bluuebunny/crossref_metadata_2025 huggingface dataset:
A comparison of six methods for the concentration of a porcine enterovirus
Authors: Hazlett D. T. G.
Published: April 2010

Single-step concentration of porcine enterovirus strain T80 by adsorption to the polyelectrolyte PE60 gave virus concentration factors of 35- to 88-fold in terms of plaque-forming units, with recovery rates of 22 to 75% of total virus present in the original virus suspension. Concentration by separation in an aqueous polymer two-phase system gave virus concentration factors of 56- to 105-fold and recovery rates of 37 to 107%. In the latter procedure, sodium dextran sulfate appeared to have no effect on plaque numbers, although plaques were sharper and clearer when this substance was incorporated in the overlay. The failure of sonication of virus concentrated by either procedure to increase plaque numbers indicated the absence of virus aggregates in the concentrates. T80 virus was not effectively concentrated by cobalt chloride or polyethylene glycol precipitation or by adsorption to either aluminium hydroxide or calcium hydrogen phosphate.
Staphylococcus aureus and the microbial ecology of atopic dermatitis
Authors: Bibel D. J. , Greenberg J. H. , Cook J. L.
Published: April 2010

Two surveys were conducted to ascertain the effect which Staphylococcus aureus has on resident flora and on skin of patients with eczema. Forty paired sites, normal and lesions, were sampled from 32 patients with chronic lichenified atopic dermatitis, and, 162 sites covering the entire body of a patient with an acute flare of chronic atopic dermatitis were examined. In the first study, 34 lesions (85%) carried S. aureus, and 85% of these positive samples supported > 104 colony-forming units (CFU) of total aerobic bacteria/cm2. About 55% of normal sites carried S. aureus with 18% of such samples supporting > 104 CFU/cm2 total aerobic bacteria. Normal sites carried fewer but more diverse flora than lesions. The composition of flora on lesion sites was mainly S. aureus or S. epidermidis biotype 1, or both. At densities > 107 CFU/cm2, S. aureus constituted almost 100% of the total aerobic bacterial flora. The total body survey of the single eczema patient yielded similar results. Evidence supports the hypotheses that (1) S. aureus is able to exploit the environment of eczematous lesions and to influence the composition of cohabiting aerobic skin bacteria, and (2) its inhabitation of normal-appearing sites is transitory.
Reduced synthesis of β-galactosidase in Escherichia coli infected with phage ϕX174
Authors: Ghosh Amit , Poddar Ramendra K.
Published: April 2010

The synthesis of β-galactosidase (EC 3.2.1.23; β-D-galactoside galactohydrolase) in E. coli was repressed as a result of infection with single-stranded DNA phage [Formula: see text]. Evidence is presented to show that this repression was not due to the restricted entry of the inducer molecules into the infected cells but to some phage-specified product(s). It was further shown that either the infected cells synthesized a fewer number of enzyme-specific mRNA or all such molecules were translated with a reduced efficiency; the half-lives of the mRNA's remained more or less unaffected.
Mitogenic activity of Neisseria gonorrhoeae surface antigens in mouse splenic lymphocyte culture
Authors: Brodeur Bernard R. , Johnson Wendy M. , Diena Benito B. , Visentin Louis P. , Johnson Kenneth G.
Published: April 2010

The mitogenic effects of Neisseria gonorrhoeae endotoxin, fractionated envelope components, and intact cells were examined on unsensitized mouse splenic lymphocytes in vitro. The stimulatory effect of these substances was measured by increased [3H]thymidine incorporation in spleen cell cultures. Intact cells, purified lipopolysaccharide (LPS), and cell envelope preparations were highly stimulatory and the stimulation index was dose dependent. Fractionated components of the envelope demonstrated variable stimulation when tested at identical LPS concentrations, reflecting the mitogenic activity of the protein moieties. The stimulatory dose responses for purified N. gonorrhoeae and Escherichia coli LPS were compared and mitogenicity was higher with gonococcal LPS at all concentrations tested. Alkaline detoxification or succinylation of N. gonorrhoeae LPS results in loss of ability to induce blast transformation. The mitogenicity of cell-surface components of N. gonorrhoeae is discussed in terms of LPS and protein content.
Flow-microfluorometric analysis of Escherichia coli, Rhizobium meliloti, and Rhizobium japonicum at different stages of the growth cycle
Authors: Paau Alan S. , Cowles Joe R. , Oro James
Published: April 2010

The applicability of flow-microfluorometry (FMF) to the study of bacterial samples was investigated on cultures of Rhizobium meliloti, Rhizobium japonicum, and Escherichia coli using fluorescent and light-scattering signals. This technique which analyzes individual bacterial cells in a population was used to monitor the relative change in nucleic acid content and cell size during the growth cycle of the three microorganisms which were known to have different growth rates.Early log-phase E. coli cells contained at least eightfold more nucleic acid and were significantly larger than the stationary-phase cells. Cultures of early log-phase R. meliloti cells contained three to four-fold more nucleic acid and were slightly larger than cells in the stationary phase. Rhizobium japonicum had very little change in either parameter. In general, the amount of change in both cell size and nucleic acid content upon initiation of log-phase growth was related to the overall growth rate of the organisms, with E. coli experiencing the greatest change and R. japonicum the least. Results obtained by FMF analyses, therefore, were consistent with observations reported by earlier workers. Cultures of R. meliloti also were used to demonstrate that the intensity of the fluorescent signals was sensitive to digestion by DNase and RNase and to prolonged storage and fixation. The potential use of FMF in the study of microorganisms is discussed.
The relationship between conidiation and alkaloid production in saprophytic strains of Claviceps purpurea
Authors: Pažoutová S. , Pokorný V. , ↠eháček Z.
Published: April 2010

