bluuebunny/crossref_metadata_2025 huggingface dataset:
Isolation and characterization of Azotobacter vinelandii mutant strains with potential as bacterial fertilizer
Authors: Gordon Joyce K. , Jacobson Marty R.
Published: May 2010

Mutant strains of Azotobacter vinelandii which might have potential for use as bacterial fertilizer have been isolated and fall into two categories: constitutive mutants that synthesize nitrogenase in the presence of ammonium and mutants that overproduce nitrogenase when grown in nitrogen-free medium. The constitutive mutants described in this paper were isolated from the wild type as methylalanine-resistant strains and express up to 23% of the fully derepressed nitrogenase level when grown in medium containing excess ammonium. By contrast, ammonium-grown cultures of wild type have less than 0.003% of the fully derepressed level. Strains which fix more N2 than the wild type in nitrogen-free medium were isolated as mefhylammonium-resistant mutants. Although the methylammonium-resistant mutant strains fix more N2 than the wild type, they grow no faster. The excess nitrogen produced by these mutants is excreted into the medium, resulting in up to 60% more nitrogen than in the medium of the wild type. Higher nitrogenase activity in the methylammonium-resistant mutant strains was found to be a result of increased levels of nitrogenase protein, suggesting that regulation of nitrogenase synthesis may be altered.
2-O-Methyl-D-mannose, a key sugar in the taxonomy of Frankia
Authors: Mort A. , Normand P. , Lalonde M.
Published: May 2010

The classification of actinomycetes in the genus Frankia Brunchorst has been based partly on morphology but primarily on their ability to form N2-fixing nodules on roots of actinorhizal host plants. To identify nonsporulating and noninfective Frankia isolates, biochemical tests are needed. Sugars present in whole-cell hydrolysates have proven useful in the taxonomy of other genera of actinomycetes. We, and others, have found a sugar in all Frankia isolates examined thus far that is absent in all other actinomycetes tested. After reduction with NaBD2H4 and acetylation, the characteristic sugar was found by gas chromatographic and mass spectrometric analyses to be a 2-O-methyl hexose. The sugar was partially purified by high pressure liquid chromatography and demethylated to give a major product of mannose. Authentic 2-O-methyl mannose as its alditol acetate and trimethylsilyl methyl glycoside derivatives cochromatographed with the sugar. By gas–liquid chromatography of its trimethylsilyl (−)-2-butyl glycoside, the marker sugar was found to be 2-O-methyl-D-mannose. The 2-O-methyl-D-mannose was present in all 68 strains of Frankia isolated from the actinorhizae of seven species of Alnus, two species of Elaeagnus, and one species each of Myrica, Comptonia, and Shepherdia. These actinorhizal host plants originated from different provenances in Canada, U.S.A., France, and Holland.
Phytomass production in young mixed plantations of Alnus rubra (Bong.) and cottonwood in western Washington
Authors: Heilman Paul , Stettler R. F.
Published: May 2010

Use of red alder in mixture with 28 clones of cottonwood in close spaced, short-rotation culture for fiber and energy was investigated. Early growth was rapid with red alder averaging 7.2 m and cottonwood mixed with alder averaging 8.2 m in height after 3 years. Alder significantly increased nitrogen content of cottonwood foliage in the 1st and 2nd years but not in the 3rd. Mean height of cottonwood at 3 years was increased in mixture with red alder. However, heights of the shortest cottonwood clones were reduced. Dry weight production on mixed plots (both species combined) was generally less than for pure cottonwood. Only with the slowest growing cottonwood clones did mixed stands show increased dry weight production. The best cottonwood clone, a hybrid (Populus trichocarpa × P. deltoides), produced 20.3 t∙ha−1∙year−1 dry weight for 3 years in pure stands compared with 2.8 t∙ha−1∙year−1 for the poorest. Production by alder was inversely related to cottonwood production in mixed plantings. Nodulation and C2H3 reduction was evaluated during the third growing season. Results indicated severe decline in nitrogenase activity where overtopping and shading of red alder by adjacent cottonwood occurred. At this site, the success of this mixture appears to depend upon use of cottonwood clones that do not outgrow the alder. Since the highest yielding cottonwood clones are much more productive at this site than the alder that we used, there would seem to be little incentive for mixed plantings of these species under the conditions of this experiment.
Factors affecting nitrogenase activity (C2H2 reduction) associated with sorghum and millet estimated using the soil core assay
Authors: Wani S. P. , Dart P. J. , Upadhyaya M. N.
Published: May 2010

Factors affecting nitrogenase activity associated with sorghum and millet roots have been studied. Plants grown in iron cores in the field and then assayed had significantly higher activity than plants cored at the time of assay. Mechanical disturbance during transportation of the cores reduced the activity significantly. Any delay between cutting off the plant top and injecting C2H2 gas led to a reduction in the level of nitrogenase activity determined. Diurnal variation in nitrogenase activity was noted but was not correlated with soil temperature. Most activity occurred at the end of the photoperiod. Seasonal variation in nitrogenase activity of plants was observed and was correlated with the ontogenetic development of the host plant, being most at flowering. A low but significant correlation existed between soil moisture content and nitrogenase activity associated with the plant.
Factors influencing the inhibition of aflatoxin production in corn by Aspergillus niger
Authors: Horn B. W. , Wicklow D. T.
Published: May 2010

