bluuebunny/crossref_metadata_2025 huggingface dataset:
Morphologic and functional effects of Clostridium difficile enterotoxin in tissue culture
Authors: Gurwith Marc J. , Langston Claire , Dunsmore Betty
Published: May 2010

The effects of the Clostridium difficile toxin were examined in HeLa and mouse adrenal tumor (MAT) cells. Cytotoxicity was evaluated by vital dye exclusion and 51Cr release. In both HeLa and MAT cells, C. difficile toxin caused rounding of virtually 100% of cells. This rounding was distinguishable from rounding produced by the Escherichia coli heat-labile enterotoxin (LT): (1) LT was inactive in HeLa cells; (2) in MAT cells, C. difficile toxin produced uniformly rounded cells, while LT-rounded cells usually had cytoplasmic extensions and a regular background of flattened cells. In C. difficile toxin affected HeLa cells, there were <2 mitotic figures per 1000 cells compared with 15–18 in controls. Clostridium difficile toxin treated HeLa cells showed <10% cytotoxicity in 24 h and no more than 30% by 74 h, similar to control cells. However, paralleling the suppression of mitotic figures, cell multiplication was inhibited in C. difficile toxin treated cells when subcultured in a short-term (72 h) assay compared with up to a 500% increase in control cells. This inhibition was also seen in a 6-week cloning assay in which C. difficile toxin treated cells had a cloning efficiency of <1% compared with approximately 10% in controls. We conclude that the major effect of the C. difficile toxin is inhibition of growth rather than immediate cell death. The relationship of this growth inhibition to colitis remains to be elucidated.
Effect of the dispersant Corexit 9527 on the microbial degradation of Prudhoe Bay oil
Authors: Foght J. M. , Westlake D. W. S.
Published: May 2010

A marine oil-degrading population grown at 8 °C showed a selective sensitivity regarding utilization of compounds in Prudhoe Bay oil in the presence of the dispersant Corexit 9527. The response was dependent on the nitrogen and phosphate levels of the medium and on the concentration of dispersant used. In the presence of a nitrogen–phosphate solution and a Corexit 9527 – crude oil substrate, degradation of the n-alkanes of the saturate fraction was temporarily retarded in proportion to the concentration of Corexit 9527 present. This retardation was overcome with extended incubation time. In the absence of nitrogen–phosphate supplementation, the effect of Corexit 9527 was pronounced, retarding n-alkane degradation even with extended incubation time. Corexit 9527 had less effect on the degradation of the aromatic fraction and may indeed be stimulatory in the case of select compounds. The development and testing of dispersants containing nitrogen and phosphate is recommended.
Degradation of wool by saprotrohic fungi
Authors: Safranek William W. , Goos Roger D.
Published: May 2010

Strains of Acremonium roseum and Chaetomium globosum were tested for their ability to attack the protein components of wool by culturing the fungi in basal medium containing wool and monitoring changes in pH and soluble protein levels occurring in the medium. Net increases in soluble protein and pH were detected in the cultures of A. roseum, C. globosum, and the positive control, Trichophyton mentagrophytes. To test for keratin denaturation by sulfite production (sulfitolysis), human hairs were exposed to the fungi in culture. Overgrown hairs were stained by the tetrazonium method, a test specific for compounds produced by sulfitolysis. Isolates of Trichophyton tonsurans, T. rubrum, T. terrestre, Microsporum cookei, and nondermatophytic saprotrophic fungi were also tested for sulfitolysis. Positive results for sulfitolysis were obtained with T. mentagrophytes, T. tonsurans, T. rubrum, T. terrestre, and M. cookei; A. roseum, C. globosum, and the remaining species were negative.
Stability of the endo-β-1, 4-glucanase and β-1, 4-glucosidase from Bacteroides succinogenes
Authors: Forsberg C. W. , Groleau D.
Published: May 2010

The endo-β-1, 4-glucanase (carboxymethylcellulase) activity in cell extracts prepared from Bacteroides succinogenes S85 was almost unaffected by prolonged incubation at 39 °C in the presence of merthiolate, a sulfhydryl inhibitor. The β-1, 4-glucosidase (cellobiase) activity, however, was rapidly inactivated by the same treatment. The cellobiase was also inactivated by exposure to air, but was stabilized by dithiothreitol in a nitrogen atmosphere. These results suggest that the cellobiase required reduced sulfhydryl groups for activity.
Halocins: salt-dependent bacteriocins produced by extremely halophilic rods
Authors: Rodriguez-Valera F. , Juez G. , Kushner D. J.
Published: May 2010

Strains of halophilic rods, presumably halobacteria, produce substances that inhibit the growth of other halobacteria but not halococci or moderate halophiles. The spectrum of action of these substances, called "halocins," was determined on 39 halobacteria or presumed halobacteria. The properties of halocin H4, produced by strain R-4, were studied using Halobacterium halobium as an indicator organism. Halocin H4 is adsorbed by the indicator organism and causes both death and lysis. It is a high molecular weight substance(s), destroyed by heat or exposure to low salt concentrations or treatment with a protease. Experiments are presented to show that it is not a virus.
Limited contribution of the outer-membrane penetration barrier towards intrinsic antibiotic resistance in Pseudomonas aeruginosa
Authors: Scudamore R. Allan , Goldner Morris
Published: May 2010

