bluuebunny/crossref_metadata_2025 huggingface dataset:
Radiorespirometry of Candida utilis in phased culture under nitrogen-, carbon-, and phosphorus-limited growth
Authors: Dawson P. S. S. , Steinhauer L. P.
Published: April 2010

The release of 14CO2 from specifically labelled glucose ([G-1-14C], [G-2-14C], [G-3,4-14C], and [G-6-14C]) by phased cells of C. utilis was examined at intervals during 6-h cycles under conditions of N-, P-, and C-limited growth.On the basis that the release of 14CO2 from [G-1-C14] could serve as a measure of hexose monophosphate pathway (HMP) activity, of 14CO2 from [G-3,4-14C] as a measure of Embden–Meyerhof–Parnas (EMP) activity, and 14CO2 from [G-6-14C] as indicative of tricarboxylic acid (TCA) cycle activity, it was concluded that a relatively uniform operation of EMP occurred throughout the cycle in N-, P-, and C-limited cells, and of HMP and TCA in C-limited cells, but considerable variations took place in HMP and TCA cycle activities in N- and P-limited cells. The patterns of 14CO2 released from [G-2-14C] were more closely related to those observed from[G-1-14C] and [G-3,4-14C] than from [G-6-14C].Changes in the rate of 14CO2 evolution during the cycle were sometimes abrupt and likely coincided with 'critical points' of metabolic activity in the cycle.
Bioproduction of rubratoxin in a glucose–mineral salts broth with nutritional supplements and metabolic inhibitors
Authors: Emeh C. Obi , Marth Elmer H.
Published: April 2010

A sterile glucose–salts broth fortified with various metabolic inhibitors and nutritional supplements was inoculated with conidia of Penicillium rubrum P3290, and incubated quiescently at 28 °C for 14 days. Potassium sulfite and sodium metabisulfite at all test concentrations caused moderate reduction in rubratoxin formation; at high concentrations (≥2.7 × 10−2 M) accumulation of fungal tissue was also retarded. Production of rubratoxin and cell mass was inhibited by p-aminobenzoic acid; syntheses of toxin were completely blocked by 7.5 × 10−2 M of the vitamin. Effects of sodium fluoride on P. rubrum cultures grown on inorganic nitrogen sources varied from inhibition of mold growth and (or) rubratoxin A production to reduction in formation of rubratoxin B. With organic nitrogen sources, fluoride caused a 30 and 60% reduction in synthesis of rubratoxins A and B, respectively. Sodium acetate at all test concentrations enhanced formation of rubratoxin; mold growth was enhanced when acetate concentration was ≥6.0 × 10−2 M. A moderate reduction in mold growth was caused by lower acetate concentrations (1.2 × 10−2 M or 2.4 × 10−2 M). Sodium arsenite and iodoacetate at test concentrations blocked mold growth and toxin formation; sodium azide and 2,4-dinitrophenol caused a marked reduction in mold growth but inhibited toxin formation completely. However, sodium azide permitted slight growth and toxin formation when mold cultures were incubated for 28 days.
Some effects of arsenic on the rumen microflora; an in vitro study
Authors: Forsberg C. W.
Published: April 2010

The rate of fermentation of the rumen microflora was inhibited almost 30% by 5 μg/ml of arsenic added in the form of arsenite, although 304 μg/ml was required to cause 50% inhibition. Arsenate was less inhibitory. The rate of fermentation of a separated bacterial fraction was inhibited 37% by 1 μg of arsenite per millilitre, whereas 100 μg/ml had little effect on the fermentation of a separated protozoal fraction. Similar results were obtained for arsenate. Both fractions had the capacity to take up arsenate, but the protozoa took it up more readily to a higher intracellular concentration. Both arsenate and arsenite inhibited the growth of a number of rumen bacteria in pure culture at concentrations as low as 5 μg of arsenic per millilitre. The greater resistance of Megasphaera elsdenii to arsenate as compared with that of Bacteroides succinogenes was not related to the inability to take up the element.In conclusion, the concentrations of arsenic causing a significant inhibitory effect on the fermentative activity and growth of some rumen bacteria are less than that reported to be toxic to ruminant animals.
La dénitrification chez Bacillus licheniformis
Authors: Pichinoty F. , Garcia J.-L. , Job C. , Durand M.
Published: April 2010

The denitrifying capacity of 15 strains of Bacillus licheniformis was evaluated. In general, N2 production by the cultures on complex media containing NO3− is irregular and quite slow and three of the strains never produce gas. Bacillus licheniformis grows rapidly in anaerobiosis on peptone medium containing NO3− which is reduced to NO2−. None of the strains grow in peptone medium with NO2− or N2O as the respiratory substrate, nor do they grow under an atmosphere of 10% NO–90% N2. Denitrification was studied in cell suspensions using gas chromatography. N2O production from NO3− or NO2− is always weak at best; nitric oxide is reduced to N2O at an appreciable rate. All the strains synthesize nitrate reductase A in anaerobiosis when NO3− is present. In cell extracts, nitrite reductase activity is always negligible or nil with tetramethyl-p-phenylenediamine as an electron donor.
Colonization resistance against potentially pathogenic bacteria in hexaflora-associated gnotobiotic mice
Authors: Srivastava Kunwar K.
Published: April 2010

