bluuebunny/crossref_metadata_2025 huggingface dataset:
DNA homology studies of the catalase-negative campylobacters and "Campylobacter fecalis," an emended description of Campylobacter sputorum, and proposal of the neotype strain of Campylobacter sputorum
Authors: Roop II R. Martin , Smibert Robert M. , Johnson John L. , Krieg Noel R.
Published: May 2010

Twenty-three strains of catalase-negative campylobacters and five strains of "Campylobacter fecalis," which is catalase-positive, were examined by DNA hybridization experiments. These organisms formed four distinct DNA homology groups corresponding to Campylobacter sputorum, Campylobacter mucosalis, Campylobacter concisus, and a currently unnamed group referred to as the "catalase-negative or weak" (CNW) strains. The strains were further characterized to determine which phenotypic characteristics provide the most reliable identification at the species level. Campylobacter sputorum ssp. sputorum, C. sputorum ssp. bubulus, and "C. fecalis" could not be distinguished by DNA homology; consequently, it is proposed that these three taxa be considered as biovars of C. sputorum. The description of C. sputorum is emended accordingly. ATCC strain 35980 is proposed as the neotype strain of C. sputorum.
Efficiency of various bacterial suspensions derived from cecal floras of conventional chickens in reducing the population level of Salmonella typhimurium in gnotobiotic mice and chicken intestines
Authors: Hudault Sylvie , Bewa Hilaire , Bridonneau Chantal , Raibaud Pierre
Published: May 2010

The antagonistic effect exerted towards Salmonella typhimurium by the flora issued from conventional chickens was studied in gnotobiotic animals. In germfree chickens and mice inoculated with S. typhimurium, the highest bacterial counts were observed in ceca, and were not significantly different in either host. The protection afforded by the inoculation of cecal flora issued from a conventional chicken was more effective when this flora was inoculated first into germfree chickens than when it was given only after inoculation with S. typhimurium. Administration of a cecal flora from a 15-day-old chick to gnotobiotic mice and chicken resulted in the inhibition of a further intestinal colonization by S. typhimurium in both hosts. Sixteen strains were isolated among the predominant populations of the fecal flora from chicken flora recipient mice. Association of 14 strains of strictly anaerobic bacteria with 2 strains of Escherichia coli and Streptococcus faecium only decreased the number of S. typhimurium in the ileum of gnotobiotic mice, but not in their cecum. Anaerobe cultures were obtained from 10−6 and 10−8 dilutions prepared from the fecal flora of gnotobiotic recipient mice. Antagonistic bacteria were present only in cultures from the 10−6 dilution. Cecal concentrations of volatile fatty acids were shown not to be the sole factor implicated in the antagonistic effect against S. typhimurium.
The role of the mitochondrial NAD+: isocitrate dehydrogenase in lipid accumulation by the oleaginous yeast Rhodosporidium toruloides CBS 14
Authors: Evans Christopher Thomas , Ratledge Colin
Published: May 2010

The mitochondrial NAD+: isocitrate dehydrogenase from Rhodosporidium toruloides CBS 14 had a molecular radius of 191 800 daltons, a pH optimum of 7.8, and an apparent Kms for isocitrate and NAD+ of 109 and 365 μM, respectively. The enzyme was absolutely dependent on AMP for activity and showed sigmoidal activation curves with respect to isocitrate concentration. ATP was shown to be a potent inhibitor even in the presence of saturating AMP and isocitrate concentrations. NADH was the most potent inhibitor, followed by L-glutamate and α-ketoglutarate, and less strongly by citrate and oxaloacetate. The inhibition by L-glutamate and α-ketoglutarate was noncompetitive, with respect to isocitrate, and indicated that the enzyme could be very susceptible to regulation by the products of organic nitrogen metabolism in this yeast. Inhibition by citrate and more so the strong inhibition by NADH illustrated the interplay between the inactivation of NAD+: isocitrate dehydrogenase and the steps leading to the biosynthesis of acetyl-CoA. The key role of this enzyme in lipid biosynthesis in oleaginous yeasts is discussed.
Inhibition de champignons phytopathogènes par des bactéries isolées du sol et de la rhizosphère de légumineuses
Authors: Gagné S. , Antoun H. , Richard C.
Published: May 2010

The antifungal activity of 644 bacterial isolates obtained from soil and from the rhizosphere of some leguminous plants was studied with one hyperparasite and six pathogenic fungi frequently associated with leguminous or gramineous plants. More than half (51.2%) of the bacterial isolates inhibited at least one fungus and 1.7% had an inhibitory effect on all the fungi tested. Stemphylium sarcinaeforme was the most sensitive fungus (inhibited by 27.0% of the bacteria tested), while Fusarium solani and Gliocladium roseum were the most resistant (inhibited by only 7.6 and 7.8% of the isolates, respectively). Verticillium albo-atrum and Fusarium oxysporum f. sp. medicaginis, important pathogens of alfalfa, were inhibited by 17.7 and 14.7% of the bacteria, respectively. Among the 166 bacteria showing the most important inhibitory effect on fungi, 7.2% inhibited strain A2 of Rhizobium meliloti and 21.1%, strain S14. In general, we obtained higher percentages of bacteria inhibiting fungi and Rhizobium meliloti from rhizospheric than from nonrhizospheric soil. When incorporated in the growth medium, some Pseudomonas spp. and Bacillus spp. reduced the growth surface of the tested fungi by more than 90%. Some bacteria reduced the mycelium density rather than the growth surface.
Temperature-sensitive mutants in rfaI and rfaJ, genes for galactosyltransferase I and glucosyltransferase II, for synthesis of lipopolysaccharide in Salmonella typhimurium
Authors: Kadam Sunil K. , Peppler Mark S. , Sanderson Kenneth E.
Published: May 2010

