bluuebunny/crossref_metadata_2025 huggingface dataset:
Fatty acid regulation of the germination of Erynia variabilis conidia on adults and puparia of the lesser housefly, Fannia canicularis
Authors: Kerwin James L.
Published: May 2010

Conidia of the entomogenous fungus Erynia variabilis germinate vegetatively on the cuticular surface of adults of the lesser housefly, Fannia canicularis, and on a basal agar growth medium in which cuticular lipid extracts of adult flies have been incorporated. Formation and discharge of secondary spores occur on puparial cuticles and on media in which puparial cuticle lipid extracts have been included. Relative free fatty acid compositions of puparial and adult cuticle lipid extracts are nearly identical, but adults average ca. five times the concentration of free fatty acids on their cuticle surface as that found on puparia. A regulatory role for esterified fatty acids in conidial germination is suggested. Limitation of E. variabilis to adult dipteran hosts is postulated to be due in part to characteristics of the fatty acids of this order of insects: the presence of sufficient oleic acid to induce germination; high levels of palmitoleic acid to enhance mycelial growth; and low levels of linoleic and linolenic acids, which have deleterious effects on spore germination and mycelial proliferation.
The relationship between yeast cell size and cell division in Candida albicans
Authors: Chaffin W. LaJean
Published: May 2010

The mean size and percentage of budded and unbudded cells of Candida albicans grown in batch culture over a wide range of doubling times have been measured. Cell volume decreased with increased doubling time and a nonlinear approach to an asymptotic minimum was observed. When cells were separated by age according to bud scars, each age showed a similar decrease. During each cell division cycle, size increased slowly during both budded and unbudded periods so that each generation was significantly larger than the preceeding. There was no difference in size between the parent portion of budded cells and unbudded cells of the same age. Time-lapse photomicroscopy of cells growing on solid medium showed that cells divide asymmetrically with larger parents having a shorter subsequent cycle time than the smaller daughter, although the time utilized for bud formation was similar. When cells were shifted from a medium supporting a low growth rate and small size to a medium supporting a faster growth rate and larger size, both budded and unbudded cells increased significantly in size. As the doubling time increased, both the budded and unbudded portions of parental and daughter cycles increased.
Metal binding by the peptidoglycan sacculus of Escherichia coli K-12
Authors: Hoyle B. D. , Beveridge T. J.
Published: May 2010

The peptidoglycan of Escherichia coli K-12 strain AB264 was isolated by treating whole cells with sodium dodecyl sulfate and was purified by deoxyribonuclease, ribonuclease, and trypsin treatment. Like the peptidoglycan of Bacillus subtilis, this peptidoglycan proved able to bind substantial amounts of metallic ions from aqueous solution. In particular, most metals of the transition I series were bound from solution in amounts ≥ 1 μmol/mg dry weight peptidoglycan.
In vitro experiments concerning the state of polyphosphate in the yeast vacuole
Authors: Miller J. J.
Published: May 2010

Globules resembling the cytological entity volutin were produced in vitro by mixing solutions of polyphosphate and certain cationic substances known to occur abundantly in the yeast vacuole, i.e., S-adenosylmethionine, Mg2+, and K+. Other cationic substances found to form globules with polyphosphate were Mn2+, Zn2+, Ca2+, Cd2+, S-adenosylethionine, spermidine, and spermine. Cationic amino acids did not form a precipitate with polyphosphate and at low concentrations they inhibited precipitation of globules of polyphosphate–S-adenosylmethionine. Two other polyanions, dextran sulfate and ribonucleic acid, also formed globular precipitates with S-adenosylmethionine. Conditions affecting the formation and stability of polyphosphate–S-adenosylmethionine precipitates were studied in an attempt to reproduce certain characteristics of vacuolar polyphosphate "granules." Procedures commonly used for extraction of polyphosphate from yeast were applied to in vitro granules and the results indicated that part of the "acid-insoluble" fraction of the polyphosphate extracted from yeast cells may exist in combination with S-adenosylmethionine.
Evidence for a membrane-bound form of a bacteriocin of Bacteroides uniformis Tl-1
Authors: Austin-Prather Sandra L. , Booth S. James
Published: May 2010

The bacteriocin of Bacteroides uniformis Tl-1 had previously been reported to have a molecular weight of ≥ 300 000. Reexamination of the B. uniformis bacteriocin revealed that the bacteriocin was found in association with membrane vesicles which had been released by bleb formation from the outer surface of the B. uniformis cells. The bacteriocin could be released from whole cells or purified membrane vesicles by treatment with 6 M guanidine hydrochloride or 7 M urea and had an apparent molecular weight of 5000–6200.
Evaluation of a pour-plate system with a rabbit plasma – bovine fibrinogen agar for the enumeration of Staphylococcus aureus in food
Authors: Beckers H. J. , Leusden F. M. Van , Bindschedler O. , Guerraz D.
Published: May 2010

Investigations were carried out concerning the selectivity and productivity of rabbit plasma fibrinogen (RPF) agar according to Beckers et al. (H. J. Beckers, F. M. van Leusden, W. M. Hogeboom, and E. H. M. Delfgou-van Asch. 1980. De Ware(n)-Chemicus, 10: 125 – 130). Its selectivity was compared with pork plasma fibrinogen (PPF) medium according to Hauschild et al. (A. H. W. Hauschild, C. E. Park, and R. Hilsheimer. 1979. Can. J. Microbiol. 25: 1052–1057) and its productivity was compared with PPF medium and Baird-Parker's egg yolk tellurite glycine pyruvate (ETGP) agar. In total 139 samples of naturally contaminated foodstuffs were examined. RPF agar scored higher than ETGP agar; although only small (mean value of differences 0.09 log units), the differences were statistically significant. While no significant differences in sensitivity between RPF agar and PPF medium were encountered, RPF agar was statistically more selective than PPF medium. It is concluded that RPF agar is very suitable for the enumeration of Staphyloccus aureus in foods.
An assay for the measurement of the protein content of cells immobilized in carrageenan
Authors: Jones A. , Razniewska T. , Lesser B. H. , Siqueira R. , Berk D. , Behie L. A. , Gaucher G. M.
Published: May 2010