A study of colonization resistance against potentially pathogenic bacteria (Escherichia coli and Pseudomonas aeruginosa) was conducted in hexaflora-associated gnotobiotic mice. Groups of germfree AKR mice were swabbed with five bacterial and a single gastrointestinal yeast species: Streptococcus faecalis, Lactobacillus brevis, Staphylococcus epidermidis, Enterobacter aerogenes, Bacteroides fragilis var. vulgatus, and Torulopsis sp. All species became established in the gut in 8 weeks. Later these associated mice were divided and challenged by four graded doses of E. coli or P. aeruginosa. The presence of challenge organism was monitored specifically in the freshly voided fecal specimens of the challenged mice. Escherichia coli colonized the gut of each mouse at each level up to 60 days post challenge. Pseudomonas aeruginosa was completely eliminated from each mouse at each dose level after 30 days post challenge. Evidence suggests that all six species were sufficient to prevent the colonization of P. aeruginosa and not of E. coli in the gut of the gnotobiotic mice.
Sequential cold-sensitive mutations in Aspergillus fumigatus
Authors: Nielsen Ole , Gregory Kenneth F.
Published: April 2010

Mutants of the thermotolerant fungus Aspergillus fumigatus I-21 (ATCC 32722) unable to grow at 37 °C were sought. Cold-sensitive mutants were enriched from progeny spores of γ-irradiated conidia by two or more incubations at various nonpermissive temperatures alternating with filtrations through cheesecloth. The approximate minimum, optimum, and maximum growth temperatures of the parent were 12, 40, and 50 °C, respectively. Mutants unable to grow at 37 °C were not successfully isolated directly from the wild type. A mutant unable to grow at 25 °C was isolated and mutations further increasing the cold sensitivity by increments of 3–5 °C were found to occur. Mutants completely unable to grow at 37 °C were obtained by five sequential mutations. All mutants grew as fast as the wild-type parent at 45 °C and higher. Each mutant produced revenants able to grow not only at the nonpermissive temperature used for its isolation but also at lower temperatures.
The lipopolysaccharide (R type) as a common antigen of Neisseria gonorrhoeae. I. Immunizing properties
Authors: Diena B. B. , Ashton F. E. , Ryan A. , Wallace R. , Perry M. B.
Published: April 2010

The ability of R-type lipopolysaccharide (LPS), isolated from Neisseria gonorrhoeae colony type 4, to protect against infection with N. gonorrhoeae colony type 1 (T1 isolates) in the mouse and chicken embryo was investigated. C57 black mice were immunized intraperitoneally with 50 μg of LPS, and challenged intracerebrally with 10–20 LD50's of N. gonorrhoeae colony type 1. Immunized mice were significantly protected (P < 0.01 to < 0.05) against challenge with different T1 isolates of N. gonorrhoeae when compared with non-immunized mice. Mice, injected with succinylated or alkali-treated LPS were not protected against gonococcal challenges.In a second animal model, leghorn hens were immunized intravenously with three injections of 500 μg of LPS followed by a booster of 2.5 mg 2 weeks later. Embryonated eggs obtained from immunized hens were protected against challenge with 5 × 103 – 1 × 104 LD50's of three different T1 isolates. When hens were injected with the chemically modified LPS, the embryos were not resistant to gonococcal challenge. The results of this study demonstrate the ability of R-type gonococcal LPS to provide protection against different T1 isolates of N. gonorrhoeae.
Biosynthesis of chloramphenicol. Studies on the origin of the dichloroacetyl moiety
Authors: Simonsen J. N. , Paramasigamani K. , Vining L. C. , McInnes A. G. , Walter J. A. , Wright J. L. C.
Published: April 2010

Chloramphenicol produced by cultures of Streptomyces species 3022a supplemented with sodium [1,2-13C]acetate was labelled with 13C exclusively in the dichloromethine (2.6 ± 0.1%) and carbonyl (0.59 ± 0.05%) carbon atoms. Satellite signals from 13C–13C coupling between covalently bonded 13C-enriched carbon atoms were too intense to be attributed to random combination of labelled atoms at the average enrichments measured, but their intensity relative to those of the signals for uncoupled 13C atoms indicated that most of the precursor had been incorporated after 13C–13C bond fission. Since [2,3-13C]succinic acid enriched only the carbonyl carbon atom of chloramphenicol, these results suggest that neither acetate nor a Krebs cycle intermediate is a direct precursor of the dichloroacetyl group. Cultures supplemented with [2-3H]-or [2H2]-dichloroacetic acid incorporated negligible amounts of isotope into the antibiotic; on this evidence, the free acid is not an intermediate in chloramphenicol biosynthesis and the acylation step may precede chlorination.
The envelope of Micrococcus radiodurans: isolation, purification, and preliminary analysis of the wall layers
Authors: Lancy Jr. P. , Murray R. G. E.
Published: April 2010

Two methods are presented that separate the complex envelope of Micrococcus radiodurans, strain Sark, into its constituent layers. The first involved treating whole cells with 0.025 M Tris buffer (pH 7.5) containing 2 mM of calcium and 3 mM of magnesium, resulting in the degradation of an intermediate ('compartmentalized') layer and consequent sloughing of the outer subunit and interior layers to form vesicles. This treatment also appears to show that the interior layer may be connected with the peptidoglycan-containing 'holey' layer. The second method involves treating whole cells with benzene followed by sonication; the results suggested that this treatment only released the outer layers from the 'compartmentalized' layer and did not degrade layers. Following benzene treatment, digestion of the 'compartmentalized' layer with cold sodium dodecyl sulfate (SDS) released the 'holey' layer.Electrophoretic analysis of some of the isolated layer preparations suggested that the subunit layer consisted of three major proteins of 90 000, 92 000, and 94 000 molecular weight, one minor protein of 100 000, a small amount of carbohydrate associated with the 94 000 protein, and a small amount of a 55 000 lipoprotein. The interior layer contained at least 10 proteins and may be attached to the peptidoglycan-containing 'holey' layer by means of the 55 000 lipoprotein.
Growth of Escherichia coli on glucosamine 6-phosphate: selection of a constitutive hexose phosphate transport system mutant
Authors: Dietz Jr. George W.
Published: April 2010

