bluuebunny/crossref_metadata_2025 huggingface dataset:
Temporary low oxygen conditions for the formation of nitrate reductase and nitrous oxide reductase by denitrifying Pseudomonas sp. G59
Authors: Aida Tokujiro , Hata Shyuichi , Kusunoki Haruo
Published: May 2010

Formation of nitrate reductase (NaR) and nitrous oxide reductase (N2OR) by a Pseudomonas sp. G59 did not occur in aerobic or anaerobic conditions, but was observed in a microaerobic incubation in which an anaerobically grown culture was agitated in a sealed vessel initially containing 20 kPa oxygen in the headspace. During the microaerobic incubation, the oxygen concentration in the headspace decreased and dissolved oxygen reached 0.1–0.2 kPa. NaR activity was detected immediately and N2OR activity after 3 h of incubation irrespective of the presence or absence of NO3− or N2O. In the presence of NO3−, NO2− was accumulated as a major product, but N2O was observed in low concentrations only after N2OR appeared. After microaerobic incubation for 3 h, N2OR formation continued even anaerobically in an atmosphere of N2O. In contrast, Escherichia coli formed NaR not only microaerobically but also anaerobically. However, NaR formation by E. coli was inhibited by sodium fluoride under anaerobic, but not under microaerobic conditions. The Pseudomonas culture did not possess fermentative activity. It is suggested that the dependence on microaerobiosis for the formation of these reductases by the Pseudomonas culture was due to an inability to produce energy anaerobically until these anaerobic respiratory enzymes were formed.
Evaluation of the reversed passive latex agglutination (RPLA) test kits for detection of staphylococcal enterotoxins A, B, C, and D in foods
Authors: Park C. E. , Szabo R.
Published: May 2010

Four lots of the SET-RPLA kit (Denka Seiken Co. Ltd., Tokyo), a commercial reverse passive latex agglutination test kit for the detection of staphylococcal enterotoxins A, B, C, and Din foods, have been evaluated for their efficacy. The kits showed high specificity and sensitivity with a detection limit of 0.75 ng enterotoxin/g of food. The test is simple, is completed within 24 h, and does not require complicated extraction or concentration procedures nor expensive equipment. In addition, the assay is semiquantitative. However, as in any other immunological system, routine verification of the specificity of the latex reagents against standard enterotoxins and toxin-free food extracts is necessary.
Fast and slow milk-coagulating variants of Lactobacillus helveticus HLM 1
Authors: Morelli Lorenzo , Vescovo Marisa , Cocconcelli Pier Sandro , Bottazzi Vitrorio
Published: May 2010

Slow milk-coagulating variants were isolated from Lactobacillus helveticus HLM 1, a fast strain which coagulates milk in 16 h at 42 °C. Variants were isolated after subculturing in reconstituted skim milk or complex broth media. Analysis of plasmid content revealed that in slow variants a 3.5-megadalton plasmid was missing.
Effect of heat on endotoxin in plasma and in pyrogen-free water, as measured in the Limulus amoebocyte lysate assay
Authors: Plotrowicz Boguslawa I. , McCartney A. Christine
Published: May 2010

Four modes of heating endotoxin in plasma and two different times of heating endotoxin in pyrogen-free water were compared. There were no significant differences in standard curves after heating endotoxin in plasma at 100 °C for 1 and for 10 min. However, the standard curve after heating for 10 min at 75 °C had a significantly less steep slope, and after heating for 10 min at 56 °C, it was completely flat. Heating of endotoxin in pyrogen-free water for 1 min also resulted in the flattening of the standard curve, which was even more pronounced after 10 min of heating.
Laboratory studies on the effect of gamma radiation on Erwinia amylovora survival on apple fruit
Authors: Janisiewicz W. J. , Zwet T. van der , Jahrling P. B.
Published: May 2010

Susceptibility of Erwinia amylovora to gamma irradiation was determined in vitro on test tube cultures and in vivo on apples and pears. Bacterial strains differed in susceptibility to irradiation. Higher doses of irradiation (ca. 80 krad (1 krad = 10 Gy)) were needed to kill the bacterium on fruit compared with test tube cultures (from 20 to more than 50 krad). Fruit with natural populations of E. amylovora collected from a severely blighted orchard, exposed to doses of 140 krad, still contained viable bacteria. Surviving E. amylovora were pathogenic to green 'Bartlett' pears. Five radiation-sensitizing chemicals (used previously against different pathogens on other commodities) were tested against E. amylovora. N-Ethylmaleimide sensitized the bacteium to gamma irradiation. Treatment of natural populations of the bacterium on apples with N-ethylmaleimide eliminated E. amylovora from the apple surface with a gamma irradiation dose one-third lower than the maximum rate tolerable by fruit.
Differentiation of Erwinia carotovora ssp. carotovora and E. carotovora ssp. atroseptica on the basis of cellular fatty acid composition
Authors: Boer S. H. de , Sasser M.
Published: May 2010

The cellular fatty acids of Erwinia carotovora were analyzed by gas–liquid chromatography with a fused-silica capillary column. All strains contained, in decreasing order of amount present, 9-hexadecenoic acid (16:1), hexadecanoic acid (16:0), 9-octadecenoic acid (18:1), dodecanoic acid (12:0), 3-hydroxytetradecanoic acid (3-OH-14:0), and tetradecanoic acid (14:0). In addition some strains contained a small amount of 13, 15, 17, and 18 carbon saturated fatty acids. Strains of E. carotovora ssp. atroseptica (Eca) and E. carotovora ssp. carotovora (Ecc) from potato could be differentiated on the basis of three different fatty acid ratios. The Ecc strains had ratios of >3.71 for 12:0/14:0, <4.87 for 16:0/12:0, and <2.70 for 16:1/18:1, while the Eca strains had contrasting values for each of the ratios. Non-potato strains of E. carotovora including strains that were neither Ecc nor Eca on the basis of biochemical reactions were more variable in fatty acid composition than the potato strains, but the fatty acid ratios were generally of the Ecc type.
Melanogenesis in murine B16 cells exposed to Aeromonas hydrophila cytotoxic enterotoxin
Authors: Bunning V. K. , Crawford R. G. , Stelma Jr. G. N. , Kaylor L. O. , Johnson C. H.
Published: May 2010