Certain rough mutants of Salmonella typhimurium LT2 were shown to be temperature sensitive for the production of lipopolysaccharide (LPS). When grown at the restrictive temperature (42 or 45 °C), the cells contained LPS deficient in O (somatic) side chains, based on phage-sensitivity data and gel electrophoresis of the LPS. Cells grown at the permissive temperature, 30 °C, made LPS resembling that of smooth cells. The mobility of the LPS in gels, the phage sensitivity patterns, and gas chromatographic analysis indicate that LPS of 45 °C-grown cells of SA126 (rfaJ3012) is of chemotype Rb2, with one glucose and two galactose units (and thus inferred to be due to a mutation in rfaJ), and LPS of 45 °C-grown cells of SA134 (rfaI3020) is of chemotype Rb3, with one glucose and one galactose unit (inferred to be rfaI). These inferences were confirmed, for pKZ26 (pBR322-rfaGBIJ) and pKZ27 (pBR322-rfaGBI) both complement rfaI3020, but only pKZ26 complemented rfaJ3012. In addition, pKZ26 carrying a Tn5 insertion resulting in loss of complementation of a known rfaJ mutation, but not of rfaG, B, or I, also resulted in loss of rfaJ3012 complementation. Based on gel analysis, there is a small amount of the LPS containing smooth side chains in cells of SA126 grown at 45 °C; following a switch to 30 °C, the amount of LPS with O side chains gradually increased, and the amount of core LPS was reduced, though even after 3 h the LPS does not fully resemble that of smooth strains. Cells grown at 42 °C show limited capacity to adsorb a smooth-specific phage, P22, but the capacity to adsorb the phage increased fourfold after 5 min growth at 30 °C, and by 60 min at 30 °C adsorption resembled that seen by smooth cells. These data indicate that synthesis of the smooth LPS begins less than 5 min after shift to the permissive temperature, and that phage adsorption is a more sensitive test for the appearance of smooth side chains than the use of polyacrylamide gels with silver stains.
Evaluation of Arthrobacter sp. for biological control of the pitch canker fungus (Fusarium moniliforme var. subglutinans) on slash pines
Authors: Barrows-Broaddus Jane , Dwinell L. D. , Kerr T. J.
Published: May 2010

Slash pines (Pinus elliottii var. elliottii) were wounded, treated with Arthrobacter sp., and then inoculated 24 h later with Fusarium moniliforme var. subglutinans, the causal organism of pine pitch canker. Among three Arthrobacter isolates tested, A6 and A16 significantly decreased the numbers of conidia of the pitch canker fungus collected from surfaces of inoculated wounds (average 17 657/mL and 28 398/mL, respectively) compared with inoculated wounds treated with isolate A50 (84 562/mL) or a control (average 156 857/mL). Another study evaluated the effects of different intervals between wound treatment with Arthrobacter and inoculation with F. moniliforme var. subglutinans. Pitch cankers developed on trees inoculated 1 day after wounding but not on trees inoculated 7, 14, or 21 days after wounding. Arthrobacter isolate A6 significantly reduced conidial production (average 2250/mL) compared with the control treatment (average 960 250/mL) on inoculated 1-day-old wounds. In both studies, 5 months after treatment, arthrobacters were recovered from treated wounds at 450 colony-forming units/mL (initial inoculum density 108 colony-forming units/mL). Thirteen months after treatment, the numbers of F. moniliforme var. subglutinans and arthrobacters were greatly reduced or were absent from washes and wood samples on wound surfaces. Treatment with Arthrobacter did not significantly reduce the size of cankers developing from inoculated wounds. Arthrobacters alone actually slowed wound closure by the tree.
Monoclonal antibodies against corn stunt spiroplasma
Authors: Lin C. P. , Chen T. A.
Published: May 2010

Monoclonal antibodies against the corn stunt spiroplasma were produced by fusing NS-1/1-Ag4-1 murine myeloma cells with splenic cells from mice immunized with corn stunt spiroplasma (I-747). Isotypes of these monoclonal antibodies have been determined to be IgG1 or IgG2a subclass by the Ouchterlony double diffusion method using class and subclass specific antibodies for mouse IgG1, IgG2a, IgG2b, IgG3, and IgM. Antibody titers for both hybridoma culture supernatants and ascitic fluids were determined with indirect biotinylated enzyme-linked immunosorbent assay and they ranged from 800 to 3200, and 312 500 to 7 812 400, respectively. In serological specificity studies, with indirect enzyme-linked immunosorbent assay, 32 spiroplasma strains belonging to 19 different serogroups were tested using both corn stunt spiroplasma monoclonal antibodies and conventionally produced polyclonal antibodies. Corn stunt spiroplasma specific monoclonal antibodies reacted specifically with any of the three corn stunt spiroplasma strains tested, but not with all of the other spiroplasma strains from different groups and subgroups. On the other hand, some nonspecific reactions to heterologous spiroplasma strains were obtained when conventional polyclonal antibodies were used.
DNA relatedness among aquatic yeasts of the genus Metschnikowia and proposal of the species Metschnikowia australis comb. nov.
Authors: Mendonça-Hagler Leda Cristina , Hagler Allen N. , Phaff H. J. , Tredick Joanne
Published: May 2010

