
Authors: Holder-Franklin M. A. , Thorpe A. , Cormier C. J.
Published: May 2010

Diurnal shifts in the predominant species of heterotrophic bacteria in a freshwater river have been detected by numerical taxonomy testing procedures. Owing to the modifications in the database which were required to accommodate the range of species in a natural system, it was necessary to substantiate the genetic homology of the clustering procedure. DNA hybridization of a cluster of Aeromonas hydrophila strains indicated that the cluster was 88.6% genetically homologous. The numerical methods grouped strains by physiological characteristics and this phenotypic similarity did not always coincide with the genetic relatedness of the strains. However, the diurnal changes in the predominant bacterial types can be demonstrated effectively by the database.
Modification of the poliovirus capsid by ultraviolet light
Authors: Sena John De , Jarvis Donald L.
Published: May 2010

Ultraviolet (UV) irradiation of type I poliovirus resulted in a modified (M) particle that had lost infectivity, lacked ability to adsorb to HeLa cells, lacked VP4, and was reduced in S value. Additional irradiation resulted in the loss of VP2, further reduction in S value, and permeability of the capsid to RNAse, This particle (C) as well as M contain the genome. Acid pH (5.5–6.5) and sulfhydryl-reducing substances (dithiothreitol, reduced glutathione, and L-cysteine) inhibited UV-induced modification of the capsid. UV irradiation at alkaline pH (7.5–8.5) resulted in more extensive modification of the capsid than irradiation at neutral pH. Ionic compounds were found to inhibit the modifying reaction.
An inducible iron-containing superoxide dismutase in Rhizobium japonicum
Authors: Stowers Mark D. , Elkan Gerald H.
Published: May 2010

Crude extracts of Rhizobium japonicum contained a single superoxide dismutase (SOD) as revealed by polyacrylamide gel electrophoresis. Rhizobium japonicum SOD was determined to be iron-containing by criteria of sensitivity to 5 mM H2O2 and 1 mM NaN3. Growth media strongly influenced SOD activity. The addition of methyl viologen to cultures of R. japonicum 61A76NS, growing in complex medium, caused induction of the enzyme. Yeast extract was essential for induction of SOD. Puromycin blocked the induction of the enzyme. Rhizobium spp. were surveyed for SOD activity, electrophoretic mobility on polyacrylamide gels, and metal content.
A new spiral structure associated with the flagellum of Azospirillum lipoferum
Authors: Nurmiaho-Lassila Eeva-Liisa , Haahtela Kielo , Sundman Veronica
Published: May 2010

N2-fixing strains of Azospirillum lipoferum, when grown in liquid culture, produce spiral structures, here named "spirae." The diameter of a spira varies between 40 and 55 nm and its length is variable. Each spira consists of a single helical thread, approximately 5 nm in diameter. These spirae are either attached to the cell, mostly wound around the single polar flagellum, or unattached in the culture medium.
A defined growth medium for the production of chloroperoxidase by Caldariomyces fumago
Authors: Pickard Michael A.
Published: May 2010

Ten strains of Caldariomyces fumago and related fungi were found to produce extracellular chloroperoxidase when grown on a glucose – malt extract medium. High enzyme levels and pigment production were observed for C. fumago ATCC 16373 and C. fumago CMI 89362. Removal of malt extract from the medium and the replacement of glucose by fructose as the carbon source provided a defined medium which, by comparison with the complex medium, produced the following results with both fungal strains. Chloroperoxidase was produced to similar levels, with maximum production after 6 days rather than 12 days of growth; pigmentation of the medium was reduced by 90% and the pH of the medium remained constant, thus stabilizing enzyme activity. Addition of urea or proline as a nitrogen supplement to nitrate enhanced enzyme production by strain CMI 89362. Comparison of the two strains indicated that CMI 89362 produced higher levels of chloroperoxidase than ATCC 16373.
Yersinia enterocolitica isolated from throats of swine in eastern and western Canada
Authors: Schiemann D. A. , Fleming C. A.
Published: May 2010