A reliable and reproducible method for the estimation of the protein content of fungal cells immobilized in a carrageenan gel is described. The procedure depends upon the acid lability of the polysaccharide gel at 90 °C and on the acetone solubility of accumulated phenolics. Freeze-dried gel beads (2–3 mm) containing entrapped cells of Penicillium urticae were ground to a fine powder and samples of powder (~20 mg) were sequentially extracted with hot 1 N HCl – 0.9% NaCl and acetone. The precipitated residue contained the cell protein, which was then solubilized with 1 N NaOH at 90 °C and quantitated by the Folin–Lowry method. Interferences from both carrageenan and phenols were thus eliminated. The presence of carrageenan (20–25 mg) did not affect the recovery of varying amounts (0–2500 μg) of bovine serum albumin. The recovery of radiolabeled protein from immobilized cells was parallel to that of Folin–Lowry positive material over a range of 0–60 beads (0–60 mg powder). Cycloheximide (0–100 μg/mL) was shown to progressively inhibit the incorporation of L-[U-14C]leucine so that the radioactivity present in the initial HCl–NaCl extract (i.e., [14C]leucine) increased as that in the final NaOH extract (i.e., 14C-labeled protein) decreased. Using this new assay for cell protein, free and immobilized cell cultures were found to exhibit virtually identical kinetics of glucose utilization, growth, and patulin production. In addition to providing a means of comparing the specific productivity of free versus immobilized cell preparations, this assay accurately measures the incorporation of [14C]leucine into cellular protein and could be used as a measure of cell viability.
Construction of a shuttle vector and expression in Streptomyces lividans of the sulfonamide-resistance gene derived from Escherichia coli plasmid pSAS1206
Authors: Shareck F. , Sasarman A. , Vézina Claude
Published: May 2010

We have constructed a hybrid plasmid using Streptomyces lividans plasmid pIJ 101 and Escherichia coli plasmid pSAS1206. This plasmid, designated pFSH102, is able to replicate in both hosts and the sulfonamide-resistance gene encoded by pSAS1206 is phenotypically expressed in S. lividans.
Glucosamine substitution and muramidase susceptibility in Bacillus anthracis
Authors: Zipperle Jr. Gene F. , Ezzell Jr. John W. , Doyle Ronald J.
Published: May 2010

Cell walls of Bacillus anthracis were found to be resistant to lysozyme, and partially resistant to mutanolysin, a muramidase from Streptomyces globisporus. Following treatment with acetic anhydride, it was observed that the walls were highly susceptible to hydrolysis by lysozyme or mutanolysin. Analyses of cell walls, prior to and following derivatization with fluorodinitrobenzene, revealed that approximately 88% of the glucosamine residues and 34% of the muramic acid residues of the peptidoglycan contained unsubstituted amino groups, thereby providing an explanation for the resistance of the walls to lysozyme. The walls of B. anthracis were approximately 19% cross-linked, based on the findings that 81% of the diaminopimelic acid residues could be modified by fluorodinitrobenzene. Walls of B. thuringiensis 4040 and B. cereus ATCC 19637 also contained high percentages of unsubstituted amino sugars, and unless acetylated, were also relatively resistant to lysozyme and mutanolysin. When B. anthracis, B. cereus, or B. thuringiensis were grown in the presence of 100 μg/mL lysozyme, there was a decrease in the average number of cells per chain, but there was no decrease in growth rates, suggesting that the enzyme was acting at septa. It is unlikely that lysozyme and autolysins act synergistically in Bacillus, because azide anion, which activates autolysins, did not enhance the lytic action of lysozyme in B. anthracis, B. cereus, or B. thuringiensis.
Oil-degrading capabilities of yeasts and fungi isolated from coastal marine environments
Authors: Fedorak P. M. , Semple K. M. , Westlake D. W. S.
Published: May 2010

Seventy-four yeasts and 224 fungi were isolated from marine water and sediment samples taken from the Strait of Juan de Fuca and northern Puget Sound. When these isolates were grown in the presence of Prudhoe Bay crude oil, only three yeasts and 63 fungi were able to degrade some or all of the n-alkanes. None degraded the isoprenoids, pristane and phytane. Forty-seven isolates were identified as Penicillium species and of these, 39 attacked the n-alkanes in the crude oil. Twelve organisms which degrade n-alkanes were tested for their ability to mineralize [14C]naphthalene and [14C]phenanthrene which had been added to the crude oil. No 14CO2 was detected from any of the cultures containing these compounds. Capillary gas chromatographic analyses of the aromatic fractions from these 12 cultures showed no loss of hydrocarbons or sulfur hetero-cycles, indicating that they were unable to completely or partially oxidize any of the resolvable compounds in this fraction.
The nucleotide sequence homologies of unique DNA's of some cultivated and wild mushrooms
Authors: Horgen Paul A. , Arthur Richard , Davy Olia , Moum Ann , Herr Frank , Straus Neil , Anderson James
Published: May 2010