Glucosamine 6-phosphate was found to be a substrate but not an inducer for the hexose phosphate transport system of Escherichia coli. Wild-type cells grow very poorly on glucosamine 6-phosphate. A mutant was selected that will grow rapidly on glucosamine 6-phosphate because it contains a constitutive hexose phosphate transport system.
Effects of ethylene on the metabolism of Saccharomyces cerevisiae
Authors: Thomas K. C. , Spencer Mary
Published: April 2010

Supply of exogenous ethylene to lactate-grown yeast initially accelerated the rate of ethanol production from glucose, but later reduced the rate, with the overall effect being to reduce the total ethanol production. The rate of ethanol production by ethylene-treated yeast was not changed by removal of metabolic carbon dioxide. However, if CO2 was allowed to build up in the absence of applied ethylene, the ethanol production decreased. Ethylene increased the activities of a number of pentose phosphate and glycolytic pathway enzymes. The largest increase in activity was observed for phosphofructokinase (EC 2.7.1.11), regulatory enzyme of the glycolytic pathway. After an initial stimulation, glucose (and also 3-O-methyl glucose) uptake was reduced by ethylene. Ethylene appears to inhibit non-competitively the glucose transport system.
Chromosomal mutants of Saccharomyces cerevisiae affecting the cell wall binding site for killer factor
Authors: Al-Aidroos Karen , Bussey H.
Published: April 2010

Fifty-two killer, factor-resistant, nuclear mutants were isolated from sensitive strains of yeast and assorted into three functional groups. All but one mutant owed their resistance to an alteration in the cell wall binding site for killer. In several mutant strains, an alteration at the site of killer binding was associated with a change in the susceptibility of the cell wall to degradation by glusulase. The killer-binding site could be inactivated by periodate but not by promise treatment. The nature of the site is discussed.
Lipid composition of Escherichia coli in relation to resistance to penicillin
Authors: Legakis Nicholas J. , Protopappas Nicholas P. , Leonardopoulos John G. , Papavassiliou John Th.
Published: April 2010

Clinical isolates of Escherichia coli sensitive and resistant to penicillin were compared in lipid composition and 14C-labelled penicillin uptake, as possible factors in resistance.Except for a slight increase in the triglyceride fraction in sensitive strains there were no qualitative or quantitative differences in the classes of extractable lipids present. Gas–liquid chromatography of the phospholipid and triglyceride fatty acids of the polar and non-polar fatty acids of the bound lipids showed that the same kinds of fatty acids were present. There was an increase of myristate in the chloroform–methanol extractable lipids of highly resistant strains accompanied by a rather general decrease of the other fatty acids. Gas-chromatographic analysis of the polar-bound lipids showed an increase of the β-hydroxydecanoic acid in the resistant strains.By studying the uptake of 14C-labelled benzylpenicillin and the crypticity of the β-lactamase, evidence has been produced that a decreased permeability of resistant strains to penicillin cooperates with β-lactamase to induce a high level of resistance. The altered lipid metabolism may reflect the special architectural changes in the cell wall which cause decreased permeability.
An ecological study of bacteriophages of Vibrio natriegens
Authors: Zachary Arthur
Published: April 2010

Effects of temperature and anaerobic conditions on the replication of two bacteriophages, nt-1 and nt-6, of the estuarine bacterium Vibrio natriegens were studied. Reduction in temperature resulted in longer latent periods and reduced burst sizes for both phages. Replication under anaerobic conditions resulted in longer latent periods; however, phage nt-6 had a reduced burst size, whereas phage nt-1 had an increased burst size, resulting in a rate of phage production nearly equal to that observed under aerobic conditions. Therefore the distribution of the phages in marsh areas could be influenced by temperature and anaerobiosis.
Glycogen metabolism in the genus Neisseria: synthesis from sucrose by amylosucrase
Authors: MacKenzie C. R. , McDonald I. J. , Johnson K. G.
Published: April 2010

Eight strains (seven species) of Neisseria were found to possess intracellular amylosucrases capable of synthesizing glycogen directly from sucrose. All eight systems were stimulated by primer glycogen, possessed similar kinetic parameters, and were competitively inhibited to similar degrees by fructose. The enzymes bound tightly to their polysaccharide products but these complexes could be readily dissociated by polyacrylamide gel electrophoresis. Some of the enzyme–product complexes appeared to be virtually free of contaminating proteins.
Inhibition of granulocyte phagocytosis of Candida albicans by amphotericin B
Authors: Chan C. K. , Balish Edward
Published: April 2010

Phagocytic activity of PMN's in five healthy and five burned patients were measured in vitro. Addition of 1 μg per millilitre of amphotericin B to the assay produced a marked inhibitory effect of the phagocytic activity of PMN against C. albicans.
Increased extracellular production of a cholinesterase-solubilising factor by Cytophaga NCMB 1314 during magnesium starvation
Authors: Bovallius Åke
Published: April 2010

A Cytophaga sp. with the property of liberating a cholinesterase which is found in body muscle of plaice was studied. The liberation was caused by a factor of which more than 90% was found outside the bacterial cell and might possibly be associated with the slime material surrounding the bacteria. Magnesium limitation during growth of Cytophaga sp. in batch cultures resulted in an about 10-fold increase in extracellular factor activity. The increase could be immediately stopped by addition of magnesium ions or chloramphenicol to the medium. The effect of the latter might indicate that the increase in factor activity is dependent on protein synthesis under magnesium-limiting conditions.
Microbiological titration of proteins and of single amino acid content in biological materials without purification and hydrolysis
Authors: Puppo Simonetta , Morpurgo Giorgio , Nardi Simonetta , Conti Giuseppe
Published: April 2010

