bluuebunny/crossref_metadata_2025 huggingface dataset:
The reduction of root colonization by mycorrhizal fungi by mycophagous amoebae
Authors: Chakraborty S. , Theodorou C. , Bowen G. D.
Published: May 2010

Two mycophagous amoebae, Saccamoeba sp. and Gephyramoeba sp., reduced the colonization of pine roots in soil by the ectomycorrhizal fungus, Rhizopogon luteolus, when added at the same time as the fungus or 2 weeks later. Another mycophagous amoeba, an unidentified leptomyxid, was unable to do so. When seedlings were grown in sterilized soil amended with different population levels of Saccamoeba, 42 and 85 amoebae g soil−1 had no effect but large reductions in root colonization by R. luteolus occurred when 430 and 860 amoebae g soil−1 were added. After 4 weeks, however, the protozoa population increased to a similarly high level in all treatments irrespective of the numbers added initially. Our results indicate that protozoa can have a large effect on the establishment of inoculated symbiotic fungi and could markedly affect the microbial composition of the rhizosphere.
Hydrogen-supported N2 fixation of Pseudomonas sp. and Azospirillum lipoferum under free-living conditions and in association with rice seedlings
Authors: Gowda T. K. S. , Watanabe I.
Published: May 2010

Hydrogen-dependent chemolithotrophic nitrogen fixation of Pseudomonas sp. strains H8 and KLH76 and Azospirillum lipoferum strain 34H was confirmed by acetylene-reduction assay (ARA) and 15N2 incorporation. Glucose at lower than 2 mM did not significantly repress H2-dependent acetylene reduction of chemolithotrophically grown Pseudomonas sp. H8 and Azospirillum lipoferum. H2 (10%) stimulated ARA associated with the root of 4-week-old rice seedlings but not ARA of bacteria associated with etiolated seedlings of rice. A difference in ARA was found among rice varieties both in the presence and absence of H2. It was, however, more pronounced in the absence of H2.
Nitrogen fixation by naturally occurring duckweed–cyanobacterial associations
Authors: Duong Tran Phuoc , Tiedje James M.
Published: May 2010

Nitrogen fixation as measured by acetylene conversion to ethylene was found to be common for duckweed blooms on ponds, lakes, and streams in Michigan. Twenty-six of 29 sites with duckweed sampled over a 2-year period showed acetylene reduction activity (ARA). These activities corresponded to N inputs of 3.7–7.5 kg N∙ha−1 per annual cycle for typical blooms but dense Lemna trisulca blooms could be 10 times greater. The ARA was stimulated five- to six-fold by light, was not removed when plants were shaken in water, and was usually associated with the leaves and not the roots. Colonies of heterocyst-bearing cyanobacteria of the genera Nostoc, Gloeotrichia, Anabaena, Calothrix, and Cylindrospermum were observed attached to the lower epidermis or in the reproductive pockets of leaves of Spirodela and Lemna plants but not on Wolffia plants. The ARA correlated reasonably well with the density of cyanobacterial colonies observed. The duckweed appeared to provide a more favorable environment for the cyanobacteria which should result in enhanced nitrogen inputs to aquatic and sediment environments harboring duckweed. The N2 fixation was not sufficient, however, to meet all the nitrogen needs of the duckweed bloom.
Effect of growth temperature on lipid composition of Streptococcus faecium
Authors: Ordóñez J. A. , Hoz L. de la , Azcona J. I. , Sanz B.
Published: May 2010

The effect of growth temperature on the lipid and fatty acid composition of Streptococcus faecium has been studied. No differences in the qualitative composition of S. faecium lipids were observed. In all isolated fractions (neutral lipids, glycolipids, and phospholipids plus other polar lipids), the major fatty acids were palmitic (C-16:0), palmitoleic (C-16:1), octadecenoic (C-18:1), and cyclopropane (C-19:0). Changes in the fatty acid composition of the different fractions were observed which depended on growth temperature; the most significant one was the decrease of octadecenoic acid and the increase of palmitic acid in glycolipids and polar lipids as the temperature increased. The level of cyclopropane C-19:0 was approximately eightfold lower at 8 °C than at the other temperatures tested (20, 30, and 45 °C).
Properties of bacteria isolated from surfaces of conidia of Cochliobolus sativus incubated in soil
Authors: Fradkin A. , Patrick Z. A.
Published: May 2010

Bacteria isolated from surfaces of conidia of Cochliobolus sativus incubated in soil were tested for their antagonistic effect on the pathogen, and their ability to degrade fungal cell wall components such as proteins, chitin, lipids, or cellulose. Of the 22 isolates tested only 12 utilized intact conidia as sole nutrient source, and 3 grew poorly on isolated conidial walls. The ability of the various bacteria to colonize conidia in vitro was not correlated with their hydrolytic capacity, or with production of exopolysaccharides. Also, the hydrolytic properties exhibited by the bacteria that were isolated from the surface of conidia were not significantly different from those isolated directly from soil. Motile isolates were not attracted to intact conidia when examined in chemotaxis tests, but they often adhered to the spore surface when in close proximity. The ability of bacteria to adhere to the spores correlated with their ability to grow on intact conidia. Some of the bacterial colonizers of the conidia were identified as species of Bacillus, Pseudomonas, Arthrobacter, and Streptomyces. The antagonistic effect of each of these bacteria to the fungus was tested on agar plates. Five of the isolates were also tested for their antagonism of conidia in soil by coincubation. The inhibition of fungal growth observed on agar tests did not correlate with the inhibition of conidial germination after the spores were incubated with bacteria in soil. The inhibitory effect imposed on the conidia by bacteria seemed to be modified by the soil microflora.
Factors affecting sensitivity of group B streptococci to an exogenous murein hydrolase
Authors: Horne Diane , Tomasz Alexander
Published: May 2010