Examination of the throat flora from swine in Ontario for Yersinia enterocolitica found the incidence of serotype O:3 to vary from 20% for tonsils to 50% for throat swabs and 55% for tongues. In contrast, there were no isolations of serotype O:3 from throat swabs taken from swine in the western provinces of British Columbia and Alberta. This incidence of serotype O:3 in swine correlates well with the human incidence of the same serotype which is 81% for all human isolations of Y. enterocolitica in the eastern provinces and 4% in the western provinces of Canada. The opposite relationship is true for serotype O:5,27, which was not isolated from Ontario swine but occurred with a frequency of 3% in British Columbia swine and 24% in Alberta swine. The relative incidence in humans for serotype O:5,27 is 5% of all isolations of Y. enterocolitica in Ontario, 8% in British Columbia, and 26% in Alberta. Serotype O:8, the most common human serotype in the western provinces (40% of all isolations), was not isolated from swine in this survey. The majority of Y. enterocolitica cultures of biotype 4 (serotype O:3) and biotype 2 (serotype O:5,27) were positive for autoagglutination, a test which has been associated with virulence, whereas all cultures of biotype 1 were negative. The results from this study strongly suggest that swine are an important source of human infections with both serotype O:3 and O:5,27 of Y. enterocolitica. The source of human infections in western Canada with serotype 0:8 remains unidentified.
Detection of cellulase inhibitor in the wheat bran culture of Aspergillus terreus
Authors: Sinha S. N. , Ghosh B. L. , Ghose S. N.
Published: May 2010

The presence of a cellulase inhibitor in the wheat bran culture of a fungus is reported for the first time. The inhibitor has a low molecular weight and is relatively stable to heat. It is absent from wheat bran and is not produced in a chemically defined medium. Unlike cellulase inhibitors of plant origin, this inhibitor is not a polyphenol. It inhibits the hydrolysis of cotton to a greater degree than that of filter paper or carboxymethylcellulose. In addition to inhibiting Aspergillus terreus cellulase, it also inhibits a variety of commercial cellulases.
Effects of various inhibitory agents on sporulation of Bacillus subtilis
Authors: Takahashi I. , MacKenzie L. W.
Published: May 2010

Electron microscopic examinations of Bacillus subtilis cells revealed that relatively high concentrations of carbon sources blocked sporulation at stage 0 in most cells. Both nalidixic acid and novobiocin blocked sporulation at stage 0. The cells treated with acridine orange showed the morphology of stage IV 5 h after the end of exponential growth, but no further progression was observed. Mutants that are able to sporulate in the presence of these agents had the characteristic morphological changes observed in uninhibited cultures.
Morphologically abnormal sclerotia of Sclerotinia sclerotiorum
Authors: Huang H. C.
Published: May 2010

Morphologically abnormal sclerotia of Sclerotinia sclerotiorum were found in samples collected from diseased sunflower head and stem tissues. The frequency of abnormal sclerotia in 22 samples varied from 0 to 30%. Whereas the surface of normal sclerotia is macroscopically smooth and the medullary tissue is uniformly pale white, the surface of abnormal sclerotia is wrinkled and the center of the medullary tissue is brown or amber. The degree of abnormality varies among sclerotia. Some have a small discolored center surrounded by a thick medullary layer, whereas others have a large discolored center encircled by a thin medulla. Abnormal sclerotia also differ from normal ones in viability on culture media as well as in pathogenicity on sunflowers.
Bacterial populations associated with the Arctic amphipod Boeckosimus affinis
Authors: Atlas R. M. , Busdosh M. , Krichevsky E. J. , Kaneko T.
Published: May 2010

Microbial populations associated with the amphipod Boeckosimus affinis were examined using scanning electron microscopy and by detailed characterization of viable isolates. Bacterial populations were observed on food particles in the midgut, on the anal plates, and on faecal matter, but no bacteria were observed on the outer surfaces or on the gut lining of the amphipod. The dominant bacterial populations associated with the amphipods were in the Vibrio–Beneckea group. Exposure to petroleum hydrocarbons resulted in a decreased dominance of the vibriolike bacterial populations associated with the amphipods. During captivity (without feeding) there were successional changes in the bacterial populations associated with the amphipods; the diversity of the bacterial community increased and the bacterial populations became less stringent in their physiological and nutritional requirements.
Differential tolerance of hydroxylamine by an Alcaligenes sp., a heterotrophic nitrifier, and by Nitrobacter agilis
Authors: Castignetti Domenic , Gunner Haim B.
Published: May 2010