A method is described for the microbiological determination of the protein content of biological materials. This method can also be adopted to titrate the concentration of a single amino acid in the protein and has the following advantages: (1) titration can be done without purification and hydrolysis of proteins; (2) the titration graph is a straight line between 25 and 800 μg/ml; (3) protein values agree with those obtained using the Kjeldhal method; and (4) each mutant requiring one amino acid may be used to titrate the concentration of a single amino acid of the protein. The leucine content of various kinds of flour was measured with this system.
Double-antibody radioimmunoassay for staphylococcal enterotoxins A and B
Authors: Robern Haskel , Gleeson Thomas M. , Szabo Richard A.
Published: April 2010

A sensitive double-antibody radioimmunoassay for staphylococcal enterotoxins A and B is described. The separation of the primary antigen–antibody complex of enterotoxin A and B was achieved with an anti-rabbit gamma globulin from goats. Radioiodinated aggregate fractions of staphylococcal enterotoxins exhibited reduced immunological activity and showed little competition with non-radioactive enterotoxin. The radioimmunoassay was successfully applied for the quantitation of enterotoxins in food.
Relationship between iron-limited growth and energy limitation during phased cultivation of Candida utilis
Authors: Thomas K. C. , Dawson P. S. S.
Published: April 2010

The yeast Candida utilis was continuously synchronized by the phasing technique (6 h doubling time) with either iron or nitrogen as the limiting nutrient. Iron limitation resulted in decreased molar growth yields with respect to the carbon substrates and ammonia and in increased specific rates of oxygen uptake. Relatively low energy-charge values were maintained by the iron-limited culture. All these taken together seemed to indicate that the growth of the yeast under iron limitation was also limited by metabolically available energy.Considerable amounts of ethyl acetate were produced by the yeast under phased cultivation when the growth was limited by iron but not by nitrogen. In vitro studies using cell-free extracts showed that the substrates for ethyl acetate synthesis were acetyl coenzyme A (acetyl CoA) and ethanol. Under iron-limited growth acetyl CoA seemed to be diverted to ethyl acetate formation rather than being oxidized through the tricarboxylic acid (TCA) cycle. The possibility of energy limitation under iron-limited growth being brought about by the reduced capacity of the yeast to oxidize acetyl CoA through the TCA cycle is considered.
A cytochrome b - like pigment with a peak at 567 nm in Pseudomonas aeruginosa
Authors: Rowe J. J. , Eagon R. G.
Published: April 2010

A cytochrome b - like pigment with an absorption peak at 567 nm was detected in Pseudomonas aeruginosa irrespective of whether the organism was grown aerobically or anaerobically under denitrifying conditions. This pigment has not been reported previously for P. aeruginosa but it has been detected in other denitrifying bacteria including closely related Pseudomonas species.
A method for the isolation of asporogenic mutants of Bacillus thuringiensis
Authors: Yousten Allan A.
Published: April 2010

Asporogenic and oligosporogenic mutants of Bacillus thuringiensis can be isolated by streaking the bacteria onto a solid medium, incubating at 42 °C, and picking small, raised areas of growth which appear on the streaks after 48 h.
Effects of interactions between different culture fractions of 'phosphobacteria' and Rhizobium on mycorrhizal infection, growth, and nodulation of Medicago sativa
Authors: Aguilar C. Azcón-G. de , Barea J. M.
Published: April 2010

Interactions between cell-free culture supernatants, cells, and the whole cultures of Rhizobium and phosphobacteria with endomycorrhizal fungi and their effects on growth and nutrition of Medicago sativa grown in a low-phosphate soil were studied. A satisfactory nodulation was greatly dependent on the mycorrhizal symbiosis. Cell-free supernatants of Rhizobium and phosphobacteria improved plant growth, nodulation, and mycorrhiza formation. The activity of phosphobacteria culture seemed to be due mainly to the supernatant and the possibility of plant hormones contained in this culture fraction being involved in such interactions is discussed. An increase of the overall pool of soluble P in soil by the inoculated phosphobacteria cells was not found in the conditions of this experiment. It was noteworthy that the best positive effect was achieved by the treatment which consisted of the whole cultures of Rhizobium, phosphobacteria, and the mycorrhizal fungi applied all together.
Energy-driven uptake of humic acids by Aspergillus niger
Authors: Ruocco J. J. , Barton L. L.
Published: April 2010

The uptake of humic acids by mycelia of Aspergillus niger was demonstrated to be energy-dependent with a sensitivity to sodium azide and to 2,4-dinitrophenol. Greatest uptake of humic acids by submerged mycelium occurred at pH 3.0 and at 32 °C. The rate of uptake was influenced by the concentration of humic acids with an apparent Km of 0.2 mg/ml and with a Vmax of 0.13 mg humic acids per gram mycelial dry weight∙10 min−1. In the absence of an added energy source, Vmax of 0.05 mg humic acids per gram mycelial dry wt∙10 min−1 was obtained; however, the affinity for humic acids by this uptake system was the same as for the energy-driven process. Apparent binding of humic acids to cell structures was indicated because only 41.8% of the humic acids taken up by the energy-dependent system could be recovered.
Characterization of the mitogenic activity elicited by Neisseria gonorrhoeae ribosomal fractions
Authors: Brodeur Bernard R.
Published: April 2010