DNA hybridization studies were conducted to determine the taxonomic status of the aquatic group of Metschnikowia species and their varieties. Among the DNAs of the four varieties of Metschnikowia bicuspidata, that of Metschnikowia bicuspidata var. australis showed 37 to 51% relative binding with the DNAs of Metschnikowia bicuspidata var. bicuspidata and of the varieties chathamia and californica. On this basis, low intervarietal fertility, and unique habitat in antarctic seawater, we have proposed to raise M. bicuspidata var. australis to the rank of species, Metschnikowia australis, comb. nov. DNA complementarity of Metschnikowia bicuspidata var. californica and Metschnikowia bicuspidata var. chathamia DNA was greater than 80% with that of M. bicuspidata var. bicuspidata. Metschnikowia australis can be differentiated from other Metschnikowia species and varieties by its inability to form chlamydospores, the formation of two needle-shaped ascospores per ascus, lack of glucose fermentation, and lack of assimilation of both methyl-α-D-glucoside and glucono-δ-lactone. Other DNA–DNA reassociation experiments showed that Metschnikowia zobellii is a distinct species when compared with both aquatic and terrestrial species of the genus.
Adaptation of estuarine bacteria to toluene at low concentrations in sea water: cometabolism of toluene
Authors: Wyndham R. C.
Published: May 2010

The ability of sediment-water interface bacteria to adapt to micromolar concentrations of water-dissolved toluene was determined. Control and experimental chambers of 200 cm2 of undisturbed sediment were fitted for continuous replacement of overlying seawater. The experimental chamber received toluene in sterile seawater at a rate determined to give concentrations of 4 to 17 μM during adaptation. Samples of seawater and sediment surface were removed at intervals and analyzed for bacterial numbers and rates of assimilation of radiolabeled glutamate, phenol, and toluene. Adaptation occurred in 3 to 5 days in the experimental chamber and was characterized by rapid increases in phenol and toluene assimilation. An increase in phenol assimilation by sediment surface bacteria was the first detectable adaptation. Kinetic analyses indicated bacteria in seawater overlying the sediments had a greater affinity for toluene (half-saturation at 50 nM) following adaptation than for phenol (half-saturation at 3.9 μM). The first-order rate constant for toluene assimilation at low concentrations decreased 10-fold on prolonged continuous culture of the seawater community at millimolar concentrations of toluene. Total numbers of bacteria by direct count and plate count, and bacterial activity measured with [14C]glutamate, did not change appreciably in the control and experimental chambers. During the early stages of adaptation the meta-ring-fission product of 3-methylcatechol accumulated in the seawater to a concentration of 4.9 μM. Tests of isolates from plate counts on phenol and toluene vapours revealed 30% formed diffusable yellow metabolites of these substrates in the absence of significant growth. One of these isolates showed partial metabolism of toluene and meta-toluate to the first metabolite following meta-ring fission, 2-hydroxy-6-keto-2,4-heptadienoate, by resting cells and cells growing on alternative carbon sources.
Isolation de micro-organismes du genre Listeria à partir de lait cru destiné à la consommation humaine
Authors: Rodriguez Lucas Domínguez , Garayzabal Jose F. Fernández , Boland Jose A. Vazquez , Ferri Elias Rodriguez , Fernández Guillermo Suarez
Published: May 2010

Refrigerated mixtures of raw milk provided by a dairy which was supplied by farms from west and central Spain were tested for the presence of Listeria microorganisms. A total of 95 samples were taken at regular intervals over a 16-month period. Listeria grayi was isolated from 89.5% of the samples, Listeria monocytogenes s. str. from 45.3%, Listeria innocua from 15.8%, Listeria welshimeri from 3.1%, and Listeria seeligeri from 1.05%. Listeria ivanovii, Listeria murrayi, and Listeria denitrificans were not isolated.[Translated by the journal]
Restriction-modification systems in Streptomyces antibioticus
Authors: Sànchez Jesùs , Barbès Covadonga , Hernandez Angeles , de los Reyes Gavilàn Clara-Rosa G. , Hardisson Carlos
Published: May 2010

Several restriction systems were detected in different strains of Streptomyces antibioticus by using actinophages as biological indicators. Adsorption of phages to the bacteria, together with the study of the efficiency of plating gave an initial indication of restriction in three strains. The alternation of efficiency of plating values obtained from restricting and nonrestricting hosts, gave evidence for the presence of a restriction-modification system in another strain. No common modification systems were detected among the different strains tested. Two specific endonucleases with a possible role in restriction were detected in strains ATCC 11891 and ETH 7451, respectively.
Some conditions influencing the association of Yersinia enterocolitica with epithelial cells in vitro
Authors: Schiemann Donald A. , Swanz Pamela J.
Published: May 2010

The association of Yersinia enterocolitica serotype 0:5,27 with Henle 407 epithelial cells in vitro was measured by using 35S-labelled bacteria with separation of unassociated bacteria by filtration (Nuclepore polycarbonate 5-μm membrane). The number of associated bacteria was related to the initial multiplicity. Changes in beginning pH, the presence of protein, availability of Ca2+ and Mg2+, and nature of carbohydrate in a defined bacterial growth medium did not change the degree of epithelial cell association. Bacteria recovered from the log phase of growth at 25 °C, or after growth to stationary phase at 35 °C, showed no association with epithelial cells. Optimal association occurred when the pH provided during interaction was between 7.6 and 8.6 and the temperature was either 25 or 35 °C. No association occurred within 30 min at 4 °C. The presence of Ca2+ and (or) Mg2+ during interaction had no effect, but the addition of peptone increased association. The results of this study demonstrate the importance of controlling both conditions provided for bacterial growth and those provided for interaction to achieve optimal association of Y. enterocolitica with epithelial cells in vitro.
Effects of cysteine and structurally related compounds on ochratoxin production by Aspergillus ochraceus
Authors: Lisker N. , Paster N. , Chet I.
Published: May 2010