Specific markers (growth, melanogenesis) of B16 murine melanoma cells in culture were used as indicators of toxin production by Aeromonas hydrophila. Cytotonic enterotoxinlike activity (inhibited growth, raised tyrosinase activity, and melanin accumulation) occurred at cytotoxic end points of purified β-hemolysin and several culture filtrates. Antihemolysin rabbit serum inhibited this activity. A hemolysin-neutralized culture filtrate concentrate (10×) failed to elevate tyrosinase relative to untreated and cholera toxin treated controls. Similar dilution profiles using Chinese hamster ovary cells showed limited cell extension only at cytotoxic end points with antihemolysin inhibiting this activity. Cytotoxicity of Chinese hamster ovary cells and B16 cells was proportional to hemolytic activity, with B16 cells showing about 100-fold greater sensitivity on a per cell basis. Cell culture cytotoxicity attributed to β-hemolysin correlated with reactivity in rabbit ileal loop assays. The ADP-ribosyl transferase activity of concentrated (10×) A. hydrophila culture filtrates and fractions thereof was negative. Apparently sublethal doses of A. hydrophila β-hemolysin can nonspecifically stimulate cyclic adenosine monophosphate mediated events in melanoma and Chinese hamster ovary cell assays, producing lower activities than cholera toxin with shorter lag times.
Inorganic salts and the growth of spiroplasmas
Authors: Chang C. J.
Published: May 2010

A chemically defined medium (CC-494M) was used to study the effect of inorganic salts on the growth of three spiroplasmas representing three distinct serogroups: Spiroplasma melliferum (AS 576), Spiroplasma floricola (23–6), and SR 3 spiroplasma. KH2PO4 or NaH2PO4∙H2O was required. KH2PO4 supported faster growth and higher yield for spiroplasmas than NaH2PO4∙H2O. The optimal concentration of KH2PO4 for S. melliferum, S. floricola, and SR 3 spiroplasma was 0.5, 0.5, and 0.25 mM, respectively, whereas that of NaH2PO4∙H2O was 0.5, 0.05, and 2.5 mM. When supplemented with NaH2PO4∙H2O, KCl promoted growth comparable with that obtained from KH2PO4-supplemented medium and RbCl supported limited growth, whereas NaCl, LiCl, CsCl, CaCl2, and MgSO4∙7H2O were inhibitory. Spiroplasma growth decreased as the concentration of LiCl and CsCl increased. At 200 mM LiCl totally inhibited the growth of S. melliferum and SR 3 spiroplasma, whereas limited growth was obtained for S. floricola. CsCl at 150 mM totally inhibited the growth of S. floricola, while limited growth was observed for S. melliferum and SR 3 spiroplasma. RbCl supported limited growth when supplemented with NaH2PO4∙H2O, whereas it was inhibitory when added in KH2PO4-supplemented medium. All the 10 potassium salts (KCH2COOH, KBr, K2CO3, KHSO4, KCl, KOH, Kl, KNO3, KH2PO4, and K2HPO4) at concentrations of 20 mM promoted growth when supplemented with NaH2PO4∙H2O.
Isolation, characterization, and inoculation of N2-fixing bacteria from dicotyledonous plants
Authors: Garvin S. , Lindemann W. C.
Published: May 2010

N2-flxing (acetylene-reducing) bacteria were isolated from roots of five species of wild plants in southern New Mexico. Ground cherry (Physalis wrightii) had the highest frequency of roots with N2-fixing bacteria. Acetylene reduction rates of subcultures were comparable with rates exhibited by Azospirillum (300–500 nmol ethylene∙h−1). Three isolates from ground cherry were characterized to the generic level and one to the level of genus and species. Three of these isolates were identified as Enterobacter spp, while the fourth isolate was identified as Azospirillum brasilense. Inoculation of ground cherry with N2-fixing isolates had minimal effects on plant growth, plant nitrogen content, or plant acetylene reduction activity 7 weeks after inoculation. Comparisons between uninoculated and inoculated plants were generally not statistically significant. Significant acetylene reduction activity and high numbers of N2-fixing bacteria occurred only on the roots of plants grown with little or no added nitrogen.
In vitro inhibition of plant pathogens by Bacillus subtilis and Enterobacter aerogenes and in vivo control of two postharvest cherry diseases
Authors: Utkhede R. S. , Sholberg P. L.
Published: May 2010