Ribosomal preparations from Neisseria gonorrhoeae types 1 and 4 were examined for their in vitro stimulation of mouse splenocytes to determine the ribosomal moiety or contaminant responsible for the immunoproliferative activity.In immunodiffusion tests with homologous rabbit antiserum, crude 70S ribosomes formed four precipitin bands while the purified 30S and 50S subunits showed one major line. The same antiserum reacted with lysed N. gonorrhoeae and Neisseria meningitidis A cells but no precipitation occurred with Escherichia coli cells or purified N. gonorrhoeae lipopolysaccharide (LPS). No membrane or LPS contaminant was detected in the purified 30S and 50S preparations. All the ribosomal preparations from virulent and non-virulent N. gonorrhoeae consistently stimulated the murine splenocytes. The mitogenic activity of the 30S and 50S ribosomal preparation was destroyed by treatment with trypsin but only slightly decreased by ribonuclease. It is suggested that the lymphoproliferative response elicited by gonococcal ribosomes is triggered by the protein moiety of the 30S or 50S subunits.
Effect of respiratory deficiency and temperature on the mitochondrial lipid metabolism of Aspergillus niger
Authors: Mandal Sukhendu B. , Sen Parimal C. , Chakrabarti Parul , Sen Kalyani
Published: April 2010

A comparative study of the mitochondrial lipid composition of a wild strain (V 35) and a respiratory-deficient mutant (rd3) of Aspergillus niger grown at different temperatures (25, 30, 35, and 40 °C) has been performed. The lipid spectrum, though qualitatively similar, differs quantitatively in both cases. At the optimum growth temperature (30 °C) depletion in ergosterol (40%) and cardiolipin (52%) was observed. This probably indicates the formation of defective mitochondria in the mutant with a resultant impaired respiratory system. Complete depletion of cardiolipin species containing fatty acid (20:5ω3) in the respiratory-deficient mutant suggests a possible role of this lipid in mitochondriogenesis at least in A. niger. The effect of temperature is predominantly on the degree of unsaturation and sterol ester formation. The linoleic acid (18:2ω6) content decreases with a concomitant increase in oleic acid (18:1ω9) content as the growth temperature increases for both cell types. Some morphological changes and effects on the vegetative life cycle have been observed with variation in growth temperature in the wild type and also in the mutant form.
Antifungal properties of 2-alkynoic acids and their methyl esters
Authors: Gershon Herman , Shanks Larry
Published: April 2010

Thirteen 2-alkynoic acids and their methyl esters (C3–C12, C14, C16, and C18) were tested against Aspergillus niger, Trichoderma viride, and Myrothecium verrucaria in Sabouraud dextrose agar at pH 4.0 and 5.6. Toxicity to Candida albicans, Trichophyton mentagrophytes, and Mucor mucedo was determined in the same medium at pH 5.6 and 7.0 in the absence and presence of 10% beef serum. The fungitoxicity of the acids was influenced by chain length, pH of the medium, and absence or presence of adsorbents. The toxicity of the esters was influenced primarily by chain length and to a lesser extent by the pH of the medium and the presence of beef serum. The order of activity of the 2-alkynoic acids is C10 = C11 = C12 > C14 = C16 > C9 > C8 > C7.When compared with other fatty acid analogs, the order of fungitoxicity on a weight basis is 2-alkynoic acids > 2-alkenoic acids > alkanoic acids > 2-bromoalkanoic acids > 2-fluoroalkanoic acids. There is an inverse relationship between chain length and pKa of the acids, suggesting that partition behavior is a fundamental determinant of fungitoxicity along with the effect of adsorbents.
Etude morphologique, physiologique et taxonomique de Bacillus azotoformans
Authors: Pichinoty F. , Durand M. , Job C. , Mandel M. , Garcia J. -L.
Published: April 2010

Seventeen strains of the new species Bacillus azotoformans were isolated by enrichment culture in peptone broth inoculated with pasteurized soil and then incubated under N2O at 32 °C. The bacterium is a Gram-negative rod, motile with peritrichous flagella, which produces oval spores without exosporia in swollen sporangia. However, the cells have thick walls, mesosomes, and persistent septa characteristic of Gram-positive bacteria. The bacterium lacks fermentative activity, does not attack carbohydrates, has complex growth requirements, and will grow anaerobically only if one of the following electron acceptors is present: NO3−, NO2−, N2O, S4O6−−, or fumarate. Nitrate, nitrite, and nitrous oxide are denitrified with the production of N2. The microorganism is mesophilic, gives a positive oxidase reaction, synthesizes a type c cytochrome, and does not hydrolyse gelatin, starch, or "Tween 80." Poly-β-hydroxybutyric acid is synthesized when the bacterium is grown in a medium containing DL-3-hydroxybutyrate. The following enzymes are present: nitrate reductase A, respiratory nitrite reductase, tetrathionate and fumarate reductases, and L-glutamate dehydrogenase. The following enzymes are absent: thiosulfate reductase, urease, lecithinase, arginine dihydrolase, phenylalanine deaminase, and catalase. For the 17 strains, the mean value of the G + C percent of the DNA is 39.8 ± 1.2. All the strains are highly similar.
Improved production of citric acid by a diploid strain of Aspergillus niger
Authors: Das Arati , Roy Ponty
Published: April 2010

Aspergillus niger strain CGU 87 was treated with UV radiation and some auxotrophic mutants were obtained. These mutants were less productive than CGU 87, which produced an average of 7.4% citric acid. All possible crosses in pair wise combinations were carried out between these auxotrophs, and three heterokaryons were synthesised. Finally, one heterozygous diploid was isolated from each of them. These heterokaryons and diploids showed improved productivity when compared with their component parents, but except in one diploid D5, all others produced less citric acid than CGU 87. The yield of D5 exceeded that of CGU 87 by 1.2 times and it produced 9% citric acid. This is a significant improvement and the increased productivity seems to be the result of successful adaptation of D5 to its fermentation environment.
Loss of chloramphenicol production in strains of Streptomyces species 3022a treated with acriflavine and ethidium bromide
Authors: Michelson A. M. , Vining L. C.
Published: April 2010