The unique sequence DNA's of several wild and cultivated fungi including Agaricus brunnescens (=Agaricus bisporus), Agaricus bitorquis, Amanita muscaria, Amanita phalloides, Pleurotus ostreatus, Lentinus edodes, and Schizophyllum commune were compared by DNA–DNA hybridization. In addition, the characterization of a number of fungal DNA's are reported for the first time. Unique sequence DNA from Agaricus brunnescens and P. ostreatus was labeled by nick translation and each was hybridized with an excess of unlabeled driver DNA. Unique sequence DNA from two different isolates of Agaricus brunnescens showed nearly complete homology with one another, while only 56% of the unique sequence DNA from Agaricus bitorquis hybridized with the same Agaricus brunnescens DNA. Furthermore, very little sequence homology existed between Agaricus brunnescens DNA and the DNA's of the other mushrooms studied. Similarly, very little hybridization occurred between P. ostreatus labeled DNA and the DNA's of the other species. The stability of the DNA duplexes was examined by thermal elution. The Tm of Agaricus brunnescens:Agaricus bitorquis duplexes was 7.7 °C lower than Agaricus brunnescens:Agaricus brunnescens duplexes. This indicated a 7.7–11.6% mismatch between the unique DNA's of these two species.
Sporulation of Gigaspora margarita on root cultures of tomato
Authors: Miller-Wideman M. A. , Watrud L. S.
Published: May 2010

Use of germinated spores of Gigaspora margarita as inoculum on tomato root culture plates routinely resulted in successful mycorrhizal infections in more than 85% of inoculated root cultures. Penetration into the root, vesicle formation, arbuscule production, and new spore formation were reproducibly observed. This represents the first description of spore formation by G. margarita under aseptic conditions.
Rotavirus survival in conventionally treated drinking water
Authors: Sattar S. A. , Raphael R. A. , Springthorpe V. S.
Published: May 2010

Samples of conventionally treated drinking water collected either as effluent (PE) at a treatment plant or out of a tap (TW) in our laboratory were seeded with simian rotavirus SA-11, which closely resembles rotavirus of human origin. The virus, grown in MA-104 cells, was suspended either in distilled water, Earle's balanced salt solution (EBSS), or tryptose phosphate broth (TPB), and added to the water samples to a final concentration of 5.7 × 103 plaque-forming units (PFU) per millilitre. After a contact time of 1 h at 22 °C, the samples were diluted and plaque assayed. There was no significant reduction in the virus titre in samples of TW (<0.05 mg/L free chlorine). The titre also remained almost the same in PE (0.75 mg/L free chlorine) when EBSS or TPB was used for virus suspension. There was, however, nearly a 1 log10 loss in the titre of the virus when it was suspended in distilled water before the contamination of PE. To study the long-term survival of the rotavirus in TW, the inoculated samples (5.0 × 104 PFU/mL) were held at either 4 or 20 °C in the dark and tested over a period of 64 days. At 20 °C it took 64 days to reduce the virus titre by 2 log10, whereas at 4 °C the virus titre dropped only 0.7 log10 during the same period. Rotaviruses could, therefore, survive well enough in conventionally treated drinking water to make it a possible vehicle for their transmission.
The effect of salt concentration on the phospholipid and fatty acid composition of the moderate halophile Vibrio costicola
Authors: Hanna Kim , Bengis-Garber Carmela , Kushner D. J. , Kogut Margot , Kates Morris
Published: May 2010

The major lipids of Vibrio costicola membranes and whole cells are phosphatidyl glycerol and phosphatidyl ethanolamine. Lesser amounts of lysophosphatidyl ethanolamine, cardiolipin, a glycolipid, and two other phospholipids, tentatively identified as lysocardiolipin and lysophosphatidyl glycerol, are also present. Phosphatidyl glycerol content markedly increased, whereas that of phosphatidyl ethanolamine decreased, with increasing salt concentration (0.5 to 3 M NaCl) in the growth medium. These changes result in an increase in the mole ratio of negatively charged polar lipids to neutral polar lipids. Little effect of growth phase on the proportions of the lipid components or their fatty acids was observed in cells grown in 1 M salt. The major fatty acids found were 16:0, 16:1, and 18:1; minor amounts of 14:0, 17:1, and 18:0, and traces of 12:0, 12:1, 14:1, 15:0, 15:1, and 17:0 were also found. The proportions of certain fatty acids also changed with changing salt concentration in the medium.
Prevalence of extreme detergent resistance among the Enterobacteriaceae
Authors: Kramer Vance C. , Nickerson Kenneth W. , Hamlett Nancy V. , O'Hara Caroline
Published: May 2010

The detergent-resistance properties of 208 independent isolates of the Enterobacteriaceae have been examined. Of these bacterial strains, 200 were able to grow in the presence of ≥ 5% sodium dodecyl sulfate, including all members of the Klebsielleae tribe. This resistance does not appear to be plasmid encoded. It is proposed that detergent-resistant organisms be termed saponotolerant or saponophilic, by analogy with other microorganisms occupying harsh ecological niches. In contrast to their prevalent resistance to anionic detergents, not one of the 208 strains tested was found to grow in the presence of three different cationic detergents. This sensitivity to cationic detergents may be of significance in combating nosocomial infections.
Studies on antibiotic biosynthesis by protoplasts and resting cells of Streptomyces echinatus. Part I. The synthesis of echinomycin
Authors: Gauvreau D. , Waring M. J.
Published: May 2010