Twenty-one isolates of the bacterium Bacillus subtilis and one of Enterobacter aerogenes were tested on agar for antagonism to Alternaria alternata, Armillariella mellea, Botrytis allii, Botrytis cinerea, Colletotrichum lindemuthianum, Monilinia fructicola, Penicillium expansum, Phytophthora cactorum, Pythium ultimum, Rhizoctonia solani, Sclerotinia sclerotiorum, Sclerotium cepivorum, Verticillium dahliae, and Venturia inequalis, causal organisms of many plant diseases. Enterobacter aerogenes was antagonisic to all of the pathogenic fungi tested except Verticillium dahliae and Armillariella mellea. Similarly, Bacillus subtilis was antagonistic to all of the pathogenic fungi tested except Pythium ultimum. When Enterobacter aerogenes and Bacillus subtilis were tested in vivo on cherry fruit for control of postharvest brown rot and alternaria rot, Enterobacter aerogenes was ineffective. Eleven isolates of Bacillus subtilis provided effective alternaria rot control and 15 isolates provided brown rot control which ranked with the best fungicide control.
Lack of protection against ascending Escherichia coli pyelonephritis in diabetic rats following immunization with purified lipopolysaccharide
Authors: Bryan L. E. , Schollaardt T. , Pak C. Y. , Kim C. J. , Yoon J. W.
Published: May 2010

Purified lipopolysaccharide of Escherichia coli produced specific antibody when injected intraperitoneally or given to rats orally. Either route of immunization did not prevent ascending pyelonephritis in a diabetic rat model. The use of purified LPS excludes the potential contribution of other virulence factors of E. coli as protective antigens in the prevention of ascending pyelonephritis and confirms that anti-lipopolysaccharide antibody is not protective for ascending pyelonephritis.
Cytochrome content in Azospirillum brasilense Sp 7 grown under aerobic and denitrifying conditions
Authors: Lalande Roger , Knowles Roger
Published: May 2010

Azospirillum brasilense Sp 7 was grown in batch cultures with O2, [Formula: see text], [Formula: see text], or N2O as final electron acceptor. There were marked differences in cytochrome composition depending on the O2 status of the culture and the electron acceptor utilized. Highly aerated cultures showed no [Formula: see text] reduction and the cytochrome composition (a soluble c-type and particulate aa3, b, and c cytochromes) was not affected by the presence of[Formula: see text]. Under low aeration, in the presence of [Formula: see text], nitrate reductase activity occurred and there was a significant increase in the soluble and particulate cytochromes. Particulate cytochrome b-556 was observed only under high aeration and the cytochrome aa3, observed under both high and low aeration, decreased as the O2 concentration decreased. A particulate CO-binding cytochrome of type o was observed in the cells grown under high aeration. Cytochrome cd nitrite reductase was observed only in the soluble fraction of [Formula: see text]-grown cultures, which also contained the highest concentrations of the soluble cytochrome c-548 and the particulate c-551. N2O-grown cultures showed b-560 and c-551 cytochromes in the particulate and the c-548 cytochrome in the soluble fraction.
The role of β-lactamase and the permeability barrier on the activity of cephalosporins against members of the Bacteroides fragilis group
Authors: Malouin François , Lamothe François
Published: May 2010

The role of β-lactamase and the permeability barrier on the activity of some β-lactams against 53 strains of the Bacteroides fragilis group was investigated. Minimal inhibitory concentrations of cefamandole, cefoxitin, and cephalothin were determined with or without the addition of clavulanic acid and (or) ethylenediaminetetraacetate using an agar dilution technique. A significant increase of susceptibility with clavulanic acid indicated a role for β-lactamase, and with ethylenediaminetetraacetate, a role for a permeability barrier. We found that both β-lactamase and low permeability decreased the activity of the β-lactams to some extent depending on the bacterial species and the antibiotic. The species-specific exception was B. distasonis which showed only a permeability barrier to all antibiotics tested.
Nitrate reduction in simulated microniches by a denitrifying marine bacterium
Authors: Bonin Patricia , Barbotin Jean Noel , Dhulster Pascal , Bertrand Jean-Claude
Published: May 2010

To mimic the behavior of the denitrifying marine bacterium Pseudmonas nautica 617 in sediment, we used immobilized cells in a carrageenan gel. This procedure was very useful to simulate the water-filled, anaerobic microspaces between sediment particles. The growth and nitrate reduction of this organism has been investigated with free and immobilized cells. The generation time in gel beads was 1.7 h as compared with 2.4 h for free cells. The nitrate reduction activity for the free and immobilized cells was 4.6 and 7 μmol [Formula: see text] transformed∙h−1∙mg protein−1, respectively. Cell growth in the gel has been followed by electron microscopy.
Urease activity related to the growth and differentiation of swarmer cells of Proteus mirabilis
Authors: Jin Tianru , Murray R. G. E.
Published: May 2010

Urease activity was measured using whole cells of both long (swarming) and short (nonswarming) populations of Proteus mirabilis from casein hydrolysate agar (CHA) and broth (CHB) cultures, and from brain heart infusion broth (BHIB) cultures. Urease is a constitutive enzyme for both long and short cells, but its activity was tremendously increased when urea was incorporated into the media. Urease production was also affected by culture age and media used. Before exponential phase, urease activity was very low, and it increased to its highest point after about 4 h in BHIB and 8 h in both CHA and CHB cultures at 37 °C. Long cells had higher urease activity than did short cells when grown on CHA, and was also expressed by two different strains cultured in BHIB. Strain PM23, in BHIB, was able to form long cells (swarming cells) to a maximum proportion after about 4 h, but strain IM47 could not differentiate in any of the liquid media. The former had more urease when swarming differentiation was initiated. PM23 grew relatively faster than IM47 when the former began to differentiate, but this fast growth could not be observed when nutrient broth or minimal medium was used. These observations suggest that long or swarming cells are "faster growing" rather than "nongrowing bactera."
Microincineration and elemental X-ray microanalysis of single Bacillus cereus T spores
Authors: Scherrer René , Shull Vivion E.
Published: May 2010