The role of the outer membrane (OM) was investigated in relation to the high level of intrinsic antibiotic resistance of Pseudomonas aeruginosa ATCC 9027. OM penetration barriers were measured by comparing turbidimetric growth curves of EDTA-treated and normal cells exposed to carbenicillin, moxalactam (LY 127935), gentamicin, tobramycin, rifampin, novobiocin, and vancomycin. OM barriers were also measured for carbenicillin and moxalactam in P. aeruginosa strain K 799/61, a hypersusceptible mutant presumed to have lost its penetration barrier in the cell envelope. Most antibiotics penetrated the OM efficiently and there was little difference between the two strains. The evidence therefore suggests that intrinsic resistance of P. aeruginosa, especially to the beta-lactam antibiotics, is not mainly due to the OM. A penetration barrier situated deeper within the cell envelope is hypothesized, the size of which in relation to any antibiotic may be estimated by comparing the IC50 values of EDTA-treated cells of the two strains.
A bacteriophage typing system for Rhizobium meliloti
Authors: Lesley S. M.
Published: May 2010

Fifteen specific bacteriophages, each active on particular strains of Rhizobium meliloti, have been selected from those isolated by enrichment of local soils. Variables affecting phage–host interaction have been examined and standardized. The differential susceptibility of individual R. meliloti strains to each phage produces a distinctive pattern of response which allows the segregation of each strain into one of the 80 different groups identified to date. Discrimination between strains with this typing system is reproducible with no change in phage type following extended subculture or plant infection and reisolation of strains from root nodules of alfalfa. The large number of different strains recognized by the system should make it very useful in experimentally controlled tests of selected strains in the nodulation of alfalfa plants.
Glucose transport in Streptococcus salivarius. Evidence for the presence of a distinct phosphoenolpyruvate: glucose phosphotransferase system which catalyses the phosphorylation of α-methyl glucoside
Authors: Vadeboncoeur Christian , Trahan Luc
Published: May 2010

A spontaneous mutant of Streptococcus salivarius ATCC 25975 was isolated by inoculating an agar medium containing 11 mM lactose and 0.5 mM 2-deoxyglucose. This mutant grew poorly on 5 mM glucose but almost as well as the parental strain on 110 mM glucose. Uptake of 2-deoxyglucose was abolished by the mutation, and phosphoenolpyruvate:glucose phosphotransferase activity could not be detected with toluenized cells under normal conditions when the glucose concentration was below 5 mM. Data from growth experiments, glycolysis, and uptake studies indicated the presence of a second phosphoenolpyruvate: glucose phosphotransferase system that could catalyze the phosphorylation of α-methyl glucoside. The activity of this system was detected by a spectrophotometric assay coupled with lactate dehydrogenase and by a radioactive isotope method using methyl α-D-[U-14C]glucoside. The phosphorylation was phosphoenolpyruvate dependent. The apparent Km of the system for glucose and α-methyl glucoside was approximately 20 mM. Studies with energy poisons ruled out the possibility of an active transport system, and accumulation of α-methyl glucoside argued against facilitated diffusion. It was concluded that the other glucose transport system which allowed growth of the mutant strain of S. salivarius was a second phosphoenolpyruvate:glucose phosphotransferase system.
Antibodies to the California group of arboviruses in animal populations of New Brunswick
Authors: McFarlane B. L. , Embree J. E. , Embil J. A. , Rozee K. R. , Artsob H.
Published: May 2010

Wild and domestic animals of New Brunswick were tested serologically for antibodies to the California group (CAL) of arboviruses. Deer (Odocoileus virginianus) blood collected during 1976 showed 6 of 129 (4.7%) sera with neutralizing antibodies to the snowshoe hare strain (SSH) of CAL. Neutralization tests on moose (Alces alces americana Clinton) sera collected during 1979 indicated 94 of 127 (74%) with antibodies to SSH, 4 of 127 (3.2%) with antibodies to the Jamestown Canyon strain (JC) of CAL, and 17 of 127 (13.4%) with equal antibody titers to SSH and JC. Hemagglutination inhibition tests on horse blood collected during 1977 showed 54 of 204 (26.5 %) with antibodies to SSH; of these, 36 also had neutralizing antibodies to SSH. This study is the first indication of CAL activity in New Brunswick and supports evidence of JC activity in northeastern North America.
Variation in fecal pollution indicators through tidal cycles in the Fraser River estuary
Authors: Churchland Leslie M. , Kan Gordon , Ages Alard
Published: May 2010

Daily fluctuations in fecal pollution indicators in the Fraser River estuary were examined by sampling through 24 h at four sites; water levels, currents, and salinities were observed simultaneously. Fecal coliforms were measured on shipboard using the membrane filter technique, and coprostanol and cholesterol were extracted using hexane and analyzed by gas chromatography. Maximum concentrations of fecal sterols and coliforms occurred after high tide at the station upstream of major sewage outfalls and on the ebb or at low tide at the stations downstream of major sewage outfalls. Fecal coliform counts were highly correlated with coprostanol and cholesterol levels at sites near sewage treatment plants. Coprostanol was highly correlated with cholesterol except where concentrations approached detection limits. In receiving waters, fecal coliform counts but not sterol concentrations were reduced by chlorination of sewage treatment plant effluents during the summer months. We concluded that, dependent on the objectives of a future monitoring program, samples should be collected either randomly in time such that the seasonal or annual mean includes tidal variability or systematically during the ebb tide to assess contributions to bathing beaches and shellfish harvesting areas. Fecal sterols deserve consideration as potential indicators of fecal contamination from chlorinated sewage effluents.
Toxigenic isolates of Fusarium sporotrichioides obtained from hay in Saskatchewan
Authors: Davis G. R. F. , Westcott N. D. , Smith J. D. , Neish G. A. , Schiefer H. B.
Published: May 2010