Aspergillus niger, a mold commonly associated with Aspergillus flavus in damaged corn, interferes with the production of aflatoxin when grown with A. flavus on autoclaved corn. The pH of com-meal disks was adjusted using NaOH–HCl, citric acid–sodium citrate, or a water extract of A. niger fermented corn. Aflatoxin formation was completely inhibited below pH 2.8–3.0, irrespective of the system used for pH adjustment. When grown in association with A. flavus NRRL 6432 on autoclaved corn kernels, A. niger NRRL 6411 lowered substrate pH sufficiently to suppress aflatoxin production. The biodegradation of aflatoxin B1or its conversion to aflatoxin B2a were eliminated as potential mechanisms by which A. niger reduces aflatoxin contamination. A water extract of corn kernels fermented with A. niger caused an additional inhibition of aflatoxin formation apart from the effects of pH.
Extracellular endodextranase from the yeast Lipomyces starkeyi
Authors: Webb E. , Spencer-Martins I.
Published: May 2010

Strain IGC 4047 of the yeast Lipomyces starkeyi grew well with dextran as sole source of carbon and energy, and was able to hydrolyse blue dextran and Sephadex G-100. The enzyme was partially purified by fractionated isopropanol precipitation from the extracellular fluid of cultures grown in a minimal medium with dextran. The enzyme preparation showed only one band by polyacrylamide gel electrophoresis. The enzyme had the following properties: molecular weight, 23 000; optimum temperature and pH for activity, around 50 °C and pH 5.0, respectively; pH stability, pH 3.5–7.5; after 2 h at 50 °C and pH 5.0, 30% reduction in activity; isoelectric point, pI = 5.4; final products of dextran hydrolysis, isomaltooligosaccharides from glucose up to isomaltohexaose, with high concentrations of isomaltose and isomaltotriose. These results suggest that the enzyme is an endodextranase.
Formation of cystlike structures by iron-limited Azotobacter vinelandii strain UW during prolonged storage
Authors: Page William J.
Published: May 2010

Slant or liquid cultures of nonencapsulated Azotobacter vinelandii strain UW survived at least 2 years at 20 °C, whereas parallel cultures died after 6 months storage at 4 °C. Survival was decreased at 20 °C when the growth medium was acidic and it was the least at 4 °C when the growth medium was iron limited. Although strain UW was capable of forming cyclopropyl fatty acids and alkyl resorcinols, these indicators of encystment were neither abundant nor present, respectively, in 1.7-year-old cells. Only lauric acid was more abundant in lipid extracts from old cells than from vegetative cells or mature cysts. The old cells were very fragile and rapidly lost viability upon dilution or dehydration. Electron microscopy revealed the production of fragile cystlike structures in iron-limited medium after 1.7 years at 20 °C. These structures had a distinct exine layer composed of membranelike plates, a poorly defined intine, and an extremely dense central body lacking storage granules or internal membranes. Iron-sufficient cultures produced similar but free central bodies, although cystlike structures were rarely seen.
Pathogenic and virulence characterization of colonial mutants of Nocardia asteroides GUH-2
Authors: Vistica Cynthia A. , Beaman Blaine L.
Published: May 2010

The pathogenicities in mice (comparing LD50 determinations) of two mutant strains and one wild-type strain of Nocardia asteroides GUH-2, each possessing a colonial morphology distinct from the other, were compared at respective stages of growth. Despite the three strains' colinear growth curves and similar physiological properties, unique patterns of pathogenicity emerged for each strain upon analysis. Ultrastructural and fatty acid profiles of cultures at the various growth stages were monitored. The mutant strain SCII-A1 was consistently less virulent than the other strains N. asteroides GUH-2 (SCII-P and SCII-C). Further, its fatty acid profiles as well as the shape and consistency of its colonies differed greatly from those of the wild-type strain. The fatty acid composition and the colonial morphology of strain SCII-C more closely resembled those of the parent, although its virulence was both greater than (before 28 h of growth) and less than the parent's depending upon the specific stage of growth. The comparative degrees of cellular fragmentation and complexity, as determined by scanning and transmission electron microscopy, were found to coincide with changes in relative degrees of pathogenicity.
Albumin requirement of Treponema denticola and Treponema vincentii
Authors: Van Horn Kenneth G. , Smibert Robert M.
Published: May 2010

Treponema denticola and Treponema vincentii were found to require albumin, oleic acid, and thiamine pyrophosphate (TPP) for growth. Previous studies indicated that commercial human alpha globulin, which is 50% albumin, was the only serum fraction that supported growth of these two oral treponemes. The alpha-globulin proteins were separated from the contaminating albumin with Affi-Gel Blue affinity chromatography. Both the albumin fraction and one of the alpha-globulin fractions were required for growth of T. denticola. Oleic acid was supplied by the alpha-globulin fraction and the albumin functioned as a chelator to maintain a low level of free fatty acid in the medium. Purified serum albumin (bovine or human) could substitute for the alpha-globulin fraction that contained albumin. Optimal growth of T. denticola and T. vincentii was in a medium supplemented with 0.4% (w/v) delipified albumin, 0.08 mg/mL of sodium oleate, and 25 µg/mL of TPP. Serum albumin tightly bound TPP (0.5 µg of TPP per milligram of albumin). Optimal growth of T. denticola was only in an albumin–oleate supplemented medium with sufficient TPP to saturate the albumin binding sites and provide excess free TPP. Albumin bound long-chain fatty acids and thus detoxified the medium. Neither starch- nor charcoal-treated Tween 80 (polysorbitan monooleate) replaced albumin for optimal growth. Short-chain fatty acids supported only limited growth of T. denticola when added to a medium with TPP or to a medium that contained 0.4% delipified albumin and TPP.
Presence of a new cytochrome b - like pigment with a peak at 567 nm in various aerobic bacteria
Authors: Jacobs N. J. , O'Hara J. , Gray C. T.
Published: May 2010