A direct relationship between alkaloid synthesis and conidia formation was observed in a series of mutants of the saprophytic fungus Claviceps purpurea 129 which produces high quantities of clavine alkaloids (4500 μg∙ml−1). Sclerotia-like mutants forming mostly arthrospores and only a low number of conidiospores were exceptional in that they were characterized by an inverse relationship between alkaloid synthesis and conidial formation. Conidiospores of the parent strain 129 differed both in their size and ultrastructure. They included oval microconidia (2 × 3.5 μm) and prolonged macroconidia (2 × 10.5 μm). Both conidial types originated on short lateral sporophores terminated by phialids. Most conidia were characterized by electron-dense cytoplasm with a number of lipidic inclusions; a minority of conidia contained granular cytoplasm and vacuoles with membrane invaginations. Bicellular conidia were only rarely observed.
Citric acid cycle enzymes and nitrogenase in nodules of Pisum sativum
Authors: Kurz W. G. W. , LaRue T. A.
Published: April 2010

Activity of isocitric dehydrogenase (isocitrate dehydrogenase (NADP+); EC 1.1.1.42) in bacterids is highest at the time of maximum nitrogen fixation. It is likely that isocitric dehydrogenase is the source of reductant fordinitrogen fixation.
Phosphofructokinase and glucose catabolism of Mucor and Penicillium species
Authors: Boonsaeng V. , Sullivan P. A. , Shepherd M. G.
Published: April 2010

The primary catabolic pathways in the fungi Penicillium notation and P. duponti, and Mucor rouxii and M. miehei were examined by measuring the relative rate of 14CO2 production from different carbon atoms of specifically labelled glucose. It was found that these organisms dissimilate glucose predominantly via the Embden–Meyerhof pathway in conjunction with the tricarboxylic acid cycle and to a lesser extent by the pentose phosphate pathway.Phosphofructokinase (EC 2.7.1.11) activity could not be detected initially in Penicillium species because of the interference from mannitol-1-phosphate dehydrogenase (EC 1.1.1.17) and N ADH oxidase (EC 1.6.99.3). A combination of differential centrifuging and a heat treatment of Penicillium cell-free extracts in the presence of fructose-6-phosphate removed the interfering enzymes.The kinetic characteristics of phosphofructokinase from P. notatum and M. rouxii are described. The enzyme presents highly cooperative kinetics for fructose-6-phosphate. The kinetics for ATP show no cooperativity and inhibition by excess ATP is observed. The addition of AMP activated the P. notatum enzyme, relieving ATP inhibition; slight inhibition by AMP was observed with the M. rouxii enzyme. In contrast M. rouxii pyruvate kinase (EC 2.7.1.40) is activated 50-fold by fructose-1,6-diphosphate whereas pyruvate kinase from P. notatum and P. duponti were unaffected by fructose-1,6-diphosphate.
Contrasting effects of rabbit and human platelets on chikungunya virus infectivity
Authors: Chernesky M. A. , Larke R. P. B.
Published: April 2010

Chikungunya virus infectivity was markedly stabilized in the presence of washed suspensions of human platelets but rapidly disappeared in similar preparations of rabbit platelets. Supernatant fluids collected from human platelets had some stabilizing effect on chikungunya virus over a 6-day incubation period at 37 °C. Rabbit platelet supernatant fluid had no virus-stabilizing effect, nor did it demonstrate any capacity to inactivate virus as compared to whole rabbit platelet preparations. Thin-section electron microscopy demonstrated that chikungunya virus formed an association with human platelets by becoming entrapped in platelet aggregates; during this process some of the platelets appeared to have undergone degranulation and lysis. Rabbit platelets exposed to chikungunya virus for 24 h demonstrated a considerable amount of platelet degranulation and lysis but virus was not visualized eitherin association with platelet membranes or within phagocytic vacuoles in the platelet cytoplasm. Human platelets, which appear to be more stable under these incubation conditions, may protect chikungunya virus infectivity from heat inactivation by surrounding viruses with large platelet aggregates whereas rabbit platelets, which appear to be more fragile, do not afford this type of protection. Thus, chikungunya virus in the presence of rabbit platelets may become inactivated by heat or may become bound irreversibly to membranes in such a fashion that infectivity assay and electron microscopy techniques may prove to be too insensitive for detection of virus.
Antimicrobial resistance and resistance plasmids in Salmonella from Ontario, Canada
Authors: Grant Robert B. , Mambro Libero Di
Published: April 2010

Collections of 589 human and 204 animal strains of Salmonella isolated in Ontario during the summer of 1974 were examined for susceptibility to 12 antimicrobial agents. Many isolates were found to be resistant to both chloramphenicol (12.4% of the human and 38.2% of the animal sample) and ampicillin. The chloramphenicol resistance almost always occurred in strains which were also resistant to ampicillin and was usually due to a self-transmissible plasmid with a resistance pattern of CmKmSmTc (chloramphenicol, kanamycin, streptomycin, and tetracycline) or CmTc. Ampicillin resistance in these strains was mediated by a variety of plasmids with patterns ApSu (ampicillin and sulfa drugs) and ApSmSu, many of which were nonself-transmissible. Ampicillin resistance in chloramphenicol-sensitive strains was transferable from 21% of the strains, and it was associated with resistance patterns which were different from the self-transferable ampicillin patterns from the chloramphenicol-resistance strains.
The role of 6-phosphogluconate dehydrogenase in Rhizobium
Authors: Mulongoy Kalemani , Elkan Gerald H.
Published: April 2010