An assay procedure was developed to detect chloramphenicol production in large numbers of Streptomyces species 3022a isolates, and was used to screen colonies from cultures exposed to acriflavine and ethidium bromide. There was a significant rise in the proportion of low- and non-producing strains in the treated cultures. Since the organism developed resistance to acriflavine but not ethidium bromide, the effects of the latter agent were examined in more detail. Loss of chloramphenicol production was not due to mutation, nor to differential sensitivity to the drug among producing and non-producing natural variants. The response of cultures varied with age, and at least three strain types — high-, low-, and non-producers could be distinguished. A study in shaken cultures of selected isolates from the screening process established the general reliability of the screening method and showed that the assay probably sometimes failed to distinguish between low- (15–20 mg/ℓ) and non-producers. It indicated that the non-producer class consisted of some very low (up to 4 mg/ℓ) producers as well as fully negative strains, and it confirmed indications from the screening results that a non-producing isolate obtained by acriflavine treatment accumulated aromatic amines and was probably blocked in the pathway for chloramphenicol biosynthesis.
The effect of growth temperature on the fatty acid composition of Thamnidium elegans Link
Authors: Manocha M. S. , Campbell C. D.
Published: April 2010

The fatty acid composition of a slightly psychrophilic fungus, Thamnidium elegans, has been determined and compared with other mucoraceous fungi. The growth temperature strongly influences the degree of unsaturation of lipids, as reported for other organisms, but in T. elegans both the quantitative and qualitative profiles of the fatty acids are affected. At low temperature, T. elegans contains both α- and -γ-isomers of linolenic acid. The α-isomer is reported here for the first time in a mucoraceous fungus. Besides the biosynthesis of α-linolenic acid at the low temperature, T. elegans shows an increase in synthesis of a relatively unknown fatty acid in fungi, i.e. octadecatetraenoic acid (18:4Δ6,9,12,15). The significance of the occurrence of both the isomers of linolenic acid as a response to temperature and in relation to fungal phylogeny is discussed.
Detection of Mycoplasma hominis and Mycoplasma orale in cell cultures by immunofluorescence
Authors: Payment P. , Corbeil M. , Chagnon A.
Published: April 2010

Mycoplasma contaminants of animal and human cell cultures were rapidly detected and identified by an indirect immunofluorescent technique. Cells suspected of being contaminated by mycoplasmas were grown as monolayers on chamber slides in a culture medium selected to promote mycoplasmal growth. Before fixation by acetone, the monolayers were subjected to a hypotonic treatment to cause swelling of the mycoplasmas. Detection and identification were then performed by indirect immunofluorescence using rabbit antisera to various mycoplasma species. The correlation between results obtained by the standard isolation procedure and those obtained by this method was very close.
A simple improved method to stain Thiobacillus
Authors: Rodriguez-Leiva M. , Pichuantes S.
Published: April 2010

Best stains are obtained by immersion of the fixed smear in 1.5–2% acid fuchsin at pH 3.2–3.6.
The use of polyethylene glycol in radioimmunoassay of staphylococcal enterotoxins
Authors: Robern Haskel , Gleeson Thomas M.
Published: April 2010

The double-antibody radioimmunoassay of enterotoxins A, B, and C was modified by the addition of aqueous polyethylene glycol which precipitated double-antibody bound staphylococcal enterotoxins with little or no precipitation of free enterotoxin. The precipitate formed appeared as a thin coating at the bottom of the test tube and was not removed by aspiration. The procedure obviates the need for normal rabbit serum and for an additional wash of the precipitate.
Ultrastructure of the dolipore-parenthesome septum in Hirschioporus pargamenus (Polyporaceae)
Authors: Traquair James A. , McKeen Wilbert E.
Published: April 2010

The septal complex in hyphae of Hirschioporus pargamenus (Fr.) Bond. & Sing, is generally similar to that described for other Homobasidiomycetes. A noteworthy distinction is the presence of imperforate parenthesomes. A dark line is frequently observed in the inner matrix of the parenthesome. We suggest that this line is an image produced by the overlapping of folded, opposing membranes differentiated from the wall endoplasmic reticulum.
Morphology, microstructure, and development of colonies of Acetobacter xylinum
Authors: Sowden L. C. , Colvin J. Ross
Published: April 2010

Development of the morphology and microstructure of colonies of Acetobacter xylinum glowing on agar was studied by optical microscopy, and transmission and scanning electron microscopy. The mass of rapidly dividing cells surrounded by a sheath of cellulose microfibrils passes from a smooth spheroid to a flattened aggregate with a characteristic 'pillowed' surface. This morphology is the result of a repeated extrusion of cells from the confining sheath, followed by regeneration of a new portion of the sheath on the extruded cell mass. Relations of this mechanism to others which produce similar shapes are indicated.
Microbial degradation of [14C]polystyrene and 1,3-diphenylbutane
Authors: Sielicki M. , Focht D. D. , Martin J. P.
Published: April 2010