An isolate of Fusarium sporotrichioides Sherbakoff obtained from hay from Kindersley, Saskatchewan, and producing metabolites toxic to insect larvae, rats, and mice was cultured on sterile rye grain and extracted with ethyl acetate. The most toxic fraction derived from column chromatography on silica gel was purified by thin-layer chromatography on silica gel and elution of the main band. This compound was identified as T-2 toxin by comparison with the pure chemical by thin-layer chromatography and, after crystallization, by determination of melting point, infrared spectrum, and nuclear magnetic resonance spectrum. This work demonstrates that strains of F. sporotrichioides capable of producing T-2 toxin may be present on hay in western Canada.
Effet de la température d'incubation sur la composition lipidique de Corynébacteriacées du genre Arthrobacter
Authors: Canillac N. , Pommier M. T. , Gounot A. M.
Published: May 2010

Lipid composition of three Arthrobacter strains (mesophilic, psychrotrophic, and psychrophilic strains) grown at their optimum growth temperature was studied. Great differences appeared only in the nature of their fatty acids: the psychrophilic strain synthesized less linear acids, C17 acids, and more iso isomers than the other two strains.Incubation of the three strains at temperatures below their optimum resulted in variations only in proportion of the different fatty acids: increase of the ratio of unsaturated, of branched, and of short-chain fatty acids.The relation between lipid composition and ability to grow at temperatures around 0 °C is discussed.
Selective assimilation of selenite by Escherichia coli
Authors: Brown Terence A. , Shrift Alex
Published: May 2010

The assimilation of selenite by Escherichia coli involves a transport process specific for this anion. Cystine, a repressor of sulfate and selenate uptake, when added to the growth medium, had no effect on selenite uptake; nor did sulfite inhibit assimilation of selenite. Cells grown aerobically in a basic salts medium transported selenite at an initial rate of 0.14 μmol∙g−1∙min−1 and a Vmax of 393.0 μmol∙g−1∙min−1. In contrast, cells grown in a medium that contained the trace elements necessary for synthesis of the selenoenzyme formate dehydrogenase took up selenite at a significantly faster rate (initial rate = 0.27 μmol∙g−1∙min−1, Vmax = 658.2 μmol∙g−1∙min−1). Km values for the transport process in the two media, however, were found to be similar. The results suggest the existence of a metabolic pathway, specific for selenite, responsible for the incorporation of selenium into formate dehydrogenase.
Stable isotope fractionation by Clostridium pasteurianum. 5. Effect of SeO42− on the physiology and associated sulfur isotope fractionation during SO32− and SO42− reductions
Authors: Harrison G. I. , Laishley E. J. , Krouse H. R.
Published: May 2010

The addition of 1 mM SeO42− significantly affected the physiology and metabolism of Clostridium pasteurianum growing on SO42− in the following ways: (1) the generation time was increased, essentially producing a biphasic growth curve, (2) cells became elongated and chains formed, (3) no H2S was liberated during the stationary phase, (4) assimilatory SO32− reductase activity was decreased, (5) ferredoxin levels decreased by a factor of 4. The effects of 1 mM SeO42− on Clostridium pasteurianum growing on SO32− were comparatively minor.H2S evolution in the stationary phase decreased by a factor of 2 and the δ34S maximum in the inverse isotope effect pattern occurred at a slightly lower percent H2S evolution. The deleterious effects of SeO42− addition were less pronounced than those associated with SeO32− addition. SeO32− but not SeO42− was reduced to elemental selenium by both whole cells and crude extracts.
Fatty acid requirement of Treponema denticola and Treponema vincentii
Authors: Horn Kenneth G. Van , Smibert Robert M.
Published: May 2010

Treponema denticola and Treponema vincentii were cultured in a medium supplemented with either 0.2 or 0.4% (w/v) alpha globulin in place of serum. The active factor(s) in alpha globulin was stable at pH 7.0 to autoclaving and was nondialyzable. Extraction of lipids from alpha globulin showed that both protein and lipid, supplied by the alpha globulin, were required for maximal growth of these two oral treponemes. The lipid component was investigated by adding sodium salts of long-chain fatty acids to the basal medium supplemented with 0.4% delipified alpha globulin. The lipid component of alpha globulin was replaced by either oleic acid (cis-18:1 (9)) or by elaidic acid (trans-18:1 (9)). No other saturated or unsaturated fatty acid tested could support good growth. Tween 80 (polysorbitan monooleate) was the only Tween compound able to support maximal growth of T. denticola. The cellular lipids of T. denticola, grown with oleate in broth supplemented with 0.4% delipified alpha globulin, were extracted and analyzed by gas chromatography. The principle fatty acids were myristic, pentadecanoic, and palmitic acids. Lesser amounts of oleic acid, eicosadienoic acid, and an unidentified fatty acid (retention time, 88 min) were also detected. Treponema denticola appears to be capable of limited synthesis of cellular fatty acids such as myristic, pentadecanoic, and palmitic acids from oleic acid.
Isolation of vesicular–arbuscular mycorrhizal spores: a rapid method for the removal of organic detritus from wet-sieved soil samples
Authors: Kucey R. M. N. , McCready R. G. L.
Published: May 2010

A method for recovery of live vesicular–arbuscular mycorrhizal spores from large soil samples is presented. Spores, hyphal material, and other organic debris are isolated by wet sieving (> 63 μm) and further purified by flotation on 50% glycerol. The organic material is then suspended in Ringer's saline solution and the spores separated from other organic material by centrifuging (10 min at 75 × g) the mixture on a two-layer discontinuous solution gradient consisting of 50% glycerol (specific gravity 1.13 g/cm3) overlaid with 30% glycerol (specific gravity 1.08 g/cm3). The efficiency of recovery is 84 ± 3.4% of the spores present after the initial flotation.
Influence of carbon source on arylsulfatase derepression in Pseudomonas C12B
Authors: Fitzgerald J. W. , Ash J. T.
Published: May 2010