Single whole spores of bacillus cereus T were analyzed by scanning electron microscopy and electron microprobe X-ray microanalysis before and after high-temperature (600 °C) ashing in air. High-temperature ashing consisted of a centripetal oxidation of the spore surface combined with pyrolysis of the spore's interior. Ashing of single spores produced a compact central ash particle, mimicking the much larger unashed spore body in outline but containing craterlike microregions, and a peripheral thin ash film. Ashing mostly eliminated the spore's organic matrix; however, ash residues still gave residual carbon-characteristic X-ray counts. Ashing of single spores produced a two-, five-, and six-fold increase of potassium, magnesium, and calcium X-ray intensities, respectively. Iron, although low in actual counts, became detectable after ashing. Phosphorus characteristic X-rays were decreased by 41% after ashing, while volatilization lowered sodium and manganese X-ray intensities by over 80%. High-temperature ashing enhanced element-characteristic X-ray intensities of the non-volatilizable mineral(ized) elements of spores by compacting them into ash residues, more so than by simply abolishing their organic matrix. Microincineration appears a generally useful preconcentration technique for elemental detection and localization in X-ray microanalysis.
Cell surface specific immunoglobulin inhibits α factor mediated morphogenesis in Saccharomyces cerevisiae
Authors: Merkel Glenn J. , Phelps Charles L. , Roeske Roger W.
Published: May 2010

Immunoglobulins raised from Saccharomyces cerevisiae a and α mating type cell envelope preparations inhibited α factor mediated morphogenesis of the a cell without inhibiting normal cell division. The Ig responsible for this inhibition was absorbed to both a and α whole cells and heat-killed cells, indicating that the immunoglobulin binding sites were exposed on the cell surface and not mating type specific. Additionally, α factor mediated cell cycle arrest was not affected by the immunoglobulin preparations, implying that the immunoglobulin was not preventing α factor from binding to its receptor.
Biological control of Fusarium wilt of cucumber with nonpathogenic isolates of Fusarium oxysporum
Authors: Paulitz T. C. , Park C. S. , Baker R.
Published: May 2010

Nonpathogenic isolates of Fusarium oxysporum were obtained from surface-disinfested, symptomless cucumber roots grown in two raw (nonautoclaved) soils. These isolates were screened for pathogenicity and biological control activity against Fusarium wilt of cucumber in raw soil infested with Fusarium oxysporum f. sp. cucumerinum (F.o.c.). The influence of three isolates effective in inducing suppressiveness and three ineffective isolates on disease incidence over time was tested. The effective isolates reduced the infection rate (R), based on linear regressions of data transformed to loge (1/1 – y). Effective isolate C5 was added to raw soil infested with various inoculum densities of F.o.c. In treatments without C5, the increase in inoculum densities of F.o.c. decreased the incubation period of wilt disease, but there was no significant difference in infection rate among the inoculum density treatments. Isolate C5 reduced the infection rate at all inoculum densities of F.o.c. Various inoculum densities of C5 were added to raw soils infested with 1000 cfu/g of F.o.c. In the first trial, infection rates were reduced only in the treatment with 10 000 cfu/g of C5; in the second trial, infection rates were reduced in treatments with 10 000 and 30 000 cfu/g of C5.
An annual cycle of abundance and activity of heterotrophic bacteria and abundance of hydrocarbonoclastic bacteria in Newfoundland coastal water
Authors: Powell James C. , Dabinett Patrick E. , Gow John A.
Published: May 2010

An annual cycle of abundance and activity was determined for bacteria in Newfoundland coastal water that is dominated by the Labrador Current. Both in abundance and activity, the population showed characteristics similar to those reported for bacteria in cold ocean environments. The number of bacteria per litre determined by the acridine orange direct count method ranged from an average low of 0.25 × 108 in winter to an average high of 2.8 × 108 in summer. Activity, determined by the kinetic method, was correlated with temperature. The average heterotrophic potential (Vmax) was 3 ng glutamate. L−1∙h−1 in winter and 54.7 ng glutamate. L−1∙h−1 in summer. The average turnover times were 2632 and 256 h, respectively, during the same periods. The population of hydrocarbonoclastic bacteria, estimated by a most probable number method, constituted 4.4% of the viable bacterial population estimated by the standard plate count method, although the former were most abundant near the water's surface. The number of hydrocarbonoclastic bacteria was correlated with temperature and with Vmax of the heterotrophic bacterial population.
Urease testing and yeast taxonomy
Authors: Booth J. Leland , Vishniac H. S.
Published: May 2010

When urease production was assayed by the hydrolysis of [14C]urea, all basidiomycetous yeasts tested, including the Cryptococcus vishniacii complex (previously reported urease negative), produced significant amounts of 14CO2. The Schizosaccharo-mycetaceae were the only urease-positive ascomycetous yeasts tested. Yarrowia lipolytica was urease negative. The stoichiometry of [14C]urea hydrolysis paralleled by Roberts' rapid urea hydrolysis (RUH) test indicated that causes of anomalous results in conventional urease testing include acidification and alkalinization of the test medium by products of endogenous metabolism and autolysis rather than urease activity. Anomalous results also occurred when cells were grown on media containing the chelating agent ethylenediaminetetraacetic acid (EDTA) prior to RUH. The addition of EDTA to a complex natural medium inhibited urease production in all yeasts reportedly growing at 35 °C (and all other yeasts tested), except Filobasidiella (Cr.) neoformans var. neoformans (NIH 12). The RUH test could differentiate at the varietal level: Fil. (Cr.) neoformans var. neoformans was about 10 times more resistant to EDTA in media used for the growth of cells prior to RUH testing than was Fil. neoformans var. bacillispora (Cr. neoformans var. gattii) (NIH 191). Urease production by Fil. neoformans var. bacillispora was specifically restored to half maximal activity by the addition of 22 μM Ni+2 (as NiCl2) to a growth medium containing 0.100 mM EDTA.
Isolation of Bdellovibrio spp. that prey on Azospirillum brasilense in soil
Authors: Germida James J.
Published: May 2010