Group B streptococci treated with cell wall synthesis inhibitors (penicillin or vancomycin) or by a variety of membrane-acting agents are sensitized to the lytic action of exogenous M1 muramidase. Muramidase without a sensitizing agent caused rupture of bacterial chains only, accompanied by the release of a small amount of cell wall peptidoglycan label and an increase of the number of colony-forming units. In combination with sensitizing agents the exogenous muramidase appeared to initiate hydrolysis of biosynthetically new peptidoglycan. Treatment of the cells with chloramphenicol or starvation for nutritionally required amino acids suppressed the rate of cell lysis and peptidoglycan hydrolysis during subsequent sensitization and muramidase treatment of the bacteria. Purified cell walls prepared from the amino acid starved cells were also hydrolyzed with a slower rate by muramidase. It is suggested that agents sensitizing the bacteria to the exogenous muramidase act by perturbing or removing some nonmurein components of the cell envelope which protect the peptidoglycan from the activity of exogenous enzyme. Agents increasing resistance against exogenous muramidase may also cause some alteration in peptidoglycan structure.
Partial purification and properties of pyruvate kinase and its regulatory role during lipid accumulation by the oleaginous yeast Rhodosporidium toruloides CBS 14
Authors: Evans Christopher Thomas , Ratledge Colin
Published: May 2010

Pyruvate kinase from the oleaginous yeast Rhodosporidium toruloides CBS 14 was partially purified and its properties investigated to determine its role during lipid production by this yeast. The enzyme (relative mass (Mr) = 190 000) showed a pH optimum of 8.0 and apparent Km values for K+, phosphoenolpyruvate (PEP), and ADP of 1.6 mM, 571 μM, and 120 μM, respectively. Enzyme activity was inhibited by citrate, isocitrate, ATP, GTP, and CTP and activated by fructose 1,6-bisphosphate, L-glutamate, and [Formula: see text] ions. Inhibition by citrate and ATP were both competitive with PEP with the Ki(citrate) = 340 μM and Ki(ATP) = 303 μM. The effect of ATP and cellular energy charge were critically dependent on the concentration of ADP present in the enzyme assay. Both L-glutamate and fructose 1,6-bisphosphate increased the affinity of the enzyme for both PEP and ADP and so were significant activators at nonsaturating substrate concentrations. [Formula: see text] ions increased the affinity of the enzyme for PEP, but not ADP. The modulation of pyruvate kinase activity by such a wide range of effectors is indicative of a major regulatory role in controlling the flux of carbon, through glycolysis, into lipid-synthesizing systems.
Membrane-bound 5′-nucleotidase in marine luminous bacteria: biochemical and immunological properties
Authors: Bengis-Garber Carmela
Published: May 2010

A novel 5′-nucleotidase previously described in halophilic Vibrio costicola was detected in marine Vibrio and Photobacterium strains. The enzyme of marine bacteria was similar in its properties to the 5′-nucleotidase of Vibrio costicola; it was outwardly oriented in the cytoplasmic membrane and dephosphorylated nucleoside 5′-tri-, di-, and mono-phosphates to respective nucleosides before uptake. The enzyme in marine strains was immunologically cross-reactive with the antibody raised against the purified 5′-nucleotidase of Vibrio costicola. The uptake of the products of ATP hydrolysis was studied in Vibrio harveyi, and it was shown that both adenosine and inorganic phosphate released upon the action of 5′-nucleotidase were rapidly taken up by the cell.
Chemotaxis of fluorescent Pseudomonas spp. to soybean seed exudates in vitro and in soil
Authors: Scher F. M. , Kloepper J. W. , Singleton C. A.
Published: May 2010

Five seed-colonizing fluorescent Pseudomonas strains (RW1 to RW5) exhibited chemotaxis toward soybean seed exudates in 1-μL capillaries held for 30 min in an 8.0 log colony-forming units/mL bacterial suspension over the temperature range of 9 to 41 °C. Dialysis (6000 molecular weight cut-off) of exudate nullified its attractiveness to RW1; heating (121 °C, 15 min) of exudate had no effect. Several amino acids present in exudate induced a chemotactic response by RW1, and asparagine, threonine, and valine at levels in exudate were as attractive as exudate. No chemotaxis by RW1 was observed toward sugars present in exudate. RW1 to RW5 actively migrated 1 cm toward soybean seeds in soil as demonstrated by a new method. A nonmotile mutant of RW3 did not migrate in soil and no significant migration by strains was observed when no seed or exudate was present. It is suggested that chemotaxis of Pseudomonas toward seed exudates may be the first step in establishment of bacterial seed and root colonization in soil.
Sugar composition and serological specificity of Erwinia carotovora lipopolysaccharides
Authors: Boer S. H. De , Bradshaw-Rouse J. J. , Sequeira L. , McNaughton M. E.
Published: May 2010

Sugar composition and serological specificity of the lipopolysaccharides (LPS) purified from 16 Erwinia carotovora strains in six different serogroups were determined. All the LPS preparations contained 2-keto-3-deoxyoctonoic acid, glucosamine, heptose, and glucose, and most contained galactose. Either rhamnose or fucose was present in LPS from 12 of the strains, and the presence or absence of these deoxy sugars was consistent for all strains within a serogroup. LPS from two strains contained mannose. One unidentified sugar was present in all LPS preparations, but six other unidentified sugars varied in different LPS preparations. All LPS preparations reacted in an enzyme-linked, immunosorbent assay (ELISA) with antisera produced against whole cells of a type strain in the same serogroup as the strain from which the LPS was extracted. Several cross-reactions among strains that previously were observed in immunodiffusion tests with whole-cell preparations were also observed in ELISA with purified LPS. Some of the LPS preparations also reacted in immunodiffusion with a precipitin line of identity with whole-cell preparations. The results indicate that E. carotovora serogroups probably are based on the LPS 0-antigen.
Pathway of ammonium assimilation in Streptomyces venezuelae examined by amino acid analyses and 15N nuclear magnetic resonance spectroscopy
Authors: Shapiro S. , Vining L. C. , Laycock M. , McInnes A. G. , Walter J. A.
Published: May 2010