Compared with growth on citrate, growth of Pseudomonas C12B with acetate as a carbon source resulted in approximately a four- to six-fold reduction in arylsulfatase activity irrespective of the sulfur source utilized to derepress arylsulfatase formation. Similarly, when O-acetyl-L-serine, oxaloacetate, malate, or α-ketoglutarate served as carbon sources in place of acetate, a reduction in arylsulfatase levels also occurred to varying degrees Trivial explanations for these results have been ruled out but efforts to provide an explanation for the inhibitory effect of acetate were unsuccessful. Some evidence suggests that growth on acetate may generate the formation of a substance which inactivates or irreversibly inhibits the enzyme.
Changes in protein and RNA during asexual differentiation of Physarum polycephalum
Authors: Larue Hélène , Masson Sylvie , Lafontaine Jean G. , Nadeau Paul , Pallotta Dominick
Published: May 2010

Some of the events during the growth and asexual differentiation of Physarum polycephalum amoebae are described. Encysted amoebae contain low levels of protein and RNA. When these cells are mixed with bacteria and inoculated onto agar plates, there is an increase in cellular RNA content followed by an increase in protein content. The cellular RNA and protein contents of all strains tested decrease during the subsequent cell divisions. In nondifferentiating cells (strain CI at 30 °C and strain LU648), RNA and protein contents continue to decrease, and the cells eventually encyst. In the asexually differentiating strain CI grown at 26 °C, the cellular RNA and protein contents stop decreasing and begin to increase when the first amoebae become committed to form Plasmodia. At early stages of differentiation a new 36 000 molecular weight polypeptide appears. In fully formed plasmodia another polypeptide of 38 000 molecular weight is observed. These two plasmodial-specific polypeptides are among the most abundant plasmodial proteins.
Hydrolysis of some natural and synthetic bile acid conjugates by Cercospora melonis
Authors: Johns M. R. , Chong R. , Maddox I. S.
Published: May 2010

Analogs of natural bile acid conjugates were incubated with both whole-cell cultures and cell-free extracts of the fungus Cercospora melonis CBS 162.60. Those conjugates containing both an α-amino group and a carboxylic acid group in the amino acid moiety were the most susceptible to hydrolysis. Substitution with a β-amino group and (or) a sulfonic acid group greatly reduced the extent of hydrolysis. With all conjugates tested, significant losses of total bile acid were observed on incubation with whole-cell cultures. Two factors have been implicated as contributing to these losses. First, bile acids may be degraded to nonsteroidal products by an inducible enzyme system. Second, bile acids may be bound to mycelia in a manner not reversed by the extraction technique.
Growth responses of race 222 of Puccinia graminis tritici in defined media
Authors: Singh Hardev , Sethi Inderjeet
Published: May 2010

Aseptically produced uredospores of race 222 of Puccinia graminis tritici were seeded on defined liquid media containing Czapek's minerals, sucrose or glucose, and various combinations and concentrations of 19 amino acids and a tripeptide, glutathione. The cultures were incubated in the dark at 16–17 °C. A medium containing a high concentration of aspartic acid (5988 ppm), cysteine (557 ppm), and glutathione (1014 ppm) supported a profuse growth of the fungus in the form of floating white, fluffy, and vegetative colonies. A sulphur-containing amino acid appears to be essential for the axenic culture of the fungus.
Purification of Pasteurella multocida antigens by ultracentrifugation and isoelectrofocusing
Authors: McKinney Kevin L. , Rebers Paul A.
Published: May 2010

A procedure was developed to purify Pasteurella multocida X-73I antigens extracted by potassium thiocyanate. The crude extract was centrifuged at 105 000 × g; the antigens were then separated into a particulate (40p) fraction and a soluble (40s) fraction consisting of proteins and polysaccharides. These fractions were antigenically different.The ultracentrifuged antigens were resolved further by preparative isoelectrofocusing. The 40p antigens focused in a pH range of 3.0 to 6.0; distinctive proteins focused at pH's of 3.5, 3.6, and 3.8. The electrofocused 40p antigens were antigenically similar. The 40s antigens were initially electrofocused in a broad pH range and were found within a pH range of 4.4 to 9.0. The process was repeated with a narrower pH range and antigens that were focused in a narrower pH range could be separated and unique antigenic activities identified. Specific antigens from defined pH ranges were pooled and examined further by immunoelectrophoresis, analytical electrofocusing, and sodium dodecyl sulphate – polyacrylamide gel electrophoresis.
The fenestrated peptidoglycan layer of Deinococcus radiodurans
Authors: Thompson B. G. , Murray R. G. E.
Published: May 2010

The peptidoglycan layer of Deinococcus radiodurans strain Sark was isolated by centrifugation after digesting broken cells with 2% (w/v) sodium dodecyl sulfate at 43 °C, and sections revealed the characteristic fenestrations (10 nm in diameter). These fenestrations were stained by or filled with 1.0% ammonium molybdate, but were not visible when the isolated peptidoglycan layer was stained with 1.0% uranyl acetate. The fenestrations were not visible when negatively stained with ammonium molybdate after modification of the sacculus by carboxymethylation of free amino groups by treatment with iodoacetate. The surface of the sacculus was smooth when shadowed with carbon–platinum. The isolated layer consisted only of peptidoglycan components. It is concluded that the fenestrations consist of peptidoglycan of different reaction to metal salts and probably enriched in available amino groups.
A method for concentrating viruses recovered from sewage sludges
Authors: Berg Gerald , Berman Donald , Safferman Robert S.
Published: May 2010