Bdellovibrios that prey on Azospirillum brasilense were isolated from a Latosol and a Podzolic soil from Brazil which were stored air-dried for 2 years. The addition of A. brasilense strain Cd or Sp 7 cells and nutrients to these soils stimulated growth of indigenous bdellovibrios; direct assay of these soils did not yield bdellovibrios. Two other Podzolic soils from Brazil and three Chernozemic soils from Canada did not contain detectable bdellovibrios. After enrichment with strain Cd cells, the Podzolic soil yielded 1340 bdellovibrios per g of soil, whereas enrichment with strain Sp 7 cells yielded only 50. Escherichia coli and Enterobacter aerogenes cells did not stimulate growth of bdellovibrios in this soil, but did stimulate growth of bdellovibrios in the Latosol as did strains Cd and Sp 7. The morphology of an azospirilla-attacking Bdellovibrio, isolated from the Podzolic soil, was typical of the genus; attack-phase cells were curved rods, 0.2–0.4 by 1.0–1.3 μm, motile by means of a single polar flagellum. In broth culture this Bdellovibrio isolate preyed on several different gram-negative bacteria, although the apparent growth rate on prey cells was A. brasilense strain Cd > strain Sp 7 > A. lipoferum strain Sp Br 17 = E. coli = E. aerogenes > A. brasilense strain Sp 35. Pseudomonas fluorescens, Ensifer adhaerens, and 20 unidentified bacterial isolates from the Podzolic soil were not suitable prey. These results indicate that Bdellovibrio survive in some air-dry soils at undetectable levels but respond quickly to the presence of a large number of prey cells. In addition, the presence in soil of bdellovibrios that exhibit a faster growth rate on A. brasilense strain Cd than on strain Sp 7 cells and other azospirilla indicates potential problems when using strain Cd as a crop inoculant in certain soils.
The API 20B microtube system to aid in the identification of N2-fixing Bacillaceae
Authors: Rennie R. J.
Published: May 2010

N2-fixing bacterial isolates from soil have been identified successfully using the API 20E and 50E microtubes in conjunction with a computer-assisted biochemical profile search. The 20E and 50E result in few positive tests with N2-fixing Bacillaceae. Recently, a new battery of 20 microtube tests, the 20B, has been introduced for identifying aerobic, heterotrophic bacteria isolated from natural environments. This system was compared with the 20E and evaluated for N2-fixing bacillus species from soil. It was then used in conjunction with guanine-plus-cytosine analysis to identify the C-11-25 (5DN+) bacillus strain that fixes N2 in association with Canadian wheat cultivars. The API 20E and 20B gave similar results for many biochemical tests, but the 20E resulted in negative tests for carbohydrate utilization by bacillus strains. The use of different growth media or 0.85% NaCl to suspend these bacteria prior to inoculating the cupules did not alter the inability of the 20E in this manner. Carbohydrate utilization in the 20B system agreed well with that in the traditional utilization tests. Hence, I concluded that the API 20E is not suitable to evaluate carbohydrate utilization in N2-fixing Bacillaceae. The spore-forming, acetylene-reducing C-11-25 strain of bacillus was biochemically similar to the ATCC type culture of Bacillus polymyxa (strain 842). Its guanine-plus-cytosine ratio of 48.0 mol% was similar to that of B. polymyxa (43–46 mol%). A general procedure for the isolation and identification of N2-fixing Bacillus from soil is proposed.
Purification and properties of a nonspecific β-fructofuranosidase (inulinase) from the mushroom Panaeolus papillonaceus
Authors: Mukherjee Khana , Sengupta S.
Published: May 2010

A nonspecific β-fructofuranosidase (inulinase) was purified to electrophoretic homogeneity from the culture filtrate of the mushroom Panaeolus papillonaceus. The enzyme is the first purified from a basidiomycete and consists of two subunits with a total molecular weight of 116 000. It is most active on sucrose, then on raffinose, stachyose, and inulin, in decreasing order. The sucrase/inulinase activity ratio (S/I) is 5.7. Fructose was detected as the liberated sugar from raffinose, stachyose, and inulin. The enzyme is highly thermostable with an optimum temperature range of 60–65 °C and a pH optimum of 6.0. The enzyme is stable over the pH range 4–10, and is also active over a wide pH range, exhibiting 50% activity even at pH 8.5. Iodoacetate, azide, and EDTA, at 20 mM concentration, and 1% (w/v) SDS have no effect on enzyme activity, whereas Ag+ and Hg2+ at 2 mM are highly inhibitory.
Growth of spiroplasmas in the presence of various nutrients and metabolic inhibitors
Authors: Chang C. J. , Garrett Meredith G.
Published: May 2010

Glycolytic intermediates replaced glucose as carbohydrate sources in a chemically defined medium CC-494N, whereas keto acids of citric acid cycle intermediates and glyoxylate were supplemented with 10 mM glucose. Glucose-6-phosphate, fructose-1,6-diphosphate, 3-phosphoglyceraldehyde, and pyruvate supported limited growth for Spiroplasma floricola (23-6), whereas only pyruvate supported SR 3 spiroplasma and Spiroplasma melliferum (AS 576). Oxalacetate and glyoxylate inhibited growth at 10 mM or greater. Hematin, 2,4-dinitrophenol, sodium fluoride, and arsenite were dramatically inhibitory, whereas acetic anhydride, tricarballylate, acetylene dicarboxylate, and sodium cyanide were mildly inhibitory at 10 mM or lower. Malonate at 50 mM was not inhibitory.
Growth, elemental composition, and formation of polyphosphate bodies in Vibrio natriegens cultures shifted from phosphate-limited to phosphate-pulsed media
Authors: Nissen Hilde , Heldal Mikal , Norland Svein
Published: May 2010