Several physiological groups of bacteria were examined for the presence of a cytochrome b - like pigment which is demonstrable in dithionite-reduced minus substrate-reduced difference spectra. This pigment is characterized by an unusually high a band at 567 nm, a low concentration relative to conventional cytochromes, and an inability to be fully reduced by endogenous substrates or NADH. Previous studies with one denitrifying Pseudomonad indicated an unusually low redox potential for this pigment. In the present study, we found the pigment in denitrifying and nondenitrifying species of the genus Pseudomonas, in Paracoccus denitrificans, in Alcaligenesfaecalis, in Azotobacter vinelandii, in Branhamella catarrhalis, and in Neisseria lactamicus. In all these organisms, the peak of the 567-nm pigment is accompanied by a peak of about equal height at approximately 559 nm, which exhibits similar properties to the 567-nm pigment. The 567-nm pigment was not demonstrable by this technique in Gluconobacter oxydans subspecies suboxydans, Bacillus subtilis, Bacillus licheniformis, Aeromonas hydrophilia, Escherichia coli, a Klebsiella species, Moraxella osloensis, Aquaspirillum itersonii, Micrococcus lysodeikticus, Micrococcus luteus, Agrobacterium tumefaciens, or Rhizobium meliloti.
Isolation and characterization of a new acidophilic Thiobacillus species (T. albertis)
Authors: Bryant R. D. , McGroarty K. M. , Costerton J. W. , Laishley E. J.
Published: May 2010

An acidophilic, rod-shaped, sulfur-oxidizing bacterium was isolated from extremely acidic soil adjacent to a sulfur stockpile at Fox Creek, Alta. This isolate was found to grow only autotrophically by oxidizing S° and reduced inorganic sulfur compounds (S2O32− and S4O62−), placing it in the genus Thiobacillus. Aerobic growth was observed over a pH range of 2.0 to 4.5 with optimum growth at 3.5 to 4.0. Analysis of its DNA revealed a mol% G + C content of 61.5. Ultrastructural studies showed that the isolate possessed a tuft of polar flagella. A glycocalyx was observed only after the antiserum stabilization procedure, which showed it extending outwards from the outer membrane of the bacterial cell envelope. Cleavage planes of this cell showed a typical Gram-negative cell wall. The cytoplasm contained two types of inclusion bodies, carboxysomes and a single large membrane-bound sulfur granule. This isolate had morphological and physiological characteristics which were not totally comparable with other known acidiophilic thiobacilli demonstrating this bacterium to be a new Thiobacillus sp. named T.albertis.
Determination of nuclear DNA content in fungi using mithramycin: vegetative diploidy in Armillaria mellea confirmed
Authors: Franklin A. L. , Filion W. G. , Anderson J. B.
Published: May 2010

Armillaria mellea, a phytopathogenic fungus, is the only member of the Agaricales (Basidiomycetes) whose fertile vegetative phase in nature is thought to be diploid, rather than dikaryotic. To examine the vegetative ploidy of A. mellea, we used the DNA-binding antibiotic, mithramycin, for fluorometry of in situ nuclear DNA. The measurements of nuclear DNA content indicated that strains derived from single basidiospores of A. mellea were haploid and that strains derived from matings of isolates of single spores were diploid. These data confirm the results of earlier genetic experiments, which show haploidy and diploidy in unmated and mated strains, respectively. Nuclear DNA measurements in known haploid and diploid strains of Aspergillus nidulans confirmed the validity of our protocol.
Phenylacetic acid production by Bacteroides gingivalis from phenylalanine and phenylalanine-containing peptides
Authors: Bourgeau G. , Mayrand D.
Published: May 2010

Phenylacetic acid production and growth of Bacteroides gingivalis were directly proportional to the trypticase content of the medium. L-Phenylalanine enhanced phenylacetic acid production; 5 mg L-phenylalanine per millilitre stimulated maximum production of phenylacetic acid. Peptides (2–4 amino acids) containing L-phenylalanine also stimulated phenylacetic acid production as did phenylpyruvic acid. Resting cell suspensions of B. gingivalis also produced phenylacetic acid when incubated aerobically in the presence of L-phenylalanine and phenylpyruvic acid. Hydrocinnamic acid (3-phenylpropionic acid) and phenyllactic acid were also produced by resting cell suspensions. Our results suggest that L-phenylalanine and phenylpyruvic acid are both precursors to phenylacetic acid.
Control of catalase and peroxidase biosynthesis by carbon source and oxygen in the yeast Saccharomyces cerevisiae
Authors: Valdivia E. , Martinez J. , Ortega J. M. , Montoya E.
Published: May 2010

The effect of carbon source and oxygen tension on catalase and peroxidase levels and on the intermediates of the biosynthesis of the prosthetic group of both enzymes has been studied. Oxygen produces an increase of both enzymatic activities, even in presence of glucose. On the other hand it seems probable that glucose does not have a direct inhibitory effect on the biosynthesis of 5-aminolevulinic acid (ALA) and porphyrins.
Utilization of fructose by Azospirillum brasilense
Authors: Das Amaresh , Mishra Ajit K.
Published: May 2010