A nicotinamide adenine dinucleotide (NAD) linked 6-phosphogluconate (6-PG) dehydrogenase has been detected in Rhizobium. The enzyme activity is similar in both slow- and fast-growing rhizobia. The nicotinamide adenine dinucleotide phosphate (NADP) dependent 6-PG dehydrogenase was detected only in the fast growers and was more than twice as active as the NAD-linked enzyme. Partial characterization of the products of 6-PG oxidation in Rhizobium suggests that the NADP-linked enzyme is the decarboxylating enzyme of the pentose phosphate (PP) pathway (EC 1.1.1.44) whereas a phosphorylated six-carbon compound, containing ketonic group(s), is the product of the oxidation catalyzed by the NAD-linked enzyme.
Virus detection on grapes
Authors: Konowalchuk Jack , Speirs Joan I.
Published: April 2010

Grapes inoculated with poliovirus 1 and coxsackievirus B5 were washed with water, 0.5% polyethylene glycol, or phosphate-buffered saline with 1% serum. These washes were equally efficient at removing virus but much of the virus in the water wash was noninfectious until treated with 0.5% polyethylene glycol.
Effect of exogenous nucleotides on the candicidin fermentation
Authors: Martin Juan F. , Demain Arnold L.
Published: April 2010

Addition of cyclic-AMP (c-AMP) to Streptomyces griseus fermentations inhibited candicidin formation. In a phosphate-free resting cell system, c-AMP inhibited net candicidin formation and incorporation of labeled propionate and p-aminobenzoic acid into the antibiotic but did not inhibit protein synthesis. All nucleotides tested, regardless of the position of the phosphate ester, were effective inhibitors; nucleosides and free bases were not. Inhibition occurred whether the nucleotide was added early or late. The results indicate that inhibition of antibiotic formation by exogenous nucleotides, including cyclic nucleotides, is similar to the effect produced by inorganic phosphate.
The effect of different nitrogen sources on pigment production and sporulation of Monascus species in submerged, shaken culture
Authors: Carels Mariette , Shepherd David
Published: April 2010

Thirty-nine strains from the genus Monascus were cultivated aerobically to study the relation between nitrogen nutrition and sporulation and pigment production. The effects of yeast extract, nitrate, ammonium, and ammonium nitrate have been compared. During cultivation the pHs of the different media are not the same, resulting in the formation of different coloured pigments. When the source of nitrogen is yeast extract or nitrate the pH is around 6.5 and red pigments are formed, whereas with ammonium or ammonium nitrate the pH is around 2.5 and the pigments are orange. It is proposed that only the orange pigments, monascorubrin and rubropunctatin, are produced biosynthetically and that the other pigments are formed from these by chemical transformations depending on the cultural conditions. The presence of organic nitrogen is optimal for growth and unfavourable for pigment production. Reduced growth and best pigment formation occurs with the three other nitrogen sources. Nitrate stimulates conidiation and sexual reproduction, while ammonium is inhibitory. Pigment production is better when conidiation is reduced. A mechanism is proposed for the control of sporulation and pigment production.
Isolation and characterization of catabolite repression-resistant mutants of Escherichia coli
Authors: Armstrong Glen D. , Yamazaki Hiroshi
Published: April 2010

A method has been developed for the isolation of Escherichia coli mutants which are resistant to catabolite repression. The method is based on the fact that a mixture of glucose and gluconate inhibits the development of chemotactic motility in the wild type, but not in the mutants. A motile E. coli strain was mutagenized and grown in glucose and gluconate. Mutants which were able to swim into a tube containing a chemotactic attractant (aspartic acid) were isolated. Most of these mutants were able to produce β-galactosidase in the presence of glucose and gluconate and were normal in their ability to degrade adenosine 3′,5′-cyclic monophosphate. Some of these mutants were defective in the glucose phosphotransferase system.
Uptake and efflux of adenine and its derivatives in Neurospora crassa
Authors: Pendyala Lakshmi , Wellman Angela M.
Published: April 2010

Conidia of wild-type Neurospora crassa, preincubated for 3½ h in growth medium, showed a typical triphasic pattern of adenine uptake. The three phases consisted of a quick initial uptake, followed by a plateau phase, and then by a resumed lowered uptake. A study of the relative influx and efflux of [14C]adenine showed that the plateau phase in fact is a period of transmembrane movement of adenine and adenine metabolites. The efflux during the plateau phase essentially cancelled out all the influx during the same period. The uptake curve derived after taking into account the effiuxed portion of radioactivity indicated that the second phase represents a period of lowered uptake activity. The beginning of the lowered uptake activity during the second phase is correlated with the presence of a high intracellular level of ATP derived from exogenous [14C]adenine. At the end of the second phase, the intracellular level of ATP is much smallerand the rate of adenine uptake increases again. Analysis of the acid-soluble pool after feeding [14C]adenine indicated the presence of other 14C-nucleotides, but no detectable levels of bases and nucleosides were present. However, chromatographic analysis of the medium indicated that efflux results essentially in the accumulation of bases. The significance of this finding in relation to efflux is discussed.
Physiological control of alkylsulfatase synthesis in Pseudomonas aeruginosa: effects of glucose, glucose analogs, and sulfur
Authors: Fitzgerald J. W. , Kight Lynda C.
Published: April 2010