Vibrio natriegens cultivated in a phosphate-limited chemostat at dilution rates of 0.32, 0.20, and 0.13 h−1 was given pulses of phosphate in an otherwise complete medium. Under the conditions used, complete depletion of phosphate occurred within 2–3 h and was followed by uptake of glucose and by cell division. For the most severely phosphate-limited cells (cultivated in the chemostat at dilution rate of 0.13 h−1), the elemental composition was determined by X-ray analysis at different times after adding phosphate. The amount of phosphorus per cell increased rapidly after the phosphate pulse but decreased when the cells started to divide after 2 h. An initial increase followed by a decrease was also found for chlorine, while the amount of sulphur remained constant before decreasing. Chlorine and calcium showed more complicated patterns. The pattern for magnesium, with a maximum after 45 min, may indicate a correlation between magnesium content and cell division. Multivariate analysis showed that cells differed significantly between sampling times. Addition of phosphate to the phosphate-starved culture also induced synthesis of polyphosphate bodies in the cells. Within 15 min an average of 3.8% of the cell volume consisted of polyphosphate bodies as shown by transmission electron microscopy. These bodies disappeared after an additional 30–60 min, indicating that polyphosphate is synthesized to facilitate phosphate uptake by minimizing the concentration gradient across the cell membrane.
Inhibition of macromolecular synthesis by caffeine in Clostridium perfringens
Authors: Labbe Ronald G. , Nolan Linda L.
Published: May 2010

Caffeine (2 mg/mL) inhibited the incorporation of [14C]adenine into actively growing cells of Clostridium perfringens NCTC 8679 in a dose-dependent manner. Also reduced by caffeine was incorporation of [14C]thymidine and 14C-labeled amino acids. No effect on guanine, uracil, adenosine, guanosine, or uridine was detected. Actual incorporation of [14C]caffeine or [14C]thymine in control cultures did not occur.
Influence of assessment methods on selection of fungal antagonists of the sclerotium-forming fungus Phymatotrichum omnivorum
Authors: Kenerley C. M. , Stack J. P.
Published: May 2010

Four attributes required by microorganisms for biocontrol of plant diseases caused by sclerotium-forming fungi, where the strategy is to reduce the number of sclerotia, are (1) an ability to adversely affect propagule germination and (or) viability, (2) growth potential through soil, (3) activity over a range of environmental conditions, and (4) survival and reproductive potential. Three methods of assessment (soil plate, SPM; soil immersion, SIM; inert carrier, ICM) were evaluated to assess biocontrol agents with regard to attributes 1 and 3. Based on the method of assessment, the fungal antagonists (Gliocladium roseum, G. catenulatum, Trichoderma harzianum, Tr. pseudokoningii, Aspergillus ustus, A. versicolor, Penicillium crustosum, Fusarium solani, Chaetomium globosum, and Stilbum sp.) were grouped by their ability to colonize sclerotia of Phymatotrichum omnivorum in nonsterile soil. Group 1 strains colonized greater than 50% of the sclerotia with any method. Group 2 strains failed to colonize greater than 18% of the sclerotia with any method. Group 3 strains effectively colonized sclerotia when assessed by the SPM but not the ICM; opposite results were obtained with group 4 isolates. With the three methods of assessment, Gliocladium roseum (strain 1620) colonized sclerotia at 19, 23, 27, and 31 °C. Colonization with the SPM or SIM was not temperature dependent, but colonization significantly decreased with increased temperature (27 and 31 °C) for the ICM. The method of assessment altered conclusions about the effectiveness of these potential biocontrol agents.
Acquisition of iron by Stemphylium botryosum under iron-replete conditions
Authors: Manulis Shulamit , Netzer David , Barash Isaac
Published: May 2010

The assimilation of iron by Stemphylium botryosum under iron-replete conditions involved mainly three steps: (i) binding of iron to the cell surface, (ii) reduction of Fe3+ into Fe2+, and (iii) transport of the ferrous iron across the cell membrane. However, the possibility that the fungus is capable of transporting ferric iron also has not been excluded. Adsorption was responsible for up to 75% of the iron accumulated by the cells. Mycelial cells exhibited a high capacity for Fe3+ reduction. Approximately 70% of the reductive activity was assigned to cell surface bound reducing compounds which were also released to the medium. Iron transport by S. botryosum was an energy-dependent saturable process that required sulfhydryl groups. Uptake was significantly inhibited by Cu2+ but not by various other cations. On the basis of inhibition studies with chelates specific for Fe3+or Fe2+ and on the high capacity of the mycelium to reduce external ferric iron, it was suggested that uptake of iron into the cell occurred predominantly in the ferrous form. The phytotoxic iron chelate stemphyloxin I induced iron adsorption on the mycelial surface but did not appear to exert a direct effect on the membrane-mediated transport of iron.
Reinfection of guinea pigs with herpes simplex virus type 2: failure to establish a second latent ganglionic infection
Authors: Richardson V. J. , Botto I. , Scriba M.
Published: May 2010