Microbial degradation of [β-14C]polystyrene and 1,3-diphenylbutane, a compound structurally representing the smallest repeating unit of styrene (dimer), was investigated in soil and liquid enrichment cultures. Degradation rates in soil, as determined by 14CO2 evolution from applied [14C]polystyrene, varied from 1.5 to 3.0% for a 4-month period. Although relatively low, these percentages were 15 to 30 times greater than values previously reported. Enrichment cultures, containing 1,3-diphenylbutane as the only carbon source, were used to determine the mechanisms of microbial oxidation of the polymer chain ends. Metabolism of 1,3-diphenylbutane appeared to involve the attack by a monooxygenase to form 2-phenyl-4-hydroxyphenylbutane followed by a further oxidation and subsequent fission of the benzene ring to yield 4-phenylvaleric acid and an unidentified 5-carbon fragment via the classic meta-fission pathway. Phenylacetic acid was probably formed from 4-phenylvaleric acid by subsequent β-oxidation of the side chain, methyl-oxidation, and decarboxylation. An initial examination of the population of microorganisms in the diphenylbutane enrichment cultures indicated that these oxidative reactions are carried out by common soil microorganisms of the genera Bacillus, Pseudomonas, Micrococcus, and Nocardia.
Oxidation of gallium sulfides by Thiobacillus ferrooxidans
Authors: Torma Arpad E.
Published: April 2010

The bacterial oxidation of a naturally occurring gallium-bearing chalcopyrite concentrate and a pure synthetic gallium (III) sulfide has been investigated at pH 1.8 and 35 °C, using an active culture of Thiobacillus ferrooxidans. This oxidation process may proceed by direct or by indirect bacterial action. The highest dissolved gallium and copper concentrations were about 2.2 and 40.2 g/ℓ respectively. The order of the specific rate of oxygen uptake by T. ferrooxidans is approximately CuFeS2[Formula: see text] gallium-bearing CuFeS2 > FeS2 > CuS > Cu2S > Ga2S3.
The metabolism of carbohydrates by extremely halophilic bacteria: the identification of lactobionic acid as a product of lactose metabolism by Halobacterium saccharovorum
Authors: Tomlinson Geraldine A. , Strohm Maureen P. , Hochstein Lawrence I.
Published: April 2010

Nongrowing cells of Halobacterium saccharovorum oxidized lactose to a product identified as lactobionic acid by thin-layer, paper, and column chromatography, and by identification of the galactose and gluconic acid produced from it after acid hydrolysis. Growing cells oxidized lactose to a product that was identical with lactobionate except that it did not serve as a substrate for galactose oxidase. While the identity of this compound has not been established, it is suggested that the product is lactobionic acid in which the galactose moeity is in the furanose form. Neither lactobionate nor the product produced by growing cells was further metabolized, suggesting that lactose oxidation is not coupled to growth.
Postbacterial sepsis and disseminated candidiasis
Authors: Chan C. K. , Balish Edward
Published: April 2010

The effect of gram-negative sepsis (Escherichia coli) on the capacity of polymorphonuclear leucocytes (PMN) to phagocytize and kill Candida albicans was assessed. The PMN's from septic dogs phagocytized C. albicans as well as PMN's from non-septic dogs. The PMN's from septic dogs that phagocytized C. albicans underwent a spontaneous lysis at a much higher rate than PMN's from non-septic dogs. A functional difference in PMN's from normal and septic dogs is indicated.
Nitrogen-fixing communities in an intertidal ecosystem
Authors: Bohlool B. Ben , Wiebe William J.
Published: April 2010

Nitrogen fixation (acetylene reduction) associated with various communities in the intertidal sand and mud flat was measured in situ. Areas which were colonized by algae, plants, and animals generally had significantly higher activities than areas which were visibly uncolonized. The highest activities were measured at sites colonized by a mixed bloom of Oscillatoria–Euglena–photosynthetic bacteria. These areas occupied only about 1% of the surface of the sediments, yet contributed nearly 50% of the biologically fixed nitrogen. Enteromorpha communities also exhibited relatively high activities. Sites were grouped according to the statistical significance of the mean of their activities: group I: uncolonized sand, mud and gravel flats, Eelgrass (Zostera) communities, and snail (Amphibola) beds, with an estimated contribution of 1 g N ha−1 day−1; group II: Cockel (Chione) beds, 3g N ha−1 day−1; group III: Salicornia, Ulva, Juncus, and Enteromorpha, 10 g N ha−1 day−1; and group IV: Oscillatoria–Euglena–photosynthetic bacteria association, 200 g N ha−1 day−1. Enteromorpha and Oscillatoria–Euglena–photosynthetic bacteria communities showed significantly lower rates of nitrogen fixation in the dark than in the light.
A taxonomic study of the Spirillum lipoferum group, with descriptions of a new genus, Azospirillum gen. nov. and two species, Azospirillum lipoferum (Beijerinck) comb. nov. and Azospirillum brasilense sp. nov.
Authors: Tarrand Jeffrey J. , Krieg Noel R. , Döbereiner Johanna
Published: April 2010

Sixty-one strains of the root-associated nitrogen fixer Spirillum lipoferum exhibited a similar morphology in peptone–succinate salts medium: vibrioid cells having a diameter of 1.0 μm. When grown in broth the cells had a single polar flagellum, but when grown on agar at 30 °C lateral flagella of shorter wavelength were also formed. The DNA base composition was 69–71 mol % guanine + cytosine when determined by thermal denaturation. DNA homology experiments indicated the occurrence of two distinct but related homology groups: 46 strains were in group I and 15 strains were in group II. Group II strains were distinguished by their ability to use glucose as a sole carbon source for growth in nitrogen-free medium, by their production of an acidic reaction in a peptone-based glucose medium, by their requirement for biotin, and by their formation of wider, longer, S-shaped or helical cells in semisolid nitrogen-free malate medium. The results indicate that two species exist, and on the basis of their characteristics it is proposed that they be assigned to a new genus, Azospirillum. Strains belonging to group II are named A.lipoferum (Beijerinck) comb, nov., while those belonging to group I are named A.brasilense sp. nov. Strain Sp 59b (ATCC 29707) is proposed as the neotype strain for A. lipoferum, and strain Sp 7 (ATCC 29145) is proposed as the type strain for A. brasilense.
Identification des actinomycètes antagonistes de champignons et n'affectant pas le Rhizobium meliloti
Authors: Antoun H. , Bordeleau L. M. , Gagnon C. , Lachance R. A.
Published: April 2010