To obtain information on the route(s) of ammonium assimilation in Streptomyces venezuelae, cell suspensions transferred to fresh medium lacking nitrogen were pulsed with [15N2]ammonium sulphate. Cells and extracellular fluids were examined by nuclear magnetic resonance and amino acid analysis to assess changes in amino acid pools and the disposition of [15N]ammonium. Following addition of [15N]ammonium, glutamate–glutamine pools of low cell density replacement cultures expanded rapidly and became progressively labelled with 15N, whereas the alanine pool size increased much more slowly and became labelled with 15N to a much lesser extent. These results are consistent with the assimilation of ammonium via glutamate dehydrogenase or glutamine synthetase – glutamate synthase rather than alanine dehydrogenase. Under anaerobic conditions, S. venezuelae assimilates ammonium into alanine rather than glutamate–glutamine. Alanine dehydrogenase may thus function as a vehicle to regenerate NAD+ to maintain substrate-level phosphorylation during periods of anaerobiosis.
Separation and characterization of an α-glucosidase and maltase from Bacillus amyloliquefaciens
Authors: Fogarty William M. , Kelly Catherine T. , Kadam Sunil K.
Published: May 2010

A novel α-glucosidase and a maltase were isolated from Bacillus amyloliquefaciens. The formation of both enzymes was induced by trehalose, sucrose, or lactose in the growth medium. Trehalose is by far the most efficient inducer of both systems. The α-glucosidase and maltase were separated and purified by ion-exchange chromatography on DEAE Bio-Gel A. Purified α-glucosidase hydrolysed p-nitrophenyl-α-D-glucoside, isomaltose, and isomaltotriose but sucrose, maltose, or related saccharides were not attacked. β-Glucosides and polymeric glucosides were not degraded. The optimum temperature for α-glucosidase activity was 40 °C and its pH optimum was 5.3. The molecular weight and isoelectric point (pI) of the enzyme were 27 000 and 4.6, respectively. Purified maltase attacked maltose and sucrose, while maltotriose and melezitose were hydrolysed at slower rates and p-nitrophenyl-α-D-glucoside was not degraded. Other properties of the maltase were as follows: optimum temperature for activity, 30 °C; pH optimum, 6.5; molecular weight, 64 000; and pI, 4.7.
Isolation and characterization of a cytolysin produced by Vibrio cholerae serogroup non-O1
Authors: McCardell Barbara A. , Madden Joseph M. , Shah Dhirendra B.
Published: May 2010

A thermolabile toxin (molecular weight, 52 711; isoelectric point, 8.65) produced by a clinical isolate of Vibrio cholerae serogroup non-O1 was cytotoxic for Y-1 mouse adrenal cells and Chinese hamster ovary cells. The toxin lysed rabbit red blood cells and produced a hemorrhagic zone in rabbit skin. When injected intravenously into adult mice, the cytolysin was rapidly lethal and caused fluid accumulation in both 5- and 18-h rabbit ileal loops. Strains of V. cholerae that produced cytolysin but no cholerae enterotoxin were able to cause fluid accumulation in rabbit intestinal loops.
Characterization of incompatibility group HI1 plasmids from Salmonella typhi by restriction endonuclease digestion and hybridization of DNA probes for Tn3, Tn9, and Tn10
Authors: Taylor Diane E. , Brose Elisa C.
Published: May 2010

Chloramphenicol resistance in Salmonella typhi is mediated by plasmids of the incompatibility group H, subgroup 1 (IncHI1). Eight IncHI1 plasmids from S. typhi strains originating in Mexico, Vietnam, Thailand, and India were examined by restriction enzyme digestion. The restriction enzymes, ApaI, XbaI, and PstI were found to be most useful for comparison of plasmid DNAs. Four plasmids from S. typhi isolated in Mexico, Vietnam, and Thailand between 1972 and 1974 had identical restriction patterns with all three enzymes. The other IncHI1 plasmids showed only minor differences. However, some significant differences were noted between these IncHI1 plasmids and the prototype IncHI1 plasmid R27, which was isolated from S. typhimurium in 1961 and for which a restriction map has been constructed. Southern transfer hybridization with a nick-translated HI1 plasmid as a probe confirmed that there is a great deal of sequence homology among the IncHI1 plasmids. DNA probes were used to locate DNA sequences for ampicillin resistance (Tn3), chloramphenicol resistance (Tn9), tetracycline resistance (Tn10), and the one-way incompatibility between IncHI1 plasmids and the F factor, a characteristic property of IncHI1 plasmids. The results demonstrate that IncHI1 plasmids isolated from S. typhi from widely different geographic sources are very similar. Comparisons between the S. typhi plasmids and R27 indicated that conserved regions of DNA were those involved in conjugative transfer.
Chemical and bacteriological composition of granular methanogenic sludge
Authors: Dolfing J. , Griffioen A. , van Neerven A. R. W. , Zevenhuizen L. P. T. M.
Published: May 2010