Addition of 10−2 ML-cysteine, L-cystine, or S-ethyl-L-cysteine to a synthetic medium containing xylose as the sole carbon source did not decrease ochratoxin production by Aspergillus ochraceus. At that concentration, DL-homocysteine thiolactone HCl, DL-cysteine HCl, L-ethionine, S-methyl-L-cysteine, and glutathione (reduced) strongly inhibited ochratoxin production. DL-Homocysteine thiolactone HCl, DL-cysteine HCl, and L-ethionine also strongly inhibited fungal growth. At lower concentrations (10−3and 10−4 M) only L-ethionine decreased the toxin production. Ochratoxin inhibition caused by DL-homocysteine thiolactone HCl, DL-cysteine HCl, and glutathione was observed only in cases where the pH of the media was below 5.0. The inhibition caused by 10−3 M ethionine was partially prevented by the addition of 10−3 M methionine but this was not the case after the addition of S-methyl-L-cysteine to the medium.
Influence of inoculum size, incubation temperature, and cell culture density on virus detection in environmental samples
Authors: Payment Pierre , Trudel Michel
Published: May 2010

The influence of inoculum size and cell culture density on virus titer by cytopathic effect or plaque assay was studied using poliovirus type 1 and BGM (Buffalo green monkey) cells as a model for this evaluation. With a plaque assay system, a linear relationship was observed for an inoculum size of up 1 mL/25 cm2; a marked decrease in the number of plaques was observed when over 1 mL of sample was inoculated on this surface area. Cell culture density also affected virus titer; maximal titers were observed when cells were seeded at 25 000 to 75 000 cells/mL and incubated for 6 days before infection with the virus. Viral density, evaluated as most-probable-number and measured by cytopathic effect under liquid overlay, revealed that the viral titer was similar up to 1 mL inoculum and increased only when over 1 mL was inoculated. Cell density had no significant effect on the viral titer measured by the most-probable-number method and cytopathic effect. Inactivation of inoculum due to an incubation temperature of 37 °C for a short period was shown to be minimal for poliovirus type 1, reovirus type 2, coxsackievirus B-5, and the simian rotavirus SA-11. Longer inactivation time led to a 2 logs reduction of the infectious titer of coxsackievirus B-5 (in 48 h) while the other viruses showed a significant reduction in titer only after 96 h.
Isolation and characterization of pyrimidine mutants of Salmonella typhimurium altered in expression of pyrC, pyrD, and pyrE
Authors: Kelln Rod A. , Neuhard J. , Stauning Lisbeth
Published: May 2010

Parental strains of Salmonella typhimurium having a specific pyr gene (pyrC, pyrD, or pyrE) fused to the structural genes of the lac operon through the specialized transducing phage Mu dl (ApRlac) were used to construct thermostable derivatives for purposes of conducting a genetic and biochemical characterization of the individual pyr genes. The direction of transcription of each pyr gene in relation to the current linkage map was defined with both pyrC and pyrE being transcribed counterclockwise and pyrD exhibiting clockwise transcription. Mutants displaying increased pyr gene expression were isolated employing a genetic strategy which is of general applicability. Among the mutants, only one isolate was found to possess a mutation which was unlinked to the specific pyr gene under study; the other isolates harbored linked mutations which were inferred to be cis-acting. Additional studies demonstrated that in conditions of severe pyrimidine limitation, further derepression could still occur in the mutant strains.
Identification of a trans-dominant mutation affecting proline dehydrogenase in Escherichia coli
Authors: Deutch Charles E. , O'Brien Jr. John M. , VanNieuwenhze Michael S.
Published: May 2010

L-Proline dehydrogenase catalyzes the oxidation of L-proline to Δ1-pyrroline-5-carboxylate, a reaction that is an important step in the utilization of proline as a carbon or nitrogen source by bacteria. A mutant of Escherichia coli K-12 lacking L-leucyl-tRNA:protein transferase had been found previously to contain about five times as much proline dehydrogenase activity as its parent strain. This difference has now been shown to be due to the presence in the parent strain of a previously unrecognized mutation. This mutation, which has been designated put-4977, specifically affects proline dehydrogenase rather than proline uptake. Although proline dehydrogenase remains inducible by L-proline in strains carrying the mutation, there is a premature cessation of differential synthesis during induction that results in a lower specific activity. The mutation shows about 50% P1-mediated cotransduction with pyrC and is therefore located at about 22 min on the E. coli chromosome. Merodiploids containing a normal F′ factor still exhibit decreased enzyme activity, indicating that the put-4977 mutation is trans-dominant. The mutation cannot be detected in present stocks of the transferase-deficient mutant, suggesting that this mutant is a revertant for put-4977.
Catalase, superoxide dismutase, and the production of O2-sensitive mutants of Bacillus coagulans
Authors: Vassilyadi Michael , Archibald Frederick
Published: May 2010