Washed suspensions of Streptomyces echinatus, and protoplasts derived from them, have been shown to synthesise echinomycin in the absence of growth. Protoplast suspensions free from significant contamination with unlysed mycelia are obtained by incubation with lysozyme followed by filtration through layers of tightly packed glass wool. Although physiologically young cells produce a better yield of protoplasts, optimal antibiotic biosynthesis is achieved with protoplasts prepared from mycelia about to enter the stationary phase of growth, i.e., approximately 24 h after inoculation into a nutrient broth – salts seed medium. As judged by the incorporation of label from L-[methyl-14C]methionine, echinomycin synthesis proceeds for about 1 h after preparation of washed suspensions, but the kinetics of incorporation by intact cells and protoplasts are different. Uptake of labelled methionine by protoplasts is critically dependent upon the presence of sucrose as osmotic stabiliser and is drastically reduced if galactose, calcium, or magnesium is omitted from the suspending buffer. Uptake by intact, washed cells is essentially independent of nutrients in the medium. Small quantities of 11 materials other than echinomycin are detectable in chloroform extracts after labelling with L-[methyl-14C]methionine; some of these may represent precursors in the biosynthesis of the antibiotic. All amino acid constituents of echinomycin as well as tryptophan, a putative precursor of the quinoxaline chromophores, are actively incorporated into echinomycin by protoplasts and resting cells, but not with equal efficiency.
Levels of trehalose and glycogen in Frankia sp. HFPArI3 (Actinomycetales)
Authors: Lopez Mary F. , Fontaine Mark S. , Torrey John G.
Published: May 2010

The levels of soluble trehalose were compared in Frankia sp. ArI3 under various conditions in batch culture. Trehalose appears to be a specialized carbon reserve which is synthesized upon transfer of cultures to fresh medium; thereafter it is metabolized and broken down. Levels reach a peak of 10–20% cell dry weight depending on cultural conditions, then drop to a minimum of 1–2% cell dry weight. A similar pattern is observed whether cells are grown in a medium containing NH4Cl or in a medium lacking nitrogen substrates; however, the total levels of trehalose are higher in the latter. The levels of endogenous trehalose showed an inverse correlation with a sharp increase in nitrogenase activity. When cells were inoculated into a medium lacking nitrogen to induce fixation of atmospheric nitrogen, trehalose levels reached their peak in 4 days. The nitrogenase activity (measured with the acetylene reduction technique) increased sharply on the 4th to 5th day. Trehalose levels fell sharply from day 4 to day 5; when they fell to half their maximum, nitrogenase activity decreased sharply. Thereafter, the decline in trehalose concentration paralleled that of nitrogenase activity. When cells were washed free of exogenous carbon, the endogenous trehalose levels dropped to half the initial value in 1 h. The cells continued to respire for 2 days on endogenous reserves. In addition to trehalose, glycogen reserves were extracted from Frankia. At its maximum, the glycogen totalled approximately 10% of the dry weight of cultures grown on a medium supplemented with NH4Cl as exogenous nitrogen source, and decreased to ca. 1.0% dry weight in starved cultures. Glycogen did not accumulate significantly in cultures that were induced to fix nitrogen.
Induction and repression of L-fucose dehydrogenase of Pullularia pullulans
Authors: Conter P. F. , Guimarães M. F. , Veiga L. A.
Published: May 2010

The growth of Pullularia pullulans on L-fucose as the sole carbon source induces the synthesis of L-fucose dehydrogenase, a NAD-dependent enzyme that catalyzes the oxidation of L-fucose to L-fucono-δ-lactone, which spontaneously hydrolyzes to L-fuconic acid. The induction of the enzyme is inhibited by cycloheximide, suggesting de novo synthesis. D-Glucose, D-galactose, and glycerol at 0.5% concentration gave rise to 62, 54, 51, and 46% of repression of enzyme synthesis, respectively. No repression effect was detected with D-arabinose and L-rhamnose. L-Arabinose repressed only 20% of the enzyme synthesis. Among the sugars tested, only L-fucose and L-galactose were oxidized by the enzyme. L-Galactose, which shares a common ring structure with L-fucose, showed only 10% of the activity observed when L-fucose was used.
Pseudomonas bacteriophage contains an inner body in its capsid
Authors: Krylov V. N. , Smirnova T. A. , Minenkova I. B. , Plotnikova T. G. , Zhazikov I. Z. , Khrenova E. A.
Published: May 2010

Electron microscopical examination of the new virulent bacteriophage [Formula: see text], specific for Pseudomonas aeruginosa, has revealed an unusual structure in its capsid. In the center of the phage head is a cylinder of low electron density ("inner body"), surrounded by fibrous material which is packed around the inner body in a spoollike manner. The inner body itself has a springlike appearance. These structures disappear after adsorption of phage particles to bacteria. Various morphological forms, which can be interpreted as intermediate steps in [Formula: see text] DNA condensation, have been seen in ultrathin sections of [Formula: see text]-infected cells.
Temperature regulation of nuclear division in apomictic yeast
Authors: Bilinski Carl A. , Miller John J.
Published: May 2010

The effect of temperature on nuclear division and spore formation in an apomictic, two-spored strain of Saccharomyces cerevisiae (19e1) was investigated. Presporulation culture at 36 °C increased markedly the frequency of asci containing three or four spores that developed in sporulation medium, indicating a morphogenic role for temperature in control of meiosis in apomictic yeast. Mild temperature shock treatments administered to cells shortly after transfer from presporulation to sporulation medium also promoted nuclear division and three classes of asci developed: binucleate, trinucleate, and tetranucleate. Nuclear divisions were not always completed before the onset of spore formation in trinucleate asci.
Control of white rot of garlic by antagonistic fungi under controlled environmental conditions
Authors: Oliveira Vetúria L. de , Bellei Margarida de M. , Borges Arnaldo Chaer
Published: May 2010