Optimum growth and acetylene reduction in Azospirillum brasilense which are comparable to those observed with organic acids, e.g., malate, succinate, pyruvate, and lactate, were obtained using fructose as the carbon source. Best yields of cell mass had been obtained with fructose and malate, while the yields were poor with other carbon sources tried. Acetylene reduction occurred at optimum levels only between pH 7.0 and 7.5. Efficiency of N2 fixation and the efficiency of the utilization of combined nitrogen were high with fructose but low with malate. Fructose as well as malate, succinate, pyruvate, and lactate were actively oxidized both in cell suspensions and cell-free extracts, while glucose, galactose, sucrose, and citrate were oxidized only in cell-free extracts.
Arginine biosynthesis in Legionella pneumophila: absence of N-acetylglutamate synthetase
Authors: Tesh Martha J. , Miller Richard D.
Published: May 2010

Legionella pneumophila was unable to grow in a chemically defined medium without arginine because it could not carry out the first step in the biosynthetic pathway, the conversion of glutamate to N-acetylglutamate. All strains examined could grow when N-acetylglutamate (or other later arginine precursors) were substituted for arginine. No activity corresponding to N-acetylglutamate synthetase could be detected in cell extracts of L. pneumophila.
Transferable tetracycline resistance in Clostridium perfringens strains of porcine origin
Authors: Rood Julian I.
Published: May 2010

These studies represent the first systematic survey of the incidence of conjugative antibiotic resistance in Clostridium perfringens. Ninety-two antibiotic-resistant porcine strains were examined to see if they could donate their antibiotic-resistance determinants to sensitive recipient strains. Fifteen of the 89 tetracycline-resistant strains transferred their tetracycline resistance in mixed-plate mating experiments but no transfer of macrolide–lincosamide resistance was detected. The efficiencies of transfer of tetracycline resistance varied from 1.3 × 10−3 to 1.9 × 10−6 transconjugants per donor cell. Significantly higher transfer efficiencies were observed when both the donor and recipient strains were derivatives of strain CW 362. These values ranged from 3.7 × 10−1 to 4.6 × 10−2 transconjugants per donor cell. This high frequency transfer system should prove invaluable for further genetic studies on this microorganism.
Nitrogenase inactivation by oxygen and enzyme turnover in Anabaena cylindrica
Authors: Murry Marcia A. , Hallenbeck Patrick C. , Esteva Diane , Benemann John R.
Published: May 2010

Nitrogenase is known to be irreversibly inactivated by oxygen in vivo and in vitro. In time-course experiments using Anabaena cylindrica, cultures treated with antibiotics and incubated under various O2 tensions, in vivo acetylene reduction activity and immunologically determined Fe–Mo protein (component I) were lost at rates directly related to O2 tension. Activity was lost at a faster rate than cross-reactive material. The half-life of cross-reactive material was 25 h under microaerophilic conditions, 12 h under aerobic conditions, and 6.6 h under an O2 tension of 245% of air saturation. In vitro, cross-reactive material was lost in O2 exposed, but not in anaerobically prepared, crude cell extracts. Loss of cross-reactive material was prevented by freezing and by α-N-tosyl-L-phenylalanine chloromethyl ketone (TPCK), an inhibitor of histidine-residue proteases. These results indicate that nitrogenase is continuously inactivated by O2, hydrolyzed, and resynthesized during growth of this heterocystous cyanobacteria under aerobic conditions.
Production of curdlan-type polysaccharide by Alcaligenes faecalis in batch and continuous culture
Authors: Phillips K. Railton , Pik J. , Lawford H. G. , Lavers B. , Kligerman A. , Lawford G. R.
Published: May 2010

The biosynthesis of a thermogelable, extracellular homo-β-(1 → 3)-glucan called "curdlan," has been studied in batch and continuous cultures of Alcaligenes faecalis var. myxogenes. Curdlan production is associated with the poststationary phase of a nitrogen-depleted, aerobic batch culture. Exopolymer is not detected in single-stage, carbon-limited continuous cultures but curdlan can be isolated from the effluent of a nitrogen-limited chemostat operating at a dilution rate (D) of < 0.1 h−1. A spontaneous variant of strain ATCC 21680 was isolated and found to be compatible with long-term, nitrogen-limited chemostat culture. The specific rate of curdlan production is approximately four times higher in poststationary batch cultures than in single-stage continuous fermentations. The product yield (Yp/s) associated with batch processing (nongrowing cultures) is approximately 0.5 g curdlan/g glucose, with CO2 being the only detectable by-product.
Acid and alkaline phosphatases of Capnocytophaga species. I. Production and cytological localization of the enzymes
Authors: Poirier Thomas P. , Holt Stanley C.
Published: May 2010

The two hydrolytic enzymes, acid (AcP; EC 3.1.3.2) and alkaline (A1P; EC 3.1.3.1) phosphatase, of the three types species of Capnocytophaga were examined. Both enzymes were produced constitutively, with their activity highest in C. ochracea strain 25. These two degradative enzymes (approximately 10% of the total activity) were released into the growth medium during the latter stages of growth, both as soluble and membrane-bound enzymes. When grown in the presence of high concentrations of organic phosphates, the synthesis and expression of AcP and AlP was unaltered. Cyto- and immuno-chemical localization situated the phosphatases in the periplasmic space, at the cell surface, and in membranous vesicles.
Acid and alkaline phosphatases of Capnocytophaga species. II. Isolation, purification, and characterization of the enzymes from Capnocytophaga ochracea
Authors: Poirier Thomas P. , Holt Stanley C.
Published: May 2010