Pseudomonas aeruginosa (isolated from soil) synthesizes an alkylsulfatase allowing this bacterium to utilize sodium hexan-1-yl sulfate as a source of carbon and sulfur for growth. The formation of the enzyme was induced by this and by other (C4–C16) primary alkylsulfate esters as well as by some (C-8 and C-9) primary alkylsulfonates. Secondary (2-yl) alkylsulfate esters did not act as inducers. The induction of alkylsulfatase was markedly inhibited by L-cysteine, L-methionine, sodium sulfide, and by high (>2 mM) concentrations of D-glucose and other related monosaccharides. Similar inhibitory effects by four glucose analogs which will not support growth suggest that prior metabolism was not a requirement for glucose-mediated inhibition. The inhibition by D-glucose of the same inducible system in P. aeruginosa (PAO-57) supported this conclusion since this glucose transport-positive mutant is deficient in the further metabolism of the monosaccharide. At low (0.1–1.0 mM) concentrations, D-glucose or D-glucose 6-O-phosphate (20 mM) caused a marked enhancement of alkylsulfatase induction in the isolate. This novel enhancement was reproduced using P. aeruginosa strain PAO. However, both monosaccharides acted as potent inhibitors of alkylsulfatase formation occurring in mutant PAO-57 which, unlike the parent strain PAO, exhibits low glucose-6-phosphate dehydrogenase activity. These results suggest that D-glucose (0.1–1.0 mM) must be metabolized to enhance the synthesis of the enzyme.
Complex medium toxicity to some DNA repair-deficient strains of Salmonella typhimurium
Authors: Amsden A. B. , Small D. K. , Gomez R. F.
Published: April 2010

The recovery of several strains of Salmonella typhimurium LT-2 which had first been grown in minimal medium varies when the organisms are grown on minimal medium agar and complex medium agar. The strains tested included mutants with deficiencies in DNA-repair systems (uvrB− and rec−), a deep rough (rfa−) mutant, and a double mutant carrying both the uvrB− and the rfa− mutations. The uvrB− and rec− mutations imparted sensitivity to complex medium agar. The rfa− mutation suppressed the sensitivity of the uvrB− mutant to complex medium agar. Differences in colony-forming ability were not observed when the bacteria were first grown in the complex medium broth.
A light and electron microscope study of the interaction of soil bacteria with Phytophthora cinnamomi Rands
Authors: Malajczuk N. , Nesbitt H. J. , Glenn A. R.
Published: April 2010

Light- and electron-microscopic examination showed that bacteria became associated with the hyphae and asexual reproductive structures of P. cinnamomi in soil. In suppressive soils this association appears to be correlated with hyphal lysis, inhibition of zoospore production, and sporangial breakdown. One notable feature of the microbial association between P. cinnamomi and soil bacteria is the formation of extensive slime material. Many of the bacteria isolated from the fungal hyphosphere display antagonism to the growth of P. cinnamomi in vitro. The bacteria are morphologically varied and include Pseudomonas, Bacillus, and Streptomyces spp. These observations suggest that the appropriate manipulation of the antagonistic bacteria may provide a means of biological control of P. cinnamomi.
Leptospira interrogans serotype pomona in Saskatchewan: isolation from a naturally infected striped skunk
Authors: Carpio Manuel , Wobeser Gary , Iversen John
Published: April 2010

Leptospira interrogans serotype pomona was isolated from the kidneys of a normal striped skunk (Mephitis mephitis hudsonicus) collected near Kindersley, Saskatchewan. Although there were no gross lesions, small foci of chronic interstitial nephritis were observed microscopically. This is the first reported isolation of serotype pomona for the prairie provinces.
Ultrastructure of Nocardia-like variants of Mycobacterium smegmatis and chemical composition of the basal cell wall layer
Authors: Hawley R. J. , Mann Nora , Imaeda T.
Published: April 2010

Mycobacterium smegmatis, its orange-red – pigmented (OR) variants, and back mutant strains were examined by electron microscopy using ultrathin sectioning, negative or positive staining, and freeze-fracture – etching methods. The parental and back mutant strains showed almost identical ultrastructures. Specifically, thick ramified fibers measuring about 15 nm in diameter were always visible in the positively stained cell wall, although they were not readily visualized with negative staining or freeze-fracture-etching. In contrast, the cell walls of OR variants contained fibrous networks measuring about 11 nm in diameter, which could be observed by positive and negative staining as well as freeze-fracture-etching. Although cytoplasmic structures appeared similar among the four strains examined, mesosomes were significantly more abundant in the OR variants. The basal layer of the cell wall obtained as a phenol residue consisted of a dense membranous matrix containing scattered fibrous structures in the parental and back mutant strains, and fibrous networks in the OR variants. Chemical analyses showed that the basal layers of all four strains contained the same neutral sugars, amino sugars, and amino acids, i.e., arabinose, galactose, muramic acid, glucosamine, alanine, glutamic acid, and diaminopimelic acid. The α-branched β-hydroxylated fatty acids contained in the basal layers differ among the four strains, however, with nocardomycolic acids being present in the OR variants and mycolic acids in the parental and back mutant strains. Our previous conclusion that OR variants of M. smegmatis have characteristics similar to those of nocardia is supported by the present study.
Microscopic examination of natural sessile bacterial populations from an alpine stream
Authors: Geesey G. G. , Richardson W. T. , Yeomans H. G. , Irvin R. T. , Costerton J. W.
Published: April 2010