A number of facultatively anaerobic members of the genus Bacillus were screened for their catalase, diaminobenzidine peroxidase, and superoxide dismutase activities. A strain of Bacillus coagulans (7050) lacking peroxidatic activity and containing single catalatic and superoxide dismutase activities was selected. Responses of the superoxide dismutase activity and catalase level to the partial pressure of oxygen, and Fe and Mn levels, as well as to aerobic and fermentative metabolism, were determined. There appeared to be a relationship between high endogenous catalase levels and the high H2O2 evolution and KCN insensitivity of B. coagulans respiration. Bacillus coagulans 7050 was mutagenized with N-methyl-N′-nitro-N-nitrosoguanidine and screened for the expression of oxygen intolerance. All of the 38 stable oxygen sensitive mutants obtained had very low or completely absent catalatic activity and catalase protein. No mutant lacked superoxide dismutase, although five showed significantly lowered levels of the enzyme. Exogenous bovine liver catalase restored aerotolerance and reduced cell pleomorphism in the mutants.
Production of cellulose and soluble polysaccharides by Acetobacter xylinum
Authors: Savidge Rodney Arthur , Colvin J. Ross
Published: May 2010

Alkali-insoluble cellulose and water-soluble polysaccharide production by wild-type Acetobacter xylinum colony and liquid cultures was investigated. The mass of cellulose exceeded that of soluble polysaccharides in liquid cultures while the reverse situation occurred in colony cultures. The soluble polysaccharide fraction, 3 × 105 to 5 × 105 in molecular weight, was found by DEAE-Sephacel chromatography to be a complex of several acidic, nitrogenfree polysaccharides. One acidic polysaccharide was predominant in the complex, and gas–liquid chromatography and mass spectrometry showed this to contain glucose, rhamnose, mannose, and glucuronic acid in molar ratio of 6:1:1:1, respectively. 13C and 1H nuclear magnetic resonance spectra are presented for this major polysaccharide component. Several minor, soluble, acidic polysaccharides were related in chemical composition to the major soluble polymer. The relation of these soluble polysaccharides to cellulose biogenesis is discussed.
Maltol, a metabolite of Scytalidium uredinicola which inhibits spore germination of Endocronartium harknessii, the western gall rust
Authors: Cunningham James E. , Pickard Michael A.
Published: May 2010

Twenty-four isolates of Scytalidium uredinicola were screened for their ability to inhibit germination of Endocronartium harknessii spores. The most active isolate, 4149, was grown in 2% malt extract broth for 10 days. From the spent culture medium an inhibitory compound was isolated and identified as 3-hydroxy-2-methyl-4H-pyranone, or maltol. This compound has rarely been described as a microbial metabolite. Maltol caused a 50% decrease in spore germination at 50 μg/mL and showed varying activity against several wood-rot fungi at 550 μg/mL.
Effect of relative humidity on the airborne survival of rhinovirus-14
Authors: Karim Yasmin G. , Ijaz M. Khalid , Sattar Syed A. , Johnson-Lussenburg C. Margaret
Published: May 2010

Rhinovirus-14, suspended in tryptose phosphate broth supplemented with uranine (physical tracer) and an antifoam, was aerosolized by use of a Collison nebulizer. The aerosols were held in a rotating drum with the relative humidity at either the low (30 ± 5%), medium (50 ± 5%), or high (80 ± 5%) level at 20 ± 1 °C. An all-glass impinger was used to recover the virus from the air in the drum, with the first air sample being collected after a 15-min period of aerosol stabilization. Subsequent air samples were withdrawn at 2, 4, 8, and 14 h after stabilization of the aerosol. At the low and medium relative humidity levels, the infectivity of the airborne virus was rapidly lost and less than 0.25% could be detected in the first air sample. At the high RH level, however, the airborne virus had a half-life of 13.7 ± 1.91 h and nearly 30% of the input infectious virus could be detected in the drum air even after 24 h of aerosolization. These findings suggest that under certain environmental conditions, notably high relative humidity, air may act as a vehicle for the spread of rhinovirus infections.
The accumulation of polyols by the yeast Debaryomyces hansenii in response to water stress
Authors: Nobre M. Fernanda , Costa Milton S. da
Published: May 2010

Growth of the yeast Debaryomyces hansenii in 1% (w/v) glucose medium containing NaCl or KCl resulted in the accumulation of glycerol during the exponential phase of growth and arabinitol during the stationary phase. Similar results were obtained during growth of the yeast in 12.5% (w/v) glucose, 25% glucose, 25% fructose, and 1% glucose plus 25% polyethylene glycol M.W.200 (PEG 200). The results indicate that the intracellular glycerol concentration increases concomitantly with the solute concentration of the growth medium, while the accumulation of arabinitol is less pronounced. Growth of the yeast in media containing meso-erythritol or D-mannitol as carbon sources without or with 1 M NaCl resulted in the pronounced inhibition of arabinitol accumulation because of the intracellular accumulation of the exogenous polyols. Mannitol accumulated primarily during the stationary phase, while erythritol accumulation occurred primarily during the exponential phase. The erythritol concentration attained very high levels during growth in media containing 1 M NaCl and effectively inhibited the accumulation of glycerol.
Sclerotia as viable sources of mycelia for the establishment of ectomycorrhizae
Authors: Grenville D. J. , Piché Y. , Peterson R. L.
Published: May 2010