Capnocytophaga ochracea acid (AcP; EC 3.1.3.2) and alkaline (AlP; EC 3.1.3.1) phosphatase was isolated by Ribi cell disruption and purified by sodium dodecyl sulphate – polyacrylamide gel electrophoresis (SDS–PAGE.) Both phosphatases eluted from Sephadex G-150 consistent with molecular weights (migration) of 140 000 and 110 000. SDS–PAGE demonstrated a 72 000 and 55 000 subunit molecular migration for AcP and AlP, respectively. The kinetics of activity of purified AcP and AIP on p-nitrophenol phosphate and phosphoseryl residues of the phosphoproteins are presented.
Characterization of Arthrobacter strains isolated from the pine environment that inhibit Fusarium moniliforme var. subglutinans, the causal agent of pine pitch canker
Authors: Barrows-Broaddus Jane , Teeslink Shari D. , Kerr Thomas J.
Published: May 2010

Forty-three Arthrobacter strains isolated from the canopy and soil in stands of southern pines were characterized and compared with seven named strains of Arthrobacter using numerical taxonomic analysis. The analysis placed 24 of the pine isolates into four overlapping clusters, leaving 8 that matched with 1 to several isolates and 18 that matched with none. All isolates within clusters inhibited fusaria in dual culture, but the nonclustered pine strains varied in their ability to produce inhibition zones against Fusarium moniliforme var. subglutinans, the causal agent of pine pitch canker. The seven named Arthrobacter strains did not cluster with any of the pine isolates nor did they inhibit F. moniliforme var. subglutinans in dual culture. Isolates tested from each cluster did not produce bacteriocinlike compounds against isolates within a cluster nor did they produce bacteriocinlike compounds against isolates that matched in other clusters. Nonmatching isolates, whether from different clusters, strains, or species, frequently produced bacteriocinlike compounds against each other. Membership in a cluster was not correlated with the source of isolation. Many of the isolates from pine bark and needles matched those from the soil. All of the nonclustered pine strains, however, came from the pine canopy, indicating a possible divergence of these isolates from those in the soil habitat.
The timing of ribonucleic acid synthesis during the germination of heat-activated Dictyostelium discoideum spores
Authors: Hamer John E. , Cotter David A.
Published: May 2010

To observe changes in the rate of RNA synthesis during Dictyostelium discoideum spore germination, we have pulse labeled germinating spores with [3H]uracil at stage-specific intervals. The labeled RNAs have been fractionated on 1.7 and 10% polyacrylamide gels. Additionally we have monitored the total changes in ribonucleic acid content during germination. In general, the rate of synthesis of various RNA species appears to increase noncoordinately, while the total RNA content remains unchanged during germination. This may indicate extensive RNA turnover during germination. Little or no RNA synthesis is observed during the first pulse period (postactivation lag). During the 1–2-h pulse period, 25, 17, 5.8, and 5 S RNA were all synthesized. The synthesis of these species increased with each pulse period, with the greatest amount of synthesis occuring during the final 3–4-h pulse. The synthesis of 4 S RNA initiated during the 2–3-h pulse and increased during the final 3–4-h pulse. The percentage of poly(A) + RNA increased with each time period from 0.1% of the total labeled RNA at the 0–1-h pulse period to 10% of the total RNA synthesized at the 2–3-h pulse time. During the final pulse period (3–4 h), this level dropped to 6%. Analysis of acid-soluble extracts from dormant spores revealed relatively high levels of the four ribonucleoside 5′-triphosphates. These levels remained unchanged during the 1st h of germination. Thus RNA synthesis during the postactivation lag stage of germination does not appear to be limited by precursor availability and may involve other regulatory mechanisms.
Effect of some physical and chemical parameters on the fermentation of cellulose to methane by a coculture system
Authors: Laube Victoria M. , Martin Stanley M.
Published: May 2010

In the fermentation of cellulose to methane by the triculture of Acetivibrio cellulolyticus – Desulfovibrio sp. – Methanosarcina barkeri, methanogenesis was the rate-limiting step. The optimal temperature was 35 °C. In the presence of initially added hydrogen, initiation of cellulose hydrolysis was delayed until most of the hydrogen was metabolized, and then the fermentation which followed was comparable with the N2: CO2 control. Increased CH4 yields and rates of formation were stoichiometrically related to the utilization of the hydrogen initially present. Added acetate had no effect on cellulolysis. The increased yields of CH4 observed could be accounted for by utilization of the added acetate. When Methanobrevibacter sp. was included in the coculture (without added H2 or acetate), no hydrogen accumulated and lower rates of acetate utilization and subsequent CH4 evolution were observed. These results suggest a requirement for hydrogen by M. barkeri for efficient acetate utilization. Controlling the pH at 6.8 increased the amount of cellulose degraded, but CH4 yields were lower and no acetate was used. Increasing sulfate levels altered the ratio of fermentation products but had no effect on cellulose degradation. Lower CH4 yields were obtained at elevated sulfate concentrations.
Mechanism of poliovirus inactivation by cell-free filtrates of marine bacteria
Authors: Toranzo Alicia E. , Barja Juan L. , Hetrick Frank M.
Published: May 2010

The mechanism of enterovirus inactivation by marine bacteria was investigated using poliovirus type 1 as a model virus and with strains of Pseudomonas and Vibrio isolated from the marine environment. Treatment of virus with cell-free filtrates from late log phase bacterial cultures produced alterations in the viral capsid as shown by a reduction in efficiency of adsorption to host cells, increased sensitivity to ribonuclease, and by the release of ribonucleic acid from the treated virions. Filtration of 14C-labelled, treated virus through 25-nm filters revealed that the majority of the isotope (85–96%) passed the filters, indicating extensive capsid disruption. However, the most rapid and pronounced change observed during virus inactivation was the loss of infectivity, suggesting that enzymatic degradation is not the first event in the poliovirus inactivation process by marine bacteria.
Further evidence for hyaluronidase activity of Treponema pallidum
Authors: Fitzgerald T. J. , Gannon E. M.
Published: May 2010