Methanogenic sludge granules grown on waste water from a sugar refinery consisted of several bacterial morphotypes embedded in a matrix of extracellular material. Comparison of critical point drying and freeze-drying methods for preparing samples for scanning electron microscopy to determine the presence of extracellular material indicated that the former method permitted observations of extracellular material and intact cells. The effects of different extraction methods used for isolation of these extracellular polymers was also investigated by scanning electron microscopy. Of the various extraction procedures (EDTA, NaOH, autoclaving, water–phenol), water–phenol left most of the cells intact and was found to be a very efficient method of extraction. Extracellular polymers equivalent to 10–20 mg hexose/g of granules were extracted. The high resistance of the granules against disintegration by various chemical methods suggested that different extracellular polymers and probably different groups of organisms contributed to the matrix in which the bacteria were embedded. The chemical composition of the granules did not differ from the composition of bacteria in general. The buoyant density of 1.00–1.05 g∙g−1of the granules indicated that a simple agglomeration was the mechanism by which these methanogenic consortia improved their settling characteristics.
Cellobiose phosphorylase (EC 2.4.1.20) of Cellulomonas sp.: investigations on its localization
Authors: Schimz Karl-L. , Decker Gaby
Published: May 2010

Cells of Cellulomonas sp. (DSM 20108) grown with cellobiose as sole source of energy and carbon, and containing induced cellobiose phosphorylase activity, were disrupted for various lengths of time by ultrasonication and by lysozyme treatment. The cytosol and particulate fractions were prepared by ultracentrifugation (105 000 × g, 1 h, 8 °C). Protein concentration as well as activities of several marker enzymes (hexokinase, D-glucose-6-phosphate dehydrogenase, and 6-phospho-D-gluconate dehydrogenase) and of cellobiose phosphorylase were determined and their time-dependent increase in the cytosol and pellet fractions was compared. The occurrence of D-glucose-6-phosphate dehydrogenase in the 105 000 × g pellet during lysozyme treatment was shown to be caused by coprecipitation with lysozyme. From the results obtained it is concluded that cellobiose phosphorylase of Cellulomonas sp. is localized in the soluble cytosol fraction.
Postfusion incompatibility in Physarum polycephalum: changes in protein pattern of a heterokaryon
Authors: Schrauwen J. A. M.
Published: May 2010

The polypeptide patterns of two different strains of Physarum polycephalum, sensitive and killer, showed only minor differences on two-dimensional electrophoretograms. After heterologous fusion of the sensitive and killer plasmodia, newly formed proteins could be demonstrated which were not detectable in homologous fused plasmodia. The lethal reaction did not occur until after the aforementioned protein synthesis.
Importance of sodium to the bioenergetic properties of Methanococcus voltae
Authors: Jarrell Ken F. , Sprott G. D.
Published: May 2010

The marine methanogen Methanococcus voltae has distinct sodium requirements for active transport and for methanogenesis. These requirements were separated by demonstrating that each process has very different sodium optima, and that sodium increases the affinity of the isoleucine transport system at least 15-fold without altering the maximum velocity. The cytoplasmic pH became alkaline upon activating methane synthesis by sodium. Ionophores collapsed the transmembrane pH gradient, and inhibited methanogenesis and transport. Comparisons of pH responses indicate that growth is limited at alkaline pH by a factor(s) other than the rates of transport of leucine or isoleucine, or methanogenesis.
Effect of phenolic compounds, ethyl alcohol, and sodium metabisulphite on the lytic activity of phage PL-1 on a Lactobacillus casei S strain
Authors: Lee A. , Eschenbruch R. , Waller J.
Published: May 2010

The effect of phenolic compounds, ethyl alcohol, and sodium metabisulphite on the lytic activity of virulent bacteriophage PL-1 on a Lactobacillus casei S strain isolated from a lactic acid beverage fermentation was investigated. Catechin, caffeic, and gallic acids, commercially produced red, white, and champagne tannins, ethyl alcohol, and sodium metabisulphite inhibited plaque formation. Catechin, caffeic, and gallic acids were the most effective inhibitors of plaque formation. Commercially supplied oenocyanin was not effective.
Discontinuity of charge on cell wall poles of Bacillus subtilis
Authors: Sonnenfeld E. M. , Beveridge T. J. , Doyle R. J.
Published: May 2010

When cell wall poles of Bacillus subtilis were treated with dilute cationized ferritin, label was found only at discrete patches. Since cationized ferritin binds to negatively charged groups, the pole regions that retain label most likely represent localized surface sites of high electronegativity, indicating that the cell wall of B. subtilis is, at least, partially differentiated.
Relationship between the ectomycorrhizal fungus Pisolithus tinctorius associated with loblolly pine and acid-generating Thiobacillus spp. on an acidic strip mine site
Authors: Hendrix James W. , Hunt Cathy Stevens , Maronek Dale M.
Published: May 2010

Loblolly pine seedlings were transplanted onto a pyritic coal mine site in a commercial reclamation effort. After 5 years, trees which became naturally infected with Pisolithus tinctorius, or other ectomycorrhizal fungi which produced sporocarps, were twice the height and stem diameter of trees not associated with sporocarps. The hypothesis that P. tinctorius promotes superior growth of its host by inhibiting the growth or activity of Thiobacillus ferrooxidans and T. thiooxidans, which catalyze production of sulfuric acid from pyrite, was examined. Soil pH was lower in the root zones of trees associated with P. tinctorius than with trees not associated with P. tinctorius, and sulfate was higher. Differences were not found in ferric or ferrous ions or in populations of the two bacterial species. Apparently P. tinctorius benefits its hosts by mechanisms other than inhibition of Thiobacillus spp.
Evaluation of a modified enzyme immunoassay for Neisseria gonorrhoeae in high- and low-risk females
Authors: Skeels Michael R. , Matsuda Bessie , Horton Henry , Sampson James , Sawyer Gary A. , Mitchell Juanita
Published: May 2010