The ectomycorrhizal fungi Pisolithus tinctorius and Paxillus involutus, which have wide host potential and diverse ecological ranges, were grown in association with pine seedlings in plastic growth pouches. Sclerotia formed under these conditions were stored at room temperature for up to 30 days and then germinated on agar medium. Pure cultures of P. involutus also produced sclerotia and these also regenerated in culture. Mycelial plugs from the sclerotia-derived cultures were subsequently reinoculated onto pine roots. Typical ectomycorrhizae with a mantle and Hartig net were established.
Activity changes of three nucleolytic enzymes during the life cycle of Saccharomyces cerevisiae
Authors: Van Ryk Donald I. , von Tigerstrom Richard G.
Published: May 2010

Conditions were established for the assay of three nucleolytic enzymes: a Mg2+-independent endoribonuclease, a Mg2+-dependent endonuclease, and a Mg2+-dependent 5′-exonuclease in Saccharomyces cerevisiae cell extracts. The changes in the activities of these enzymes were determined throughout the life cycle of the organism. As the cells progressed from the exponential to the stationary growth phase, the specific activities of the Mg2+-independent endoribonuclease and of the Mg2+-dependent 5′-exonuclease increased, whereas the Mg2+-dependent endonuclease decreased. During sporulation the Mg2+-independent endoribonuclease and the Mg2+-dependent 5′-exonuclease increased several-fold over the first 10 h, but, since a similar increase was seen in nonsporulating control cells, the increases did not appear to be related to sporulation. However, the specific activity of the Mg2+-dependent endonuclease showed a sporulation-related increase during the first 3 h of sporulation, with a subsequent decline to very low levels. The specific activity of this enzyme increased again during germination to the levels seen in exponential phase cells. The Mg2+-independent endoribonuclease and the Mg2+-dependent 5′-exonuclease showed little change during germination of the ascospores. The high specific activity of the Mg2+-independent endoribonuclease during periods of nutrient deprivation is in agreement with the proposed role for this enzyme in the degradation of rRNA under these conditions.
Modification of the outer surface of Erwinia carotovora ssp. atroseptica by the phytoalexin rishitin
Authors: Robertson W. M. , Lyon G. D. , Henry C. E.
Published: May 2010

The phytoalexin rishitin (500 μg/mL) modified the wall of Erwinia carotovora ssp. atroseptica by removing an outer layer and causing holes to appear through which the cell contents were extruded. A lower concentration of rishitin (300 μg/mL) produced effects on the cytoplasm visible by electron microscopy but no obvious differences in membrane integrity, although sections stained with the periodic acid – thiosemicarbazide – silver proteinate reaction showed a reduction in the intensity with which the carbohydrate layer in the outer membrane was stained which was similar to that found at the higher concentration (500 μg/mL). Labelling rishitin-treated cells with cationized ferritin showed the presence of negative charges on the outer surface of all cells treated with 500 μg rishitin/mL which were absent on nontreated cells and present in only a few cells treated with 300 μg/mL. After incubation of E. carotovora ssp. atroseptica with rishitin, cells bound to fluorescein isothiocyanate labelled lectins from Ricinus communis, Solanum tuberosum, and Triticum vulgaris and rhodamine-labelled avidin; cells of E. carotovora spp. atroseptica treated with ethanol were not labelled. Rishitin-treated cells did not bind to lectins from Arachis hypogaea, Dolichos biflorus, Glycine max, Limulus polyphemus, or Ulex europaeus. These results suggest that the phytoalexin rishitin can modify existing sites or expose previously blocked sites which may be involved in host–pathogen recognition, and may therefore indicate a reinforcement of other recognition processes in vivo.
Cellular and chitosomal lipids of Agaricus bisporus and Mucor rouxii
Authors: Weete John D. , Furter Rolf , Hänseler Edgar , Rast Dora M.
Published: May 2010

The lipid composition of Agaricus bisporus mycelium (submerged culture) and Mucor rouxii yeast cells was determined. The mushroom mycelium contained about 5.0% lipid which consisted of oleic, linoleic, and palmitic as the principal fatty acids in the polar lipid, free fatty acid, and triacylglycerol fractions. The free sterol content (85% ergosterol) was 0.2% of the mycelial dry weight. Mucor rouxii cells contained 3.4% lipid to which phospholipid, sterol (25% ergosterol), and squalene contributed 35, 4, and 2%, respectively. Yeast cell total fatty acids ranged from C12 to C20 with oleic and palmitic being predominant. Phosphatidylcholine and phosphatidylethanolamine were major glycerophospholipids of both species. The lipid composition of chitosomes from both species was generally similar to that of the respective total cellular lipid. Chitosomal lipids had no characteristic feature that suggested a particular functional significance with respect to chitin synthetase.
Immobilization and neutralization of Treponema pallidum attached to cultured mammalian cells
Authors: Fitzgerald Thomas
Published: May 2010

The in vitro effects of antibodies, complement, and (or) macrophages on Treponema pallidum have been previously characterized using relatively simple systems of organisms incubated with the immune components. In vivo, the more complex environment may alter immune reactivity. Experiments were performed to determine whether immobilizing and neutralizing antibodies retained their effectiveness in a more complex environment involving cultured mammalian cells. Two different protocols were used. In protocol A treponemes and normal or immune serum were mixed and added immediately to the cultured cells. In protocol B treponemes were preincubated for 18 h with cultured cells to maximize treponemal attachment; then normal or immune serum was added. With both protocols, attachment of organisms resulted in less effecient immobilization and neutralization. In further experiments, cultured cells were disrupted with Triton X, leaving cytoskeletal remnants on the vessel surface. Identical immobilization and neutralization experiments were performed in the presence of these remnants. In contrast to the findings with viable cultured cells, treponemal attachment to these nonviable remnants did not effect either antibody reaction. Attached organisms were immobilized or neutralized just as efficiently as unattached organisms. Results are discussed in terms of the altered immune reactivity in more complex in vitro environments.
Microbes, warfare, religion, and human institutions
Authors: Doyle R. J. , Lee Nancy C.
Published: May 2010