The presence of hyaluronidase in preparations of Treponema pallidum was previously shown using acidified bovine serum albumin reactions and Ouchterlony immunodiffusion. To expand on these preliminary findings more sensitive techniques of viscometry, additional immunologic reactions, and altered capillary permeability were used to characterize treponemal-associated hyaluronidase. The pathogens T. pallidum and T. pertenue degraded hyaluronic acid, whereas the nonpathogens T. denticola and T. vincentii did not. As syphilitic infection progressed, hyaluronidase activity decreased; organisms harvested from 14-day testicular infections degraded hyaluronic acid less rapidly than organisms from 4-day infections. Uninfected rabbit testicular extract also exhibited significant enzyme activity. The neutralizing activity of immune sera was decreased by prior adsorption with bovine hyaluronidase, suggesting that some of the neutralizing factors are associated with this enzyme. Radioimmunoassay was used to quantitate antibodies to hyaluronidase in immune sera. Antihyaluronidase sera were isolated from rabbits immunized with bovine hyaluronidase. Treponema pallidum, as well as uninfected rabbit testicular extract, cross-reacted with these antisera. Immunofluorescence indicated that the hyaluronidase was uniformly distributed along the treponemal surface. As a final indicator of hyaluronidase activity, alterations in capillary permeability were detected 1 h after intradermal injection of T. pallidum.
Partial purification and characterization of isopenicillin N epimerase activity from Streptomyces clavuligerus
Authors: Jensen Susan E. , Westlake Donald W. S. , Wolfe Saul
Published: May 2010

Epimerase activity, which converts isopenicillin N to penicillin N, has been partially purified from cell-free extracts of Streptomyces clavuligerus. No stimulating cofactors of this activity were found, and neither EDTA nor anaerobic incubation caused significant inhibition of activity. Although pyridoxal phosphate did not stimulate epimerase activity, the presence of this cofactor was necessary for the stabilization of enzymic activity during the purification process. Epimerase activity was purified 35.5-fold by a combination of salt precipitation, gel filtration, and ion exchange chromatography. Gel filtration indicated that the epimerase has a molecular weight of 60 000 and sodium dodecyl sulphate – polyacrylamide gel electrophoresis of the 35.5-fold purified epimerase showed a major protein band running near that location. Pyridoxal phosphate antagonists did not uniformly inhibit epimerase activity, but the inhibitory effect of hydroxylamine could be partially reversed by pyridoxal phosphate.
Carbon monoxide oxidation by chemolithotrophic ammonium oxidizers
Authors: Jones Ronald D. , Morita Richard Y.
Published: May 2010

Chemolithotrophic nitrifying bacteria were examined with respect to their ability to oxidize carbon monoxide in the presence and absence of ammonium. All of the ammonium oxidizers tested, including Nitrosomonas europaea and Nitrosococcus oceanus, were able to oxidize CO to CO2 in the presence and absence of ammonium. None of the organisms tested incorporated any of the carbon from CO into cellular components in the absence of ammonium. All were able to oxidize CO at trace concentrations of <0.5 nM. None of the nitrite oxidizers examined were capable of CO oxidation. CO oxidation by Nitrosomonas europaea, Nitrosococcus oceanus, and Nitrosomonas sp. 4S30, a marine ammonium oxidizer, were examined with respect to CO concentration and time course of CO oxidation, both in the presence and absence of 10 mg/L NH4 N. The CO oxidation rates at a CO concentration of 300 nL/L in the absence of ammonium ranged from 0.048 nmol/h per 106 cells for Nitrosomonas sp. 4W30 to 0.0025 nmol/h per 106 cells for N. europaea.
Etude ultrastructurale de la différenciation des hétérocystes chez la Cyanobactérie, Anabaena cylindrica Lemm
Authors: Roussard-Jacquemin Monique
Published: May 2010

The differentiation of heterocystes from vegetative cells of Anabaena cylindrica, induced after transfer from a NH4+ medium to a medium without NH4+ under aerobic conditions, was studied by electron microscopy, the material being fixed with osmium tetroxide. The narrow septum separating the heterocyst and the vegetative cell originates from the median region of the normal septum which separates two adjacent vegetative cells. Its peripheral region is transformed into a thickened ring on which rests the complex envelope of the heterocyst. This structure presumably helps to create an anaerobic condition for nitrogenase. At the final stage of heterocyst maturation, the thylakoid membranes are significantly modified. They become flattened while at the previous stages they were expanded and vesiculated. In addition, some of them seem to be closely associated either with the remaining vesicular structures or with the plasmalemma. Polyphosphates bodies, cyanophycin granules, DNA fibres, and polyhedral bodies disappear. The presence of ribosomes, few polyglucosides, and numerous lipid droplets are observed at the end of the differentiation. A possible relationship between these ultrastructural changes and N2 fixation in the heterocysts of Anabaena cylindrica is discussed.
Studies on the mode of action of a bacteriocin produced by Bacillus stearothermophilus
Authors: Fikes J. D. , Crabtree B. L. , Barridge B. D.
Published: May 2010

Thermocin 10 was purified by elution from a carboxymethyl cellulose column. The eluted thermocin was homogeneous and yielded single bands with identical relative mobility when stained for protein or glycoprotein. Thermocin 10 inhibited RNA synthesis 3 min after its addition. Cell motility, oxygen uptake, ATP synthesis, and DNA synthesis were inhibited 10 min after the addition of thermocin 10. Total cell protein was reduced to one quarter of its normal content in cells treated with thermocin.
Impairment of virulence of in vitro subcultures of Mycobacterium lepraemurium
Authors: Turcotte R. , Ishaque M.
Published: May 2010