An Alcaligenes sp. isolated from soil and shown to be an active heterotrophic nitrifier was found to be highly tolerant of hydroxylamine. Growth of this organism occurred in medium containing as much as 235 mg NH2OH-N∙L−1. Joint culturing of the Alcaligenes sp. and Nitrobacter agilis in medium containing 18 mg NH2OH-N∙L−1 resulted in the eventual synthesis of nitrite and nitrate. However, N. agilis cultured separately in the presence of hydroxylamine at concentrations as low as 5 mg NH2OH-N∙L−1 was subsequently unable to convert nitrite to nitrate.
Cell-associated cations of the moderate halophile Micrococcus varians ssp. halophilus grown in media of high concentrations of LiCl, NaCl, KCl, RbCl, or CsCl
Authors: Kamekura Masahiro , Onishi Hiroshi
Published: May 2010

Micrococcus varians ssp. halophilus ATCC 21971 showed abundant growth in complex media containing 1 M NaCl, NaBr, NaI, NaNO3, Na2SO4, KCl, KBr, KI, or KNO3, and 2 M RbCl or RbBr at 30 °C.Spontaneous mutants were isolated which were able to grow in a medium of 1.5 M LiCl (strain Li-5) or 2.5 M CsCl (strain Cs-7-Cs). Determination of cell-associated cation concentration at the exponential phase of growth showed that the cells contained monovalent cations of almost equivalent concentration as that in the medium: 0.570 m Li+ + 0.951 m Na+ in 1.5 M LiCl grown cells; 2.88 m Na+ in 3.0 M NaCl grown cells; 2.66 m K+ in 3.0 M KCl grown cells; 1.57 m Rb+ in 2.0 M RbCl grown cells; 1.44 m Cs+ in 1.5 M CsCl grown cells.
The nature of human erythrocyte receptors for Neisseria gonorrhoeae
Authors: Wiseman G. M. , McNicol P.
Published: May 2010

Normal and trypsinized human erythrocyte membranes were used as a model in the study of host cell receptors for Neisseria gonorrhoeae. Receptor sites were identified by adherence inhibition assays of fractions of membranes eluted from polyacrylamide gel electrophoresis columns. Results indicated that inhibition of gonococcus T1 and T4 adherence was associated with erythrocyte protein bands 3 and 4 and glycophorin A, the major sialoglycoprotein. Further investigation revealed that band 3 preparations isolated by affinity chromatography on concanavalin A – Sepharose 4B columns continued to inhibit T1 adherence to erythrocytes but did not inhibit adherence of T4 organisms. It is suggested that protein band 3 is the receptor on erythrocytes for T1 gonococci and that glycophorin A may be the receptor for T4 cells.
Synchronisation of mitosis in a cell division cycle mutant of Schizosaccharomyces pombe released from temperature arrest
Authors: King Stephen M. , Hyams Jeremy S.
Published: May 2010

When cultures of Schizosaccharomyces pombe cdc 2.33 were shifted to 25 °C, after 5 h at the restrictive temperature of 35 °C, cells entered cycles of synchronous division as judged by the appearance of peaks in the cell plate index at 1.5, 3, and 4.75 h. The timing and ultrastructural morphology of events occurring in such synchronous cultures were examined. Most cells underwent mitosis between 10 and 50 min after the temperature shift, with a maximal value after approximately 30 min. The ultrastructure of mitosis was consistent with previous descriptions of this process in wild-type cells.
A rapid screening method for Rhizobium meliloti symbiotic nitrogenase activity
Authors: Sirois J. C. , Peterson E. A.
Published: May 2010

A method for screening Rhizobium meliloti isolates for their symbiotic nitrogenase activity with alfalfa (Medicago sativa L.) cv. Apollo is described. The nitrogenase activity of each isolate is assessed by measuring the reduction of acetylene (C2H2) to ethylene (C2H4) by 50 intact plants grown in 10 plastic pouches for 2 weeks. The method is rapid, sensitive, reproducible, and accurate enough to differentiate 29 Rhizobium isolates and 5 authentic strains into 13 subsets. Under the experimental conditions used, nodulation occurred within 5 days of inoculation and there was a significant positive relationship between the nitrogenase activity of those isolates which reduced more than 60 nmol C2H2∙plant−1∙h−1 and the dry weight of the shoots of the nodulated plants in 2 weeks of growth.
Leucine dissimilation to isovaleric and isocaproic acids by cell suspensions of amino acid fermenting anaerobes: the Stickland reaction revisited
Authors: Britz M. L. , Wilkinson R. G.
Published: May 2010