Guinea pigs were infected with herpes simplex virus type 2 (HS V 2) and at various times thereafter reinfected at a different site with the same or a different strain of HSV 2. Viruses were isolated from infected tissues either from the site of primary or secondary infection or from regional ganglia. Viral isolates were characterised by DNA fingerprinting using restriction endonucleases capable of differentiating between the virus strains used. The second infection resulted in a second site of peripheral persistence of the virus, but did not establish a second site of ganglionic infection.
Purification and characterization of a thermostable xylanase from a thermophilic fungus Thermoascus aurantiacus
Authors: Tan Larry U. L. , Mayers Paul , Saddler John N.
Published: May 2010

A thermostable endo-β-D-xylanase (1,4-β-D-xylan xylanohydrolase, EC 3.2.1.8) was purified from the culture filtrate of a thermophilic fungus Thermoascus aurantiacus C436, using a single chromatographic step on SP-Sephadex C50. The purified preparation was homogeneous based on denaturing polyacrylamide and isoelectric focusing gels. The xylanase had a subunit molecular mass of 32 000 daltons, isoelectric point at pH 7.1, apparent Km and Vmax of 0.17% (w/v) xylan and 61.3IU/mg protein, respectively, at 50 °C. The pH and temperature optima for xylan hydrolysis were pH 5.1 and 80 °C, respectively. The xylanase retained full activity following incubation at 60 °C for 97 h or 70 °C for 24 h. At 80 °C, the half-life of the enzyme was 54 min. The xylanase was not affected by copper sulfate, zinc sulfate, calcium chloride, cobalt chloride, barium chloride, magnesium sulfate, and EDTA at concentrations of 2 mM. Mercury chloride at 2 mM concentration abolished all xylanase activity, while lead acetate at the same concentration reduced xylanase activity by approximately 25%. From the initial hydrolysis products of xylan, the xylanase was deduced to hydrolyse xylan through an endo-acting mechanism.
ESR study of copper(II) retention by entire cell, cells walls, and protoplasts of Saccharomyces cerevisiae
Authors: Kihn Jean Claude , Mestdagh Michèle M. , Rouxhet Paul G.
Published: May 2010

Copper retention by whole cells, protoplasts, and isolated cell walls of Saccharomyces cerevisiae was investigated in the absence of any energy source in the medium. The cell walls accounted only for a small fraction of the cation retention by whole cells. ESR results showed that copper was not bound only at the outer face of the plasma membrane, but it was also distributed in the plasma membrane and (or) in the cytoplasm. ESR studies also showed that, in all three systems, copper was chelated by peptides or proteins. The binding sites were formed by an amide and a strongly complexing ligand such as an amine. Their configuration depended upon pH: in slightly acidic conditions, copper was bound by the oxygen of the amide; at basic pH, NHCO became deprotonated and the negatively charged nitrogen bound to the metal.
The ecological role of killer yeasts in natural communities of yeasts
Authors: Starmer William T. , Ganter Philip F. , Aberdeen Virginia , Lachance Marc-Andre , Phaff Herman J.
Published: May 2010

The killer phenomenon of yeasts was investigated in naturally occurring yeast communities. Yeast species from communities associated with the decaying stems and fruits of cactus and the slime fluxes of trees were studied for production of killer toxins and sensitivity to killer toxins produced by other yeasts. Yeasts found in decaying fruits showed the highest incidence of killing activity (30/112), while yeasts isolated from cactus necroses and tree fluxes showed lower activity (70/699 and 11/140, respectively). Cross-reaction studies indicated that few killer-sensitive interactions occur within the same habitat at a particular time and locality, but that killer-sensitive reactions occur more frequently among yeasts from different localities and habitats. The conditions that should be optimal for killer activity were found in fruits and young rots of Opuntia cladodes where the pH is low. The fruit habitat appears to favor the establishment of killer species. Killer toxin may affect the natural distribution of the killer yeast Pichia kluyveri and the sensitive yeast Cryptococcus cereanus. Their distributions indicate that the toxin produced by P. kluyveri limits the occurrence of Cr. cereanus in fruit and Opuntia pads. In general most communities have only one killer species. Sensitive strains are more widespread than killer strains and few species appear to be immune to all toxins. Genetic study of the killer yeast P. kluyveri indicates that the mode of inheritance of killer toxin production is nuclear and not cytoplasmic as is found in Saccharomyces cerevisiae and Kluyveromyces lactis.
Determination of glucose level needed to induce aflatoxin production in Aspergillus parasiticus
Authors: Wiseman Dana W. , Buchanan Robert L.
Published: May 2010

Previous studies have established that aflatoxin production is induced by high levels of glucose (or other compatible carbohydrates). However, the minimal amount of glucose needed to achieve this effect had not been determined. Aspergillus parasiticus was induced to produce aflatoxin when incubated for 18 h in the presence of ≥ 0.1 M glucose before addition of cycloheximide. Toxin formation was not induced at any glucose concentration in the mycelia incubated for 8 h. These results suggest that aflatoxin synthesis would not be expected in substrate containing < 0.1 M of a carbohydrate source.
The influence of higher temperature on Dengue-2 virus infected C6/36 mosquito cell line
Authors: Corner Linda C. , Ng Mah Lee
Published: May 2010

Dengue-2 virus infection of C6/36 cells was studied at 28 and 37 °C. In infected cells maintained at 28 °C, syncytial development was seen on day 4 postinfection, whereas at 37 °C, extensive syncytial development was seen by 32 h. Extracellular virus titre was found to correlate with the cytopathic changes. Nine Dengue-2 virus specified proteins were observed in polyacrylamide analyses of cytoplasmic extracts of C6/36 infected cells. All the proteins were observed, although in varied intensities by 32 h postinoculation at 37 °C and only on day 4 postinoculation at 28 °C. The GP60 glycoprotein appeared at 32 h postinfection when the cells were maintained at 37 °C and became prominent only on day 5 at 28 °C. The results revealed that a higher temperature accelerated the onset of cytopathic effects, hastened the development of virus specified proteins, and also enhanced the titre of extracellular infectious virus. The importance of the accumulation of the envelope protein GP60 for the development of CPE was indicated.
Analysis of spinin expression and spina development using phenethyl alcohol
Authors: Easterbrook K. B.
Published: May 2010