Mycobacterium lepraemurium was cultivated in vitro on Ogawa egg-yolk medium. The pathogenicity of the third and eighth subcultures for C3H and C57BL mice was compared with that of in vivo grown murine bacilli by evaluating the mean survival time of infected mice. The results strongly suggest that a significant drop of virulence occurs during the in vitro cultivation of M. lepraemurium.
The role of respiratory protection on increased survival of Treponema pallidum (Nichols) when cocultivated with mammalian cells in vitro
Authors: Steiner Bret , Wong Grace H. W. , Drummond Linda , Graves Stephen
Published: May 2010

The ability of mammalian cells in tissue culture to protect against oxygen toxicity for Treponema pallidum was examined. Addition of catalase to the incubation medium enhanced T. pallidum survival when co-incubation was carried out under aerobic conditions. When co-incubation was carried out under 3% oxygen, catalase had no enhancing effect on survival despite the fact it was still highly stimulatory when T. pallidum was incubated under 3% oxygen in the same medium with no tissue culture cells present. Inactivation of the catalase present endogenously in the mammalian cells by the addition of the catalase inhibitor 3-amino-1,2,4-triazole largely eliminated the enhancing effect of mammalian cells on the survival of T. pallidum under 3% oxygen. Increasing the oxygen consumption of the host mammalian cells with 0.1 mM 2,4-dinitrophenol enhanced T. pallidum under both aerobic and microaerobic conditions; a much greater effect was seen under aerobic conditions. The results indicated that mammalian cells offer significant protection against toxic oxygen reduction products for T. pallidum in vitro under microaerobic conditions.
Dual effect of meningococcal antigens on a T cell dependent immune response
Authors: Sparkes Brian G.
Published: May 2010

Meningococcal antigens (MA) showed adjuvant activity when administered to mice at the same time as antigen (sheep erythrocyte (SE)), by increasing the splenocyte plaque-forming response in a dose-related manner. However, when SE were given 1 day after MA administration, the subsequent plaque formation was diminished from normal in proportion to the dose of MA injected. Splenocytes taken from mice up to 5 days after MA injection actively inhibited plaque formation when mixed with splenocytes immunized with SE 4 days earlier. Two days after MA injection the nonspecific inhibition of plaque formation was mainly due to adherent spleen cells, while at 5 days nonadherent cells had acquired the inhibitory activity. It appears that it is the degree of activation of adherent cells resulting from the timing and dosage of MA which modulates the subsequent development and secretion of antibody-forming cells.
Fatty acid composition and primer specificity of de novo fatty acid synthetase in Bacillus globispores, Bacillus insolitus, and Bacillus psychrophilus
Authors: Kaneda Toshi , Smith Eleanor J. , Naik Devarray N.
Published: May 2010

The fatty acid compositions of three psychrophilic species of Bacillus were determined by gas–liquid chromatography. The proportions of straight-chain fatty acids, branched-chain fatty acids, and unsaturated fatty acids were found to be 13.3, 86.7, and 26.1 % of the total cellular fatty acids for Bacillus globispores, 36.6, 63.4, and 25.1 % for Bacillus insolitus, and 6.9, 93.1, and 18.4% for Bacillus psychrophilus, respectively. In all three organisms the de novo fatty acid synthetase specificity towards acyl-CoA primers was butyryl-CoA > propionyl-CoA [Formula: see text] acetyl-CoA. This shows that B. insolitus, which has an unusually large proportion of straight-chain fatty acids for Bacillus, does not possess a different de novo fatty acid synthetase than the other two organisms. Therefore, the greater proportion of straight-chain fatty acids in B. insolitus may be explained by a large supply of straight-chain primer.
Interaction between bile acids and staphylococcal polysaccharide: inhibition of capsule formation in encapsulated mutant strains (taurine+, taurine−) of Staphylococcus aureus
Authors: Ohtomo Toshichika
Published: May 2010

In a previous paper, we showed that bile acid derivatives inhibit capsule formation as well as taurine biosynthesis in a taurine+ (Tau+) encapsulated strain of Staphylococcus aureus. In the present study, binding of [14C]cholic acid ([14C]CA) and [14C]taurocholic acid ([14C]TA) to the staphylococcal polysaccharide antigen (SPA) of the capsular fraction was examined. The bile acids were found to bind with SPA via taurine of the Tau+ cells. [14C]CA bound with the SPA fraction of the Tau+ strain within 10–30 min, whereas 60–120 min was required in the binding of [14C]TA. Various bile acids competed with cholic acid binding to Tau+ cells which was shown by the inhibition of binding with cholic acid or taurocholic acid but not with glycholic acid. Binding of bile acid derivatives to a Tau− encapsulated mutant or to capsular material from this mutant was not observed.
Prevention of the enhancing effect of mucin and iron in mouse meningococcal infection
Authors: Dupuy J. M. , Sparkes B. G. , Desrosiers M. , Skamene E. , Micusan V. V.
Published: May 2010

In vivo resistance of mice to Neisseria meningitidis was entirely abrogated by a concomitant administration of mucin and iron with N. meningitidis organisms. Resistance, however, was restored when the latter challenge was given to animals which had been immunized 7 days previously with a crude extract of meningococcal antigens (MA), BCG, or proteose peptone. These results suggest that depression or activation of the reticuloendothelial system (RES) may be important in resistant of mice to meningococcal infection. Also, like BCG, MA inoculation was able to prevent infection by Listeria monocytogenes indicating its marked ability to activate the RES. The data show that immunization can induce nonspecific RES stimulation and that the nonspecific resistance persists for at least 7 days.
Persistence of naturally acquired cell-mediated immunity to rubella virus during the first trimester of pregnancy
Authors: Rossier Edmond , Phipps Peter H. , Weber John M.
Published: May 2010