Natural populations of bacteria associated with the slime on submerged surfaces in a mountain stream were examined by phase-contrast and electron microscopy. The slime contained large numbers of bacteria which were predominantly gram-negative as determined by their cell wall structure. Examination of the in situ distribution of cells revealed that they were enmeshed in an extensive fibrous matrix whose component fibrils were stained with ruthenium red. The arrangement of slime fibrils immediately around individual bacterial cells suggested that this material was produced by these bacteria. This slime facilitated microcolony development and also anchored the bacteria to a particular surface. It is proposed that these slime-enmeshed microcolonies constitute functional communities within which most sessile bacteria live.
Infection of inbred strains of mice with Sendai virus
Authors: Stewart Robert B. , Tucker M. Jane
Published: April 2010

A comparative study of the consequences of Parainfluenza type 1 (Sendai) virus infection in inbred (C57B1/6J, C57Br, CBA, DBA) strains and a randomly bred (Swiss white) strain of mice showed significant mortality in the inbred strains but not in the randomly bred ones. This difference may be partly related to the high levels of virus growth obtained in the lungs of the inbred strains contrasted to little or no virus growth in the lungs of the Swiss white mice. A similar difference between these mice was found in the incidence of virus involvement of a variety of mouse tissues. These differences in mortality and in vivo growth of virus were not clearly mimicked in antiviral-antibody production in these different mouse populations.
Typing of fluorescent phytopathogenic pseudomonads by bacteriocin production
Authors: Vidaver Anne K. , Buckner Shareen
Published: April 2010

Several phytopathogenic fluorescent Pseudomonas species, primarily P. syringae, could be grouped into 16 bacteriocin producer groups, including new and previously described groups. At least 86% of the P. syringae strains could be typed by bacteriocin production. There was poor correlation between bacteriocin type and host plant origin. No correlation was detected between syringomycin (a phytotoxin) production and bacteriocin type.
Morphogenetic expression of Arthrobacter globiformis 425 in continuous culture with carbon or biotin limitation
Authors: Wills Adrian P. , Chan E. C. S.
Published: April 2010

When deprived of biotin, Arthrobacter globiformis 425 exhibits abnormal morphology (large, branched forms of variable size) and a retardation of its normal growth rate. In chemostat cultures, when cells were grown under glucose limitation, the morphology was normal (coccoids or rods) at specific growth rates between 0.05 and 0.125 h−1 (doubling times between 14 and 5.5 h, respectively) at 25 °C. The coccoid-to-rod morphogenesis occurs at a specific growth rate of 0.11 h−1. At the same specific growth rates and temperature, but under biotin limitation, abnormal morphology was observed.
Survival and reversion of a stable L form in soil
Authors: Horwitz A. H. , Casida Jr. L. E.
Published: April 2010

The stable L form of Agromyces ramosus reverted to a bacterial form when incubated in sterilized soil. The cellular and colonial morphology of this bacterial form resembled that of the original parent bacterial form. The two forms differed, however, in that the revertant maintained its bacterial form when transferred onto a low-salt (NaCl) medium but was virtually completely induced into the L-form state on a high-salt medium. The original parent bacterial form was not sensitive to salt. The possibility is discussed that an L-form ↔ bacterial-form cycle for this bacterium might occur naturally in soil. This cycle would be mediated by fluctuations in local salt concentrations in the soil.
Lipid body content and persistence of chlamydospores of Fusarium solani in soil
Authors: Eck W. H. van
Published: April 2010

Chlamydospores of Fusarium solani f. sp. pisi, low or high in lipid content, were produced in soil from "low and high reserve" macroconidia, respectively. The development of "low and high reserve" populations of macroconidia and chlamydospores in soil was studied. The rate of conversion of macroconidia into chlamydospores is influenced by the lipid content of the macroconidia. The long-term persistence of chlamydospores in soil seems to be independent of the lipid content of the chlamydospore cells.
Phosphate metabolism in blue-green bacteria. V. Factors affecting phosphate uptake in Plectonema boryanum
Authors: Sicko-Goad Linda , Jensen Thomas E. , Ayala Robert P.
Published: April 2010

Plectonema boryanum requires approximately 5 days of exposure to a culture medium lacking phosphorus to induce the "polyphosphate overplus" phenomenon. At pH 9, phosphate uptake is greatest both from normal culture medium and from dilute salt solutions. Phosphate uptake from dilute salt solutions was greatest when Na+ or K+ are combined with Ca2+ or Ca2+ and Mg2+. Cells starved of phosphorus in the presence of a high concentration of K+ or Ca2+ in the medium, and then allowed to take up phosphorus under the same conditions, assimilate more phosphorus than with other major ions.
Diminution de l'activité antibactérienne d'antibiotiques dans des cultures et des infections expérimentales mixtes
Authors: Lebrun M. , Repentigny J. de , Mathieu L. G.
Published: April 2010

We have studied interactions between Staphylococcus aureus and Pseudomonas aeruginosa in the absence and the presence of four different antimicrobials in mixed cultures and experimental infections. These two bacterial species, in addition to having different properties, are known to be opportunistic pathogens often present in human microflora.Two main aspects have been investigated and they are related to modifications in two species affecting their equilibrium in the mixed bacterial population and also their pathogenicity markers.Our results indicate that individual growth of S. aureus and P. aeruginosa is not modified in vitro in mixed cultures in the absence of antimicrobials; in vivo, in mouse peritoneal cavity, there is a synergism favorable to S. aureus.In the presence of rifamycin SV and three cell wall inhibitors, penicillin G, D-cycloserine, and vancomycin, we have observed that P. aeruginosa protected S. aureus against the inhibitory effect of these antimicrobials in vitro and in vivo. Such results were obtained in different conditions of culture, stationary, shaken, and in special apparatuses, an "Ecologen" and a "Chemostat."When any one of the antimicrobials was allowed to be in contact for 6 to 8 h with P. aeruginosa cells in a culture, we observed a decrease in their inhibitory effects against S. aureus. These results were supported by microscopical observation.It seems that the inhibitory effects of the antimicrobials have hindered the formation of toxic products of S. aureus, e.g., alpha toxin, and that it was not restored in the presence of P. aeruginosa.Conversely, P. aeruginosa remained apparently unchanged through all these experiments. Our observations may imply that the inhibitory effect of an antimicrobial towards a bacterial species may be significantly decreased in the presence of another species, sometimes present in human microflora.
Protein–lipopolysaccharide interactions. 1. The reaction of lysozyme with Pseudomonas aeruginosa LPS
Authors: Day D. F. , Marceau-Day M. L. , Ingram J. M.
Published: April 2010