Thirteen isolates of actinomycetes that have broad antifungal activity and do not affect two efficient strains of Rhizobium meliloti were identified as: Nocardia autotrophica, Streptomyces antimycoticus, S. anulatus, S. capoamus, S. lydicus, S. murinus, S. roseo-luteus, and S. thermotolerans.
Direct lymphocytotoxicity against herpes simplex virus infected cells
Authors: Fujimiya Y. , Babiuk Lorne A. , Rouse Barry T.
Published: April 2010

This study was undertaken to determine if direct cytotoxicity (DC) against herpes simplex virus infected cells, perhaps mediated by T cells, could be demonstrated in individuals subject to recurrent herpes labialis. The mononuclear cells from 7 out of 17 individuals with recurrent herpes expressed DC whereas no DC was ever exhibited by 7 individuals without a previous history of herpes infections. Several approaches were used to show that the cytotoxicity being detected was predominately of the direct type rather than antibody-dependent cell cytotoxicity (ADCC). Since the effector cells of the DC were sensitive to trypsin treatment and behaved as do natural killer (NK) cells upon cell fractionation, the results were taken to imply that the DC was attributable to a NK-effector cell type rather than a classical T lymphocyte.
Des acides aminés stimulateurs et inhibiteurs à la croissance de Corynebacterium sepedonicum (Spieck. et Kott., Skapt. et Burkh.) dans des milieux synthétiques
Authors: Ikin G. J. , Hope H. J. , Lachance R. A.
Published: April 2010

Some aspects of the growth and amino acid metabolism of Corynebacterium sepedonicum, the organism responsible for potato ring rot, have been studied in synthetic media. It has been demonstrated that organic sulfur is required for growth. Methionine supports growth and can be replaced by methionine sulfoxide and cystathionine. Methionine is a micrometabolite for this species as indicated by the fact that optimum growth can be obtained in an asparagines–methionine (asn-met) containing medium when the molar ratio of these amino acids is 56:1. Increasing the proportion of methionine does not increase the growth. Both asparagine and glutamine are metabolized very quickly and provide for equivalent rapid growth unlike aspartic and glutamic acids. In the case of the last two amino acids, growth can be increased if dibasic ammonium phosphate is added to the medium although this compound alone will not support growth in the culture medium. The intracellular soluble asparagine level is extremely low in cells from the asn-met medium indicating a high rate of metabolism compared to aspartic acid. Cystine and cysteine were found to be inhibitory to the organism: they do not affect the rate of uptake of asn or met but do alter the organism's metabolism as reflected by changes in the free amino acid pool. The concentrations of cystine and cysteine required for measurable inhibition are much higher than those found in soluble amino acids of potato tubers.
Rapid spectrophotometric determination of Acholeplasma laidlawii membranes
Authors: Dresdner George
Published: April 2010

The amount of Acholeplasma laidlawii membranes can be accurately, rapidly, and simply determined by spectrophotometric measurements after solubilization in 0.02 M SDS, 0.02 M Tris-HCl (pH 8.0). Extinction coefficients from the 260- to 300-nm-absorption region are adequate for quantitative membrane determination. The following values were found: E1%1 cm,280 = 9.11 ± 0.63, E1%.s1 cm,280 = 8.52 ± 0.40 (corrected for light scattering), E1%1 cm,280–310 = 8.15 ± 0.35. The last value is the most satisfactory for routine analysis. These coefficients are not affected by large differences in the carotene and flavin contents of the membranes or by spectral changes that occur when the membranes are exposed to light. The precision obtained with this method is comparable with that achieved in spectrophotometric determinations of proteins. As little as 6 μg of membrane can be measured in 50-μl samples.
Inhibitors of DNA synthesis cause excessive DNA synthesis in dnaA mutants of Escherichia coli K12
Authors: Heinonen Jukka , Pekola Marja-Leena
Published: April 2010

The relative rate of net DNA synthesis was stimulated when cells of dnaA mutants of Escherichia coli K12 were grown in the presence of low concentrations of DNA synthesis inhibitors. This led to a supernormal DNA/cell mass ratio. The excessive DNA was similar to the normal chromosomal DNA in size and stability in vivo. However, the cells did not divide but turned into long filaments. Excessive DNA synthesis in the presence of inhibitors of DNA synthesis was observed in the cultures of two independent dnaA mutants of E. coli, but dnaB and dnaC mutants behaved like the wild type in this respect.
Production and characterization of two hemolysins of Bacillus cereus
Authors: Coolbaugh James C. , Williams Robert P.
Published: April 2010

Bacillus cereus strain B-48 produced two hemolysins with molecular weights of 52 000 (H-I) and 31 000 (H-II). A mutant was isolated that produced only H-II but was identical with the wild type in all other respects. We exploited this mutant to produce H-II for study that was free of contamination by H-I. By manipulation of media composition, we produced H-I in the absence of H-II. The hemolysins were precipitated differently by ammonium sulfate, and both exhibited the Arrhenius effect when heated. Both hemolysins attached rapidly to erythrocytes; however, lysis by H-I was immediate, while lysis by H-II followed after a lag. Hemolysis by H-I and H-II increased in rate with increasing temperature and was absent at 0 °C. Only H-I was inhibited by cholesterol. The hemolysins of B. cereus appeared similar to the hemolysins of B. thuringiensis. H-I probably is identical with cereolysin.