A recently modified commercial enzyme immunoassay (Gonozyme; Abbott Laboratories, North Chicago, IL) for Neisseria gonorrhoeae antigens was compared with bacteriological culture for diagnostic sensitivity, specificity, and predictive value. A total of 480 specimens were tested by both methods; 355 from females attending a sexually transmitted disease clinic ("high-risk") and 125 from female Family Planning clients ("low-risk"). Sensitivity and specificity of enzyme immunoassay for sexually transmitted disease clinic specimens were 79.7 and 97.9%, respectively (55 positive, 280 negative, 6 false positive, 14 false negative). In the low-risk population, sensitivity and specificity were 100 and 97.5%, respectively (3 positive, 119 negative, 3 false positive, 0 false negative). Despite modification, sensitivity of the method remains low for our sexually transmitted disease clinic population, but the test may have applicability for preliminary screening in low-prevalence settings.
Analysis of xylose operon regulation by Mud (Apr, lac) fusion: trans effect of plasmid coded xylose operon
Authors: Batt C. A. , Bodis M. S. , Picataggio S. K. , Claps M. C. , Jamas S. , Sinskey A. J.
Published: May 2010

The regulation of the Escherichia coli xylose operon was investigated by Mud (Apr, lac) fusion. β-Galactosidase activity from the xyl::Mud (Apr, lac) fusion was induced by xylose but not by arabinose and repressed by glucose. The chromosomal fusion was used to analyze the trans effect of plasmid borne xyl genes. The xylA gene repressed the expression of the xyl::Mud (Apr, lac) but xylose isomerase activity was not required for this repression. The results suggest that the regulation of the xylose operon may not be exclusively by a separate regulatory element but that the xylA gene may control the expression of the operon.
Sélection et analyse de mutants thermotolérants de Zymomonas mobilis, producteurs d'éthanol
Authors: Berthelin Bénédicte , Zucca Joseph , Mescle Jean-François
Published: May 2010

Mutagenesis of Zymomonas mobilis ATCC 10988 induced by nitrosoguanidine and ethyl methanesulfonate leads to the acquisition of thermotolerant character. The nitrosoguanidine allows the obtention of the best mutants. At 38 °C, these mutant strains have growth kinetics and ethanol production rates similar to those of the wild-type strain grown at 30 °C. The mutants show delayed ethanol production when compared with Zymomonas mobilis ATCC 10988: this production occurs in part during the exponential growth phase and is still active at the beginning of the stationary phase.
Intralaboratory comparison of drug susceptibility testing of Mycobacterium tuberculosis by BACTEC and conventional methodology
Authors: Laszlo A.
Published: May 2010

The BACTEC radiometric method of drug susceptibility testing of Mycobacterium tuberculosis is a reliable and rapid diagnostic tool in clinical mycobacteriology. However, large scale comparative studies have also shown that the level of agreement with standard methodology was less satisfactory with strains resistant to ethambutol and streptomycin than with strains resistant to rifampin and to isoniazid. Since disagreement with drug resistance strains is far more frequent than with drug susceptible strains, it was felt that only the comparison of a large number of resistant strains would be needed to further refine this new technique. The analysis of BACTEC-derived data for isoniazid and rifampin shows that the level of agreement with conventional methodology falls well within accepted limits. Statistical analysis of the radiometric versus conventional comparisons shows no significant differences between the two methods in the case of isoniazid, rifampin, and ethambutol (3 mg/L). Streptomycin and two other ethambutol concentrations tested showed lower levels of agreement and significant statistical differences with conventional methodology.
Structural studies of the cell wall polysaccharide of Nocardia asteroides R 399
Authors: Voiland Annie , Michel Georges
Published: May 2010

As with other bacteria belonging to the corynebacteria, mycobacteria, and nocardia group, Nocardia possess in their cell walls a neutral polysaccharide. Structural analysis of the cell wall polysaccharide of Nocardia asteroides R 399 was undertaken. The carbohydrate polymer contained D-arabinose and D-galactose as in mycobacteria. Besides these two carbohydrates we pointed out the occurrence of two additional components: D-glucose and a polyol. This polyol, because of its small amount and its uneasy detection, had been for a long time ignored. It has been proven to be the 6-deoxy-D-altritol or 1-deoxy-D-talitol. The polymer consists of a main strand composed of →5 Araf 1→ and →4Galp1→ or→5Galf1→; oligoarabinosyl side chains were localized on C3 of an arabinosyl residue. Other shorter ramifications also occur on some galactosyl units. A characterization of the linkage between polysaccharide and peptidoglycan inside the cell wall has also been carried out. The two polymers are joined by a phosphodiester bond which involves 6-deoxyaltritol. As some corynebacteria previously analyzed were also shown to contain mannose (and sometimes glucose), we can conclude that the main skeleton of cell wall polysaccharides of the corynebacteria, mycobacteria, and nocardia group of bacteria is an arabinogalactan; however, individual structural features of the polysaccharide are varying according to the bacterial species. These results might be connected with variations that were observed in immunological analysis.
Proton motive force as a function of the pH at which Methanobacterium bryantii is grown
Authors: Sprott G. Dennis , Bird Sharon E. , McDonald Ian J.
Published: May 2010

Methanobacterium bryantii was grown on CO2 and H2 over a pH range between the extremes of 5.0 and 8.1. Generation times were shortest between pH 6.6 and 7.1. Cells grown at optimum pH had a proton motive force consisting predominantly of the membrane potential but those grown at nonoptimal pH generated a transmembrane pH gradient as well. This pH gradient was, however, insufficient to maintain a constant cytoplasmic pH during growth in very acidic or basic media. The results suggest that in acidic media growth may be limited by the cytoplasmic pH and that in alkaline media it may be limited by the cytoplasmic pH and (or) by the magnitude of the proton motive force.
Enzymes of the intermediary carbohydrate metabolism of Polyangium cellulosum
Authors: Sarao Renu , McCurdy Howard D. , Passador Luciano
Published: May 2010