We studied the persistence of naturally acquired cell-mediated immunity to rubella during early pregnancy. We compared lymphocyte transformation responses to phytohemagglutinin and rubella virus in 35 naturally immune women aged 17–37 years, in the first trimester of pregnancy, with 49 naturally immune age-matched nonpregnant controls. A significant lower lymphocyte transformation response to phytohemagglutinin was observed during the first trimester of pregnancy (P = 0.008), but lymphocyte transformation responses to rubella virus were not significantly different (P = 0.901). These data indicate that, in naturally immune women, cell-mediated immunity to rubella virus is not significantly altered by the physiological changes in early pregnancy.
Étude comparée de la dégradation de lignocelluloses par différentes souches de Fomes annosus
Authors: Bono J. J. , Gas G. , Boudet A. M. , Fayret J. , Delatour C.
Published: May 2010

The ligninolytic activity of Fames annosus has been estimated by radiorespirometric methods using lignocelluloses of Norway spruce and poplar, as substrates, labelled on the lignin moiety. Although F. annosus is mainly a parasite of coniferous wood, poplar lignins were more extensively degraded. 14C-labelled poplar lignocelluloses, labelled either on the lignins moiety or on the overall polymers, were used to compare wood degradation or only specific lignin degradation by the different strains. Moreover, using the best strain, we studied the effect of culture parameters which are known to influence lignin degradation by Sporotrichum pulverulentum. The rate of lignonolysis was enhanced in media with low nitrogen content but was not stimulated by increasing the O2 concentration of the atmosphere. Such data point out the specific behaviour of F. annosus, which differs in some respect from other white-rot fungi.
Nitrogen metabolism and chloramphenicol production in Streptomyces venezuelae
Authors: Shapiro S. , Vining L. C.
Published: May 2010

The relationship between chloramphenicol production and nitrogen metabolism in Streptomyces venezuelae was examined in stirred jar cultures under pH control. Nitrogen sources that supported rapid biomass accumulation gave low rates of antibiotic synthesis during growth. This was consistent with a general incompatibility between fast growth and high yields of chloramphenicol. In media where the growth rate was reduced below the attainable maximum by the rate at which nitrogen could be assimilated, chloramphenicol production was associated with biomass accumulation. Enzymes that are potentially associated with nitrogen assimilation pathways were assayed in cultures supplied with nitrogen sources supporting markedly different growth rates. The results indicated mat glutamine synthetase and alanine dehydrogenase levels were relatively insensitive to changes in growth rate and nitrogen source depletion. Glutamate dehydrogenase and glutamate synthase, on the other hand, showed high activity in cultures assimilating ammonium nitrogen and markedly decreased activity with poorer nitrogen sources or when ammonium was depleted. If chloramphenicol biosynthesis is coordinately controlled by mechanisms that regulate nitrogen assimilation, glutamate synthase and glutamate dehydrogenase are the most likely enzymes that manifest the regulatory linkage.
Polyphosphate body and acid phosphatase localization in Nostoc sp.
Authors: DuBois John D. , Roberts Keith R. , Kapustka Lawrence A.
Published: May 2010

Polyphosphate bodies and acid phosphatase activity were characterized in Nostoc sp. to determine if the hydrolysis of polyphosphate bodies occurs during dark (energy stress) periods. Electron and light microscopy were used to locate polyphosphate bodies. Acid phosphatase activity was measured using p-nitrophenyl phosphate as the substrate to determine net changes in the level of the enzyme activity. To induce energy stress, Nostoc sp. cells were kept in the dark for 72 h to deplete stored carbon compounds. Cells incubated in the light for 72 h (controls) showed acid phosphatase activity localized around the perimeter of polyphosphate bodies. When cells were incubated in the dark, acid phosphatase activity occurred throughout the polyphosphate body matrix. However, complete hydrolysis of the polyphosphate body did not occur and the rate of acid phosphatase activity was not affected.
Flocculation of wine yeasts: frequency, differences, and stability of the character
Authors: Suzzi Giovanna , Romano Patrizia , Zambonelli Carlo
Published: May 2010

Flocculating ability in yeasts of the genus Saccharomyces which cause the spontaneous fermentation of grape musts is not rare. About 6.8% of isolates are flocculent. The strains show a different degree of flocculation and also variable developmental behaviour. The genetic analysis, carried out immediately after strain isolation and again after 3 years, shows that only flocculating homozygote strains ensure the stability of the flocculation character over time. Flocculation of some strains shows a degree of instability in the expression of the character which is typical of cytoplasmic inheritance.
Étude comparative de la transformation et de la fusion induite par les polyéthyléneglycols chez Acholeplasma laidlawii B
Authors: Goulay J. L. , Darbord J. C. , Desvignes A.
Published: May 2010

This study showed in Acholeplasma laidlawii the possibility of transformation and fusion of protoplasts after induction by polyethylene glycol. Recombination in a genome of the resistance to chloramphenicol and neomycin has been obtained. Minimal inhibitory concentraiton of these antibiotics towards the recombined strain are identical to those measured with the parental strains. The most suitable experimental conditions have been studied. It appeared that the fusion, which is carried out more easily than the transformation, led to a higher frequency of recombination.[Translated by the journal]