Buffered 10% beef extract eluates of primary, activated, and anaerobic mesophilically digested sludges were concentrated 20-fold by the Katzenelson organic flocculation procedure after diluting the beef extract in the eluates to a final concentration of 3%. The weighted mean recovery of virions from the concentrates was approximately 58% of the numbers present in the unconcentrated buffered 10% beef extract eluates. Flocculation of eluates that contained buffered 10% beef extract at times produced poor flocs. Application of the Katzenelson procedure to the diluted buffered 10% beef extract procedure for recovering virions from sludges permits an economy in the numbers of cell cultures required for assays of virions in beef extract eluates that is necessary in most laboratories.
The early synthesis of RNA, protein, and some associated metabolic events in germinating vesicular-arbuscular mycorrhizal fungal spores of Glomus caledonius
Authors: Beilby John P. , Kidby Dennis K.
Published: May 2010

A comparison of the kinetics of [1−14C]leucine and [2-14C]uracil incorporation into germinating spores of Glomus caledonius showed that RNA and protein synthesis had begun by 35 min after imbibition of water. Protein synthesis was essential for spore germination, and cycloheximide-sensitive protein synthesis occurred after the onset of germination. Early RNA synthesis was not affected by cycloheximide. Within 35 min of imbibition the tricarboxylic acid cycle, gluconeogenesis, and most amino acid biosynthetic pathways were operating.
Glycogen and various other polysaccharides stimulate the formation of exolipase by Pseudomonas aeruginosa
Authors: Schulte Gabriele , Bohne Leuthold , Winkler Ulrich
Published: May 2010

Glycogen enhances the formation of exolipase by Pseudomonas aeruginosa ATCC 9027 although the cells cannot utilize it as sole carbon and energy source. Glycogen is unable to influence exolipase activities in conditioned media after removal of the cells. Treatment of cells with glycogen does not promote overall protein synthesis but inhibitors of protein synthesis (e.g., rifampicin and chloramphenicol) prevent the glycogen effect, suggesting that specific de novo protein synthesis is required. In addition to glycogen, 5 other polysaccharides (among 13 tested) were found to have exolipase-enhancing ability. The results are discussed with regard to the detachment hypothesis of U. K. Winkler and M. Stuckmann (1979. J. Bacteriol. 138: 663–670). According to this hypothesis polysaccharides are assumed to dislocate cell-bound lipase to the medium via specific interactions with the bacterial cell surface.
Sensitivity of various salt forms of Bacillus megaterium spores to the germinating action of hydrostatic pressure
Authors: Bender Gary R. , Marquis Robert E.
Published: May 2010

Spores of Bacillus megaterium ATCC 19213 were subjected to a complete ion-exchange regimen, which included titration to a pH value of 2, heating at 60 °C for up to 18 h, back titration with various base solutions to a pH value of 8, and heating again at 60 °C. Spore populations maintained high levels of viability throughout this rigorous procedure, and the various salt forms prepared showed a wide range of sensitivities to the germinating effect of hydrostatic pressure. Native spores showed the expected germination response when subjected to pressures of 350–750 atm (1 atm = 101.325 kPa) at 24 °C. There was a threshold pressure for germination of some 300 atm, and the apparent activation volume for the process was calculated to be 188 mL/mol, indicating that these spores had approximately the same pressure sensitivity as those of Bacillus subtilis or Bacillus pumilus. The optimum pH for germination was approximately 8, and the optimum temperature was approximately 45 °C. The hierarchy of resistance of the various salt forms tested to the germinating action of 493 atm pressure was H > K > Ca, Mg, Na > native. The H form was particularly insensitive, even to pressures as high as 1020 atm, but germinated in response to chemical germinants. We concluded that the specific mineralization of bacterial spores has major influence on pressure-induced germination, which can occur even in the absence of added salts. Sensitivities to pressure could not be correlated with previously reported heat sensitivities, electrostasis, or states of dehydration.
Evaluation of an X-ray microprobe technique as a possible aid to detect salmonellae
Authors: Richter E. R. , Banwart G. J.
Published: May 2010

The X-ray microprobe was examined as a possible aid in the detection of salmonellae. Results obtained indicate that specific bacterial antigen (Salmonella) increased in phosphorus and sulfur after reaction with the fluorescein isothiocyanate tagged*** specific antibody. Nonspecific antigen (Escherichia coli) did not increase in phosphorus and sulfur after reaction with fluorescein isothiocyanate tagged anti-Salmonella antibody. The technique developed supports the hypothesis that X-ray microprobe analysis may be useful in detecting salmonellae, or other bacteria, by determining increases in the elemental constitutents of bacterial cells when reacted with elemental-tagged antibodies.
The occurrence of filamentous fungi in drinking water distribution systems
Authors: Nagy L. A. , Olson B. H.
Published: May 2010

The densities of filamentous fungal colonies, together with physicochemical and bacteriological parameters, were assessed in a chlorinated and unchlorinated drinking water distribution system at eight separate times over a period of 1 year. Filamentous fungal colonies were enumerated by membrane filtration on Czapek–Dox agar. The mean number of filamentous fungal colony-forming units per 100 mL of drinking water was 18 in the unchlorinated and 34 in the chlorinated system. The majority of filamentous fungi isolated were saprophytic Deuteromycotina. The four most frequently occurring genera were Penicillium, Sporocybe, Acremonium, and Paecilomyces. In the chlorinated system, only physicochemical parameters correlated with observed fungal frequencies, whereas in the unchlorinated system, none of the parameters exhibited significant correlations with fungal numbers.
In vitro inhibition of nonsymbiotic nitrogen-fixing bacteria by rhizosphere actinomycetes associated with grasses
Authors: Zuberer D. A. , Roth Mark
Published: May 2010