Crude extracts of vegetative cells of the cellulolytic myxobacter Polyangium cellulosum contained significant levels of the enzymes of the tricarboxylic acid cycle and the glyoxylate cycle. Key enzymes of glycolysis and the pentose phosphate shunt were also detected. Specific activities of hexokinase and fructose- 1,6-diphosphate aldolase exhibited a 10-fold increase when the cells were grown in complex medium containing glucose. Cytochromes of a, b, and c type were demonstrated. By the use of a dispersly growing strain of P. cellulosum, its generation time was determined to be 22–24 h. This study suggests that the organism probably uses glycolysis and citric acid cycle for complete oxidation of glucose. The exact role of the glyoxylate cycle and pentose phosphate shunt cannot be deduced from this study. This is the first report on the study of intermediary carbohydrate metabolism in any member of the family Polyangiaceae.
Effect of temperature on growth of guanidine-resistant mutants of poliovirus
Authors: Tershak Daniel R.
Published: May 2010

Guanidine-resistant (gr) mutants of poliovirus were previously categorized into four groups by electrophoretic properties and peptide maps of nonstructural virus protein 2C. Growth of mutants in the presence of guanidine depends upon temperature of incubation. The four groups of gr variants respond differently to temperature when guanidine is included in the culture medium. The data suggest clustering of gr mutations at several sites in the guanidine locus.
Inhibition of growth in canola seedlings caused by an opportunistic Pseudomonas sp. Under laboratory and field conditions
Authors: Campbell James N. , Conn Kenneth , Sorlie Linnea , Cook Fred D.
Published: May 2010

If Pseudomonas rp2, a field-isolated fluorescent pseudomonad, is present on canola (rape) seeds at the time of sprouting, it causes an inhibition of root growth leading to death or delayed maturation of the plant. Inhibitory strains of this type comprise less than 10% of the fluorescent pseudomonads isolated from local field samples, but they were found in widely dispersed sources. By present standards, these Pseudomonas strains would be considered soil saprophytes, since they survive in sterile soil at 4 and −20 °C in the absence of plant material, and since they do not match taxonomically with established plant pathogenic Pseudomonas spp. tested. Under laboratory conditions, inoculation of seeds with Pseudomonas rp2 caused death in 30%, and delayed development in 68% of infected plants. Minimum bacterial load, recoverable from the seed surface and capable of causing inhibition, was 10–20 colony-forming units per seed. The effect of inoculation of seeds with Pseudomonas rp2 on stand, rate of growth, and seed yield was quantitated under field conditions. The results reflected values obtained under laboratory conditions. The potential economic and ecological significance of this type of infection is discussed.
Predominant bacterial genera in granular activated carbon water treatment systems
Authors: Burlingame G. A. , Suffet I. H. , Pipes W. O.
Published: May 2010

Granular activated carbon (GAC) beds may be used for removal of dissolved organic matter during the treatment of drinking water. However, they might also change the microbiological quality of the water entering the distribution system either by changing the predominant bacteria or the bacterial density of the treated water. A 3-year pilot plant study of water treatment using GAC beds was conducted at the Baxter Water Treatment Plant in Philadelphia. During the study, bacteria were isolated from the raw water and from the effluents of the GAC treatment units. At the end of the study, bacteria were also isolated from the GAC units and from sand beds operated in parallel with the GAC units. Bacterial genera in the GAC effluents and in the GAC units themselves were similar to those found in the raw water and in the sand beds. Prechlorination and (or) preozonation of the water before GAC treatment had no noticeable effect on the bacterial genera found as compared with GAC unit having no predisinfection. The bacterial genera found in this study were similar to those found in seven other studies of GAC water treatment that used a variety of treatment schemes and a variety of heterotrophic plate count techniques to evaluate bacterial populations. From these several studies it appears that GAC treatment does not change the nature of the bacterial populations associated with drinking water.
Microcrystalline structure and surface area of elemental sulphur as factors influencing its oxidation by Thiobacillus albertis
Authors: Laishley E. J. , Bryant R. D. , Kobryn B. W. , Hyne J. B.
Published: May 2010

The effect of particle size, surface area per unit weight, and molecular composition of S0 on the rate of S0 oxidation by Thiobacillus albertis was studied. Spherical S0 prills varying in size and surface areas were prepared and added as the sulphur source to synthetic salts medium. The rate of S0 oxidation by T. albertis was found to be a function of surface area/unit weight of sulphur. In all these experiments [Formula: see text] was produced in a linear manner with time indicating sterically favorable cell–sulphur oxidation binding sites for bacterial growth. Different powdered forms of S0 (high-purity orthohombic, high-purity polymeric, and mixed molecular sulphur) were oxidized at a significantly faster rate than the prilled S0. Also the initial oxidation was exponential up to 3 days at which point [Formula: see text] production from mixed molecular sulphur utilization fell off substantially with time as compared with similar [Formula: see text] rate curves obtained with high-purity orthorhombic and high-purity polymeric oxidation. It was implied that the increased Sx content in mixed molecular sulphur was responsible for the slower oxidation rate by altering the sulphur crystal lattice formation which affected the number of sterically favorable oxidation binding sites for T. albertis growth. Thiobacillus albertis was shown to colonize S0 surfaces as microcolonies. It was concluded that particle size, surface area/unit weight, and the crystal microstructure of S0 affects the oxidation rate of S0 by T. albertis.
Effect of various growth conditions on spore formation and bacillomycin L production in Bacillus subtilis
Authors: Chevanet Catherine , Besson Françoise , Michel Georges
Published: May 2010