A significant number of practicing microbiologists are not aware of the historical impact of infectious agents on the development of human institutions. Microbes have played a profound role in warfare, religion, migration of populations, art, and in diplomacy. Boundaries of nations have changed as a result of microbial diseases. Infectious agents have terminated some kingdoms and elevated others. There is a need for microbiologists to have a historical perspective of some of the major ways in which a pathogen may influence civilized populations. Conditions may exist in contemporary society for a repeat of some of the kinds of plagues suffered by previous societies. The purpose of this paper is to review examples of situations where pathogenic microbes have forced societal modifications on centers of human population.
Studies on in vivo inactivation of gramicidin S synthetase and its retardation
Authors: Demain Arnold L , Agathos Spyridon N
Published: May 2010

The oxygen-dependent in vivo inactivation of gramicidin S synthetase was investigated in Bacillus brevis ATCC 9999. Inhibitors of energy metabolism and of protein synthesis added to aerated cell suspensions did not provide any protection against inactivation, thus indicating that the process does not depend on energy-yielding metabolism nor on de novo protein synthesis. Organic thiols added to anaerobic long-term incubations retarded synthetase inactivation for several hours, whereas in short-term incubations of previously air-exposed cells they resulted in partial restoration of activity. The in vivo inactivation of the enzyme was found to be accompanied by a parallel drop in intracellular thiols. These results implicate enzyme SH oxidation as a mechanism of in vivo inactivation. Retardation of inactivation was achieved upon addition of utilizable carbon sources (glycerol, fructose, inositol) to aerated cell suspensions in buffer, the degree of stabilization being proportional to the ease of uptake and to the concentration of C source. This effect involves actual consumption of the exogenous C source and is accompanied by lower dissolved oxygen levels in the cell suspension. Pulsed additions of C source could retard inactivation but could not restore partly or fully lost activity. The C-source effect was blocked by the uncoupler dinitrophenol, while dissolved oxygen levels in the suspension remained low. C-source-supplemented cell suspensions incubated under air had a decreased intracellular redox state, as revealed by intracellular SH concentration.
Microbial interactions in heterotrophic nitrification
Authors: Rho Jinnque
Published: May 2010

An Arthrobacter sp. capable of extensive nitrification was isolated from a eutrophic lake sediment employing inorganic salts medium with acetamide as the carbon source. This heterotrophic nitrifier was found to be closely associated with a Corynebacterium sp. both in growth and in nitrification. When the Arthrobacter sp. was jointly cultured with the Corynebacterium sp. in medium containing ammonium ion, acetate, and inorganic salts, the concentrations of nitrification products (nitrite and nitrate) increased approximately 10-fold. This stimulatory interaction was also determined in filter-sterilized sediment water samples amended with ammonium ion and acetate. Although both organisms failed to grow singly in media containing 1 mg/mL of nitrite N and of acetaldoxime N, they grew well in both media when cultured jointly. Nitrification, however, occurred only in the acetaldoxime medium. This is the first reported instance of mutualistic relationships in heterotrophic nitrification arid appears to be significant to our understanding of nitrogen transformation in lacustrine environments.
Manganese and antibiotic biosynthesis. III. The site of manganese control of patulin production in Penicillium urticae
Authors: Scott Richard E. , Jones Alan , Gaucher G. Maurice
Published: May 2010

Although manganese had been shown to be an essential requirement for patulin biosynthesis, its site of action was unknown. Four possibilities were considered. A manganese requirement for the second pathway enzyme, a decarboxylase, was discounted since mid and late pathway intermediates were not converted to patulin in manganese-deficient cultures. A major disruption in primary metabolism and hence secondary metabolism was discounted since eight primary metabolism enzymes showed no evidence of unusual changes in specific activity when normal and manganese-deficient cultures were compared. Inhibitor studies using actinomycin D and cycloheximide showed that there was no activation of preexisting enzyme proteins and that manganese did not influence translation. The inhibitor studies did show, however, that manganese exercised its effect on patulin biosynthesis by influencing the coordinate appearance of pathway enzymes through an effect at the level of transcription.
Use of spermosphere model for the screening of wheat cultivars and N2-fixing bacteria for N2 fixation
Authors: Jain Devender K. , Rennie R. J.
Published: May 2010

The spermosphere model showed very high seedling-to-seedling variation in the ability to induce acetylene-reducing activity in bacteria associated with wheat roots. Several seedlings failed to induce nitrogenase in N2-flxing strains of Bacillus and Azospirillum brasilense. Increasing the concentration of yeast extract or the inoculum density, adding NaOH solution in the side arm of Pankhurst tubes to absorb CO2, and vernalizing the seeds did not increase the percentage of nitrogenase-positive tubes and did not decrease variation in acetylene-reducing activity. Increasing the incubation temperature from 25 to 27 °C induced nitrogenase in Bacillus, but not in Azospirillum strains; at 30 °C nitrogenase was also induced in Azospirillum strains. It appears that the spermosphere model is not a practical technique for screening nitrogenase induction by wheat, unless the use of genetic lines of unimpeachable uniformity can provide control of variability.
Regulation of oosporogenesis by Lagenidium giganteum; promotion of sexual reproduction by unsaturated fatty acids and sterol availability
Authors: Kerwin James L. , Washino Robert K.
Published: May 2010