Several fungi were isolated from soil samples collected in areas with a high incidence of white rot disease of garlic at Amarantina county, Minas Gerais, Brazil. After the screening in vitro for antagonists to Sclerotium cepivorum, three fungi were found to be highly inhibitory to the pathogen. These fungi were identified as Trichoderma harzianum Rifai, Paecilomyces lilacinus (Thom.) Samson, and a Penicillium sp. The three antagonists produced in vitro nonvolatile antibiotics towards Sc. cepivorum. These substances were thermolabile (120 °C, 15 min) and significantly inhibited the growth of Sc. cepivorum. Interactions between the pathogen and each antagonist, studied by a dual slide-mount technique, showed that Pa. lilacinus and Penicillium sp. caused an inhibition halo to Sc. cepivorum although hyphal contact never occurred. Trichoderma harzianum showed inhibitory activity at a distance, and after contact with Sc. cepivorum, caused hyphal cytoplasm disintegration and cell wall collapse. This detrimental effect occurred either after direct penetration of the cell wall or after the formation of "coilings." The efficacy of the three antagonists in the biocontrol of white rot was tested under controlled environmental conditions in a nonsterilized, artificially infested soil (1 sclerotia per gram of soil). Trichoderma harzianum VL1 applied as a conidial suspension (106 conidia/mL) during the transplanting period significantly reduced the severity of white rot and increased the number of healthy plants when compared with the untreated control. Trichoderma harzianum gave significantly better protection to the plants than Coniothyrium minitans, a known biocontrol agent of sclerotia-forming fungi. Paecilomyces lilacinus, Penicillium sp., and the mixture of the three antagonists gave no protection against the disease.
Effects of various parameters on carbon monoxide oxidation by ammonium oxidizers
Authors: Jones Ronald D. , Morita Richard Y.
Published: May 2010

The effects of temperature, pH, nitrogen source, cell concentration, and the interactions between ammonium and carbon monoxide were examined with respect to the oxidation of carbon monoxide by several chemolithotrophic ammonium-oxidizing bacteria. The ammonium oxidizers Nitrosomonas europaea, Nitrosomonas sp. 4W30, a marine isolate, and Nitrosococcus oceanus were examined. All of the organisms were able to oxidize significant amounts of CO over wide ranges of temperature and pH. Ammonium at concentrations as low as 1 mg/L [Formula: see text] N initially inhibited CO oxidation in all three organisms; however, after 48 h, the presence of ammonium stimulated the CO-oxidizing ability of Nitrosomonas europaea and Nitrosomonas sp. 4W30, while Nitrosococcus oceanus remained inhibited. None of the other nitrogen sources examined had a significant effect on CO oxidation. No carbon from CO was incorporated into cellular material in the absence of ammonium, even in the presence of alternate nitrogen sources. Cells incubated in the presence of ammonium at concentrations as low as 1.0 mg/L [Formula: see text] N were able to incorporate CO carbon into cellular material. Increasing [Formula: see text] N concentrations to 50 mg/L stimulated the incorporation of CO carbon by Nitrosococcus oceanus. Concentrations of 10 mg/L gave the highest incorporation levels for Nitrosomonas europaea and Nitrosomonas sp. 4W30 and 50 mg/L inhibited the incorporation by these two organisms. The presence of CO inhibited the oxidation of ammonium by all of the organisms tested.
Multiplicity of extracellular β-(1,4)-endoglucanases of Bacteroides succinogenes S85
Authors: Schellhorn H. E. , Forsberg C. W.
Published: May 2010

During growth on 0.2% (w/v) microcrystalline cellulose, Bacteroides succinogenes S85 produces endoglucanase activity which can be separated by centrifugation into sedimentable and nonsedimentable fractions. The sedimentable activity, after solubilization with Triton X-100, was resolved into four components by ion-exchange chromatography and these were further fractionated by nondenaturing polyacrylamide gel electrophoresis (PAGE). The nonsedimentable activity contained three enzymic components as determined by gel filtration. Like the preparations derived from the sedimentable fraction, these components yielded a multiplicity of endoglucanases when electrophoresed under nondenaturing conditions. The fractions obtained by ion-exchange chromatography and by gel filtration were assayed for endoglucanase activity by both viscometric assays and reducing sugar production using carboxymethylcellulose as the substrate. Plots of the fluidity change in the enzyme–substrate preparation in relation to reducing sugar production revealed the presence of two distinct groups of endoglucanases differing in catalytic activity. Two of the components from the nonsedimentable fraction had more exoglucanase-like activity than either the third nonsedimentable fraction or any of the four fractions derived from the sedimentable material. These two enzymes could be further differentiated on the basis of glucose production from microcrystalline cellulose and by their relative activity toward p-nitrophenyl cellobioside, a chromogenic substrate.
Bulking in an industrial wastewater treatment system due to Geotrichum candidum
Authors: Meyers Jr. A. J.
Published: May 2010

During a brief period of low pH in the primary aeration basin of an industrial wastewater treatment system, severe sludge settling problems (i.e., bulking) occurred. Microscopic examination of the sludge solids revealed a profusion of fungal hyphae disrupting proper floc formation. A yeastlike fungus was isolated from the sludge capable of growth on compounds common to the treated chemical waste and with a preference for lower pH values. The fungus, identified as Geotrichum candidum, disappeared from the sludge upon raising the pH of the aeration basin with the concomitant return of normal settling characteristics.
Ammonia-induced mycostasis is not mediated by enhanced release of carbon compounds
Authors: Löffler H. J. M. , Schippers B.
Published: May 2010

Ammonia applied as NH4Cl in a Tris–HCl buffered solution (pH 7.5 or 8.5) reduced germination of conidia of Fusarium solani f. sp. phaseoli at 250 mM NH4Cl (pH 7.5) or 5 mM NH4Cl (pH 8.5) and of conidia of Cochliobolus victoriae at 5, 50, or 250 mM NH4Cl (pH 7.5) or 5 mM NH4Cl (pH 8.5). Under these conditions the rate of 14C release from conidia of these fungi and of Botrytis cinerea, grown on a medium with [14C]glucose, did not increase. It is concluded that no enhanced release of carbon compounds from conidia is involved in ammonia-induced mycostasis.
Experimental meningococcal infection in neonatal mice: differences in virulence between strains isolated from human cases and carriers
Authors: Salit Irving E. , Tomalty Lewis
Published: May 2010