Bacillomycin L is produced by Bacillus subtilis NCIB 8872 in the stationary phase; it is excreted into the culture medium, without prior accumulation in the bacterial cells. The production of bacillomycin L is largely dependent on the composition of the culture medium. The action of specific inhibitors of sporulation, netropsin and diethyl malonate, on antibiotic synthesis is dependent on the composition of the culture medium. Although they occurred at the same time, there appears to be no direct correlation between sporulation and antibiotic synthesis.
Susceptibility of Haemophilus aegyptius to trooleandomycin: lack of taxonomic value
Authors: Martel A. Y. , Sottnek F. O. , Thomas M. L. , Albritton W. L.
Published: May 2010

Two hundred and nine strains of Haemophilus influenzae and Haemophilus aegyptius were screened for trooleandomycin susceptibility. Four strains were shown to be sensitive to the drug. Of these four, two were Haemophilus aegyptius (ATCC 11116, NCTC 8134), and the other two were Haemophilus influenzae biotype I (1-605) and IV (80-212. One strain of Haemophilus aegyptius (NCTC 8135) was resistant to trooleandomycin. Restriction enzyme assays and DNA homology were carried out to establish relationships between the strains. It is concluded that trooleandomycin susceptibility has no taxonomic value to differentiate between Haemophilus aegyptius and biotype III Haemophilus influenzae.
Microbiological transformation of pyridine N-oxide and pyridine by Nocardia sp.
Authors: Shukla Onkar P. , Kaul Shanti M.
Published: May 2010

A Nocardia sp., which utilises pyridine N-oxide (PNO), 2-hydroxypyridine, and pyridine as sole sources of carbon, nitrogen, and energy, has been isolated from soil by enrichment on PNO. PNO-adapted cells rapidly oxidized PNO and 2-hydroxypyridine; pyridine was oxidized very slowly. 2-Hydroxy pyridine- and pyridine-adapted cells oxidized their respective substrates, but PNO was not oxidized. Dihydroxypyridines did not accumulate during growth of the organism, but the formation of blue pigments during fermentation of PNO and 2-hydroxypyridine suggested their transient participation. The pigment has been characterized as 4,5,4′,5′-tetrahydroxy-3,3′-diazadiphenoquinone-(2,2′). No pigment was formed during pyridine metabolism. 2,5-Dihydroxypyridine was oxidized by PNO- and 2-hydroxypyridine-adapted but not by pyridine-adapted cells. Succinic semialdehyde was characterized as the intermediate of pyridine metabolism from semicarbazide-inhibited cultures; it was rapidly oxidized by pyridine-adapted cells. Pyridine N-oxide is therefore metabolized in this Nocardia sp. via 2-hydroxypyridine and 2,5-dihydroxypyridine, but these compounds do not serve as intermediates of pyridine metabolism.
Nitrogen fixation (acetylene reduction) by lines composing 'Park' Kentucky bluegrass
Authors: Lee Keuk-Ki , Shearman Robert C. , Klucas Robert V.
Published: May 2010

Response of 'Park' Kentucky bluegrass to inoculation with Klebsiella pneumoniae strain W-6 was tested under field conditions. Field inoculation did not increase nitrogenase activity measured in situ, but did increase the nitrogenase activity as measured using an excised root assay which included a 10-h incubation before the addition of acetylene. Fifteen lines composing 'Park' were grown in fritted-clay medium, inoculated with soil, and compared for nitrogenase activities using the excised roots assay. Significant differences were observed between two lines. Six lines were selected from the 15 lines, grown hydroponically, inoculated with soil, and assayed for nitrogenase activity using intact 105-day-old plants. Nitrogenase activities were immediately detectable and increased curvilinearly. Differences in nitrogenase activities among the six lines were detected within 1 h and significant differences were evident in 4 h. The six selected lines were also tested for levels of anthrone-reactive sugars in roots and root exudates of hydroponically grown plants. Significant differences were detected in levels of sugars in roots but not in root exudates. Possible correlations were sought among and within the three different experiments involving the six selected lines. With hydroponically grown plants, nitrogenase activities during the first 4 h were highly correlated with those after 24 h incubation. Correlations were found between nitrogenase activities in excised roots and soluble sugar concentrations in root tissue and root exudates.
α-Aminoadipate pool concentration and penicillin biosynthesis in strains of Penicillium chrysogenum
Authors: Jaklitsch W. M. , Hampel W. , Röhr M. , Kubicek C. P. , Gamerith G.
Published: May 2010