Induction and maturation of the sexual oospores of the facultative mosquito parasite Lagenidium giganteum (Oomycetes: Lagenidiales) are influenced by exogenous lipid media supplements. Sterols structurally related to cholesterol are necessary for induction of sexual reproduction and possibly have at least a structural role in oospore maturation following spore wall formation. Sterols also enhance uptake of certain exogenous fatty acids from growth media. Palmitoleic, oleic, and linoleic acids, especially when added to media as triacylglycerols, enhance oospore induction and maturation. It is hypothesized that enrichment of the fatty acyl compounds of the fungus with unsaturated moieties affects cyclic nucleotide metabolism and promotes cellular and vesicular fusion events associated with oosporogenesis by regulating (increasing) membrane fluidity. Results are discussed in relation to mediation of fusion events in a number of diverse model membrane and biological systems by fatty acids and sterols.
Cloning and characterization of chromosomally encoded cephalosporinase gene of Enterobacter cloacae
Authors: Guerin Sylvain , Paradis François , Guay Roger
Published: May 2010

The cephalosporinase gene, cpa, which codes for an inducible class I chromosomal β-lactamase in Enterobacter cloacae was cloned on a fragment of 6.05 kilobase pairs inserted into plasmid pACYC184 and transferred into Escherichia coli HB101 recipient cells. The constructed hybrid plasmid, designated pGGQ101, carried a genomic fragment which retained its parental inducibility characteristics, although its expression level in transformed E. coli cells fell to 40–65% of its initial level in E. cloacae. The localization of the cpa gene on pGGQ101 plasmid was determined by Bal31 exonuclease deletion mapping and further confirmed by subcloning HindIII–AvaI restriction fragment on pMB9 plasmid vector. Labeling with [35S]methionine of pGGQ101 specified proteins in a minicell system showed that six or seven proteins are encoded by the insert. Two proteins with apparent molecular mass of 42 000 and 39 500 daltons, respectively, most probably represent the premature and mature cephalosporinase forms.
Phosphoproteins and the phosphoenolpyruvate: sugar phosphotransferase system of Streptococcus salivarius. Detection of two different ATP-dependent phosphorylations of the phosphocarrier protein HPr
Authors: Waygood E. Bruce , Mattoo Roshan L. , Erickson Ellen , Vadeboncoeur Christian
Published: May 2010

Phosphoproteins which arise from incubation of Streptococcus salivarius ATCC25975 crude extracts with [32P]phosphoenolpyruvate and [γ-32P] ATP, were separated and detected by sodium dodecyl sulphate – polyacrylamide gel electrophoresis and autoradiography. These procedures were carried out using the methodology that has been developed to allow for the detection of phosphoproteins containing 1-P-histidinyl and 3-P-histidinyl residues, and also to distinguish between these and phosphoproteins containing acid-stable phosphoamino acids such as phosphoserine, phosphothreonine, and phosphotyrosine. Extracts of cells which had been grown with various sugars as carbon sources were investigated to determine both constitutive and inducible phosphoproteins. No evidence was found for phosphoproteins specifically induced by a sugar, and in particular no evidence was found for any IIIsugar phosphocarrier protein of the phosphoenolpyruvate: sugar phosphotransferase system (PTS). Incubation with [γ-32P]ATP showed that histidine-containing phosphocarrier protein (HPr) of the PTS could be phosphorylated to give both acid-stable and acid-labile phosphoamino acid residues. The acid-labile ATP-dependent phosphorylation activity was activated by glucose-6-P and appeared to produce a 3-P-histidinyl residue in HPr.
Isolation and characterization of rhizobiophages specific for Bradyrhizobium japonicum USDA 117
Authors: Hashem F. M. , Angle J. S. , Ristiano P. A.
Published: May 2010

The isolation and characterization of two phages specific for Bradyrhizobium japonicum USDA 117 are reported. The original phage was isolated from a Chester silt loam soil cropped to soybeans. A mutant of this isolate was obtained during long-term incubation in soil of the original isolate. Both phages were specific for B. japonicum USDA 117. The primary distinction between the two phages was the plaque size produced on the host. The original isolate produced plaques with a maximum size of 2.2 mm2. The mutant phage produced plaques with a maximum size of 11.4 mm2. Both phages exhibited similar morphologies. The head was hexagonal in shape with a diameter of 60 nm. An adsorption rate experiment revealed that the mutant phage was adsorbed faster to the host than the original isolate. Maximum adsorption of the original isolate to the host occurred after 10 min, while the mutant phage required 7 min. Characterization of the original isolate in a one-step growth experiment revealed that the burst size, rise period, and generation time were 100 plaque-forming units/cell, 12 min, and 80 min, respectively. A similar experiment for the mutant phage demonstrated a burst size, rise period, and generation time of 210 plaque-forming units/cell, 6 min, and 70 min, respectively. The ecological competitiveness of the mutant phage appeared to have been altered. In a greenhouse soil incubation experiment, the original isolate reduced nodule number, nodule weight, shoot weight, and acetylene reduction activity to a significantly greater extent than the mutant phage. These results indicate that, while the overall growth rate of the mutant phage was faster, it was less efficient in its parasitism of its host.