The lack of availability of a suitable animal model has limited understanding of the pathophysiology of meningococcal disease. We have utilized a neonatal mouse model in which atraumatic intranasal inoculation of meningococci results in nasopharyngeal colonization and ultimately bacteremia. Using this model, we compared the virulence of seven encapsulated meningococcal carrier strains with eight meningococcal strains which were isolated from cerebrospinal fluid or blood of patients (disease strains). Intraperitoneal (IP) iron dextran was given to some animals to enhance meningococcal virulence. After IP iron, carrier strains were still poorly invasive with rates of bacteremia ranging from 0 to 15% (mean = 3%), whereas disease-associated strains were significantly more invasive and caused bacteremia in 31–64% of animals (mean = 39%). Without iron injections, nasopharyngeal colonization rates were similar (36 versus 30%, P > 0.1) for case and carrier strains IP iron dextran significantly enhanced rates of colonization and bacteremia caused by the disease strains only. We have therefore, shown that the relative virulence of meningococcal strains for humans is maintained in this experimental model.
Siderophore production by Proteus mirabilis
Authors: Evanylo Lisa P. , Kadis Solomon , Maudsley James R.
Published: May 2010

Studies on the isolation and characterization of Proteus mirabilis siderophores provided no evidence that these bacteria synthesize catechol- or hydroxamate-type siderophores. However, gas chromatograph analysis in conjunction with mass spectroscopy revealed the presence of α-hydroxyisovaleric acid, a previously unknown metabolite. Additional substantiating evidence for the presence of α-hydroxyisovaleric acid in these bacteria was obtained from experiments involving the use of thin-layer chromatography and an ultraviolet absorption spectrum. This compound was found to be capable of removing iron from the synthetic chelator, ethylene-diamine-di-orthohydroxyphenyl acetic acid, and supplying that iron to the bacteria both in a solid agar medium and in a liquid medium. Proteus mirabilis was found to possess an enzyme capable of catalyzing the reaction by which α-hydroxyisovaleric acid is converted to α-ketoisovaleric acid, an intermediate in the valine biosynthetic pathway.
Tyrosinase activity in Streptomyces glaucescens is controlled by three chromosomal loci
Authors: Crameri Reto , Hintermann Gilberto , Hütter Ralf , Kieser Tobias
Published: May 2010

In Streptomyces glaucescens the production of the enzyme tyrosinase (EC 1.14.18.1) is controlled by at least three loci: MELA, MELB, and MELC. Mutations in MELA and MELB are rare. They both map on the S. glaucescens chromosome in the interval between the markers leu-2 and ura-3. MELC, however, shows an exceptionally high mutation rate. MelC strains arise spontaneously with a frequency of about 0.1%, and they can be specifically induced with ethidium bromide, acridine orange, or by prolonged storage of spores or mycelium at 4 °C. Ultraviolet (UV) irradiation or treatment with N-methyl-N′-nitro-N-nitrosoguanidine under conditions which induce auxotrophic mutations, however, do not specifically induce the appearance of tyrosinase-negative strains. Most, but not all, of the melC strains acquire additional mutations which make them sensitive to streptomycin (strS) and unable to produce hydroxystreptomycin. Mapping of the mutations classified as melC proves to be difficult. Some of the matings indicate a map position between his-2 and pro-1, while others, all highly unbalanced crosses, can not be analyzed in a meaningful way because of abnormal segregation of the reference markers. This is probably due to some of the additional mutations which occur frequently with the melC mutations and not to extrachromosomal inheritance of MELC.
Genetics of fungicide resistance in Talaromyces flavus
Authors: Katan Talma , Dunn M. T. , Papavizas G. C.
Published: May 2010

Three mutants resistant to the fungicide benomyl and two resistant to dicarboximides were developed from a wild-type strain of Talaromyces flavus. Based on sensitivity of various isolates to benomyl concentrations, two levels of resistance were recognized. One isolate with low resistance (LR) was resistant to 5 μg/mL, but sensitive to 50 μg/mL benomyl; and two highly resistant (HR) isolates grew uninhibited at 50 μg/mL. Crosses between resistant isolates and sensitive wild types, as well as between different resistant isolates, showed that the two levels of benomyl resistance are conferred by different alleles at a single locus. The LR allele pleiotropically brings about slow growth. The dicarboximide-resistant isolates were little affected (mean effective dose (ED50) > 250 μg/mL) by iprodione, vinclozolin, dichlozolinate, or Co 6054. Crosses showed that the two dicarboximide-resistant isolates carry allelic mutations that can be characterized by the level of osmotic sensitivity pleiotropically conditioned by them. Dicarboximide resistance was not linked to benomyl resistance.
Lectin grouping of Bacillus thuringiensis serovars
Authors: DeLucca II Anthony J.
Published: May 2010

Twelve lectins, 11 of plant and 1 of animal origin, were tested against the 28 serovars of Bacillus thuringiensis to study their agglutinating specificities. Except for the sialic specific lectin from Limulus polyphemus, tube agglutination assays were performed using lectin concentrations of 10, 50, and 100 μg against 0.2 mL of 109 cells/mL in a final volume of 1.0 mL. The agglutination studies with the Limulus lectin were performed using 10 and 50 μg of lectin. Tubes were incubated overnight at room temperature (25 °C) and observed for aggutination patterns. Ten of the 28 serovars were individualized according to their ability to bind with various lectins. The study shows that the various serovars have different carbohydrate residues which indicates that the O-somatic antigens differ.
Recovery and survival of nontuberculous mycobacteria under various growth and decontamination conditions
Authors: Brooks Robert W. , George Karen L. , Parker Bruce C. , Falkinham III Joseph O. , Gruft Howard
Published: May 2010