Eighty-five isolates of actinomycetes were obtained from the rhizospheres of 10 indigenous grasses of central Texas. Of these, 10 were classified as members of the genus Nocardia; the remainder were members of the genus Streptomyces. To determine whether antibiotic production might be a significant factor in the establishment of associative symbioses between grasses and diazotrophic bacteria, 12 strains of free-living nitrogen-fixing bactria were cross streaked against each actinomycete isolate. This in vitro assay indicated that 78% of the 85 isolates were antagonistic to at least one of the 12 nitrogen-fixing bacterial strains.
A simple device for growing Clostridium perfringens and its application in bacteriocin studies
Authors: Mahony D. E.
Published: May 2010

A simple device constructed of common laboratory material served as a minifermenter for the growth of Clostridium perfringens. A constant flow of nitrogen gas into a culture tube containing C. perfringens assured agitation of the culture and a mechanism for dispensing small volumes of liquid from the culture without disturbing the growth environment. The method was applied to examining the growth-inhibiting effect of bacteriocins of C. perfringens where a very economical use of radioactive isotopes was possible. The activity of some bacteriocins differed when compared with previous data obtained with stationary cultures. Two major categories of bacteriocin appear to exist for this species: those bacteriocins which block the incorporation of DNA, RNA, and protein precursors and those which interfere with the organism's cell wall.
Nutritional iron status and susceptibility to Proteus mirabilis pyelonephritis in the rat
Authors: Hart Robin C. , Kadis Solomon , Chapman Jr. Willie L.
Published: May 2010

Moderately iron-deficient rats were significantly less susceptible to experimentally induced Proteus mirabilis pyelonephritis than iron-sufficient or severely iron-deficient littermates, as indicated by significantly lower prevalence of infection, mean pyelonephritic lesion scores, and numbers of P. mirabilis cells recovered from the kidneys.
Degradation of plant pathogenic fungi by Trichoderma harzianum
Authors: Elad Y. , Chet I. , Henis Y.
Published: May 2010

Trichoderma harzianum excreted β-1, 3-glucanase and chitinase into the medium when grown on laminarin and chitin, respectively, or on cell walls of the pathogen Sclerotium rolfsii, as sole carbon source. Trichoderma harzianum also showed high activity of both enzymes when grown on homogenized S. rolfsii sclerotia. Glucanase activity increased by 67% when the fungus was grown on a mixture of laminarin and glucose (3:1, v/v). Similarly, high lytic activity was detected in wheat bran culture of the fungus and in soil inoculated with this culture. Protease and lipase activity were detected in the medium when the antagonist attacked mycelium of S. rolfsii.Isolates of T. harzianum were found to differ in the levels of hydrolytic enzymes produced when mycelium of S. rolfsii, Rhizoctonia solani, and Pythium aphanidermatum in soil was attacked. This phenomenon was correlated with the ability of each of the Trichoderma isolates to control the respective soilborne pathogens.
The role and expression of β-glucosidase during spore germination of mutant and wild-type Dictyostelium discoideum
Authors: Chan Agnes H. , Cotter David A.
Published: May 2010

Dormant spores of Dictyostelium discoideum are contained in a viscous matrix of extracellular material at the top of sorocarps. Analysis of crude extracts of the sorus demonstrates that there is a higher specific activity of β-glucosidase in the matrix than in the dormant spores. Polyacrylamide gel electrophoresis of the matrix material reveals the presence of β-glucosidase 2 with trace amounts of β-glucosidase 1. In the dormant spores only β-glucosidase 2 is detected. Upon heat activation of the spores, β-glucosidase 2 activity decreases to approximately 25% of the activity found in the preheated spores. The enzyme appears to have a surface location in dormant spores, since trypsin treatment will destroy all of the β-glucosidase 2 activity. The normal germination of dormant spores after trypsin treatment suggests that β-glucosidase 2 activity is not required for activation, swelling, or emergence processes.During the emergence of myxamoebae, β-glucosidase 2 is replaced by a newly synthesized enzyme, β-glucosidase 1. The formation of this new enzyme requires both RNA and protein syntheses. The complete germination of a β-glucosidase 1 minus mutant, however, casts doubt on the necessity for β-glucosidase1 activity during emergence. This is further supported by the normal germination of strain SG1 which contains four- to five-fold higher β-glucosidase activity than that found in wild-type amoebae at the end of the germination period. In addition, strain SG1 may be activated with a number of techniques which results in a separation of the time of β-glucosidase synthesis from the time of myxamoebae emergence. Furthermore, spores (which have been blocked from emerging by cycloheximide treatment) will slowly release spheroplasts when treated with only pronase and D. discoideum cellulase. However, addition of D. discoideum β-glucosidase 1 to the cellulose–pronase-treated spores does accelerate the rate of spheroplast formation. Thus, β-glucosidase 1 activity may only play a minor and dispensable role in D. discoideum spore germination.
Exoenzymes of Propionibacterium acnes
Authors: Kabongo Muamba Martin L.
Published: May 2010