Spination in marine pseudomonad D71 is progressively inhibited by phenethyl alcohol, over the range of 0.006 to 0.04%, without either bacterial morphology, growth, or overall protein composition being significantly affected. If 0.04% phenethyl alcohol is present at the time of shift of an unspined culture to spina-promoting conditions, the culture remains unspined; delayed addition of phenethyl alcohol after shift may inhibit the establishment of new base structures, but does not prevent the extension (growth) of spinae already present. Spinin cannot be detected in the medium of inhibited cultures and since the continued extension of spinae in the presence of phenethyl alcohol can be accounted for as continued expression of a stable mRNA, the results are compatible with the hypothesis that phenethyl alcohol can inhibit expression of spinin genes as well as initiation of spinae construction without affecting either translocation or subsequent assembly of spinin. Continued division of spined bacteria in the presence of phenethyl alcohol leads eventually to a decrease in both the average number of spinae per cell and the proportion of spined bacteria, but at higher concentrations division, but not necessarily growth, is also inhibited leading to extremely long bacteria with polar spinae; unspined bacteria seem less affected. Spination is not affected by phenethyl alcohol in "Agrobacterium E59," a constitutively spinate bacterium, suggesting a possible correlation between the mechanisms of phenethyl alcohol inhibition and spina induction.
Genetic and physical characterization of trimethoprim resistance plasmids from Shigella sonnei and Shigella flexneri
Authors: Tonin Patricia N. , Grant Robert B.
Published: May 2010

Analysis of six Shigella flexneri and four S. sonnei isolates with trimethoprim (Tp) resistance from clinical cases in Ontario has shown that, in all isolates, the Tp resistance is mediated by gene(s) on conjugative, multiple antibiotic-resistance plasmids. The physical and genetic characterization of these plasmids revealed that there are three different Tp resistance plasmids. One group, composed of all six S. flexneri plasmids, consists of plasmids which are about 70 megadaltons (MDa) and inhibit the fertility of an Escherichia coli Hfr strain (Fi+). A representative member of this group, pPT4, demonstrates a weak incompatibility reaction with IncFI plasmid R455-2. Another group, three of the four S. sonnei plasmids, contains plasmids which are about 43 MDa, Fi−, and mediate propagation of phage PRD1. The third group, the remaining S. sonnei plasmid, is 53 MDa,fi+, mediates propagation of phages fd and MS2, and is incompatible with IncFII plasmid R100. These plasmids also have been differentiated by restriction endonuclease fragment profiles. Analysis of pPT4 has revealed that the Tp resistance of this plasmid is transposable. The transposon, Tn536, is different from previously described Tp resistance transposons; it is 16 MDa, and in addition to Tp, it encodes resistance to mercuric chloride ions, spectinomycin, streptomycin, and sulfonamides.
Respiratory syncytial virus fusion glycoprotein: further characterization of a major epitope involved in virus neutralization
Authors: Trudel Michel , Nadon Francine , Séguin Cécile , Payment Pierre , Talbot Pierre J.
Published: May 2010

Competition experiments and biological assays with a panel of 15 monoclonal antibodies confirmed the presence of at least four antigenic sites on the fusion protein of human respiratory syncytial virus, three of which were involved in virus neutralization. One antigenic site, recognized by two strongly neutralizing antibodies, was conserved after reduction and denaturation and shown by immunoblotting to be localized on the F1 fragment of the fusion protein. Cleavage of this protein with staphylococcal protease V8 or papain produced a series of smaller peptides from 11 to 7 kilodaltons that retained this important neutralization determinant. Compared with the other neutralization sites, the epitope defined by monoclonal antibody 7C2 thus appears as the major neutralization epitope. Our peptide mapping results support the hypothesis that this major epitope is composed of a continuous sequence on the viral genome.
Xylem-residing bacteria in alfalfa roots
Authors: Gagné Serge , Richard Claude , Rousseau Hélène , Antoun Hani
Published: May 2010

Bacteria were consistently isolated from the root and crown xylem of symptomless field-grown alfalfa plants. Most of the plants tested contained more than one bacterial genus. Pseudomonas spp. accounted for 52% of the 387 isolates identified and the fluorescent pseudomonads were the most frequent bacteria isolated. About 23% of the isolates were Erwinia-like bacteria. Bacterial population ranged from 6.0 × 103 to 4.3 × 104 CFU/g of fresh xylem, and was not affected by plant age or cultivar or by the sampling locations. The surface-sterilized seeds of the cultivars Iroquois and Titan were bacteria free and only 3 and 5% of the seeds of the cultivars Apica and Saranac, respectively, contained bacteria. In a greenhouse experiment, double antibotic resistant bacteria were inoculated into the soil of artificially wounded and intact roots of alfalfa plants, and on the stubble. The highest incidence of bacteria in the root xylem occurred when the roots were wounded. The highest numbers of bacteria (CFU/g fresh weight) were found when plants were wounded (stubble or roots) as compared with intact plants. The results suggest that bacteria are normal residents of the root xylem and that their main avenues of entrance to the xylem are natural root wounds and plant stubbles remaining after harvest.