Lysozyme (EC 3.2.1.17) complexes with extracted Pseudomonas aeruginosa LPS in two distinct stages. The initial stage does not produce turbidity detectable by nephelometry (measured as nephelos units (N) per time) but does permit low-speed sedimentation of the lysozyme–lipopolysaccharide (LPS) complex. This association is 100% disrupted by the action of 0.1 M Mg2+. Monovalent cations at equal ionic strength to the Mg2+ concentration used for these studies failed to alter significantly the lysozyme–LPS complex, indicating that the role of Mg2+ was not strictly an ionic one. The study of lysozyme–LPS complexes may provide a model system for investigating in vivo protein–LPS interactions.
Transformation of Azotobacter vinelandii strains unable to fix nitrogen with Rhizobium spp. DNA
Authors: Page William J.
Published: April 2010

The phenotypes of Azotobacter vinelandii ATCC 12837 strains defective in nitrogen fixation (Nif−) were characterized by intrageneric transformation with known Nif− strains of A. vinelandii OP. These former mutant strains were used as recipients for intergeneric transformation by deoxyribonucleic acid (DNA) prepared from Rhizobium spp. to determine if the rhizobia would transform the Azotobacter Nif− phenotypes to Nif+. The frequency of Nif+ transformants using Rhizobium DNA was always less than the frequency using Azotobacter wild-type DNA but was greater than the spontaneous reversion frequency. The Azotobacter Nif+ recombinants also were stable. DNA from all of the Rhizobium spp. transformed to Nif+Azotobacter mutants defective in the nitrogenase component I (molybdoferredoxin); however, some recombinants had a lower nitrogenase activity and a delayed nitrogenase depression time. Mutants defective in the pleiotrophic transcriptional control of both nitrogenase components were transformed to Nif+ by the asymbiotic nitrogen fixing Rhizobium sp. 32H1 and 41A1, but not the symbiotic nitrogen-fixing species. The significance of these results and the possible future applications of this system are discussed.
Purification and some properties of the citrate synthase from a marine Pseudomonas
Authors: Higa Azucena I. , Massarini Esther , Cazzulo Juan José
Published: April 2010

Citrate synthase (citrate-oxaloacetate lyase (CoA acetylating), EC 4.1.3.7) has been purified to electrophoretic homogeneity from a marine Pseudomonas. The enzyme was made up of identical subunits, with a molecular weight of about 53 000, as determined by sodium dodecyl sulphate – polyacrylamide gel electrophoresis. The native enzyme (citrate synthase II, CS II) could be dissociated by dialysis against 20 mM phosphate (Pi), pH 7; the enzyme thus obtained (citrate synthase I, CS I) was still active, but presented different molecular weight and kinetic and regulatory properties.CS II was activated by adenosine monophosphate (AMP), Pi, and KCl, and inhibited by reduced nicotinamide adenine dinucleotide (NADH), being apparently insensitive to adenosine triphosphate (ATP) and adenosine diphosphate (ADP). The inhibition by NADH was completely counteracted by 0.1 mM AMP, but not by 50 mM Pi or 0.1 M KCl. The activation by KCl and Pi, or by KCl and AMP was nearly additive, whereas that by AMP and Pi, was not. The activators acted essentially by increasing Vmax, although they also caused a decrease in the Km values.CS I was inhibited by ATP, ADP, AMP, and KCl, and was insensitive to NADH.CS I could be reassociated after elimination of Pi by dialysis, regaining the higher molecular weight and the activation by AMP characteristic of CS II.
Genetic fate of DNA in a strain of Bacillus subtilis which is impaired in genetic transformation
Authors: Devanathan T. , Iyer V. N.
Published: April 2010

A mutation in Bacillus subtilis called recC4 which results in an impairment of genetic transformation was transferred to a new strain using the closely linked marker mit-2 (mitomycin C-resistance) for selection. This derived strain was in turn impaired in transformation but showed normal levels of sensitivity to ultraviolet irradiation and methyl methane sulfonate. The genetic and molecular fate of transforming DNA in the recC4 strain was studied. Normal amounts of DNA were taken up by the cells and this DNA or parts of it became associated with recipient DNA. Linkage between genes on donor and recipient molecules was, however, not established and transformants were not generated. The recC4 mutation therefore affects a step in the recombination pathway during transformation. Either the association between donor and recipient DNA molecules is abnormal or the cells are deficient in the further processing of the associated complex.
Ultrastructural and chemical distinction of melanins formed by Verticillium dahliae from (+)-scytalone, 1,8-dihydroxynaphthalene, catechol, and L-3,4-dihydroxyphenylalanine
Authors: Wheeler M. H. , Tolmsoff W. J. , Bell A. A. , Mollenhauer H. H.
Published: April 2010