Freshly prepared cell suspensions of Clostridia (Clostridium bifermentans, C. botulinum proteolytic type A, C. difficile, C. sordellii, and C. sporogenes) and Peptostreptococcus anaerobius converted leucine to isovaleric (iV) and isocaproic (iC) acids in the absence of other amino acids. The optimal pH for conversion was between 8 and 9 at 37 °C. The stoichiometry of reaction was compatible with that expected for the Stickland reaction, as the ratio of iV to iC was 1:2, the amount of CO2 produced was equivalent to that of iV, and ammonium ion concentrations were equal to the total C5 and C6 acids formed. The presence of alanine and valine (proton donors in the Stickland reaction) in incubations effectively increased the concentration of iC at the expense of iV production, implying that leucine acted here primarily as a proton acceptor. Glycine and proline (proton acceptors) stimulated both iV and iC production from leucine, but increases in iV concentrations were proportionately greater than for iC, so that leucine was primarily a proton donor in the presence of proton acceptors. Glucose stimulated the conversion of leucine to volatile fatty acids but favoured iC production. Production of iC from leucine was inhibited by surface active compounds (cetyltrimethylammonium bromide and desoxycholate) as well as arsenite and iodoacetate. The redox dyes methyl viologen and phenosafranine inhibited iC production more severely than iV production, as did the nitroimidazole antimicrobial agent, metronidazole.
Effect of acetylene on autotrophic and heterotrophic nitrification
Authors: Hynes R. K. , Knowles R.
Published: May 2010

Acetylene (C2H2) strongly inhibited (Ki 0.25 μM or 0.66 Pa) the oxidation of ammonia (NH4+) to nitrite (NO2−) by Nitrosomonas europaea but did not affect the oxidation of hydroxylamine (NH2OH) to NO2− by this organism. We suggest that the C2H2-sensitive step is associated with the ammonia oxygenase. Oxidation of NH4+ was inhibited only approximately 50% by 0.4 mM (10 kPa) ethylene and by 2.1 mM (10 kPa) nitrous oxide and was unaffected by 0.1 mM (10 kPa) methane. The oxidation of NO2− to nitrate (NO3−) by Nitrobacter winogradskyi and of NH4+ to NH2OH and NO3− by the heterotrophic nitrifier, Arthrobacter sp., was not affected by 3.83 mM (10 kPa) C2H2.
Rapid detection of bacteremia caused by Enterobacteriaceae with subculture in broth and laser nephelometry
Authors: Bayardelle Paul , Brazeau Michel
Published: May 2010

The early detection of Gram-negative rod bacteremia favors the prompt institution of appropriate antimicrobial therapy. During a 6-week period, blood cultures were subcultured in broth during the first 18 h of incubation. The turbidity of these subcultures was studied by laser nephelometry. Fifty-five percent of the blood cultures positive for Enterobacteriaceae were reported on the same day the sample was taken from the patient; this constitutes a marked acceleration in comparison with the results obtained by a conventional method. The identification and results of the antimicrobial susceptibility tests were available 2 days after the specimen was taken. Early subculture in broth combined with laser nephelometry studies of broth turbidity is readily applied to the study of bacteremia due to Enterobacteriaceae and may favorably influence the outcome of such disease by providing specific results more rapidly.
Ultraviolet-induced autofluorescence of arbuscular mycorrhizal root infections: an alternative to clearing and staining methods for assessing infections
Authors: Ames Robert N. , Ingham Elaine R. , Reid C. P. P.
Published: May 2010

Arbuscules in vesicular–arbuscular mycorrhizal (VAM) infections in untreated roots autofluoresced when viewed with an epifluorescence microscope. Ultraviolet-induced fluorescence was observed with the same filtering system used to detect fluorescein staining. Plant roots were examined from five plant families, grown under a variety of conditions, and infected with several species of VAM fungi. In every case, autofluorescent arbuscules were observed. Vesicles, spores, and hyphae did not autofluoresce under these same conditions. Fluorescence was not observed in ectomycorrhizae or pathogenic fungal infections. Cut mycorrhizal root segments from greenhouse- and field-grown plants were evaluated for infection using ultraviolet light and clearing and staining. No significant differences were found in the percent VAM infection as determined by the two methods on the same root segments. Applications and considerations in the use of the ultraviolet method for measuring infections as well as some preliminary observations on using fluorescein diacetate are discussed.
Characterization of Bacteroides gingivalis by direct fluorescent antibody staining and cellular fatty acid profiles
Authors: Lambe Jr. Dwight W. , Ferguson Kaethe P. , Mayberry William R.
Published: May 2010