The survival of microorganisms of the Mycobacterium avium, M. intracellulare, and M. scrofulaceum (MAIS) complex was evaluated after various soil and water decontamination regimens. Survival was reduced by growing cells in natural waters compared with laboratory media and by inclusion of malachite green in media as an antifungal agent. Decontamination with benzalkonium chloride, while reducing survival significantly less than 1% NaOH, failed to eliminate many fungi. Recovery from soil was further reduced by transfer losses and by irreversible cell adsorption onto particulates.
Examination of an acid forest soil for ammonia- and nitrite-oxidizing autotrophic bacteria
Authors: Hankinson T. R. , Schmidt E. L.
Published: May 2010

An acid forest soil (pH 3.9 – 4.4) from an undisturbed mixed oak stand in southern Indiana was examined for the occurrence of ammonia- and nitrite- oxidizing chemoautotrophs. Populations of both nitrifiers were detected in pH 7 most-probable-number (MPN) autotrophic media, and a Nitrosospira was isolated from highest dilution ammonia oxidizer MPN tubes. Populations of nitrite oxidizers were 10 to 1000 times higher than those of ammonia oxidizers. In pH 4.0 MPN media, ammonia oxidation was slight and unsustainable on 10% transfer to fresh medium, whereas nitrite oxidation was vigorous and sustainable. In pure culture the Nitrosospira isolate (Np IO1a) was completely inhibited by nitrapyrin at 5 μg mL−1, tolerant of 1.0 and 10.0 mM chlorate, and capable of growth only at pH 6.2 and above. Fluorescent antibodies raised against Np IO1a were used to confirm the predominance of Np IO1a in all MPN series examined. These results suggest that autotrophic ammonia oxidizers may be restricted to circumneutral microsites in this acid soil, whereas autotrophic nitrite oxidizers may not be limited to such sites.
Properties of oral asaccharolytic black-pigmented Bacteroides
Authors: Mayrand D. , Bourgeau G. , Grenier D. , Lacroix J.-M.
Published: May 2010

Bacteroides endodontalis, a newly described asaccharolytic black-pigmented Bacteroides, along with the other two recognized species of this group (B. gingivalis and B. asaccharolyticus) were studied for their susceptibility to various dyes and inhibitory agents and for some of their enzymatic activities to facilitate differentiating between them. Bacteroides endodontalis resembles B. asaccharolyticus physiologically except for the fact that the former cannot grow on media containing methylene blue, neutral red, or 3% sodium choride, whereas B. asaccharolyticus can. On the other hand, B. endodontalis and B. gingivalis can grow on a medium containing Congo red while B. asaccharolyticus cannot.
Purification and characterization of an exoglucanase from Streptomyces flavogriseus
Authors: Mackenzie C. R. , Bilous D. , Johnson K. G.
Published: May 2010

Streptomyces flavogriseus, a mesophilic actinomycete, produces high levels of extracellular enzymes capable of hydrolyzing cellulose and xylan. One such enzyme, an exoglucanase, has been purified to molecular homogeneity by a sequence involving DEAE Bio-Gel A chromatography, gel permeation chromatography on Bio-Gel P-60, preparative isoelectric focusing, and concanavalin A affinity chromatography. This purification sequence disclosed the presence of several distinct endoglucanase and xylanase fractions. Homogeneity of the purified enzyme was demonstrated by analytical isoelectric focusing and sodium dodecyl sulphate – polyacrylamide gel electrophoresis. The purified enzyme had a molecular weight of approximately 45 000 and an isoelectric point of 4.15. The enzyme demonstrated negligible activity with carboxymethylcellulose as the substrate. It was able to extensively hydrolyse acid-swollen cellulose; the main product of enzyme action was cellobiose.
Rhizomorph exudate of Armillaria mellea
Authors: Mallett K. I. , Colotelo Nicholas
Published: May 2010

Droplets of exudate from rhizomorphs of Armillaria mellea (Vahl ex Fr.) Kummer, grown on carrot agar, grew larger in size and darkened with age. The exudate was found to contain free amino acids, protein, and inorganic elements, but no oxalic acid was detected. β-Glucosidase, peroxidase, polyphenoloxidase, and acid and alkaline protease activities were also detected. Gel electrophoresis was used to analyze the dark brown exudate. A single dark brown band was obtained using the disc gel procedure, whereas many brown bands were formed using the isoelectric focusing technique.
Inefficient in vitro killing of virulent or nonvirulent Salmonella typhimurium by murine polymorphonuclear neutrophils
Authors: Baron Ellen Jo , Proctor Richard A.
Published: May 2010

The bactericidal capability of murine peritoneal polymorphonuclear neutrophils against virulent and nonvirulent Salmonella typhimurium was examined in an in vitro system. Although preincubation of the bacteria in specific murine antiserum elicited greater chemiluminescence from phagocytizing neutrophils than did incubation in normal murine serum, antiserum did not enhance ingestion, as less than 5% of the challenge was taken up by neutrophils under any of the conditions studied. Nonvirulent salmonellae showed a transient decrease in viable numbers early during in vitro incubation with or without intact neutrophils. Virulent salmonellae, however, were able to multiply without a lag period except when these bacteria were pretreated with antiserum and incubated in association with intact murine neutrophils. Results of these in vitro studies suggest that the murine polymorphonuclear neutrophil and antisalmonella antibody must act together to effect neutrophil-associated bactericidal activity against virulent salmonellae, and thus, that the neutrophil alone does not play a major role in the protection of unvaccinated, sensitive mice from disease caused by S. typhimurium.
Selection for moderately halophilic bacteria by gradual salinity increases
Authors: Ventosa A. , Rodriguez-Valera F. , Poindexter J. S. , Reznikoff W. S.
Published: May 2010