Microsclerotia of three melanin-deficient mutants of Verticillium dahliae formed melanin from (+)-scytalone, 1,8-dihydroxynaphthalene, catechol, and L-3.4-dihydroxyphenylalanine. The melanins formed from (+)-scytalone or 1,8-dihydroxynaphthalene resembled wild-type melanin chemically and ultrastructurally, whereas the melanins formed from catechol and L-3,4-dihydroxyphenylalanine were different. This suggests that scytalone and 1,8-dihydroxynaphthalene but not catechol or L-3,4-dihydroxyphenylalanine are natural intermediates of melanin biosynthesis in V. dahliae.
Free proline content and sensitivity to desiccation and heat during yeast sporulation and spore germination
Authors: Ho K. H. , Miller J. J.
Published: April 2010

Ascospores of a strain of Saceharomyces cerevisiae Hansen were less sensitive to desiccation and heat than vegetative cells. Desiccation resistance was acquired earlier during sporulation and lost later during spore germination than heat resistance. As spores matured, resistance to both stresses increased. With the exception of the first few hours in sporulation medium, when proline appeared to be utilized, the intracellular free proline content increased during sporulation and decreased during spore germination. Not all the proline lost could be detected in the germination medium, indicating that some was metabolically utilized by the germinating spores. Since exogenous proline supplied to vegetative or sporulating cells before desiccation increased their survival, it is suggested that the high level of free proline in mature spores may protect against desiccation stress.
Breakdown of psyllium hydrocolloid by strains of Bacteroides ovatus from the human intestinal tract
Authors: Salyers Abigail A. , Harris Charlotte J. , Wilkins Tracy D.
Published: April 2010

Strains of Bacteroides ovatus from human feces produced extracellular enzymes which degraded psyllium hydrocolloid. Other species of saccharolytic bacteria which are found in high concentrations in human feces did not degrade psyllium.
Effects of growth temperature on protoplast membrane properties in Bacillus megaterium
Authors: Eisenberg A. D. , Corner T. R.
Published: April 2010

Changes in the protoplast membrane of the KM strain of Bacillus megaterium were assessed after growth at 20, 30, or 37 °C. Although the overall membrane concentrations of lipids and proteins were virtually unchanged, increased culture temperature resulted in cells with membranes that contained relatively more unbranched and long-chain fatty acids and more acidic phospholipids, as well as different proportions and numbers of individual proteins. Electrophoretic analyses revealed 23, 31, or 29 protein bands, respectively, in membranes from cells grown at the three temperatures. Protoplasts from cells grown at higher temperatures were considerably less susceptible to lysis by shearing forces. As judged by passive leakage at 30 °C, intact cells from cultures grown at 37 °C were the least permeable to erythritol. Relatively low ambient concentrations of Ca2+ or Mg2+ protected protoplasts from osmotic lysis but even much higher concentrations left erythritol leakage virtually unaffected. Thus, growth temperature affected not only membrane lipids but also membrane proteins and these changes resulted in membranes with altered mechanical properties and permeabilities.
Characteristics of Streptomyces coelicolor A3(2) aerial spore rodlet mosaic
Authors: Smucker Richard A. , Pfister Robert M.
Published: April 2010

Cytochemical analysis of Streptomyces coelicolor A3(2) indicated that the aerial growth rodlet mosaic is a polysaccharide. Statistical analysis of frequency distributions of individual rodlet lengths from control and ether-reoriented spore mosaics indicated that the rodlet fibrillar image is the result of individual particulates, rather than evaginations in a continuous sheet of material. A model of the mature spore envelope was developed from freeze-etch-replicated, thin-sectioned, and critical point dried S. coelicolor A3(2) mature spores. The rodlet mosaic was situated between the outer spore wall and an external granular matrix. Mature spore envelope layers from the inner surface to the external surface are plasma membrane, inner spore wall, outer spore wall, rodlet mosaic, an undefined granular matrix, and the sheath. The granular matrix had an uneven thickness and much of the matrix was frequently absent from the interspore spaces of mature spore chains. Streptomyces coelicolor A3(2) mosaic rodlets were isolated by acetic acid refluxing, then ethanol precipitation. Complete acid hydrolysis of rodlets released one sugar which cochromatographed with D-glucosamine-HCl and released acetic acid at 139% of the expected level. Cell-associated rodlet mosaics and isolated mosaic rodlets were hydrolyzed with chitinase. Infrared spectra of isolated rodlets were similar to crab chitin spectra.
An alkaline phosphatase mutant of Pseudomonas aeruginosa. 1. Effects of regulatory, structural, and environmental shifts on enzyme function
Authors: Marceau-Day M. L. , Day D. F , Ingram J. M.
Published: April 2010

An alkaline phosphatase mutant of Pseudomonas aeruginosa exhibiting both regulatory and catalytic changes was isolated. Under repression conditions (i.e. high inorganic phosphate (Pi)) the mutant culture produced an alkaline phosphatase (APase) displaying significant activity against both β-glycerol phosphate (βGP) and p-nitrophenyl phosphate (pNPP), while the wild type displayed no activity directed towards these substrates under the same conditions. In vivo, the mutant enzyme's ratio of specific activities was 45:1 in favour of βGP versus pNPP, whereas this ratio was reversed to 1:9 βGP versus pNPP for the same enzyme isolated from mutant cells. In addition, the kinetic parameters and stability requirements for the mutant-derived enzyme was altered in comparison with those of the wild type. A study of lipopolysaccharide(LPS) preparations from both the mutant and wild type indicated the mutant to be deficient in the core region of its LPS. The authors propose that the modifications in the catalytic activity of the mutant enzyme, demonstrated in vivo, are due to a change in the enzyme's microenvironment.
Torulopsis pampelonensis sp. nov. A new species of yeast isolated from beech forest soil
Authors: Ramirez C. , Martinez A. T.
Published: April 2010