Bacteroides gingivalis is a newly proposed species which includes strains isolated from the mouth. Thirteen strains of B. gingivalis isolated from three geographic locations in the United States and France were examined with direct fluorescent antibody staining and analysis of total cellular fatty acids and compared with 16 strains of B. asaccharolyticus of nonoral origin by the same methods. Bacteroides gingivalis strains reacted with the B. gingivalis conjugate (fluorescein isothiocyanate labeled antibody reagent) only, while the B. asaccharolyticus strains reacted with the B. asaccharolyticus conjugate only. The B. gingivalis strains showed negative fluorescence with fluorescein isothiocyanate conjugates for other black-pigmented Bacteroides species. The specificity of the B. gingivalis conjugate was demonstrated by its failure to stain 88 strains of aerobic and anaerobic bacteria other than B. gingivalis. The fatty acid profiles of B. gingivalis and B. asaccharolyticus were readily distinguishable. The B. gingivalis profile was also distinguishable from those of other pigmenting Bacteroides species on the basis of concentration ratios among the characteristic components. These results support the species separation of B. gingivalis and B. asaccharolyticus. Further, they indicate the usefulness of cellular fatty acid profiles as an adjunct to the use of specific fluorescent antibody conjugates for identification of Bacteroides species.
The cell surface of Propionibacterium acnes: effect of specific chemical modifications on the ability of vaccines to produce splenomegaly in mice
Authors: Pringle Alastair T. , Cummins Cecil S.
Published: May 2010

The surface of Propionibacterium acnes, VPI 0009, was studied using microelectrophoresis following chemical treatments intended to modify specific charged groups. The effect of these specific chemical modifications on ability of cells to induce splenomegaly, an indicator of stimulation of the reticuloendothelial system, was also determined. There was little difference between pH mobility curves of P. acnes VPI 0009 and other strains of propionibacteria which were not able to stimulate the reticuloendothelial system. Amino and carboxyl groups were found to be the sole ionizable groups at the cell surface and modification of these groups caused a substantial decrease in the ability of cells to stimulate the reticuloendothelial system. No phosphate groups were detected. Evidence for two types of amino groups was found: one type was present on protein moieties and their modification did not affect ability to stimulate the reticuloendothelial system, whereas modification of the other type, which was present on carbohydrate moieties, caused a loss of ability to stimulate the reticuloendothelial system. Mild oxidation with sodium metaperiodate caused abolition of reticuloendothelial system stimulation, but had no effect on surface charged groups, indicating it was acting on the unsubstituted linkages of sugar residues. Treatments with strong acids caused abolition of ability to stimulate the reticuloendothelial system and this was accompanied by release of polysaccharide material.
Optimal conditions for induction of competence in nitrogen-fixing Azotobacter vinelandii
Authors: Page William J.
Published: May 2010

Competence development in nitrogen-fixing Azotobacter vinelandii cells was optimal at pH 7.2–7.4 which necessitated additional buffering of the iron-limited nitrogen-free competence medium or the addition of a suitable organic acid salt, e.g., sodium acetate. An autolysin was active in this pH range and competent cells were more susceptible to autolysis than the general cell population. Competence development also required restricted aeration of the culture, and only those cultures that attained zero dissolved oxygen became competent. Restricted aeration served to protect the iron-limited cell nitrogenase from oxygen inactivation thus allowing the culture to reach zero dissolved oxygen. The inclusion of additional sources of reductant, e.g., malate, in buffered competence medium resulted in increased respiration and protection of nitrogenase, increased cell mass, and poly-β-hydroxybutyrate synthesis, but decreased competence. A possible explanation for the apparent competition between competence development and nitrogenase activity is discussed.
Antibodies to Francisella tularensis in the snowshoe hare (Lepus americanus struthopus) populations of Nova Scotia and Prince Edward Island and in the moose (Alces alces americana Clinton) population of Nova Scotia
Authors: Akerman M. B. , Embil J. A.
Published: May 2010