Intracellular amino acid pools in four Penicillium chrysogenum strains, which differed in their ability to produce penicillin, were determined under conditions supporting growth without penicillin production and under conditions supporting penicillin production. A significant correlation between the rate of pencillin production and the intracellular concentration of α-aminoadipate was observed, which was not shown with any other amino acid in the pool. In replacement cultivation, penicillin production was stimulated by α-aminoadipate, but not by valine or cysteine. Exogenously added α-aminoadipate (2 or 3 mM) maximally stimulated penicillin synthesis in two strains of different productivity. Under these conditions intracellular concentrations of α-aminoadipate were comparable in the two strains in spite of the higher rate of penicillin production in the more productive strain. Results suggest that the lower penicillin titre of strain Q 176 is due to at least two factors: (i) the intracellular concentration of α-aminoadipate is insufficient to allow saturation of any enzyme which is rate limiting in the conversion of α-aminoadipate to penicillin and (ii) the level of an enzyme, which is rate limiting in the conversion of α-aminoadipate to penicillin, is lower in Q 176 (relative to strain D6/1014/A). Results suggest that the intracellular concentration of α-aminoadipate in strain D6/1014/A is sufficiently high to allow saturation of the rate-limiting penicillin biosynthetic enzyme in that strain. The basis of further correlation of intracellular α-aminoadipate concentration and penicillin titre among strains D6/1014/A, P2, and 389/3, the three highest penicillin producers studied here, remains to be established. Preliminary studies which attempted to explain the differences in intracellular α-aminoadipate concentrations in strains Q 176, D6/1014/A, and P2 in terms of differences in activities or kinetics of two enzymes of lysine biosynthesis (homocitrate synthase and saccharopine dehydrogenase) did not reveal differences in those enzymes among the three strains.
Isolation and characterization of Schizosaccharomyces pombe mutants with defective NAD-dependent malic enzyme
Authors: Osothsilp C. , Subden R. E.
Published: May 2010

To obtain NAD-dependent malic enzyme mutants of Schizosaccharomyces pombe, a colony color indicator screening system was developed. Mutants defective for malic acid utilization (mau mutants) are yellow, while wild-type colonies are blue on the defined bromcresol green based indicator medium. NAD-dependent malic enzyme mutants were distinguished from other mau mutants by subsequent, starch gel electrophoresis, spectrophotometry, complementation tests, and intermediate pool analysis with cell-free extracts.
Properties of urease from Ureaplasma urealyticum: kinetics, molecular weight, and demonstration of multiple enzyme isoelectric point forms
Authors: Eng H. , Robertson J. A. , Stemke G. W.
Published: May 2010

In the several strains of Ureaplasma urealyticum that we examined, all originally isolated from human sources, the ureases were found to have a pH optimum between 7.2 and 7.5, and the Km was approximately 2.5 mM urea. Using nonreducing, nondenaturing conditions for polyacrylamide gel electrophoresis, the molecular weight of the holoenzyme was determined to be approximately 380 000. Treatment with reducing agents did not affect the electrophoretic mobility and, therefore, the molecular weight of ureaplasma urease. Immunoblot analysis (using antiserum to U. urealyticum urease) after sodium dodecyl sulfate – polyacrylamide gel electrophoresis under nonreducing, denaturing conditions revealed two antigenically reactive bands of molecular weight 174 000 and 179 000. Under reducing, denaturing conditions, a single band of molecular weight approximately 179 000 was detected. Multiple forms of urease were detected by isoelectrofocusing but not by zonal electrophoresis.
Degradation of ferulic acid via 4-vinylguaiacol by Fusarium solani (Mart.) Sacc.
Authors: Nazareth S. , Mavinkurve S.
Published: May 2010

Fusarium solani (Mart.) Sacc. metabolizes ferulic acid to a transient intermediate, 4-vinylguaiacol, a compound hitherto not reported in the metabolic pathway of ferulic acid in fungi. The compound was isolated in pure form and identified spectrometrically. 4-Vinylguaiacol was further metabolized to vanillin, vanillic acid, and protocatechuic acid, followed by ortho cleavage of the aromatic ring. The organism was also found to catabolize eugenol and p-coumaric acid, but not cinnamic acid.
Granule contents from rat polymorphonuclear leukocytes: antimicrobial properties and characterization
Authors: Hodinka Richard L. , Modrzakowski Malcolm C.
Published: May 2010

The nonoxidative antibacterial properties of isolated rat polymorphonuclear leukocyte granule contents were examined using Salmonella typhimurium LT-2 and a series of progressively rough lipopolysaccharide mutants of this strain as target bacteria. The granule extract was most active at 37 °C, with a substantial decrease in activity observed at lower temperatures. Deep rough bacterial mutants were killed best within a pH range of 6–8, while killing of mutants with increased lipopolysaccharide content was most efficient at an acid pH of 5. The activity of the extract was dependent on incubation time but was independent of the number of bacterial cells present in the assay mixture. The killing action of the granule extract was inhibited by the cations Na+, K+, Mg2+, Ca, and Fe2+. The degree of inhibition was dependent on the type and concentration of ion used. Rough mutants grown with aeration to log phase were killed more efficiently than the same mutants grown to stationary phase under static conditions. Also, gram-positive bacteria were more susceptible to the extract than were gram-negative organisms.
Cadmium transport by a Cd2+-sensitive and a Cd2+-resistant strain of Bacillus subtilis
Authors: Burke Brian E. , Pfister Robert M.
Published: May 2010

Cadmium uptake by a Cd2+-sensitive (1A1) and a Cd2+-resistant mutant (1A1r) strain of Bacillus subtilis was investigated. Uptake of 109Cd2+ was determined for cells of both strains grown in tryptone broth and in broth containing tryptone, yeast extract, and glucose (TYG). The extent of 109Cd2+ uptake by cells of 1A1r was less than by cells of 1A1 under both growth conditions. In both growth media, 109Cd2+ uptake by 1A1 cells demonstrated saturation kinetics and was energy dependent. In both TYG and tryptone broth, 109Cd2+ uptake by 1A1 cells was inhibited by the addition of unlabeled Mn2+. Although lower in magnitude, the kinetics of 109Cd2+ uptake by 1A1r cells were similar to those of 1A1 cells when grown in tryptone broth. However, no obvious saturation kinetics, energy dependence, temperature sensitivity, or inhibition of 109Cd2+ uptake by the addition of unlabeled Mn2+ was observed in 1A1r cells grown in TYG. Differential Mn2+ accumulation by 1A1r cells in TYG and tryptone broth correlated with differential 109Cd2+ uptake by 1A1r cells in these media.