These studies addressed the question as to whether oceanic water contains halophilic bacteria and so could serve as their medium of dispersal between hypersaline sites. Bacteria were collected by filtration from water of Vineyard Sound, whose shores lack extensive hypersaline sites. Enrichments inoculated by these samples and in which salinity was increased were carried out. A few colonies of extremely halophilic bacteria identified as Halococcus representatives were detected in the initial samples, but these types were not subsequently enriched. Moderately halophilic bacteria were strongly favored in each culture when salinity reached 14 – 15%; they accounted for a majority of each population by the time the salts concentration reached 20%. Nonhalophilic bacteria decreased in numbers and diversity when salts concentrations reached 14 – 15% and were not detectable at higher concentrations. Salinity alone accounted for enrichment of moderate halophiles. The results of these laboratory studies imply that halophilic bacteria of natural hypersaline sites occur in seawater and can be enriched during the course of solar evaporation.
PZ-peptidase activities of some black-pigmented Bacteroides species
Authors: Ng Stephen K. , Fung Samuel S.
Published: May 2010

Bacteroides gingivalis (both W 83 and ATCC 33277 strains), B. asaccharolyticus (ATCC 25260), and B. melaninogenicus (ATCC 25845) produced hydrolytic activity on the synthetic peptide 4-phenylazobenzyl-oxycarbonyl-L-prolyl-L-leucyl-glycyl-prolyl-D-arginine (PZ peptide) during their early logarithmic phase of growth. The PZ-peptidase activity of the ATCC 25260 strain was the highest with an initial rate of reaction at 0.54 nmol PZ-pro-leu/h per 108 cells. Relatively low levels of PZ peptidase were produced by the pathogenic W 83 cells. In all the strains tested, no further increase in PZ-peptidase activity was detected after the late logarithmic phase, even when the cultures lysed. The result of the protease test seems to indicate that the PZ-peptidase activity of both oral strains of B. gingivalis is collagenase, while that of B. asaccharolyticus may be a mixture of protease and collagenase enzymes.
Production of nitrous oxide by Nitrosomonas europaea: effects of acetylene, pH, and oxygen
Authors: Hynes Russell K. , Knowles Roger
Published: May 2010

Aerobic cell suspensions of Nitrosomonas europaea oxidized ammonium [Formula: see text] to nitrous oxide (N2O) and nitrite [Formula: see text], and exogenous [Formula: see text] in the presence or absence of [Formula: see text] did not stimulate N2O formation. Acetylene (C2H2) inhibited the production of [Formula: see text] and N2O from [Formula: see text] but not from hydroxylamine (NH2OH). The total amount of N2O formed in air was proportional to the amount of [Formula: see text] oxidized; however, the total N2O N formed as a percentage of [Formula: see text] N formed varied very little (0.05–0.15%) over the range of [Formula: see text] concentrations examined (0.05–20.4 mM). Rates of production of N2O and [Formula: see text] showed similar response to pH over the range of 5.4–9.5, with maxima at pH 8.5. Anaerobically, five times more N2O was formed than under aerobic conditions. The highest rates of anaerobic N2O formation were observed in the presence of [Formula: see text] and [Formula: see text] combined (2 and 1 mM, respectively) and C2H2 reduced this rate of N2O formation to that observed with 1 mM[Formula: see text] alone in the presence or absence of C2H2. The presence of the [Formula: see text] oxidizer Nitrobacter winogradskyi had no effect on the formation of N2O by Ns. europaea either in liquid culture or in sterile soil. However, the presence of sterile soil as a suspending matrix increased by 10-fold the production of N2O, and broadened the range of O2 concentrations under which relatively high rates of N2O production occurred. Maximum N2O production by Ns. europaea occurred at 0.75 kPa O2 in liquid suspension and at 2.5 kPa O2 in sterile soil.
Influence of soil microorganisms on the trapping of nematodes by nematophagous fungi
Authors: Rosenzweig W. D. , Ackroyd D.
Published: May 2010

The influence of 29 species of soil organisms (21 bacteria and 8 fungi) on nematode capture by 3 species of nematophagous fungi was investigated. Only the yeast, Saccharomyces cerevisiae, was found to bind to lectin-containing traps of Arthrobotrys conoides and Monacrosporium rutgeriensis and prevent nematode capture. None of the organisms studied bound to the traps of Monacrosporium eudermatum. The trap lectin of Arthrobotrys conoides, being specific for glucose – mannose, apparently binds to the mannan component of the yeast cell wall. At this time, it is not clear why the yeast binds to traps of Monacrosporium rutgeriensis since the trap lectin is highly specific for 2-deoxyglucose, a saccharide that does not appear to occur in nature.
Purification and chemical characterization of an exopolysaccharide isolated from Capnocytophaga ochracea
Authors: Dyer J. K. , Bolton R W.
Published: May 2010

Purification and chemical characterization of an immunosuppressive exopolysaccharide from Capnocytophaga ochracea strain 25 are described. This polysaccharide was extracted from spent culture medium by cold ethanol precipitation. Purification was accomplished by trichloroacetic acid and pronase treatments in combination with diethylaminoethyl-Sepharose and concanavalin A-Sepharose chromatography. Purity of the exopolysaccharide was ascertained by polyacrylamide gel electrophoresis using periodic acid – Schiff staining. The exopolysaccharide was free of protein, nucleic acid, and lipopolysaccharide, but contained large amounts of mannose with lesser quantities of glucose, galactose, glucuronic acid, and glucosamine.