A serological survey showed antibodies to Francisella tularensis present in 1.55% of snowshoe hares (Lepus americanus struthopus) and 1.06% of moose (Alces alces americana Clinton) sampled in Nova Scotia. No antibody-positive hares were found in Prince Edward Island, however. We believe this to be the first report of antibodies to F. tularensis in the moose.
The evolution of Antarctic yeasts: DNA base composition and DNA–DNA homology
Authors: Baharaeen Siavash , Bantle John A. , Vishniac Helen S.
Published: May 2010

The 16 biotypes of the Cryptococcus vishniacii complex of anamorphic yeasts (Basidioblastomycetes), unique to the Dry Valleys of Antarctica, include seven species separated by DNA–DNA homologies of less than 52%. Since species belonging to the complex can be as distantly related as C. bhutanensis (a Himalayan yeast, guanine + cytosine (G + C) 54.18 mol%) is to these species, a common ancestor probably originated and speciated outside of the Dry Valleys. The species C. vishniacii (G + C 54.52–55.48 mol%) comprises seven varieties with greater than 59% DNA–DNA homology and must therefore have been established in the Dry Valleys long enough to have evolved these divergent genomes. In the C. vishniacii complex, G + C values differing by more than 1 mol% are accompanied by DNA–DNA homologies of less than 23%.
Recombination-deficient mutations and thymineless death in Escherichia coli K12: reciprocal effects of recBC and recF and indifference of recA mutations
Authors: Nakayama Hiroaki , Nakayama Koji , Nakayama Ritsuko , Nakayama Yasuko
Published: May 2010

In an approach to characterizing the nature of the lethal event in thymineless death (TLD), rec mutants of Escherichia coli K12 were examined for their sensitivity to TLD. The recB21 and recC22 mutations sensitized cells of the AB1157 line to TLD but not cells of the HF4733 line. This increased sensitivity was not suppressed substantially by either sbcB15 or xonA1 mutation. In contrast, a recF mutation appeared to make cells more resistant to TLD than rec+ cells. Three different recA alleles were shown not to affect TLD appreciably. These results not only provide further support for the view that the site of the lethal event in TLD is cellular DNA, but also strongly suggest the involvement of the recBC and recF gene products in TLD. The apparent indifference of recA mutation implies that the conventional recombination and repair pathways per se are not involved in TLD and that the hypothetical lethal damage to DNA may be unique in nature.
Interaction of a biological control agent, Chaetomium globosum, with seed coat microflora
Authors: Hubbard J. P. , Harman G. E. , Eckenrode C. J.
Published: May 2010

The mechanism by which Chaetomium globosum, applied as ascospores to squash, snap bean, and pea seeds, reduces damage caused by larvae of the seed-corn maggot, Hylemya platura (Meigen), and soilborne plant pathogens was investigated. Chaetomium globosum ascospores germinate rapidly and cover the seed coat with a dense mat of mycelium soon after seeds are planted in soil. However, if seeds are not treated with C. globosum before planting, other organisms rapidly colonize the seed coat during germination. Seed flies oviposit near seeds in response to the growth of pseudomonads on the seed surface. Studies employing a selective medium indicate that Pseudomonas become the most prevalent genus occurring on the seed coat during seed germination. Treatment of seed with C. globosum suppresses the logarithmic growth of pseudomonads on the seed coat but affects neither bacterial populations in the soil surrounding the seed nor germination of Fusarium solani f. sp. pisi chlamydospores, either on the seed coat or in the soil surrounding the seed. A water-insoluble antibiotic was extracted from C. globosum treated seeds. After systemtic examination of other possibilities, it was concluded that this nondiffusable antibiotic substance produced by C. globosum suppresses pseudomonads responsible for stimulation of oviposition by seed flies as well as the soilborne plant pathogens.
Nitrogenase activity associated with Zostera marina from a North Carolina estuary
Authors: Smith Garriet W. , Hayasaka Steven S.
Published: May 2010

Nitrogenase activity (at in situ temperatures) associated with Zostera marina reflected the active growth periods of this plant in North Carolina coastal waters. During the plants most active growth period (late winter – spring) nitrogenase activity was primarily rhizospheric (8.47 μmol nitrogen fixed∙m−2∙day−1), while during its fall – early winter period it was primarily phyllospheric (8.03 μmol nitrogen fixed∙m−2∙day−1). No nitrogenase activity was detected during the warmer summer months when the plant is dormant. Phyllospheric nitrogenase activity (possibly the result of epiphytic heterocystic blue-green bacteria) was highest when plants were incubated aerobically in the presence of light.
Isolation and identification of N2-fixing bacteria associated with sugar cane (Saccharum sp.)
Authors: Rennie R. J. , Freitas J. R. de , Ruschel A. P. , Vose P. B.
Published: May 2010