Thirty strains of Propionibacterium acnes were grown in basal salt medium containing lecithin as a lipid substrate and in other media. The cultures were assayed for production of lipase (measured as fatty acid esterase) and other exoenzymes. Lipase was assayed spectrophotometrically; other enzymes were assayed using the API ZYM system (Analytab Products Inc., Plainview, NY). Substrates for lipase were α- and β-naphthol esters of propionic, butyric, valeric, caprylic, lauric, myristic, and oleic acids. All strains showed fatty acid esterase activity. Using the API ZYM system 19 enzymes were detected, 8 of which were found frequently and had high activity in most strains. Acid and alkaline phosphatases, phosphoamidase, ester lipase, trypsin–chymotrypsin-like proteases, β-glucuronidase (80%),β-galactosidase (80%), and N-acetyl-β-glucosaminidase were found. Many enzymes of P. acnes appear to be adaptive, dependent on the culture subtrate.
Studies on comparative gel electrophoretic patterns of proteins and enzymes from isolates of Rhizoctonia solani causing sheath blight disease in rice
Authors: Zuber Mohammed , Manibhushanrao K.
Published: May 2010

Protein and isoenzyme patterns of polyphenol (DOPA) oxidase, peroxidase, acetyl esterase, and acid and alkaline phosphatases from mycelial and extracellular extracts, as detected by polyacrylamide gel electrophoretic techniques, reflected marked variations among five differentially virulent isolates of Rhizoctonia solani, the causal organism of sheath blight disease of rice. Although no correlation could be obtained with the enzyme patterns and virulence of the isolates, two isolates with the lowest virulence showed mycelial and extracellular peroxidase bands and only the least virulent isolate gave mycelial alkaline phosphatase bands.
Sulphur requirements for growth of Acetivibrio cellulolyticus
Authors: Patel G. B. , Breuil C. , Agnew B. J.
Published: May 2010

The sulphur requirement for growth of Acetivibrio cellulolyticus was determined using a mineral salts basal medium reduced with titanium(III) citrate and supplemented with 1% (w/v) cellobiose and 0.05% (w/v) yeast extract. Inorganic sulphide (Na2S∙9H2O) in the range of 0.7–1.0 mM was found to support maximum growth whereas 8.0 mM sulphide caused complete inhibition. Of the other sulphur-containing compounds tested (cystine, sodium thioglycollate, methionine, glutathione, homocystine, S-methyl-L-cysteine, inorganic sulphate) cysteine-HCl at 10–15 mM concentration was the only one which supported maximum growth that was at least 80% of that obtained in the optimum sulphide medium. A modified medium incorporating the optimum inorganic sulphide concentration supported maximum growth that was about twice that obtained in a conventional medium reduced with cysteine-Na2S. The possible reasons for the inhibition of growth in defined media containing Na2S as the sole reducing agent and the sulphur source are discussed.
Preformed magnesium hydroxide precipitate for second-step concentration of enteroviruses from drinking and surface waters
Authors: Vilagines P. , Sarrette B. , Vilagines R.
Published: May 2010

A method is described for the second-step concentration of viruses from large volumes of drinking and surface waters. Seeded viruses present in the first eluate, performed with 50 mM glycine buffer, pH 11.5, were adsorbed on a preformed magnesium hydroxide precipitate. After low-speed centrifugation they were desorbed and ajusted to pH 7 with McIlvaine citrate–phosphate buffer. In these experimental conditions 90% of the viruses present in the 300-mL first eluate were reconcentrated in a final volume of 40 mL. The recovery efficiency was independant of either virus concentration or water quality.
Simplified growth media for Entomophthora egressa protoplasts
Authors: Dunphy Gary B. , Nolan Richard A.
Published: May 2010

The protoplast stage of Entomophthora egressa utilized cysteic acid, L-isoleucine, L-leucine, L-methionine, L-proline, DL-serine, L-threonine, L-glutamine and (or) L-asparagine, and L-valine during the initial 16 h of incubation in modified Grace's medium but did not utilize glucose. Medium A, containing the above amino acids (excluding L-isoleucine) plus L-tyrosine, L-glutamic acid, L-aspartic acid, and L-lysine, supported normal growth and cell wall regeneration. The amino acid composition was further simplified to include only L-glutamine, L-asparagine, and L-methionine (medium B). The growth rates and morphogenesis of the protoplasts in media A and B were compared with those in medium A plus albumin. Fetal calf serum was essential for protoplast growth in shaken cultures in both simplified media; however, it was not required for growth in stationary cultures. Depending on the medium employed, E. egressa exhibited complete or partial vitamin auxoautotrophy.
Survival stages of a psychrotrophic Cytophaga johnsonae strain
Authors: Reichardt Wolfgang , Morita Richard Y.
Published: May 2010

Cells of a psychrotrophic strain of Cytophaga johnsonae, when exposed to starvation in a mineral salts medium, produced short viable rods, viable coccoids, and moribund elongated cells as a function of the incubation temperature. Starvation for 14 days or longer resulted in an increase of the cellular DNA to protein ratio. While rod-shaped cells possessed an intermediate layer identified as murein sacculus, coccoid cells displayed the common properties of spheroplasts, and their formation was frequently preceded by a pestlelike intermediate stage. During survival, substrate affinities (1/Km) for transport, respiration, and incorporation of glucose increased in both rod and coccoid cells. The rods appeared to possess dual, concentration-dependent metabolic pathways for glucose. Glucose incorporation by starved cells into macromolecular pools had lower Km values (10 to 203 times lower) than the values found for exponentially growing and nonviable rods. Coccoid cells demonstrated a slightly increased resistance to mild heat stress compared with log phase cells but were equally susceptible to ultrasonic vibration and ultraviolet irradiation. The data obtained indicated that unbalanced cellular divisions of multinucleate cells at low temperature and starvation result in coccoid cells. The coccoid cells are probably the survival forms in nature when low temperatures and nutrient deprivation exist.
The degradation of Eucheuma spinosum and Eucheuma cottonii carrageenans by ι-carrageenases and κ-carrageenases from marine bacteria
Authors: Bellion C. , Hamer G. K. , Yaphe W.
Published: May 2010