A new yeast species, Torulopsis pampelonensis is described. Six strains were recovered from a gleyic Andosol under a beech forest and two other strains from the surface of fallen leaves of Fagus silvatica L. Although it showed some morphological and physiological similarities with Torulopsis tannotolerans Jacob and Torulopsis navarrensis Ramírez and Moriyón, it differed from all Torulopsis species presently known.
RNA and protein synthetic patterns during germination of Polysphondylium pallidum microcysts
Authors: Gwynne David I. , O'Day Danton H.
Published: April 2010

During microcyst germination in the cellular slime mould Polysphondylium pallidum, an immediate rapid increase in the rate of protein synthesis ([3H]leucine incorporation) is observed within 15 min after the initiation of germination. The data, corrected for amino acid pool changes, reveal that the rate of protein synthesis reaches its peak at [Formula: see text], after which it decreases. A low level of RNA synthesis ([3H]uridine incorporation) is observed after 1 h and this rate increases markedly after 2 h. Analysis of the RNA species shows a low level of synthesis of all ribosomal RNA's which begins between 1 and 2 h and increases after 2 h. The synthesis of a heterogeneously distributed, poly(A)-containingfraction of RNA (presumptive mRNA) is initiated some time after 2 h and the synthesis of a small molecular weight species in the 4–5S region is observed after 3 h. Thus, it seems that Polysphondylium microcysts show sequentially initiated synthesis of RNA during germination.
Biologic properties of bacterial lipopolysaccharides treated with chromium chloride
Authors: Snyder Stephen L. , Walker Richard I. , MacVittie Thomas J. , Sheil James M.
Published: April 2010

Addition of small amounts of chromium chloride to a saline suspension of Salmonella typhosa lipopolysaccharide (LPS; Difco) caused a marked reduction in several of the biologic activities of this substance including toxicity, B-cell mitogenicity, plasma colony-stimulating activity (CSA), radioprotective effect, and induction of the dermal Shwartzman reaction. Nevertheless, LPS treated with chromium chloride was found to be at least as effective as untreated LPS in enhancing resistance of B6CBF1 mice to the lethal effects of Klebsiella pneumoniae infection.
A rapid radiometric technique used to trap and quantitate 14CO2 evolved by slow-growing microorganisms
Authors: Moser S. A. , Pollack J. D.
Published: April 2010

An apparatus to trap and quantitate 14CO2 is described. When used to measure antibiotic effects on Histoplasma capsulatum and Mycobacterium bovis (BCG), there was an inverse quantitative relationship between 14CO2 evolved and antibiotic concentration. The technique should prove useful for analyses that require trapping and quantitation of 14CO2, including antimicrobial sensitivities of slow-growing organisms.
The dependence of Escherichia coli asparaginase II formation on cyclic AMP and cyclic AMP receptor protein
Authors: Russell La Verne , Yamazaki Hiroshi
Published: April 2010

The amount of asparaginase II in an Escherichia coli wild-type strain (cya+, crp+) markedly increased upon a shift from aerobic to anaerobic growth. However, no such increase occurred in a mutant (cya) lacking cyclic AMP synthesis unless supplemented with exogenous cyclic AMP. Since a mutant (crp) deficient in cyclic AMP receptor protein also did not support the anaerobic formation of this enzyme, it is concluded that the formation of E. coli asparaginase II depends on both cyclic AMP and cyclic AMP receptor protein.
A general method for the lysis of Streptomyces species
Authors: Huber M. L. B. , Godfrey O.
Published: April 2010

A procedure for the gentle lysis of Streptomyces is described. Complete lysis is obtained and covalently closed circular (CCC) DNA remains intact. This procedure was successfully used to lyse 14 different species of Streptomyces.
Utilization of oleuropein by microorganisms associated with olive fermentations
Authors: Garrido-Fernandez Antonio , Vaughn Reese H.
Published: April 2010

Oleuropein, the bitter glucoside of olives, and its hydrolysis products can possess antibacterial action. However, there is no information on the possible utilization of this polyphenolic compound; therefore studies have been made to assess its utilization as a major source of carbon, Various microorganisms associated with fermentation of olives (both desirable lactic acid bacteria and spoilage organisms) did use oleuropein, many without a significant delay in growth resulting in the appearance of a strong visible turbidity. Although the increase in oleuropein from 0.2 to 0.4% (w/v) had little or no effect on the spoilage organisms, the additional glucoside caused a delay in development of growth with some of the lactic acid bacteria. However, all of the latter cultures tested eventually grew and developed strong visible turbidity.
Interaction between Rhizobium japonicum phage M-1 and its receptor
Authors: Dandekar A. M. , Modi V. V.
Published: April 2010

The receptor for phage M-1 was present in the exopolysaccharide (EPS) of Rhizobium japonicum D211. The EPS was a heteropolysaccharide consisting of glucose, galactose, glucuronic acid, and glucosamine units. These monosaccharides prevented phage–cell attachment indicating that they may mimick the receptor. Phage–cell attachment was either stimulated or inhibited by Mg2+ and Ca2+ depending upon their concentration.An enzyme which depolymerized the exopolysaccharide releasing oligosaccharides was detected in the phage-infected cell lysates. A comparison of the properties of adsorption and those of the depolymerase enzyme indicated that the latter was a component of the phage and appeared to be involved in the phage–receptor interaction.