Acetylene-reducing bacteria isolated from the setts (stem cuttings used as seed pieces) and roots of two sugar cane varieties propagated aseptically from stem cuttings were identified using a computer-assisted scheme based on 75 biochemical tests. Because 106 to 108 acetylene-reducing bacteria per gram (fresh weight basis) were found in the roots, while 10 to 100 times fewer were present in the sett, we suggest that the root is the site of bacterial multiplication. Sterilization of the sett surface before planting or root sterilization at harvest reduced or completely removed acetylene-reducing bacteria and associated whole plant acetylene-reducing activity. This indicates that most of the active bacteria were on the sett and root exteriors. Setts did not exhibit acetylene-reducing activity until after emergence of the roots. Since shoot emergence was not necessary for acetylene-reducing activity, the extensive carbohydrate supply of the sett itself must have provided the carbon substrate for bacterial N2 fixation. The acetylene-reducing bacteria isolated were facultative anaerobes of the families Enterobacteriaceae and Bacillaceae. Klebsiella pneumoniae, Enterobacter cloacae, Erwinia herbicola, and Bacillus polymyxa were present inside the sett and the roots but E. herbicola was the dominant bacterium on the root exterior. No Beijerinckia spp. or Azotobacter spp. were found associated with the sett or the roots.
The effect of decomplementation on the infectious course of Sendai virus in mice
Authors: Finnie J. C. , Aston W. P. , O'Shaughnessy M. V. , Stewart R. B.
Published: May 2010

The course of an intranasal infection of Sendai virus in CBA and DBA mice was investigated in animals decomplemented with purified cobra venom factor. The mice were decomplemented either immediately before inoculation or at 4 days postinfection. Depletion of complement after the infection had been established had no apparent effect on the course of the viral infection in the two strains of mice. In contrast, both strains of mice were protected completely from the lethal effects of an infectious dose of 1 LD50 of virus when the serum C3 levels were depressed by more than 80% during the early stages of infection. The symptoms of morbidity were less pronounced in these animals and there was a delay in the production of hemagglutination-inhibiting antibody. There was no apparent effect on the growth of the virus in lung tissue. The results suggest that the complement system plays a significant pathogenic role during the course of Sendai virus infections in CBA and DBA mice.
Dietary influence on microbial activities in the caecum of mice
Authors: Brockett Michelle , Tannock Gerald W.
Published: May 2010

The nature of the diet (pellets, wheat, breakfast bran) ingested by conventional mice influenced the microbial production of indole, β-glucuronidase, urease, and volatile fatty acids in the caecum. We also observed that the nature of the mouse strain influenced the amount of urease activity present in the caecum.
Thermophilic biomethanation of acetic acid: morphology and ultrastructure of a granular consortium
Authors: Bochem H. P. , Schoberth S. M. , Sprey B. , Wengler P.
Published: May 2010

The ultrastructure of a thermophilic methanogenic consortium appearing as morphologically distinct bacterial granules (up to approximately 3 mm in diameter) has been studied. The consortium was enriched and maintained at 60 °C in continuous culture in a defined mineral – vitamin – acetic acid medium at a hydraulic retention time of 44 h. Thin-section electron microscopy showed three morphologically distinct layers of the granules. (1) The outer division zone bears resemblance to a pseudoparenchyma and consists of "macrocysts" and coccoid cells, resembling Methanosarcina cells. (2) The inner zone is built up of loosely packed ovoid cells and (3) internal cavities containing rods.The cavities were the exclusive site of gas formation, as shown with a specially designed minifermenter allowing direct light microscopic observation of gassing granules. Based on labeling studies with cationic ferritin and scanning electron microscopy a working model for methane formation from acetate by the consortium is presented.
Isolation of Frankia from nodules of Casuarina equisetifolia
Authors: Diem H. G. , Gauthier D. , Dommergues Y. R.
Published: May 2010

Using the simple serial dilution technique, five strains of actinomycetes were isolated from nodules of Casuarina equisetifolia. In spite of the fact that these strains did not nodulate the host plant, they were assumed to belong to the genus Frankia because they possessed the morphological and cultural characteristics now admitted as specific to this genus.