Seven marine bacteria, which degraded carrageenan from Eucheuma spinosum, a hybrid ι–κ-carrageenan, were isolated and the specificity of the bacterial carrageenases synthesized was determined. An enzyme preparation having only ι-carrageenase activity was obtained from one bacterium. Preparations with only κ-carrageenase activity were obtained from two bacteria; four bacteria synthesized both κ- and ι-carrageenases. 13C nuclear magnetic resonsance spectroscopic procedures were used to identify the products of enzymic hydrolysis of κ-carrageenan (Eucheuma cottonii) and ι-carrageenan (E. spinosum).
An L-lactic acid dehydrogenase based method for detecting microbial colonies performing a malo-lactic fermentation
Authors: Subden R. E. , Lin W. L. , Lautensach A. , Meiering A. G.
Published: May 2010

Microbial colonies capable of fermenting L-malic acid to L-lactic acid were identified by means of a dark blue halo which formed after the colonies had been grown on medium containing malic acid and then covered with a soft agar overlay containing L-lactic acid dehydrogenase, nicotinamide adenine dinucleotide, phenazine methosulfate, and nitro blue tetrazolium. The system is stereospecific and discriminates between the production of D-lactic and L-lactic acid. Chromatographic analysis of the medium adjacent to the colony distinguishes between those colonies producing L-lactate from L-malate and those producing DL-lactate from glucose. The system may be used to identify wine microbes capable of performing a malo-lactic fermentation, comparing two bacterial strains for their ability to perform a malo-lactic fermentation, and for the identification of clones of an organism carrying a recombinant DNA vector with the genetic material necessary for malo-lactic fermentation.
Biodegradation of lignin-derived molecules under anaerobic conditions
Authors: Colberg P. J. , Young L. Y.
Published: May 2010

Soluble fragments of lignin origin obtained by thermochemical treatment of [14C]lignin-labeled lignocellulose served as substrate for anaerobic enrichment cultures. This study demonstrates that oligolignols, thought to be refractory under anaerobic conditions, can be degraded to lower molecular weight compounds and to methane and carbon dioxide.
Effects of adamantane derivatives on the stability and assembly of bacteriophage PM2
Authors: Choo Soo-Young , Vollherbst Kathryn , Keith Alec , Snipes Wallace
Published: May 2010

1-Adamantanamine and several related compounds were tested for their effect on the lipid-containing bacteriophage PM2. 2-Adamantanol and 1-adamantane methanol were virucidal, while 1-adamantane acetic acid inhibited virus production in a highly pH-dependent manner.
Biochemical and physiological changes during spore germination and swarm cell morphogenesis in the acellular slime mold Fuligo septica
Authors: Nelson Rodney K. , Orlowski Michael
Published: May 2010

Spores of the acellular slime mold Fuligo septica germinated and developed into motile, flagellated swarm cells using only endogenous carbon and energy sources. We observed no increase in the amount of any cell component during this time, whereas we did note a decrease in the amount of several substances. Glucose and glycogen were important reserves which were apparently catabolized via glycolysis and the tricarboxylic acid cycle. The synthesis of large amounts of ATP via a respiratory chain with oxygen as the terminal electron acceptor was essential for development. Another potential carbon and energy source was lipid which also decreased in amount during development, although the metabolism of glycerol could not be demonstrated. RNA synthesis was unnecessary for any of the morphological changes and did not occur at any time under these conditions. Protein synthesis was not essential for any step of morphogenesis but did occur. This synthesis did not result in the net accretion of protein nor in any change in the protein composition discernable by sodium dodecyl sulfate – polyacrylamide gel electrophoresis. Intracellular cyclic AMP levels increased fourfold coincident with the start of rapid glycogen depletion.
Seasonal fluctuations in river bacteria as measured by multivariate statistical analysis of continuous cultures
Authors: Bell Colin R. , Holder-Franklin Maxine A. , Franklin Mervyn
Published: May 2010

Forty-eight continuous culture enrichments were performed on summer and winter water samples from two contrasting rivers. The cell output from each chemostat was dependant on the temperature and nitrogen concentration of each enrichment. The diversity of the populations from the continuous cultures, as assessed by species diversity analysis, was always greater than populations obtained on agar plates. However, the species isolated exclusively by continuous culture in these experiments were not unique to the chemostat. All of these species had been isolated at some time on plates directly. High nitrogen concentrations were found to decrease diversity. Populations sampled during the winter were influenced primarily by the concentration of nitrogen. Summer isolates were affected mainly by the temperature of the culture medium. The nutritional versatility of the population was not affected by enrichment of the continuous culture.
Les pyro-spectrogrammes de masses multiples (PSMM): moyen rapide de différenciation bactérienne à l'aide d'un ordinateur
Authors: Lambert N. G. , Laurence R. A. , Harbec P. S. , Robert J. , Drapeau A. J.
Published: May 2010

Direct pyrolysis at 800, 900, 950, and 999 °C of bacterial samples at the entrance of the ionization source of a mass spectrometer is proposed. This technique is called multiple masses pyrospectrometry (MMPS). Its results are used for the automated rapid identification of unknown strains via computer memory and data bank facilities.